Building Regs relating to insulation of disused chapel

[Thenewsusieq]

Hi all,

Hope someone can offer advice...

I'm hoping to convert a disused chapel to a dwelling and am a little confused over how the Building REgs will apply, particularly in relation to insulation and windows. The building is red bricks laid in Flemish Bond. There isn't enough rebate to the numerous arched original doors and windows to insulate with modern materials such as Celotex (and I worry about the long term effect of dry lining period buildings....and loathe the resulting square box effect). The first question is, will BC insist that I insulate the walls? Can I gain points by insulating floors as well as ceilings and re glazing windows with eg Pilkington Spacio sufficient to be let off insulating walls? Are these things at all negotiable with BC?

Second question is regarding alternative and more Eco/period building-friendly alternatives if I have to insulate the interior walls..... I've come across two products, Newton Diathonite Insulating Plaster and Thermapor Insulating Plaster. Has anyone got experience of them? Cost? U rating achieved with 25-50mm? Spray-on technique as quick and user-friendly as it sounds? Can Thermapor really be left unpainted?

All advice gratefully received.

 

[PeterI]

Giving this a bump (first posts can get a bit lost in the forum)

The current double glazed windows thread here http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=14194 might be of some indirect use.

 

[Penners]

Hello Thenewsusieq

The first thing I have to say is that I am not any kind of expert in this topic. The second thing is that the whole subject of insulation, and how to qualify older buildings to comply with the building regs, is an extremely complex one.

The first and possibly most important question is this: is the building listed? If so, then you may find that the constraints of conservation will exempt you from some aspects of the insulation regulations.

So it's probably best if you answer that question first, after which some people on this forum may be able to give you more informed guidance.

 

[malcolm]

If you haven't yet read Building regs part L 1b then it's worth a good read through. http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partl/approved Part 1b applies to existing buildings and conversions to residential use.

Still vague after that but my take is you won't have to insulate walls if the payback time is more than 15 years or if the work changes the character of the building (if listed or in a conservation area), or if it will cause the building to deteriorate (damp).

For some guidance on adding insulation to old buildings see http://www.english-heritage.org.uk/publications/eehb-insulating-solid-walls/ and look at the free download link on the left and other documents on the right.

 

[MatthewC]

Agree the above, especially the listed question.

As I understand it, because you are converting the use then the new building has to meet the modern standards - potentially very difficult. One fundamental question here is the approach that you intend - a "modern" approach with DPC and modern materials, or a "traditional" approach with breathable walls, paint and plaster? If the latter (which is what I would think it needs) then you might have a stronger argument to support your case. However I think the rules have changed since I did my house in 2010-2011.

Matthew

 

[Thenewsusieq]

Hi all,

Thanks for replies to date. The building is not listed and not within the local cons area. However I am very keen on treating period buildings with the respect they deserve and will fight my corner not to be made to use modern materials which would destroy the character and almost certainly cause deterioration. In fact since I wrote my post I've had a very good conversation with the BCO for the area who understood where I was coming from, made some helpful suggestions, and generally speaking agreed with me that the EH take on upgrading special period buildings to conform to Part L is the right one. Upwards and onwards!

 

[Thenewsusieq]

PS no replies as yet about Diathonite and Thermapor....any info?

 

[Penners]

I have no experience or knowledge of either, I'm afraid. See what others have to say.

 

[MatthewC]

Second question is regarding alternative and more Eco/period building-friendly alternatives if I have to insulate the interior walls..... I've come across two products, Newton Diathonite Insulating Plaster and Thermapor Insulating Plaster. Has anyone got experience of them? Cost? U rating achieved with 25-50mm? Spray-on technique as quick and user-friendly as it sounds? Can Thermapor really be left unpainted?

Well, I've not used them but details of both are readily found on-line, as I'm sure you have already found. Both claim a "high vapour permeability" which sounds OK for breathability but the rest of their websites indicate that perhaps this is not necessarily so, especially the Thermapor. The Diathonite stuff uses NHL3.5 so is more likely to be breathable, I suggest.

Somehow I would think that if I had developed something that could be used happily in place of lime plaster on old buildings then I would be saying so very clearly and loudly on my sales material... The absence of this suggests that either it doesn't do that, or else they just do not appreciate the significance - either way, not good!

Would you be able to find somewhere insignificant where you could do a small patch and/or somehow test some?

 

[Thenewsusieq]

Thanks for that.....can anyone help with U values of lime hemp plaster applied internally to a depth of 20-25mm max and curving in to meet architraves and frames.....and rough cost incl labour and materials per SQ metre? S

 

[MdB]

Thought I would pop back up to post here.

Unfortunately, it isn't good news. Yes you can insulate some things better to compensate for poor insulation elsewhere. Unfortunately, your walls are such a large area that you haven't a hope of doing this. Rough figures are that you need 80mm of celotex in the walls, 160mm of rockwool / sheeps wool or 200mm+ (300mm?) of lime hemp. 25mm is just won't cut it.

Unfortunately, playtheregs.com isn't working as this was useful for giving rough figures on what you need to do.

One thing that may get you a solution is to use a heat pump for your heating. This will reduce your insulation requirements by roughly a factor of 2 to 3 due to the efficiency of heatpumps and the way they are integrated into the calcs. (It is a bit of a cheat in my book as it doesn't include losses in generating the electricity). However, if you fit a heat pump, you need very good insulation anyway due to their relative low heat output when running underfloor.

I suggest you speak to someone who can do a SAP calculation for you as they may have some ideas. Expect no easy answers though.