Green Building Forum - Advice and sensible London-based contractor for internal insulation

Advice and sensible London-based contractor for internal insulation

DamonHD — Sun, 03 May 2009 13:26:28 +0100

Hi,

First of all: hello from a newbie... B^>

Now, on to the substance.

We've done a lot of obvious things to our 1968 timber-frame end-of-terrace house to more-or-less double heating efficiency over the last year or two and shrink our home carbon footprint considerably (maybe from 6tCO2/y to 2t/y):

http://www.earth.org.uk/towards-a-LZC-home.html#todo

and:

http://www.earth.org.uk/saving-electricity.html#meter

But what I *believe* we need to do next is improve the exterior walls from an estimated U-value of 0.8W/m^2/K (in part from the SAP tables and guessed plasterboard / small void / brick outer leaf) to better than current building regs, ie maybe 0.3 or less.

I *think* that this would be possible with a foil-based insulant insert in the void and a lining of something like Spacetherm aerogel inside without losing too much space. I think that would also allow enough air circulation to avoid rot in the structure.

What I'm *sure* I need is (a) grown-up advice and (b) a sensible localish contractor to do any install (I'm certainly not handy enough to attempt it myself). I thought I'd got both but everything went very quiet. B^>

At some point I hope to save ~2MWh/y in gas DHW with solar thermal (in addition to our existing solar PV), and would expect to have to pay ~Â£4k for that. I'm prepared to pay pro-rata a similar amount for space-heating savings from insulation if needed, ie up to ~Â£2k/MWh/y saved for a job well done.

So, any suggestions from anyone? Does this sort of work need building control/consent/permission?

Rgds

Damon Hart-Davis
Kingston, London

Advice and sensible London-based contractor for internal insulation

tony — Sun, 03 May 2009 16:05:05 +0100

You should consider external insulation as if internal you will build in thermal bridges at junctions of internal partitions and the floors.

Advice and sensible London-based contractor for internal insulation

DamonHD — Sun, 03 May 2009 16:53:05 +0100

Thanks Tony!

External insulation will be difficult IMHO as (a) we are not allowed to alter the appearance without permission (b) front and back walls are hung tiles and (c) the blank north-facing wall overhangs a footpath and we might need permission to clad over it and intrude into it.

And the chap I spoke to at the association of exterior wall insulators (or whatever it was) thought it was very unlikely that anyone would come to do a job as small as ours (40m^2)!

However, I'm not against it at all.

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

jon — Sun, 03 May 2009 17:08:32 +0100

As Tony said. You should not consider internal without professional advice. If you get the advice though, it will probably be to do it externally.

Advice and sensible London-based contractor for internal insulation

tony — Sun, 03 May 2009 17:39:01 +0100

Sound like very easy to me to remove the tile hanging and add insulation and replace tiles -- problem half solved ( so my fee is only half )

The footpath problem is not insurmountable nor the other elevations -- is the house brick?

Advice and sensible London-based contractor for internal insulation

DamonHD — Sun, 03 May 2009 17:51:45 +0100

Tony: timber frame with brick outer leaf on north wall and parts of the east/west walls, otherwise hung tiles.

Jon: well, yours is some of my advice too, thanks!

I don't think I made clear above: I'm trying to cut 2MWh/y off hard-winter space-heating demand, from ~6MWh/y.

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

Wruck11 — Wed, 06 May 2009 14:24:59 +0100

My advice follows the same lines as everyone elses, it would be much easier to take of the tiles and fiz a foil insulation before replacing them. It also sounds like the cheapest option. I don't think you would need permission as you would not be changing the external appearance. I used Triso super9 on a barn coversion a few years ago and it has to be the easiest insulation to install with the mere click of a stapler and some scissors!

http://www.just-insulation.com/super10.html

Advice and sensible London-based contractor for internal insulation

Johan — Wed, 06 May 2009 17:10:18 +0100

tony, jon,

Damon is saying its timber frame with brick cladding. In witch case external insulation is pretty pointless as it would be (should be at least...) timber frame stud work, breathable membrane, 50mm VENTILATED cavity, brick/tile cladding. In which case sticking insulation on the outside of the brick/tile cladding will do zilch...

Internal insulation on a timber frame sounds like the more sensible option I would have though. Thermal bridging at junctions with stud walls will be small in a timber frame compared to brick/block work.

Fitting foil based (i.e. PUR/PIR boards) on the outside of the timber frame would be a very bad idea. These boards are not vapour permeable, which means the timber frame won't be able to breath.

Damon,

Yes, you'd need building regs involved if you're doing changes to a thermal element of the property.

If doing external insulation on a timber frame you'll have to remove the cladding, fit battens/studs, insert insulation (something like glasswool/rockwool/sheepwool/flax) between battens/studs, fit new breather membrane on outside, refit cladding. Pretty complicated and expensive operation...

Advice and sensible London-based contractor for internal insulation

DamonHD — Wed, 06 May 2009 18:36:49 +0100

Johan, many thanks for that!

If we purely lined the inner surfaces of the exterior walls, is there some kind of part-P competent person that could do it obviating some of the red-tape, eg presumably at least avoiding a formal building inspection for example?

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

Saint — Thu, 07 May 2009 08:23:08 +0100

DamonHD, it might be worth giving Russell Smith at Parity Projects a call. He's round the corner from you (I think) 0208 296 0863 and has just done some projects like this. He presented at Futurebuild/Ecobuild this year

Advice and sensible London-based contractor for internal insulation

DamonHD — Sat, 09 May 2009 22:02:14 +0100

Thanks Saint, will do.

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Mon, 11 May 2009 14:09:48 +0100

Well, I've had two visits today (there was one no-show) and I'm hoping for some informal quotes shortly.

One of them pushed a 6.5cm nail through the plasterboard and it touched the outer brick leaf.

Two obvious (to me) possibilities to follow to insulate internally are:

1) To leave the current plasterboard envelope intact (since we know the air permeability and U-value) and build a new insulating wall inside it fastened through (small, resealed) holes to the existing timberwork. If the new stuff has a U value of << 0.8 then the overall U value should be << 0.4, ie in the right ballpark, and might not need any building control at all.

2) To strip back the current plasterwork, ie to the timbers, and rebuild the inner wall, being more careful so as to ensure that we have actually improved matters re U value and air permeability, and presumably building control would have to get involved.

With 1) I think something like less than an inch (25mm) of spacetherm (k-factor of 0.013) and plasterboard might do it (yes/no?), but things that I'm not at all clear about are condensation/moisture risks. Any comments?

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

Saint — Mon, 11 May 2009 14:29:18 +0100

Damon,
Your estimated U value of 0.8W/m2K for the construction you cite seems a little too good to me. Are you assuming some partial insulation already in the void?
Otherwise the U value would appear to me to be around 1.3W/m2K?
Nevertheless 25mm Aerogel would then give you 0.4W/m2K or so. Certainly check out the condensation risks. The suppliers will do this for you

Advice and sensible London-based contractor for internal insulation

DamonHD — Mon, 11 May 2009 15:13:21 +0100

Hi again Saint,

The 0.8 figure comes from the SAP tables for this type and age of building, and our actual measured heating requirement based on heating-degree-days and actual fuel consumption over the last winter suggest the whole house is something close to 1W/m^2/K, so I think that the 0.8 figure is plausible. (The man who did the SAP assessment thinks that there may be some quilting in the void.)

But in any case, you can see why I want to improve it! B^>

Thanks also for confirming my back-of-a-plasterboard calcs...

You've opened a new mystery to me though: how can my supplier check the condensation risks for me? What questions will they be gilling me with? %-P

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

Saint — Mon, 11 May 2009 15:30:14 +0100

Damon,
Just supply them with your construction details existing and proposed and they slap them into their program. This will calcuate the U value and also do a condensation risk analysis based on those details....simples..eh?

Advice and sensible London-based contractor for internal insulation

DamonHD — Mon, 11 May 2009 15:35:06 +0100

OK, I hear you! Though I don't know of anyone but Proctor that does the the Aerogel, and I'm not completely sure of our construction details, so... %-P

(I am probably going to pay someone to do some investigation on the construction and I'll donate a copy of the report to the council since most of this stock is their social housing and *they* have very poor records to their dismay!)

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Fri, 05 Mar 2010 10:51:18 +0000

OK, long pause, ... , may have found sensible builder to dry line living room walls with 37.5mm (or thicker) Kingspan K17 (plus related works) to halve U-value.

I am sitting on a quote that I'm inclined to go with.

Any problems likely from dry lining existing plasterboard / ventilated void / brick outer leaf with the K17?

Now also I want to consider upgrading the glazing in that room; the best I can get from my friendly local glazier is:

Window approximately 1.45m width by 2.05m height.

This window will be split vertically with a small opening fanlight to one side.
The triple glazed glass sealed unit specification will be as follows;

4mm toughened Diamant outer pane, 6mm cavity with Krypton, 4mm toughened Planitherm Total, 8mm cavity with Krypton, 4mm toughened Planitherm Total. Please note a warm edge spacer bar cannot be used with this combination.

The glass only centre pane U value would be 0.8W/m2K & g value 0.59.

Cost: Â£ 1983.00 inc vat at 17.5%

Alternatively, if you settle for BFRC 'A' rated which will be 4mm toughened Diamant outer pane, 18mm cavity with warm edge space bar and Argon Gas and an inner pane of 4mm Planitherm Total giving a centre pane U value of 1.4W/m2K & g value 0.45 the cost will be
Â£ 1028.00 inc vat at 17.5%

A trickle vent can also be fitted in addition to the opening fanlight which would be Â£ 25.00 inc vat at 17.5% more.

But can I do much better in U-value and/or cost?

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

tony — Fri, 05 Mar 2010 11:20:46 +0000

I would try some European windows there were some at Ecobuild

If you have MHRV then no to trickle vents

It would be mad to do all that insulating and then make a hole to outside!!

Advice and sensible London-based contractor for internal insulation

DamonHD — Fri, 05 Mar 2010 11:31:10 +0000

No MHRV (yet). I think air exchange still 10x Passivhaus levels though our gas (ie mainly heating) consumption did *drop* 30% this year after some tightening works so I'm getting *something* right I think!

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Sat, 06 Mar 2010 08:20:00 +0000

Any comments on the glazing?

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Wed, 17 Mar 2010 10:20:31 +0000

One last bump, then I'll crawl into a corner and cry! %-P

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Mon, 05 Apr 2010 17:59:56 +0100

OK, done sulking now, even if no wiser on the glazing front: will have to be left to another year!

In the mean time SpaceTherm / Proctor Group is being very very helpful and I'm hoping that I'll be able to dry-line the livingroom in June with something like 9mm plasterboard + 30mm aerogel to get our wall U-value to about current building regs or better.

Also aiming to use another (new) product of theirs internally to improve U-value of a v small bedroom's external wall from about 2 to well under 1.

All very exciting...

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

RobinB — Tue, 06 Apr 2010 13:07:30 +0100

Hi Damon, exciting indeed, glad it's happening for you. How does cost of plasterboard+30mm aerogel compare to cost of plasterboard+kingspan k17? I guess London property prices probably warrant it.
RobinB

Advice and sensible London-based contractor for internal insulation

DamonHD — Tue, 06 Apr 2010 14:00:29 +0100

Hi,

I don't know yet; I was going to use 12.5mm plasterboard + 45mm insulant K17 but expect to go with 9mm plasterboard + 30mm or 40mm aerogel SpaceTherm-P. The 30mm aerogel case would be reasonably comparable in thermal performance to the 45mm K17 I think.

I haven't yet discussed pricing in detail (though I'm expecting my eyes to water) but SpaceTherm previously claimed a 2.5x cost premium for a given degree of insulation when I spoke to Sam Proctor in 2008: http://www.earth.org.uk/note-on-Spacetherm-aerogel-thermal-insulation.html

I'm not expecting the insulation cost to be necessarily the largest part of cost of the whole job, but who knows...

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Fri, 09 Apr 2010 08:24:08 +0100

The 40mm-insulant SpaceTherm comes in somewhere north of Â£100/m^2, but given that the room is small I think that I'm going to close my eyes and do it. I've asked the builders for a firm quote and plan... Luckily our holiday this year looks like being very cheap. %-P

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Wed, 05 May 2010 19:14:25 +0100

Right, I've put in my order for 5 x 2400x1200 boards with 40mm insulant (and 9mm plasterboard).

I'm hoping that I'll get some free unicorn pelts for the money...

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Wed, 14 Jul 2010 17:11:33 +0100

Basic works done (ie insulation is installed): needs plastering and repainting and installation of new slimline radiator, etc.

http://www.earth.org.uk/superinsulating-our-living-room.html

Pics:

http://gallery.hd.org/_virtual/ByCategory/demolition/superinsulating/a/living/room/

The builder disliked the aerogel since it was unpleasant to work with (difficult to cut, lots of nasty dust), and for the differential in cost and space for most other purposes I'd be tempted to go for 'normal' high-performance insulation board such as Kooltherm.

So, plasterer is in on Monday, and if the weather is kind and everything dries quickly, we may be all finished by Friday.

Having discovered that behind the existing plasterboard is a ~0.5" fibre mat in/behind a plastic membrane, still in good nick, the final U-value might be as good as 0.2W/Km^2.

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

DamonHD — Mon, 19 Jul 2010 09:00:38 +0100

Having pondered the effects of the unexpected bonus plastic membrane behind
the plasterboard, I realise that it will form a vapour barrier.
The usual rule of thumb as I understand it is the have such a barrier
1/3 of the way from the warm side to the cool side (thermally)
so that the inside will generally be above the dew point to avoid condensation
which might result in condensation, mould and rot.
The existing membrane is way way further out than that,
so to try to minimise vapour migrating towards it from the inside
we will vapour-tape the edges of the aerogel around the door reveals,
and try to find a vapour barrier primer paint coat, oil or latex based.

Any comments?

Rgds

Damon

Advice and sensible London-based contractor for internal insulation

arnyj — Mon, 19 Jul 2010 13:57:09 +0100

Hello there use

ORCON F WHICH IS A PRO CLIMA PRODUCT www.proclima.com

it is a airtight adhesive, Brilliant stuff. as is the tape they do,,,, have a look at the web for guarrantee

bought through green building store with help from chap who i found when searching for something..? who got me a goods at a discount give me a ring on 07791958983

arnyj

Advice and sensible London-based contractor for internal insulation

DamonHD — Mon, 19 Jul 2010 20:28:39 +0100

Thanks: any ideas on impermeable paint/primer?

Rgds

Damon