Tue, 12 May 2026 19:19:18 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18399 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18399 Sat, 24 Jan 2026 16:41:33 +0000 gravelld
Tescon Vana works up to 90C, but that would be no good for the flue, certainly.

What have people used?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18395 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18395 Sat, 17 Jan 2026 11:30:06 +0000 Rex
Easy peasy! But he and his wife do live in what can only be described as a complete and utter chaotic mess (think those house clean TV shows!) and there was not way I was going to empty the under sink cupboard with the very limited space they have. They can do that.

He called his friendly plumber and later reported to me that is was a fat-ball in the trap. But he also told me that the plumber told him that there is now a kinda fat-ball vacuum that plumbers use to clear kitchen traps without having to access the trap

Purely out of interest, what is this tool? Surely it cannot be as efficient as dismantling the trap and giving it a through clean?

But what do I know?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18393 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18393 Fri, 09 Jan 2026 14:09:23 +0000 alant We are going to install an engineered wood floor on top of 22mm OSB subfloor in the living area (first floor) of our house and we need to reduce the impact / noise transmission to the bedrooms underneath. We fitted 100m of Hemp batts between the I joists but this has been pretty useless at reducing much sound.
Does anyone have any recommendations of what to install as an underlay of up to 10mm thickness to reduce impact noise. Ideally we don't want to use material that has lots of VOC's or off gasses. We have tried several specialist retailers and it seems that they are very good at quoting dB reduction for complete systems of floor make ups not for providing reliable figures for just underlay. Some say Cork is good but its relatively light so i can't see how that helps much.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15876 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15876 Tue, 25 Sep 2018 19:55:13 +0100 andyman99
Render - 150 EPS - 215 Block - Plaster (poss plaster board on battens).

Will this be OK or do I need add a vapour control layer?

Many thanks again

Andy]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18392 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18392 Thu, 08 Jan 2026 15:52:17 +0000 Jeff B 2025
It seems all our efforts to improve the insulation in the place combined with solar PV and solar thermal panels have paid off in that we are now in band B (previously D).

I have a question regarding the estimated annual figures for the space heating and hot water requirement:

The annual heating figure in the new EPC is 9168 kWh and for hot water 2195 kWh – total 11,363.
1 litre of kerosene yields 10.35 kWh of potential energy. As my boiler is obviously not 100% efficient and is actually 90%, then I assume in my case that 1 litre of kerosene potentially would produce 0.9 x 10.35 = 9.31 kWh of “useful” heat. So 11363 kWh of useful heat would require the burning of 11363/9.31 = 1220 litres of kerosene.
This is odd because we use on average 1500 litres of kerosene p.a. combined with the fact that our solar thermal system provides us with hot water for most of the summer months and the boiler is off for weeks at a time. 1500 litres is equivalent to 13965 kWh (boiler efficiency 90%), some 2602 more than the EPC prediction.

My question is why is there such a large difference between the calculated and the actual oil consumption? Is the boiler less than 90% efficient? I’d be surprised, as it is only 4 years old and regularly serviced. Or is there some other factor that I am overlooking?

I’m just concerned because a prospective buyer (if a bit geekish like me) might question this inconsistency!

Thanks for any feedback.
Jeff]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18387 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18387 Thu, 25 Dec 2025 09:52:44 +0000 minisaurus
I can’t see any downsides to doing this?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18386 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18386 Sun, 21 Dec 2025 22:08:00 +0000 reed https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18390 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18390 Sat, 03 Jan 2026 00:37:17 +0000 ChrisinYorkshire
What do you recommend for insulating an RSJ when:

- the wall is mostly solid stone build, and being insulated internally with wood fibre board, lime plasters, breathable system, however;
- there is a retrofit cavity section that spans approximately 4m width of the wall, which involves a row of windows and an external door.
- the inner leaf of this part of the wall has the RSJ above it, with a cavity tray extending to the outer leaf.

I'm concerned that if I fill the RSJ with wood fibre batts between the flanges and front this with rigid wood fibre insulation, that vapour might reach and condense on the beam and saturate/overload the insulation more often than it can dry out, particularly in the winter months - is this a valid concern? Equally I'm concerned that if I fill the RSJ and cover with non-breathable insulation, XPS/PIR or similar, that moisture will creep in and be trapped against it. Since the RSJ is already in situ, I cannot fit a perfect DPM around it.


Other factors:

The RSJ has had considerable rust with flaky rust sheets that I've mostly removed and were presumably caused by approx. 30 years of kitchen humidity with no extraction. I am planning on scraping off any remaining flaky rust and treating RSJ with Jenolite rust convertor.

I can quite easily reach into the cavity and insulate the cavity side of the RSJ.

I also need to consider fire boarding, particularly with this being above the main entrance/exit to the house.

Any guidance most greatly received! :-)

Chris]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18371 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18371 Tue, 18 Nov 2025 17:34:03 +0000 djh
PS They've also included subsidies for 'heat batteries', but since heat batteries are now more expensive than electrical batteries for the same capacity, it seems like another poorly thought-out scheme!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18389 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18389 Wed, 31 Dec 2025 09:14:59 +0000 fostertom https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18388 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18388 Fri, 26 Dec 2025 10:35:16 +0000 Nick Parsons
I don't know how many I'm writing this to now, but hang on in there and let's get GBF/AECB forum thriving again!

All the best]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18306 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18306 Mon, 16 Jun 2025 23:49:03 +0100 stonecold (leaks keep happening). DHW uses immersion heater which will go.

1. Heat pump hot water cylinder of under 130L recommended by eco energy retrofit report but quotes all suggest 200-240L. We have 1 mixer shower and second shower may be mixer or electric. Which cylinder size is best - small or large? Is the large cylinder worth trying to use to store extra hot water as an alternative to a second battery for the solar PV we have planned? ASHP shift will move us 100% to electric and main heating need is daytime (I am housebound so always home, get cold fast and very little solar gain).

2. Cylinder location: no garage, can't use space boiler or current hot water cylinder currently use. Is it really really bad to use a bedroom alcove? Possibility covered by acoustic access panel and nicer boxing in. Another option is far end of kitchen but this crosses a doorway and it can't go under solid uninsulated flow - pipes would need to go in ceiling void above doorway then around corner and down - a long pipe run on coldest side of house.

3. See photo - could space 850mm x 450mm be used for cylinder? The 450mm wide is the frpnt, basically next to MVHR. Is there enough elbow room and plumbing room? If not would solar PV 2 inverters and 2 batteries fit here? Second inverter should apparently allow solar PV use during our very very frequent power cuts (30+ gets you a cheque from energy network company).

4. We would be looking at around 8kw solar PV and ASHP between 7.5 - 15 kwh plys obviously some stored hot water. We already use electric for hob and oven, if we have ASHP connected to solar PV with batteries are we going to have enough power to actually run the ASHP (colder temp ok)? This is for daytime since I am home all day, housebound and easily get cold.

5. Upstairs and downstairs zones for heating - any thoughts? Atypical use means lounge and downstairs office are used all day (I am housebound and get cold easily) and very very little solar gain. It seems daft to heat bedroom when it is empty. MVHR helps kitchen and bathroom temp a lot.

6. The Gulf Stream looks set to collapse or become dramatically unstable within the next 20 years.. causing Artic temperatures in the UK. We already have -10C several nights a year here. Is it worth getting the larger size of heat pjmp suggested (15kw) rather than 8-11 kw and will the larger size be environmentally much worse? Local experienced plumber always overspecs and suggested 15kw but is not familiar with our degree of insulation or MVHR and Internorm triple glazing. Aira also said the same. Others are in the 8-11kwh range. We have accurate plans (dwg) and accurate U values but energy needs are estimates (only 6 months since EWI and MVHR). Do small or large?

Basic details are
1830s stone house, 3 bed 2 bath, 150 sq m
Full repiping needed, microbore is at the end of its life and like spaghetti
loft 0.11-0.13 U, walls 0.60 U (EWI), MVHR in use
no floor insulation and too little head height for underfloor heating
Oil use should be approx 16,000 to 18,000kwh/year maybe less (from eco report) - because MVHR and triple glazing to near EnerPhit standards
Water heating 1,800 kwh/year - scrapping immersion heater]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18378 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18378 Thu, 27 Nov 2025 18:11:24 +0000 Rex
I have the boiler and DHW cylinder adjacent to each other in the utility room. Probably less than two metes away, is a toilet with hot water to the basin. The HW pipe, obviously goes from the top of the cylinder, into the ceiling and drops down to the basin HW tap.

Recently, when turning on the tap, based upon the noise from the issuing water, there is considerable air in the system. It does clear but like the Terminator, it will be back. All other HW taps do not have air coming out.

Since it's running at around 3 bar, I assume if air is entering, water is leaking out somewhere? But there is no evidence for that. Where could this air be entering and how can I prevent it.

As an aside, all cold water is mains and there is no air from any taps.

Grateful for any ideas.

Thanks and toodle pip]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18385 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18385 Fri, 19 Dec 2025 18:35:34 +0000 fostertom https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18375 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18375 Wed, 19 Nov 2025 23:10:46 +0000 mattp
The cavity above the window has some sort of membrane on the external side. On the other side of that is pebble dash render. It is supported on a timber frame and it is tied into the external skin of the cavity wall either side and on top of this frame is the bay window of the room above. It is completely open to the void under the floor of the room above, but there is a block wall built on top of the floorboards in the room above, which is tied into the inner skin of the cavity wall either side and supports the window ledge for the room above.

I am thinking of cutting out squares of plasterboard the right size and foaming them into position, then foaming round all the gaps to close the first floor cavity. There are also a couple of joists that go into the brickwork of the outer layer of bricks, so I was thinking of sealing these too, maybe with the same foam. Is this a good approach?

I am thinking of using one of these two foams:

https://www.toolstation.com/soudal-flexible-expanding-foam/p69089

https://www.toolstation.com/soudal-flexible-expanding-foam/p69089

I will attach 2 or 3 photos so you can see what I am talking about. Thanks.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18356 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18356 Mon, 29 Sep 2025 16:38:37 +0100 Artiglio
My mother ( mid 80’s years old) is downsizing and we’ve purchased a small 1920’s bungalow , it’s pretty much untouched in terms of insulation since it was built. Basically only 100mm of fibreglass in the loft.

There’s a bit of money to make some improvements , with the caveat that where possible we do it ourselves.

The aim is substantial improvement and comfortable living rather than ultimate energy efficiency.

I’m struggling to find a definitive guide to iwi with insulated plasterboards. Rooms are small and we don’t want to loose too much space.

Wall construction is 9” flettons, painted pebble dash on 3 sides, 4 side has only 700mm to neighbours wall and the eaves and guttering mean there is only a 6” gap. Gutters have been cleaned and leaky joints fixed.

Other side has 2.O overall gap to neighbours. Again very protected from weather, only front and rear elevations have any real exposure.

There is evidence of damp internally but this is pretty much all related to condensation behing previously fitted cupboards and units and very old aluminium framed windows.

Is it possible to bond insulated board direct to the existing wall? If so i can use a thicker board than if I were to use a battened system.

There will be mvhr . Heating is going to be gas combi boiler. Floors have been lifted, sub floor swept clean, joists repaired. Where fireplaces had been removed but screeded flush to the floor, these have been lowered and now the timber floor joists extend over. Floor joist are on sleeper walls and don’t touch the walls. There will be rockwool insulation between the joists before chipboard flooring goes down.

At least that’s the plan, i’m struggling a bit to find an easy to understand comprehensive guide to what i should be doing . Can anyone point me in the right direction?

Thanks in advance.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18384 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18384 Sat, 13 Dec 2025 14:22:50 +0000 Rex
Have the replacement panel up and running and since if it activates, it is impossible to hear the external sounder in the house and particularly if entry is from the back.

So this time, I have fitted a sound bomb, if for no other reason that the excessive inside noise is slightly disorienting.

However, I now have a very faint humming from the sounder and wondering if it is induced by the incoming mains.

The red line is roughly the cables from the sounder that go on the bell terminal on the board. These two wires go under the plastic housing and enter the interior just below the terminals. The yellow lines are the mains to the transformer.

I know little about the science of electricity but could the transformer and/or the incoming mains be inducing a micro current in the sounder wires that is causing the sound to hum?

If so, what is the solution? Reroute the wires so they do not cross the incoming mains or go under the transformer? Reposition the sounder?

Grateful for any suggestions.

Compliments of the season to one and all,

Rex]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18363 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18363 Sat, 11 Oct 2025 11:24:00 +0100 Rex
Want to replace the 6v 330mAh Ni-MH back-up battery. The one I have removed has the following markings - 280H5A1H

When I Google search for a similar, I have found 7.2v Hi-MH GP320BVA6 (https://www.buyabattery.co.uk/alarm-bell-box-battery-7-2v-7-2-volt-ni-mh-gp320bvh6a6.html) Apparently, this replaces 6N280BC

What does all this mean? Can I replace a 6v with a 7.2V? What does the code tell me?

Thanks and toodle pip]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18383 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18383 Tue, 09 Dec 2025 11:54:43 +0000 Dai Gwynne We knew that such a response was likely, and we actually submitted an alternative application where the roof is insulated from below. This has been granted approval, but particularly now that we have estimates of the cost of dropping ceilings to give us a bit more headroom, we are keen to question this policy through a Planning Appeal. The client was formerly a councillor- Liverpool's first Green Party councillor in fact - so he is not unused to pushing for changes in policy.

We want to argue that placing insulation outside the rafters is inherently safer from a condensation point of view, as well as allowing more headroom inside. We see this as a fight that may be worth taking on for the whole city (and wider?) rather than just one house. It could be useful to have expert opinion to support us in our Appeal. What evidence would be best to show. (We need to get the appeal statement in before Christmas best by say 18th December)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18203 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18203 Sun, 29 Sep 2024 15:01:01 +0100 Victorianeco
Could I get them in 1900mm width and 1200mm height? If so I'd like 5 of them for the following property:
https://drive.google.com/file/d/1B-VpHGUqUlascnhMbsdKpxQxifg7WSUV/view?usp=drivesdk


The concern we have is that the width of 1900mm means that they'd take up a lot of room opening internally - do people really use them to open inwards or just useful for cleaning? I guess if we were to open them we wouldn't open them fully anyway, I don't think we've ever opened our existing windows fully...

By using one large pane as opposed to the existing 2 per window we feel would give better views and cleaner look from the curb

Thoughts please]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18369 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18369 Thu, 13 Nov 2025 10:13:17 +0000 owlman
TRÅDFRI
LED bulb E27 470 lumen, smart wireless dimmable/warm white globe
£12Price £ 12
Energy efficiency class C]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18382 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18382 Sat, 06 Dec 2025 10:15:46 +0000 revor
https://insideevs.com/news/780568/tesla-lg-battery-pack-defects-china/]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18364 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18364 Tue, 14 Oct 2025 20:15:08 +0100 Rex
Just been watching an item on the BBC regarding below standard EWI (https://www.bbc.co.uk/news/articles/c203rnepzexo) I guess this is similar to the poor cavity insulation.

Is the failure of either type of insulation because it is a mistaken concept, or because of poor installation by snake oil installers?

As an aside, am not considering either, just interested.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18381 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18381 Fri, 05 Dec 2025 20:03:36 +0000 blubb
I am extending our MVHR system and I need an extra run of 125mm spiral air ducting. Does anyone in the Cambs area have any leftovers from their installation sitting quietly in the garage?

Any advice where to source it?

Many thanks!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18377 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18377 Mon, 24 Nov 2025 13:54:13 +0000 mattp
I'm getting a small lean-to at the back of the house rebuilt next year, which will make an open plan kitchen / dining area when it's done. The existing floors are all suspended wood and the drawings I've had done add a new suspended floor in the new part (the new floor area is only about 2.5 m x 6 m).

I would quite like to get liquid underfloor heating throughout the dining / kitchen area (total area maybe 6m x 6 m).

I think underfloor heating is generally considered to be much better with a solid floor, but my budget is already a bit stretched so I'm fairly reluctant to get the whole area filled in and concreted.

There are some options for underfloor heating with suspended floor and I have seen examples of people doing it by insulating between the joists then embedding the pipes in a screed that sits flush with the top of the joists. My worry with this is - won't it crack with time? Also it is putting a lot of weight on the joists. The spans between the sleeper walls are small - roughly 4 feet, so I suppose it can take a bit of weight but I've no idea how much.

The other option I've seen is to replace the floorboards with a thick chipboard that has pre-cut grooves for the pipes.

My question is are either of these good options, or am I better off just installing radiators and spending my budget elsewhere?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18370 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18370 Sun, 16 Nov 2025 19:34:48 +0000 Rex
https://www.bbc.co.uk/news/articles/c0rpy7envr5o]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18376 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18376 Fri, 21 Nov 2025 14:47:45 +0000 ChrisGT https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18373 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18373 Wed, 19 Nov 2025 12:10:13 +0000 Simon Still
The approach was low flow/low temperature and no internal thermostats or motorised valves. We were also advised not to use inhibitor - although at 10 years we'd have probably exceeded the lifespan of that in any case.

Has anyone done their own flushing for bio sludge - is mains water pressure normally enough or does it need pumps?

(though since I've got a broken collarbone at the moment so I think we're going to have to pay someone to do it rather than DIY)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18372 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18372 Tue, 18 Nov 2025 18:21:57 +0000 rsk1 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18374 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18374 Wed, 19 Nov 2025 15:56:14 +0000 Rex
When I built, I really want screw piles but was told that I could get the 10 year warranty. So whet with conventional piles.

There is a small site near me that I am watching with interest. I was eight lock-up garages and is now becoming three, small, two story terraced houses. And they are using screw piles with a steel ring beam.

Watching the process, and I am amazed at the amount of work. First. the piles have been cut to a predetermined height so the top-hat can be fitted. The top-hat part has not been drilled, so they are doing that on site; 56 piles with four holes each in 20 mm steel. That is a lot of work.

Next, the top-hats are fitted and the ring beam assembled, fully bolted together and the top-hot holes are marked ont he underside to the ring beam. Then, remove the ring beam, drill all the bolt holes before the ring beam is sent off to be galvanized.

A lot of work but I'm following with interest.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18350 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18350 Sat, 13 Sep 2025 15:34:59 +0100 jam295
A couple of years ago, we bought a two-storey 4-bedroom 1890 detached Victorian house in north-west England (108 sqm footprint, 350 sqm wall area) in need of substantial rennovation. We have replastered, replumbed and rewired the interior and it is now heated by a modern gas boiler and radiators, with wet underfloor heating for the kitchen-diner area. The exterior was rendered long ago, and the rendering is in extremely poor condition and needs to be replaced. At the same time as replacing the rendering, we are trying to decide whether to also add external wall insulation (EWI), as the walls are currently uninsulated. We would use breathable external wall insulation, and prefer a natural product such as wood fibre. We have quotes for (uninsulated) Ksystem TC15 Silicone Solo for the render (base, mesh, primer, silicone), which is marketed as "breathable".

The house has "early cavity walls", so the cavity is only a few cm, and not wide enough for cavity wall insulation. We decided not to insulate internally due to worries about condensation forming in the walls. There is a loft, and a cellar under the front of the house.

I have used the SapJS calculator at https://openenergymonitor.org/sapjs/ and entered our building's properties, as best as I can estimate them. The modelled annual heating energy usage is about 48,000 kWh, which matches our actual annual usage (measured from gas bills) to within about 8%. I am somewhat skeptical that this is not a fluke, due to all the uncertainties involved, but for the moment let's assume it is roughly right. The model predicts 42% of total heat loss going through the walls.

I used a current U-value for the walls of 1 W/m2K, based on the different layers (inner surface, plasterboard, timber battens/gap, inner leaf, air gap, outer leaf, render, outer surface). Bringing this down to 0.3 W/m2K with EWI to meet building regulations would reduce total heating energy usage to 33,000 kWh, and save about £1000 per year.

Our motivations are not purely financial; we would also like to reduce our energy expenditure for environmental reasons, so even if it took a while to pay back, we would probably still do it, so long as the upfront cost (over and above the existing project cost of rerendering) was not prohibitive.

Ideally, we would eventually like to install a heat pump and solar panels, but our understanding is that the heat pump would only be powerful enough if the house is well-insulated.

My concerns are:
- My modelling with SapJS is a lay-person's calculation, and I would like to get this professionally assessed. The important question is "How effective will the EWI be?", because if it does not save significant energy, it is not worth doing.
- The house has many other heat losses, e.g. from draughts and uninsulated suspended floors in the front of the house. Does this reduce the effectiveness of the EWI, or is this an entirely decoupled problem?
- The wall cavities open at the top into the (cold) loft, and there are air bricks in the outer skin for ventilation to reduce moisture in the cavity. If the walls are left like this, then hot air will easily convect out of the top, presumably causing massive heat loss. We could seal the cavities at the top and block the air bricks, but will this cause problems with moisture/condensation? Could the cavity instead be vented internally? Since the cavity will now be warm, as it will be inside the insulation, maybe this is not a problem? Alternatively, could we fill the cavities, since now that they will be warm, interstitial condensation shouldn't be a problem?

What sort of professional could I hire to give me the best advice, taking into account the particular nature of this old building, and all the "edge cases" that might be relevant to the decision? I have found companies who will do an energy assessment, but will this be careful and customised enough? I've heard that EPC assessments are often very rudimentary, and I need more than a basic tick-box exercise. Do I need an architect? Some sort of building engineer?

How can I know whether the EWI installer will take proper care of all the junctions and edges, which I understand are vital for avoiding cold bridges? Do they need to worry about interstitial condensation?

I would appreciate any advice that people here might have.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18366 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18366 Mon, 20 Oct 2025 19:39:15 +0100 Victorianeco
2 products with differing specs:

Ali Vu
https://www.seniorarchitectural.co.uk/architectural-systems/ali-vu-window/
Standard Casement Opening Outward (not available in T&T)
Total Project Cost (S&F) = £21,030

PURe
https://www.seniorarchitectural.co.uk/architectural-systems/pure-window/
Tilt & Turn
Total Project Cost (S&F) = £30,115

Both are based on 28mm Triple Glazing (4-8-4-8-4), Low 'e', Black Warm Edge Spacer
Inclusive of aluminium cills - not required as EWI?

My query is T&T worth an additional ~£10k?

I am trying to work out what the U-Values are as the spiel states the former as low as 1.0 and the latter 0.71 but I don't know what configuration of glass these are based on as both frames can accommodate up to 44mm

So my questions are thus;

1. What is optimum make up of glass so I can get a more accurate spec. The fabricator said the glass cost wont make much difference to the price
2. Anything else to ask at this point?

Thanks]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18332 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18332 Fri, 15 Aug 2025 08:11:35 +0100 fostertom a) sound existing roughcast render
b) new OSB3 wall sheathing
c) new OSB3 over-rafter sheathing, unrendered.
Done by main contractor already on site, no allowance for his site set-up, scaffolding (already in place), all drain, RW etc alterations accounted elsewhere.

And ditto for blown-in Warmcel between studs and rafters (plasterboard under-lined).
Done by visiting specialist, and AFAIK they apply a flat fee for a minimum m3 volume, thereafter per m3 - what is that minimum?
Anyone found the problem I've had - refusal to supply unless a certificate of condensation-performance can be submitted, for the proposed construction?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18348 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18348 Thu, 11 Sep 2025 18:07:10 +0100 Julio
- Circular saw chucks dust everywhere and not very good for them
- Reciprocating saw is hard to cut good square lines with (could maybe make a jig, but becomes quite unwieldy.
- Jigsaw with long insulation cutting blade, probably the best option, but still likes to track out and bend, not giving squarest cut.

Intrigued if anyone has tried the festool, as quite an investment..

Cheers
Jules]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18352 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18352 Sun, 14 Sep 2025 19:15:10 +0100 Victorianeco
Property requires a re-roof anyway. What is best for terms of longevity? concrete tiles again or slate?

We're thinking Marley Modern's or equivalent? Any recommended brands appreciated
Slate - We don't like how fibre slates wear around the edges so would be looking at natural slates? Again - brands?

Area is approximately 150m2

What are the best mounting options for solar that blend in seamlessly? Either for concrete tiles or slate?

Roof has a South facing area and also an East and West hip. Mounting East and West would be more discrete as the South facing roof area *may* be used as a dormer at a later date. How much of a real world difference would this make?

Property will have ASHP]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18314 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18314 Thu, 03 Jul 2025 16:54:28 +0100 Modelmechanix
One for the experts here.
I have sufficent south facing space for a 3-4kWh Solar PV Ground Array on my rural property. No planning issues where I live in the north of Ireland. The proposed array site is within 10m of where I intend on installing a 6kWh A2W Mono Heat Pump. I intend to use the heat pump for UFH only as I have ample DHW heat served by other means.
Essentialy for it to heat/preheat the floor screed via UFH during the day whilst PV is generating. The screed will cool overnight and charge again where PV is available the enxt day. Thats the line of thinking anyway.
The UFH has multiple input methods so where there are low PV production days or multiple poor days in a row, I can fire the wood boiler stove or boiler pellet stove to cover the heat needs.

So I am wondering, is it possible to have the solar array, via AC inverter supply the A2W heat pump without a grid connection?

As I understand it, the inverter can supply the AC but I don't fully understand if when PV generation vaies, how that would affect the A2W heat pump. Would it work at all, or short cycle? Would the compressor start up amps requirement cause an issue if the PV wasn't generating sufficent power?
I have read several other threads but none seem to discuss how it's done or controlled, maybe its a straight forward wiring connection and I'm over analysing here.

I would be very greatful for any advice or guidance, even if its a simple - it wont work matey!

Cheers fellas,
Karl]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18365 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18365 Sat, 18 Oct 2025 09:15:57 +0100 revor an example here.

https://www.youtube.com/watch?v=1AEZgmQvUDc

This video by Artisan Electrics (who I follow and has some very excellent videos on a number of electrical topics)
highlights a solar install he was called in to inspect for poor performance. He found a can of worms blaming it on Solar Together schemes backed by LA's driving down quality (and competence) to get the cost down. Whilst on the job took a look at a EV charger that was not working another can of worms.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18368 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18368 Tue, 04 Nov 2025 08:24:42 +0000 Victorianeco
They offer both Alu-Clad and Timber windows, my brief research suggests they may import them but they appear very helpful so far:
https://www.allanbrothers.co.uk/ab-product/alu-clad-timber-windows/

Just received some prices for my project. Which I'll add to my other thread when the other suppliers prices come back in.

As a benchmark for my project the cheapest is 2G Side guided windows:

2G Side Hung - Base price
3G Side Hung +10.2% premium

2G Tilt and Turn - Base price
3G Tilt and Turn - +8% uplift

I might ask them to price as just timber as well

Any input would be appreciated]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18367 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18367 Wed, 22 Oct 2025 12:01:02 +0100 Nick Parsons https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18362 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18362 Wed, 08 Oct 2025 12:52:52 +0100 wookey
The supplier tells me to install a 150mm deep reinforced concrete base (600mm wider than the tank - i.e 300mm all round). Which is fine, but I'm wondering if there is a lower-carbon way of doing this? Can one make a strong-enough base to avoid settling and potential damage to the tank base without just pouring 0.6m3 of concrete?

Concrete is about 380 kg/m3 so this would be 228KgCO2e, or approx one-way flight Stansted to Barcelona. It feels like there should be a better way.

Maybe the way driveways are made with an MOT subbase, and a solid perimeter to avoid spreading.
The point loading is very much lower with the tank (1.54m2 vs 0.09m2 for the tyres of a van of similar weight - i.e 1/17th of the load). I'm not sure what surface material to use to avoid risk of puncturing over time.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360 Mon, 06 Oct 2025 15:46:14 +0100 Victorianeco
https://drive.google.com/file/d/12ZZsoLmjjSMoA4AW8HBQ_oQzmi9waWuE/view?usp=drive_link

Obviously this is a thermal bridge and we'd like to engineer it out.

Option A
Remove pillar - replace with a structural beam, disc out all cavities around window openings and fit cavity closures. Then EWI.
Appears to be messy, labour intensive, minimal gain?

Option B
Just install new windows outside of external skin, EWI over pillar and walls - and be done. Perhaps not as thermally efficient but cheaper, faster, less mess?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17788 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17788 Mon, 20 Mar 2023 18:34:29 +0000 Devlin
I should be having some new double glazed uPVC windows installed in about 1.5 months. I know if left to their own devices the installers will do the bear minimum - ACME expanding foam round the edges and finish with a trim. I want a better job done so been looking at alternatives. One of them is this expanding foam which is a little pricey:

https://www.partel.co.uk/product/conpreseal-3v-bg1/

Alternatively this expanding foam doesn’t look too bad:

http://www.soudalairtight.com/INT/raam_schuim.html

Has anyone used any of these products or similar? Is it worth spending the £130 on the expanding foam tape when this expanding foam will do?

Thanks]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18355 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18355 Sun, 28 Sep 2025 08:47:48 +0100 Victorianeco
We are looking to add them to the EWI layer of our cavity wall property.

We are thinking:

- Remove 25mm of render all around the existing window opening
- Make the windows 20mm wider all around than the window opening
- Mount then externally with brackets
- Use compactfoam below window to support them horizontally?
- Then use air tightness tape around inside and outside the windows?
- Render outside using sand/cement
- Then EWI?

Is there a better detail than this?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18359 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18359 Sat, 04 Oct 2025 14:17:24 +0100 Rex https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18357 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18357 Wed, 01 Oct 2025 16:14:39 +0100 sgt_woulds
In other parts of the world, you can buy white EPDM to keep the summer temperatures down, but not in Blighty, so I had to use bog-standard black.

I've done everything I can to mitigate the summer heat on our 55m2 dormer flat roof (ventilated deck, woodfibre insulation, careful airtightness detailing), and whilst these have helped over summer, it could be better.

Does anyone have any recommendations for a reflective paint that works well on EPDM and is available in the UK?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18358 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18358 Thu, 02 Oct 2025 16:54:07 +0100 Rex
Leaving the house today and pressed the Set button on the Accenta Mini Gen 4 RKP, only to get an immediate beep, beep, beep from the external sounder. It was not the normal alarm sound, but certainly sound more like a warning noise.

Additionally, the red 'power' led on the RKP is flashing at around 10 second intervals. Unsetting the alarm, and the sounder beeping continues for around another 30 seconds.

Cannot find any reference to the issue in the manual but would appear to be power related. I will check the control panel fuses and the date of the back-up battery but of 'greater' concern is the back-up battery in the Reson 8 external sounder. It is a 6v Ni-Cad and has never been replaced in the 15 years since installation. (I only use the term 'greater' concern because that requires tallish ladder work to replace it.)

Presumably, the Ni-Cad should be replaced but the manual has no mention of a life expectancy.

Grateful for any thoughts or suggestion as to any other possible causes.

Thanks and toodle pip

Rex

PS. I have an mp4 and m4a sound files of this warning beep but am unable to attach. Does the forum not allow such attachments?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18343 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18343 Sun, 07 Sep 2025 19:17:46 +0100 tony
It might need topping up. But in my view it is an unsustainable action to remove and presumably dispose of insulation.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18345 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18345 Wed, 10 Sep 2025 18:25:22 +0100 Peter_in_Hungary
The wall needs to be vertical, the question is how best to achieve this. There is not enough space to build a false wall in front of it. I am reluctant to batten out and plasterboard the wall as I am afraid that the battens will rot out in a few years and any damp from the wall would be v. detrimental to the plasterboard. Whilst the bottom part could be levelled with increasing thickness of render by the time you are half way up you are looking at about 60 mm of render which is about as much as I would want to put on, I can't help thinking that 100 mm of render at the top would be too much even if built up in layers.

What would be the best way of levelling out this wall?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18354 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18354 Sun, 21 Sep 2025 09:23:13 +0100 chrisinbrighton
In the past ive used timber beads but found these are not good long term.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18320 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18320 Fri, 18 Jul 2025 22:35:41 +0100 Bryan_Rendall
This evening has involved building a 'climbing frame' (calling it a scaffold would be stretching it a bit...) up the roof and around the collector so I can get a right look at it and decide where to go next. Something definitely seems to be awry inside it as there are a couple of things that look like they are meant to be tubing / pipe clips, made of wire, loose and visible around the edge of the aluminium sheet with the selective coating on it. That sheet also seems to have slipped down a bit, as there is a gap at the top of the panel, where you can see by the sheet to the insulation behind it, and this gap is visible at the top, but not the bottom. And in one corner of the sheet, some of the selective coating has come off in what I guess must be flakes, revealing the aluminium underneath

As its an inroof install, deciding what to do next needs some careful consideration. Options;

• Reverse the installation process. This involves taking off the cemented on clay ridge tiles, about 3 rows of Welsh slate and then the top flashing / hood to get to the top pipe connection and brackets. This will be reasonably painful, as those top 3 rows of slates are cut into some unusual shapes to fit round the flashing, and being the last courses, will only likely have one full course, the rest being cut down ones, with a reasonable amount of "creative fixing". Once released, lower the complete panel to the ground for further investigation.


• Cut access holes in the top flashing / hood to gain enough access to disconnect the top pipe and brackets, then lower the complete panel to the ground. Saves disturbing ridge tiles and slates, but then a dilemma on how to rebuild the flashing on completion again. Its made of aluminium (alloy) sheet and has quite a complex set of folds and then folded / rolled seams. Trying to release it and getting it to bend up will likely just result in creases all over the place. Cutting access holes will probably keep it flatter as a base for a subsequent repair.
  That could be done with lead, suitably patination oiled, but difficult to beat into shape if its over aluminium.
  Else get some more of that brown coloured sheet and make a panel that covers the whole existing flashing, holes and all


• Try and split the panel up there - Lift off the glass and frame, and do the investigation in situ. Tricky as there is no obvious and accessible fixings that hold the glass frame onto the body of the panel. There is also the fun then of handling the glass and frame on a pitched roof, and finding somewhere to set it so that it remains put and doesn't get broken.


• Take the glass only out of the frame in situ, after popping out the bead seal that is holding it in. In theory, this is straightforward, as 100% of that seal is accessible without disturbing anything. However, there is then the fun of handling a large sheet of glass on a pitched roof, with no frame to protect it. Chances of breakage probably about 1000%!

I think I am leaning more towards option 2 - Cut access holes in the existing flashing - then get a sheet of aluminium flashing material and cut a piece that can still slip under the slates above, and be suitably fixed to the existing flashing, but in a way that can be readily removed again in the future. That then becomes a full panel down to the ground job, which is slightly challenging given the 6 Velux windows in a bank of 2 x 3 underneath it. But the panel went up after the windows went in, so I just need to reverse that process. My 'climbing frame' already involves 2 x 6m long lengths of 6 x 2 up the sides of the panel / Veluxes, so these can act as a railway track to slide the panel down on.

Another scorching hot day today here in Orkney, and the store temperature is still sitting at just 52 degrees. So something needs to be done! :cry:]]>