Green Building Forum - General

U bend survey

Rex — Wed, 12 Mar 2025 22:40:42 +0000

What ho one and all,

I own a first floor maisonette (which I rent out) and have a minor issue with one of the drains. The drain only handles water from the kitchen sink and washing machine, but for whatever reasons, it is too frequently blocking in the below ground U bend. I jet wash it both up and down stream, but it frequently blocks again.

Unfortunately, the owner of the g/f flat is kinda doing a full Donald Trump, doesn't want a meeting, does not want me as a non-professional (I did build my house which is more than he has ever done!) to wash it and wants me to invest is a full drain survey. I would do so, but ......

From where the outflow pipe is located to the nearest inspection chamber, is only one meter!!! There is obviously a U bend; my question is, if I reluctantly agree to a drain survey, does a camera go around a U bend?

I cannot get either my drain snake or the sewerage pipe cleaner pressure hose all the way through the U bend, so can a camera go through?

Frankly, I do not believe there is a problem, more likely whatever the tenants are putting down the pipe, but they assure me it is only kitchen washing and not pans full of fat. I believe them as they are good tenants.

Thanks and toodle pip

Warning - whispers no longer private

Mike1 — Wed, 26 Mar 2025 10:41:59 +0000

I've just spotted that 'whispers' on this forum are no longer private. If you, like me, have sent any that include information that you don't want broadcast to across the internet, you may want to delete them now.

Not sure if this is an unintended consequence of the move to the AECB, but it seems to have happened within the last 48 hours.

Which building system

Rubbermuppet — Wed, 12 Mar 2025 12:59:01 +0000

Hello

Have read your various posts in recent years which I have found really useful, informative and insightful.

I am building a tricky extension, two storeys with flat/green roof/parapet (due to angled relationship to existing house, which is a 1976 bungalow with undercroft garage, like a bank barn). Would build pitched roof otherwise. Dimensions ground floor 7.5m x 6m, first floor 5.5m x 6m. So quite large.

Extension will have lounge/utility downstairs. Bedroom with ensuite upstairs. Intending to retrofit the house with external insulation and vertical timber cladding + MVHR. It is presently a standard 250mm cavity wall, no cavity wall insulation (which I will do before I fit EWI), harling to outside. Well built, dry cavities but ugly and walls that currently feel like a refrigerator!

Intending to insulate the new extension well and have sizeable full width sliding doors to south elevation giving access to the garden. Render proposed to ground floor walls, timber cladding above. Tight budget.

I was originally going for timber frame but I am paranoid about leaking flat roofs in our wet location (Cumbria!) and water finding it's way into the structural parts without me knowing! Plus more experience of laying blocks and stone - I am an "experienced" DIYer having previously built a cavity wall outbuilding in block and stone at my previous house. Plus done up two Victorian houses. Still working full time unfortunately but retiring this time next year.

My question is which way to go in terms of construction. Was planning to do 100mm cavity wall with 425mm teplo ties (which I bought cheap on EBay), cavity 275mm full fill. But now having second thoughts.

Cavity walls are such a fiddle! And what's the point if I am covering with timber cladding? I also have to keep that cavity insulation dry during what is certain to be a slow build. It pours down here at most times of the year, except some springs.

Looking at all your previous posts, and "Understanding Passivhaus" by Emma Walshaw, I am, instead, attracted to building a single block work wall, 215mm thick with blocks on their flat side over 100mm thick Marmox thermoblocks at the base. The external side would have 300mm EPS/XPS at the base, with 300mm wide Larsen trusses above dpc filled with mineral wool. All cross battened and clad.

I can do all this work in a nice linear process - get the walls up, roof on, make the trusses inside, hopefully over winter, then insulate/clad in the following spring/summer. Much easier for a DIYer. Seems a lot simpler than cavity wall - ie. cavity trays, weep holes, cavity ties, keeping cavity clean, full-fill insulation all as we go along etc. Then having to protect wall tops and insulation as winter rain/storms arrive. In fact, this weather can arrive at any time of the year so it's a constant issue.

I am also hoping my SE says I can avoid a structural goalpost frame for the big slider at ground floor with this thicker wall, if I allow a single block for a nib. Again the frame makes cavity construction more or a phaff.

The questions I have are:

1. Cavity wall v single leaf/larsen truss? Which way is easier/better? Building Control are a bit old school so not sure what they will say about single leaf and Larsen truss (still awaiting their response but anticipating "computer says no" or for them to make things difficult). Cavity wall is definitely cheaper but much trickier to build. And are you aware of any issue with mortgage lenders with this type of non-standard construction?

2. Structurally, can I cantilever a Larsen truss/OSB/cladding/insulation off a two storey high block wall 215mm thick laid on flat? The external structure would not be that heavy but approximately 384mm total cantilever might exert pressure in the blockwork at the base of the wall. That said, the mass of a 215mm thick masonry wall must considerably outweigh this. Perhaps one for my engineer.

3. Against that, would the XPS/EPS insulation provide a sufficient base for the truss to reduce the cantilever? (perhaps another question for my SE). They sometimes do this with timber frame but such cantilever loading is less of a problem for timber construction. But I reckon my structural engineer will probably discount any structural role of the XPS/EPS base. Alternatively, do I need to consider a low masonry outer leaf to support the Larsen truss at the base? This would be annoying as it would eat into my insulation thickness - probably could then only manage a 200mm cavity insulation below DPC. Would 200mm be sufficient?

4. Do you have any other ideas you have for external insulation and hanging timber cladding? I had hoped there would be some nifty GRP cladding bracket by now to use with EPS (has anyone ever tried to fabricate one or seen one you can buy?). But the Larsen truss is at least very easy for a DIYer, cheap with readily available materials, and I can do the existing house in the same way after (the house is easier as can attach the trusses to the rafters to relieve the cantilever). I find the lack of experience/knowledge about Larsen trusses over here is unnerving (though Beattie passive houses uses a similar system). They 2x2 trusses look a bit "waffy", not very robust somehow but presumably good enough for Canada’s harsh climate. Increasingly their size, or using a 4x2 outer stud as modified Larsen systems do, only adds to the weight.

5. In the proposed lounge downstairs, should I go for insulation above or below concrete slab, bearing in mind its wide south facing sliding door? Ideally I would put a solid floor in for thermal mass but I wanted to run an oak floor through from an oak floor in the next room (a bedroom created from the old downstairs utility in the existing house). I have already bought the oak floor but could put it upstairs in the bedroom. Had originally intended putting insulation above the slab and floating the oak floor and installing under floor heating (Wunda system or similar).

6. Any ideas/preferences for the green roof? Is EDPM the way to go or liquid membrane? Was looking at Flexitec which looks like a really good system and easier to do with a parapet than EDPM. Again slightly paranoid about leaks, especially under a green roof. Easier to find a leak in EDPM.

7. Any other useful advice welcome.

Thanks in advance and sorry for so very many questions! I'm probably overthinking, over researching and definitely indecisive!

David

75% of what you pay for electricity, isn't for electricity..

cjard — Sun, 06 Aug 2023 07:19:30 +0100

Ripple seem to have a sensible idea. Instead of paying 10 grand for my own solar panels or turbine and suffering constraints imposed by own install site, I give Ripple 10 grand and they perform a perfect install in an ideal location, and (simplistically) ship the energy to me via the grid

I was a bit disappointed by the numbers though:

We estimate if you own enough to meet 100% of your home's electricity consumption, you'll save up to 25% off your bills when you join Ripple.

A typical bill is made up of your electricity usage plus 'non-energy' costs. These include grid charges, taxes and supplier costs. As your power is still supplied via the grid, you will still need to pay these. This is why your electricity won't be free, but your bills should be a lot more stable.

So even though I've bought enough generation to cover my needs, getting it to me costs so much that it will only cover 25% of my needs. If I'm on a 30p tariff I get a discount of 7.5p per kWh on my bill and Ripple spend 22.5p getting it to me.

What I don't quite get is, if I have an install so big that I can sell to the grid I might get 20p/kWh on a tariff where if I consume then it's 30.. so somehow Octopus can take my generated electric and get it to someone else via the grid for about half what Ripple can get my electricity to me for..

-

Got me wondering if smaller scale grid would be viable and legal; I've got a big roof - what's stopping me installing more solar than I need and selling it to the neighbours by throwing a wire over the wall? Could local mini grids be operated more viably and cheaper for all than what Ripple propose? And is it worth it when Octopus will give you 20p for an MCS accredited install? Is it worth having a non accredited install, installed for less and selling the electricity to the neighbours for less than 20p?

Advice wanted on MVHR for a bedsit

Peter_in_Hungary — Thu, 27 Feb 2025 17:24:31 +0000

I have 2 single storey terraced bed sits (each with kitchen/diner, shower room and bedroom) with a pitched roof to be rental properties. I am thinking to put in a MVHR unit in each to help with ventilation and hopefully to stop any mould issues on the walls. (limestone and rubble walls with no DPC) The eaves are about 3M high. The referb. will include UPVC windows, EWI and 30cm glass wool loft insulation.

Would it be reasonable to route the MVHR intake and exhaust under the eaves out to gutter level (about 60cm from the wall). I can get about 3M separation.

I plan to put a humidity stat to automatically switch the MVHR to boost. What RH should trigger the Boost?

Humidity stat to be located in the shower room unless the team think somewhere else would be better.

I plan to use the MVHR as the (windowless) shower/loo room vent with a switch to boost when the light is turned on. Bad idea or OK ??

The kitchen area will have a recirculating cooker hood which the tenants may or may not use. How far away should the extract be from the cooking area to avoid too much contamination of the MVHR filters.

EWI and cavity walls ... not advisable?

scrimper — Thu, 12 Sep 2013 22:56:47 +0100

Talking to a builder tonight about our project, and he advised in the strongest terms against trying to put EWI on an existing 30's cavity wall (which has no current insulation).

His opinion was that all your heat goes through the brick and simply warms the air in the cavity up, before escaping. He seemed to suggest that all the EWI firms promise that this won't be the case because the EWI will form a perfect seal, but he suggested that in reality this was extremely hard to achieve. He said he'd take 60mm of IWI over 100mm EWI in such a situation any day ...

Thoughts anyone?!

Damp coming through brick wall

DannySheffield — Thu, 27 Feb 2025 08:11:38 +0000

I've got damp coming through on my garage wall (showing up as efflorescence and stain on whitewash). The garage has been connected to the house so I'm more careful about air quality than I would be otherwise. The problem is, I can't figure out the cause! It's just over the area of a few bricks towards ground level - photos here: https://postimg.cc/gallery/ppG4jq2

The floor is concrete, tanking slurry, SLC and vinyl. The tanking slurry runs up one course of bricks on this wall, so my best guess is the damp is soaking up from below. The external wall is covered in cladding, the photo with the yellow circle shows where the issue is on the outside, so no obvious cause of ingress from there.

I'd appreciate thoughts on my guess. And if that is correct, any thoughts on how to keep the infill below the garage (it's built up a few metres at the deepest point as we're on a hill) more dry - some way to fit a drain?

ASHP + battery... good news story

neelpeel — Wed, 26 Feb 2025 10:41:12 +0000

I had an ASHP and 15kWh battery fitted last year. I already had 5kW of PV, but added another 5kW last year.
To give some context...House is 135m2, 1890 build. Refurbed in 2005 so insulation is not terrible, but not great.
Our heating was previously circa 1500ltr oil and 4m2 of hardwood logs per year. So nearly £2000 a year and the house was not warm, unless the woodburner was on. Bedrooms were very cold overnight.
Electricity use before the ASHP was around £1000/year at current rates (inc EV charging).

Fast forward to this year, where I charge the battery overnight on cheap IOG rates and use for the heat pump and house - also topped up with solar. Almost all of my energy is now at 7p IOG rate and due to my PV exports through Spring-Autumn I'm pretty sure that this year I will be net POSITIVE with electricity cost. I.e. no bills, Octopus will be paying me. So that's all my house electric, heating, DHW and driving.
I was lucky enough to get a £9k grant (rural Scotland) for the ASHP so it only cost £2k (less than it would have cost to replace my old oil boiler). Also a £1250 grant for the battery, bringing that cost down to about £2k. The solar I DIY'd and panels were cheap as chips so the additional 5kW cost <£2k.
I calculate just over 3 years to 'payback' my investment and then it's the gravy train after that. Yes...3 years.

AND...
House is toasty warm (19.5deg living area, 16deg sleeping area), all day and night, every day of the year (Mrs is well chuffed).
No more burning filthy oil.
No more chopping and ferrying wood to and fro.

Fair to say it's been transformational.

Solar - too many panels?

minisaurus — Mon, 17 Feb 2025 19:29:48 +0000

I post this in the hope of helping others.

Here in Sweden, I think we can say we were perhaps misadvised (ripped off?) when we installed our solar panels.
The recommendation was - fill the entire roof! - so 11 kW effect it became.
And in a way the advice was correct - last year we bought 8.5 MWh and produced 9.2 MWh (sold approx 7 MWh). Great! Yet we paid circa £1500 for incoming electricity, saved £350 on not buying, and received maybe £30 for selling ...

We have no battery, and only electric energy (no gas, no stove, no pellets, no district heating), so when we really need electricity (nov, dec, jan, feb), we're not producing much.

In summer, when we have no need for space heating, we use around 15 kWh/day. Yet we'll produce up to 70 kWh and give almost all of it away on the Nordpool market, at prices of maybe 10-20p/kWh

Obviously a battery would help a little with this situation, but from April to Sept we're nearly always producing at least double our need, and at a time of the day when loads of other people are producing electricity. If we had a Nordpool hour-price tariff, and it was windy, we'd often have to pay to export our electricity on a sunny May day!

In winter we can use up to 50 kWh a day, but produce almost nothing, and it doesn't feel like e.g. a 10 kWh battery would make a massive difference to things.

So, my tip would be, if purchasing panels, just buy enought to cover your requirements on a sunny April day :)

EWI - general question

Rex — Wed, 14 Feb 2024 14:03:02 +0000

What ho one and all,

I do read many of the threads relating to EWI and although I do understand, I also don't understand.

I am not considering it as I have quite a lot of insulation in my t/f house. However, a neighbour is in the process of having it fitted. Naturally, I do understand the insulation benefits,

But !

My house has the insulated inner wall, the cavity and a block and render external. During building, I did consider changing the block and rend for some kind of external insulation and render but wa told by the BCO that as I was changing the specs, I would have to reapply for Building Control.

But he also told me, and this is what I don't understand about EWI, that since the cavity is ventilated, the outer wall is considered external as it has cold air on both sides and does not improve the insulation values.

So what am I missing?

Thanks

Home batteries.

owlman — Mon, 01 Jul 2024 13:30:43 +0100

I'm interested in finding out if the hitherto uneconomic?? landscape, regarding home batteries has shifted and if anyone has first hand experience of them.
My lucrative three year electricity contract ends in 3 months and I'm number crunching with new tariffs e.g. EV, Economy7, and I thought I'd throw home batteries into the mix.

Mould again

tony — Fri, 31 Jan 2025 21:44:53 +0000

I can’t post pics, please download and post this one for me. https://www.dropbox.com/scl/fi/mpr1e9emsj74pa062rw83/IMG_1515.HEIC?rlkey=jxay1jb7ecr8972m01c7mvww4&st=alp18uky&dl=0

In children’s bedroom, private rented, landlord unconcerned and not acting

Mu values and breathability. Stated values and the perfect construction

Mike George — Sun, 22 Jul 2012 10:56:46 +0100

There is much discussion here and elsewhere relating to 'breathability' of structures. Critical to how this 'mechanism' works or [or does not work] is the placement of materials based on their relative Vapour Resistance Factor [Mu value]. The understanding of this is however confused by the way in which values are sometimes stated:

Mu values (no units)
Vapour Resistance (MNs/g) or even
Vapour Resistivity (MNs/gm)

are all used as a measures of a materials reluctance to allow water vapour to pass through it/them.

A good document explaining the conversion between these can be found here http://www.builddesk.co.uk/files/BuildDesk_UK/Home/Software%20support/Vapour%20Resistances%20and%20Mu%20values.pdf

This is all very muddled :( especially when considering the placement of insulation / breather membranes / vapour control layers etc.

Manufacturers sometimes promote their products as fitting the breathability concept. This is in turn sometimes based on rules of thumb for relative 'resistance' to vapour.

I'd like to understand all of this to a level where I can competently justify insulation placement based on not just thermal properties but Hygrothermal properties as well.

A good starting point for me would be justifying the breathability rule of thumb by actual numbers for example constructions. I've read that the internal surface 'resistance' should be 3 - 5 times greater than the outside, with presumably a gradient in between.

So what is 'the perfect breathable construction/ and what are the associated hygrothermal properties?

Anyone care to raise their head above the parapet?

Stromdry

Ross87 — Fri, 27 Dec 2024 16:27:36 +0000

Hi,

Does anyone on here have much experience using Stormdry (or similar products)?
It seems to divide opinions..

I have a couple of exposed sash window reveals on an 1890s Victorian end terrace that occasionally get a penetrating damp issue.

This only happens very occasionaly (perhaps once a year) when driving rain makes a small damp patch on the internal plaster.

Previous owners seem to have experimented with renders on the reveal, indicating the original Victorian detail wasn’t perfect.

The pointing and sealants are in pretty good shape.

Presumably lime plaster with a good breathable paint would also be more forgiving than gypsum which leaves a slight brown stain?

In most cases I’m reluctant to apply non reversible modern materials to old buildings. But this could be an exception.

Thanks
Ross

Paying for a new electric meter!

tony — Fri, 03 Jan 2025 18:39:09 +0000

Can a supplier charge for a new electricity meter?

Supplier is offering a free smart meter and saying that if the householder/landlord says no and later the meter breaks then they would need to pay for a new meter

Sounds awfully like blackmail to me.

Cleaning waste pipes

marktime — Thu, 02 Jan 2025 18:40:16 +0000

I've been asked to clear a blocked waste pipe and so far have got it partly open but it's full of gunk and not easily accesable with a drain rod. Any ideas about a liquid that will dissolve or at least move the grease? Got a 2 metre run to clear.

PIV vs dehumidifier

daveking66 — Sat, 23 Nov 2024 11:00:41 +0000

Hi all,

My sister in laws house (old, poorly insulated and single glazed) suffers from condensation and is considering installing PIV. From what I’ve read on other posts it seems that a dehumidifier, or two, might be a better option. Any comments or considerations?

Balcony doors, glass, U-values, cold bridges

minisaurus — Mon, 23 Dec 2024 16:45:13 +0000

This might interest some. We have new baclony doors! wood on aluminum frame, with a window, supposedly U-value 1.0 W/(m2.K). (Probably this one: https://www.swedoor.se/produkter-sv/ytterdorrar/advance-line-classic/classic-castilla-ytterdoerrar - sorry can't find a site in English)

Triple-glazed. The triple glazing works fantastic, and the solid parts seem to also keep out the cold.

But - see photo - that join where the glass pane meets the wood - ouch! 12 or 13 degrees when its 4 or 5 outdoors and 20-21 indoors.

Interestingly our 40 year old original windows have identical temperatures at this junction.

I wonder if any door manufacturers have cracked this issue.

OpenERV

gravelld — Tue, 17 Dec 2024 13:39:42 +0000

Popped up on Hacker News today (well, yesterday, but I always catch up in digest form): https://www.openerv.ca/

Might be worth following.

Solar Farm becomes an aeroplane.

revor — Tue, 10 Dec 2024 10:06:43 +0000

Here is what happened to a solar farm on the most northernmost tip of Anglesey.

Interesting the pattern of destruction will give the experts some food for thought.

Perimeter practically untouched guess the wind had free channels to escape and uplift suction has pulled the panels off their mounts. Being so close together they have effectively formed an aircraft wing of some size.

Probably best it happened the way it did rather than the whole frame being lifted into the air, then it may really have flown.

The panels do not look broken.

https://www.msn.com/en-gb/news/uknews/storm-darragh-leaves-uk-s-biggest-solar-farm-in-pieces/ar-AA1vyCVI?ocid=msedgdhp&pc=EDGEESS&cvid=7efad1c6d5cd456b9d1fad28fad4ea77&ei=18#fullscreen

Push fit or press fit?

Victorianeco — Fri, 18 Oct 2024 21:54:45 +0100

If you were to replumb a house for central heating and water which system would you choose?

I did the last house in hep20 without issue but thinking press fit seems popular lately.

Also, are people still preferring to run 15 to showers, 22 to baths, 10 to sinks all from manifolds?

EDF are running a "Sunday Saver" Plus a Christmas day scheme

Peter_in_Hungary — Sat, 21 Dec 2024 16:08:24 +0000

EDF are running a "Sunday Saver" Plus a Christmas day scheme too.

"Shift your electricity usage from Monday to Friday, avoid peak times (4pm - 7pm), and get free electricity the following Sunday. You have four or five chances each month to meet your goal, so even if you miss it one week, there are more opportunities to smash your target the following week."

P.S. I tried to open this as a separate discussion, (6 times), but no joy.

separate discussion opened for owlman (see above)
P.S. I'm using firefox if that makes any differance

More gas powered generators - honestly!

fostertom — Tue, 23 Jul 2024 08:28:35 +0100

https://www.theguardian.com/environment/article/2024/jul/23/uk-may-need-new-gas-fired-power-stations-to-decarbonise-grid
A report by an engineer group, which may possibly have a finger in the fossil pie, or just conservative.

Not a mention, in the article, of the growth of battery storage which, like the growth of renewable generation in the last two decades, is going much faster than even the optimists imagined. Nor of the prospect of the electric vehicle fleet equiped to discharge as well as charge, as grid storage. The latter promises to destroy the case for nuclear as baseload - stop building now!

Periscope air vents

tony — Sat, 07 Dec 2024 19:21:20 +0000

I took out some plastic air bricks today as vermin had been trying to eat their way into them.

The plastic was brittle, clearly suffering from UV damage.

The void behind them, the short horizontal section before the downward section was completely full of cobwebs caked with dust and detritus to such an extent that air movement would have been severely impeded.

Anyone else encountered this? Or has anyone managed to clean out any periscope vents?

Why Electricity Standing Charge Is so high

revor — Thu, 07 Nov 2024 18:55:15 +0000

This week 2 employees of a company contracted by SP Energy Networks turned up unannounced with a cherry picker on the back of a long base pickup truck. Normally I get a visit to make arrangements for access. They wanted access to one of my fields to replace a hazard warning sign on the pole in the field. They wanted to take the truck into the field to use the cherry picker but it is the wettest of my fields and I do not go in there myself with my tractor so as not to cause ruts The sign was about 10/11 ft up so I said could they not use a ladder to which they replied they were not allowed to. So reluctantly I allowed access, so they set up with hard hats and about the most heavy duty harness I have ever seen, set up the cherry picker and replaced the sign even though the original was very legible. In all a 5 min job took about 40 mins. I think both guys were immigrants one could not speak English and they spoke to one another in a language I did not recognise. I chatted to one who could speak English about the fact that they had a brand new pickup from from which I then gathered that a fleet of these had been acquired to go round replacing hazard signs. Talk of a sledgehammer to crack a nut. I am all for H&S particularly on agri properties but this was just too much.

Boiler upgrade scheme

Victorianeco — Wed, 02 Oct 2024 21:38:50 +0100

Has anyone had experience good or bad?

Looking to upgrade our gravity fed gas system boiler, and had a quote after the grant for supply and fit of just the heat pump and cylinder for £3800

Thought it seemed excessive in my opinion...

Void in internal wall causing condensation, maybe?

Kenny_M — Wed, 20 Nov 2024 16:41:34 +0000

Hi all,
I have been working over the last month or so on replacing a suspended timber floor, and insulating it and the internal walls (200 year old house in conservation area).

I have had dampness on the internal wall in the bottom left corner since moving in about 6 years ago. There have been other issues, including ground high external ground levels and the suspended floor/subfloor ventilation which I have hopefully resolved. However, at this particular spot, directly above where the metal vent pipe comes in, there has been a vertical line of dampness that doesn't seem to fit with the other issues. As I had the skirting off to do the floor I gouged out what seemed like soggy clay or maybe lime mortar and found that there was a void at this point, directly above where the pipe comes in and a draught coming in the hole I just created.

The metal vent pipe looks very old and is actually two pipes at an angle to each other in order to create the bend. My theory is that the draught I am getting through the internal wall is coming from this join in the vent pipe getting into this void, which in turn is creating a cold bridge in the thin mortar fillet where condensation has built up over time. There was previously an electrical socket cut into a skirting board at this point, so an easy route for warm damp air to get to this point. At first I thought this void might have been intentional, so as not to bridge dampness from the higher solid floor in the next room, but I put an endoscope in there and it doesn't seem to run the whole length of the wall, just about 300mm or so.

My question is, does this theory sound credible? And should I attempt to fill the void, and if so with what? I thought about maybe attempting to pour some EPS beads in but if there is a gap the beads might end up in my subfloor void which I can't access now that it is closed up.

Any thoughts welcome.

Wet cavity insulation

KBabs — Wed, 05 Dec 2018 20:54:36 +0000

Hello

During this wet weather, my fibreglass cavity wall insulation is getting wet while the walls to an extension are going up. I asked the building to cover them up but he said it doesn't matter as it will dry out.

Is he right? I guess it will eventually? Some of the insulation hasn't quite expanded fully, I'm assuming due to the water making it heavier than normal. Will it expand over time as it dries out?

Thanks!

Who to hire to help damp issue?

luz13827 — Sun, 10 Nov 2024 22:31:27 +0000

Hello, we have a couple patches of damp in our Victorian solid wall which seem to be getting damp. We've had the drain at the front checked + a crack repaired a few months ago, but I don't know what else could be the cause. I don't believe it's condensation as we have good ventilation & heating indoors. Both patches look like water/damp patches. One of the patches is midway up the external wall, the other is a small patch (around 10cm x 10cm) right at the bottom of the external wall (same wall, but opposite sides). The wall has been plastered and finished with clay on the inside. The outside we didn't change, and it could be an unsuitable material causing the issues, but I'm not 100% sure.

I'm at the point where I just want to hire someone to come look and tell me what could be causing the issue, but I don't know what specialist would know this (familiar with old buildings, the material on the outside, etc). Does anyone know of someone recommended in London? We are in a converted ground floor flat, so this room is set to become my baby's room, and before we re-decorate, I really want to solve the issue once and for all.

Electrical cables and insulation

Kenny_M — Sun, 03 Nov 2024 08:58:23 +0000

So, I have just finished internally insulating the walls of a 200 year old house. I remove lath and plaster from the internal walls, left the sound original plaster on hard on the walls, and stuck PIR then plasterboard over.

The pic shows the one section I have yet to finish as I am not sure what to do around this mass of electrical cables, which was originally run behind the lath and plaster. I have left a space around the cables and my choice now is either to stick the plasterboard over the top and leave this section completely uninsulated, or fix 10mm PIR over the top before the plasterboard to reduce the cold bridge.

Its really difficult to find anything definitive about insulation and cables, on one side its clear that burying cables in lots of insulation is a fire risk, but how much insulation is not so clear. My gut tells me that a channel like this with a cold outside wall on one side of the cables and 10mm PIR on the other is probably not going to be a problem, but not really clear on what’s allowed/sensible in this situation.

Baumit Klima glatt

RosieB — Thu, 17 Oct 2024 11:29:36 +0100

Hoping someone with any experience of this plaster can offer some advice. My lovely plasterer with no experience of lime has been giving this a shot. Got the base layer of baumit RK70 done without a problem. Has now attempted the first wall with the glatt finishing coat (under coat completely dry) and has really struggled. The main issue is that there seem to be small bubbles in the plaster on the wall. He has just been mixing up another bag and again these little lumps (which seem like bubbles) are appearing in the mix. Does anyone have any tips on exactly how this stuff should be mixed and applied? I’m really struggling to find any info online and the official documents tell us very little! All help massively appreciated.

Wide roller blinds

revor — Wed, 30 Oct 2024 16:54:29 +0000

Have a requirement for a wide 4.7M x 2.4m drop motorised roller blind. Have had great difficulty locating someone who makes them but have found one at last but would like to find somewhere else so that I have a choice.
Anyone ever bought wide blinds or know of an outlet?

Shiney floor

Rex — Wed, 30 Oct 2024 12:17:52 +0000

What ho one and all,

Not a housing issue, but just interested.

There is a small building net to my local station. Was previously a coffee outlet but has been empty for some time. Recently, The Arch Co (owners) did a major refurb in preparation for renting to A.N.Other.

My question is regarding whatever they have used for the floor. As the photo, it is a very flat, even high gloss. I know it was poured, but what could it be? It looks like water!

Thanks and toodle pip

Rex

Future Proofing - Ceilings Down

Victorianeco — Tue, 22 Oct 2024 08:21:06 +0100

All my ground floor ceilings are down ready for rewire, replumb and potentially MVHR

Anything else I can do at this stage to futureproof? Ethernet cables? Anything else you can think of?

Thanks all

MVHR cooling vs Fan Coil Units

maxsm1 — Thu, 26 Sep 2024 09:36:48 +0100

Hi all, just hoping for some advice regarding cooling. We are about to start an eco retrofit aiming for 34kWh pa and <1.5ach @50pa. We would like to build in some form of cooling as several low energy builds we have visited have suffered from overheating issues. We are already planning external shutters on all South-ish facing roof lights and have the option of a brise soleil on the ground floor.

We were looking at adding a Comfopost CW8 unit to our Zehnder MVHR but I have doubts about how effective it will be.

Another option would be FCUs in the three rooms which are most likely to be affected by overheating. There is also a useful void space which attaches to all three rooms, which would make plumbing in the FCUs (or installing one larger concealed unit?) relatively straightforward.

I'm interested in advice on the relative merits of whole-house Comfopost vs localised FCUs... the cost should be quite similar.

Thanks in advance for any help, L

Safety - re battery storage of solar energy

minisaurus — Sat, 07 Sep 2024 14:36:02 +0100

We'd like to purchase a battery system for storing electricity generated from our solar panels. Our only indoor option is to place the battery in our wooden shed (340 cm wide, 270 cm deep, 235 cm high). The battery package we like is this: https://emaldo.com/products/emaldo-power-store-ai; it complies with IEC62619:2022 safety for industrial batteries, and is designed to stand & store outdoors in the nordics.

I'm worried about fire - our house is also wooden and positioned 80cm from the shed. We'll have to install an industrial grade smoke & heat detector with a loud alarm so we get woken up in case of fire.

Does anyone have experiences or opinions on assessing the risk of fire in such settings? And how fast a fire might develop/spread?

Domestic dynamic demand

djh — Fri, 11 Oct 2024 11:39:11 +0100

Is anybody aware of any ready-to-use dynamic demand equipment suitable for use in a house? That is, something that will turn my heating on and off and minimise the costs,or ideally pay me for network balancing services?

I imagine I might be able to cobble something together using the Agile tariff or somesuch, but I'd prefer something more ready-to-use and ideally cheap.

What to do with this problem subfloor void

Kenny_M — Mon, 26 Aug 2024 14:14:35 +0100

Hi all,
Long time since I have been on here. Sorry to see that the forum is closing soon. I have received so much good advice on here, occasionally I have hopefully contributed occasionally in the other direction, but most importantly the end result has been a house that is a lot more energy efficient than it was before I started following the forum.

I am now tackling a small north-east facing room that has major dampness problems. I have already rectified some external issues like an open gutter at the external wall and dropped the ground level as much as is practical, but have finally had to bite the bullet and lift the floor as the air quality problem seems to be coming from below, rather than any visible dampness present in the walls of the room. I have lifted and numbered the solid wood floor as I intend to put it back down, sand the varnish off and cover with hard wax oil as I have done with the same flooring on the rest of the ground floor. I don't know what type of wood it is , but it has been remarkably resilient to dampness and is showing no signs of rot. There were parts of the house where the skirting boards had rotted and this wood right next to it showing no issues.

On lifting the first view boards of the subfloor I found what I had expected. The joists are more or less resting on the ground with at best a centimetre or so of clearance in places. Mould is growing on the ground and some of the bottom of the joists are rotted through. Once I have the rest of the subfloor lifted I will have to decide what to do next. Its seems that my options are:

a. Dig as much of the loose soil out and replace the joists, then rebuild a traditional raised wooden subfloor.
b. Dig out as much as I can and then fill with something like Leca insulation, then levelling screed and just float or bond the solid boards on top.

The problem with a is that it's unlikely that I will be able to dig very deeply due to the construction of the house. I can possibly create space by using joists of a lesser depth, reducing the spans with a few bricks, but the best I can hope for is about 80mm gap between floor and joists. This also leaves very little scope for floor insulation.

The problem with b is that it is a bit of an unknown. A Leca installation it looks fairly easy, but there are a lot of unknowns and possible complications due to the old and odd design of the house.

The room is north and east facing and I think the problem began with dodgy builders in the 1880's, possibly made worse by dodgy builders in the 1980's! I believe that the original house, built in around 1820, had solid floors and lower ceilings. The Victorians appear to have dug down to lower the floors in order to get higher ceilings in the two rooms at the front of the house and installed suspended timber floors at that time. On the west side due to a combination of factors this has worked and that side is reasonably dry. Where this room sits on the East side it backs on to a room with a solid floor, which currently has a solid wood floor, sitting on top of a thin concrete base and I suspect that it's just soil underneath that. The room with the solid floor is about 320mm higher than the room I am working on, which means I have an internal wall backing on to earth, probably without a damp proof course behind the wall. On another side of the room there is a hallway with a solid floor.

Sorry for the long post, but in summary, my preference is probably for the Leca fill, but that removes any chance of ventilating the base of the interior walls backing on to solids internal floors. If I go with Leca I was thinking of a DPM between the Leca and the screed and run the DPM up the wall to just above the final floor level, then have vents on the internal wall skirting boards so that any moisture that gets up past the DPM can vent into the room rather than build up. The unknown for me is how the Leca would interact with any build of dampness underneath. As the subfloor space is below ground level if it does start to fill up with water then there is no ventilation to dry it off.

Grateful as always for any input, or suggestions of something else I haven't considered.

Room plan - https://www.dropbox.com/scl/fi/8s0ped6n43cfpesl2qlz9/Room-plan.jpg?rlkey=9r44hga25pls6webfx73a6bnw&dl=0

Pics:

https://www.dropbox.com/scl/fi/bk4u0itzyr16mcvypj1mg/2024-08-24-17.06.25.jpg?rlkey=ium901mmuyzw6o3rke3hb8d1n&dl=0

https://www.dropbox.com/scl/fi/6mjkdirtcxc49n9579dfv/2024-08-24-17.06.52.jpg?rlkey=drbwp3mhdk9jb3mh6o6pb7dp2&dl=0

https://www.dropbox.com/scl/fi/xebiayoymyaoveeu5pek9/2024-08-24-17.08.04.jpg?rlkey=8h3ih13dan0yjfxunpoxfxhvl&dl=0

https://www.dropbox.com/scl/fi/3n5tw0pfrzqd39ey35950/2024-08-24-17.09.31.jpg?rlkey=3e5uolomk5wub8ljthx63yoou&dl=0

UV water treatment

Cliff Pope — Sat, 21 Sep 2024 06:58:16 +0100

I have fitted a UV treatment unit in the water pipe in the house, on advice following boring of our new borehole.

I was a bit surprised that the unit got hot, but on reading up about these apparently that is normal, as the unit runs continuously even during periods of no water useage. The temperature is supposed to stabilise as the heat diffuses along the pipe and radiates to the surroundings.

But ours is not remotely what you could call "warm". It is scaldingly hot, way above its specified maximum operating temperature of 40 degrees, more lke 80 - 90, and far inexcess of what the HDME plasic pipe is meant to stand.

I'd assumed that the unit should be wired to operate only when the water pump is running, but that apparently shortens the lamp life, so it is meant to run continuously. Radiation is in fact minimal as the unit is shiny stainless steel, not matt black.

Has anyone any experience of these units? Is this really normal, or should I complain to the supplier and report a fault?

Sheepswool vs Woodfibre for walls

bobso — Tue, 01 Oct 2024 22:42:27 +0100

Hi all

Trying to internally insulate our old coal shed. (now a study, which has been previously plastered (badly) and has various wires/ cables in the walls.

Trying to do this in natural (read water permeable materials) to help control moisture/ warmth in the shed.

Two options seem to be open to me:

1) Sheep’s wool - So Bricks, Breather membrane, Wool, AVCL, Plasterboard (and held up by battens as thermal bridges) But does let us hang pictures/ shelves to the studs.

2) Woodfibre - So Bricks, Lime coat, Woodfibre, Lime plaster (not too many thermal bridges, but hanging shelves etc difficult),

Which is best from a breathability / insulation perspective? While the coal shed isn’t wet; but it is single skin brick... Likely can do 100mm of either insulation, so both work out at a U of approx. 0.3.

If we go sheep’s wool, which seems easier to install / more like what our builder has experience with (And less lime plaster!), how much prep of the internal wall do we need to do? - i.e. does it have to be smooth etc for the membrane to go on? - Or would an old plaster and paint be ok?

Thanks for any insights!

Battery Capacity portable power station.

revor — Tue, 01 Oct 2024 16:53:34 +0100

I have a portable battery "power station" a handy piece of kit and have not really assessed it properly for the claims it makes until this last week or so. This what I wrote to customer service. I have not includes the make.

"I have got a ????? bought back end of last year.

I have used it sporadically to use in power cuts and a shed with no
power and found it very useful.

However have just started using it for an LED panel to grow cress and
other micro greens and realise I am not getting the full spec.

The LED light is 35 W but getting 11/12 hours from it display shows
12hrs power when unit fully charged and showing 100% when unit is fully
charged.

So effectively 420 w not 768w that is claimed."

This is response I got and do not know what make of it.

"Thank you for contacting Customer Service Centre.
You say the problem is caused by a conversion rate issue. When the power station is powering less powerful appliances, the output conversion rate is lower,
The battery unit provides 35W at about 50-60%, so the usage time will be less. If the appliances used are more powerful, the conversion rate can reach 80%-90%, so the usage time will not be in doubt."

To me it makes no sense it is akin to saying that you can get more mileage out of an EV battery if you drive it hard but actually having a light foot give you more.
Anybody understand the response I got.

Chimney breast (1/3 flues working) INSULATION in warm attic

blubb — Wed, 18 Sep 2024 18:54:06 +0100

Dear GBF,

I am insulating the loft space to convert it into a warm attic. I am thinking what to do with the chimney breast in the loft. It has three flues, of which one is working (wood burner in occasional use, with a steel liner, vermiculate around it). The chimney breast is channeling the cold from the roof bit and from the neighbour's loft, which is cold. Hence it seems natural to insulate the chimney breast. However, the question is:

how to insulate the chimney breast in the loft?

I believe that one could use normal insulation board like e.g. Celotex GX4100, since the flue is insulated inside the chimney breast, but since we are talking about a wood burner, I would like to hear some opinions if this would be a safe thing to do?

Many thanks!

Structural Engineers

big_mike — Tue, 24 Sep 2024 22:56:49 +0100

So, how does one find a decent one? Based in South Devon if that helps.

EWI System

Victorianeco — Wed, 11 Sep 2024 20:03:24 +0100

I think I'm going to go for EWI on my cavity wall detached property.

Primarily because we want to renew the facade anyway, the existing render is traditional roughcast.

What is the best EWI system in terms of overall cost per r-value? From what I've seen all of the K-rend jobs in my area look awful with staining, algae and so on. What is the best finish for a seafront property that will be low maintenance?

We may look to DIY the cladding and pay to have it rendered. Can it go on existing roughcast??

And if we do install ne wiwndows in teh outer insulation layer - can the EWI be added next year or is this just asking for leaks?

Cleaning a U bend

Rex — Thu, 19 Sep 2024 09:51:42 +0100

What ho one and all,

I posted some months ago regarding a 4" pipe kitchen waste blockage. I figured the 'fatball' was inside the ceramic U bend in the ground.

My tenant has cleared the blockage with a jet washer but I am going to do it again as I have a right angle fitting for car arches that will blast water directly into the U bend.

However, the owner of the g/f property where the issue occurs is quite adamant that I should get a 'professional' to investigate and clean / replace it properly, 'once and for all.' That is not going to happen unless he pays for the work, which would involve digging up a few meters of his patio!

My question is, what do 'professionals' use to clean a below ground 4" U bend? My drain shake kinda refuses to negotiated the bends, as does my 10m long sewer cleaning hose for the pressure washer.

Thanks and toodle pip

Back box sealing with Tescon Vana

oliviaaa99 — Wed, 11 Sep 2024 18:54:19 +0100

Hello everyone!

We are hoping to make the socket and switch back boxes as airtight as possible (sealing the knockout holes, screw holes etc), but they are already installed so will need to retrofit. Is it safe to use Tescon vana to do this?

My current thought is using a strip of tape across the back/sides of the inside box to cover all the holes in one go, then to seal the hole around the wires using sealant. I've only seen posts online of people using sealant to cover every single hole, but to me it seems more efficient to use tape? So I wanted to see if anyone else has done it or if it's not recommended as we absolutely want to make sure it’s 100% safe.

I'm also not sure what exactly to use for sealant around the wires as I see some people call it fire caulk and others heat resistant silicone? This is what I'm thinking at the moment but want to make sure we get the right product: https://www.everbuild.co.uk/products/sealants/specialist-sealants/everflex-heat-mate-heat-resistant-sealant/

Thank you so much!

Grenfell tower fire

Silky — Wed, 14 Jun 2017 08:17:01 +0100

http://www.knaufinsulation.co.uk/news/news-residential/10m-tower-renovation-london

apparently the cladding went up like a match stick.. I wonder what type of insulation was under there, if it was Polystyrene then surely this is a major FU!

SAP 10 is it an own goal?

an02ew — Mon, 02 Oct 2023 22:29:26 +0100

Has anyone had experience with the new SAP10?

i am designing and building a small 2 bed detatched bungalow (in total 58m2 int floor) it follows our usual building fabric design:

-insulated raft foundation conncted to EWI connected to EPS loft insulation (totally unbroken insulation element and lots of thermal mass)
-ATness below 0.6 m3/m2
-MVHR (90%)
- 3g window and doors
- 3kW slimjim direct to UFH
-direct cylinder with twin immersion or instant water heaters(budget dependant)

i had this run through the new SAP10 (pre design) and it failed, not due to the fabric efficiency but becuase of the fuel price calc, it seems the only way to get a new building through the new SAP10 is with bolt on PV or ASHP (good news again for installers) In this particular build the budget is very tight and both are costly the ASHP has to low return due to the the low kW/m2/yr and the single occupant has low daytime electrical usage and no EV resulting in a low return value.

IMO SAP10 sends the wrong message, should'nt we be rewarding liftime energy efficient construction methods not short term panels and pumps?

refusal of heat pump grant

finny — Thu, 29 Aug 2024 11:46:10 +0100

Hi All..

Just posting to see what comes up..

Have discovered from OFGEM that our proposed heat pump installation would not attact the £7.5k grant as it would be replacing a pellet boiler that received the RHI..

Any thoughts?

WUFI & unventilated ceiling

Mike1 — Mon, 03 Jun 2024 21:19:33 +0100

I mentioned some time ago that I had a unventilated ceiling to insulate for my current renovation. It's on the top floor of a small apartment block. The existing structure, top to bottom, is:

- a tiled pitched roof attic that's subdivided into storage units used by various residents
- terracotta floor tiles in lime mortar
- thick timber planks
- joists at close centres that span between beams.

to which I'm adding insulation and a dense plasterboard ceiling.

Being rather tricky, I thought I'd better commission a WUFI analysis, and being optimistic I thought I'd kick off seeing what the results would look like with 300mm of hemp insulation batts. The results are now back and don't look pretty. With luck, the images will be below.

I'm now considering how far to change the spec for another run of WUFI. I know that some of you - Tom, maybe Tony, maybe others? - have played with WUFI in the past, so am hoping that you may have some thoughts on this.

An obvious track would be to cut the insulation. 200mm would be my ideal minimum (U = 0.21 W/m²K). In view of the results for 300mm, any opinions on this or an alternative thickness?

No doubt adding a smart VCL would make WUFI results look better, but in reality the stud partitions would pass through and bypass it (they're fixed to the structure). That's leaving aside the advisability of using VCLs in retrofit anyway (I think my scepticism is shared with Tom too?).

So, as I don't have endless funds to spend on WUFI models, what to try next?