insulating solid walls

[wavetrain]

Your not doing any structural alterations so you do not need to contact your local authority building control office...

I think the above is how the Law is currently, whatever the planningportal guide or LBO might say, remember their advice has a disclaimer.

A friend of mine had a LBO tell him that if you built a brick outbuilding (smaller than the 15/30m3 BC limit) as soon as you incorporated some insulation, then part L applied! The officer also said something like.."the question arises as to why you would want to insulate an outbuilding??". The answer of course is: insulated outbuildings do not cook in the summer and freeze in the winter, items stored in there - paint for example, last longer, chest freezers like them, and if you want to use it for a bit of DIY its a joy to use in the extremes of weather. My friend didn't bother giving that answer to the BCO, is was not worth wasting time to reply.

I have found LBOs do vary. Not all go in for intimidatory tactics.

 

[ajrobb]

Interesting point about insulation in outbuildings. I get confused by outbuildings. They are all largely exempt from building regulations. I want to know if there is a legal difference between a conservatory and other outbuildings?

However, within the context of this thread, a house is subject to building regulations. If LABC get wind of insulation they will probably insist it is done to current regulations.

I appreciate that my original suggestion of lining with foil-backed plasterboard is generally debunked. However, a solid brick 9" wall has a U-value close to 2.5 but a reflective cavity drops this just below 1.0. Sure this is still over 3 times current regs, but returns 2/3 of the savings for much less outlay and loss of space. More importantly, it should be just enough to prevent condensation.

 

[wavetrain]

I

I appreciate that my original suggestion of lining with foil-backed plasterboard is generally debunked. However, a solid brick 9" wall has a U-value close to 2.5 but a reflective cavity drops this just below 1.0.

I have only now read your origonal post. Yes a 9" brick wall has a U value of around 2.5, but putting in a reflective cavity brings it down to 1.0? I don't think so! Do you have the BRE 'hot-box' data that proves your U value of 1.0? From memory a 11" brick wall with 50mm cavity has a U value of 1.7ish so I would expect the U value of your proposal to be a little be less than 1.7 only. Stop Press, I have just download the BRE
[url]http://www.google.co.uk/url?...sg=AFQjCNGOmfe8fwr-nHVC4cWjm15_JUqvkw&cad=rja
[/url]
And it seems your foil lined cavity has an R value of 0.44 which would make your U value to be 1.2 not 1.0. I am however very surprised at the amount of reduction from 1.7. But we have not taken into account the battens, so the overal U value would be perhaps 1.4.


To give some ideas for thought: if you have a 50mm gap, then fill it with kingspan etc. If you have 150mm gap, then perhaps fill it with a cheaper product like loft insulation. Oh and don't forget that vapour barrier on the plasterboard side.

 

[ajrobb]

A sealed reflective cavity typically has an R-value of 0.6 whereas a vented reflective cavity has an R value of 0.4, as you say. So for space blanket loft insulation you can add another 0.4.

http://www.proctorgroup.com/Products/CondensationControl/ReflectathermFoil.aspx claims an R-value of 0.644

I take your point about the battens: taking conductivity of softwood = 0.13
U-value of 19mm softwood is 0.13/0.019 = 6.84
U-value of sealed reflective cavity is 1/0.644 = 1.55
Take 10% timber and 90% cavity
U-value for layer is 2.08 or R-value 0.48

Overall U-value of the wall becomes 1.128 or a saving of 55%

 

[wavetrain]

BRE say a sealed reflective cavity has an R-value of 0.44

BRE are THE recognised independent reliable source for building info. The link you have provided is a commercial body.


Tip: If BRE have data on something obtained by their own test methods, quote their data only.

BAck to the origonal topic, here is part L doc http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdf

Reading through it, I fell asleep a few times, didn't see a mention of outbuilding so I am sure that BCO was talking rubbish, anyway who has heard of conserving heating energy in a building without heating?

Regarding upgrading insulation, when plaster is stripped off, there is a 15 year payback period condition so if you say hardly ever heated that room whatever you did would have to have a payback period not greater than 15 years so plenty of ways to work it your own way.

 

[ajrobb]

I agree with using BRE figures and am happier with 0.44 for a single foil, thanks for that and the PDF link. I remember seeing a Canadian Government figure of 0.6 for a sealed cavity of at least 20mm with foil on BOTH sides.

I am somewhat dubious about misusing manufactures' claims as they don't declare the exact conditions and assumption. For instance, for Reflectatherm foil, their value of 0.644 might assume a large cavity on one side (at least 20mm) and a partial cavity between foil and mineral wool on the other.

Using the BRE R-value of 0.44 and increasing the depth of the 10% softwood battens to 25mm, we get an R-value for the battens and reflective cavity layer of 0.39 giving an overall U-value of 1.26, a saving of 50%.

Quite reasonably, using 90% Crown Dritherm 32* treated mineral wool slabs and 10% softwood battens, we get better insulation than a reflective cavity and a U-value of 1.0 for 25mm (-60%), 0.62 for 50mm (-75%), 0.45 for 75mm (-82%) and 0.36 (-86%) for 100mm. Returns diminish quite quickly. Finally, adding a 19mm Reflectatherm foil sealed cavity with 10% battens and 100mm of Dritherm, we get down to 0.30 (-88%). The Reflectatherm foil also gives us a vapour barrier.

* The slabs are not available in all these thicknesses (just 65, 75, 85 and 100mm)

 

[ajrobb]

Just checked U-value for solid layer of Celotex GA4000 held in place by 19mm non-treated battens (as per manufacturer's application sheet). You need 60mm of Celotex to get below 0.3 U-value (-88%). 50mm gives 0.34 (-86%), 25mm gives 0.53 (-79%).

 

[kingspandirect]

Hi

I work for Kingspan Insulation and our standard recommendation for insulating a solid wall would be to use the Kooltherm K18 insulated plasterboard on a set of 25mm treated timber battens at 600 centres. This board has an integral vapour check and creating the 25mm cavity with the battens allows issues with any moisture ingress to be avoided. On a general solid wall the 72.5mm board (including plasterboard) will achieve current building regulations for extension or refurbishment (0.28 W/m²K).

Hope this helps.

Anna

 

[freddiemercurystwin]

Hi

I work for Kingspan Insulation and our standard recommendation for insulating a solid wall would be to use the Kooltherm K18 insulated plasterboard on a set of 25mm treated timber battens at 600 centres. This board has an integral vapour check and creating the 25mm cavity with the battens allows issues with any moisture ingress to be avoided. On a general solid wall the 72.5mm board (including plasterboard) will achieve current building regulations for extension or refurbishment (0.28 W/m²K).

Hope this helps.

Anna

Hi Anna why the hell can I never get through to Kingspan on your tech line? I used to be able to get through all time (I'm going back about 3 years) and this is actually why I started specifying Kings rather than Celotex as your support was better. Nowadays I can hardly ever get through and as for actually speaking with the same person more than once on the same query forget it!

 

[kingspandirect]

Hi

I can only apologise for you not being able to get through to us of late. If there is anything i can help with now or in the future please do not hesitate to contact me.

Thank you.

Anna

 

[holmslaw]

Hi

I work for Kingspan Insulation and our standard recommendation for insulating a solid wall would be to use the Kooltherm K18 insulated plasterboard on a set of 25mm treated timber battens at 600 centres. This board has an integral vapour check and creating the 25mm cavity with the battens allows issues with any moisture ingress to be avoided. On a general solid wall the 72.5mm board (including plasterboard) will achieve current building regulations for extension or refurbishment (0.28 W/m²K).

Hope this helps.

Anna

Why can't the boards be stuck straight on the wall and then nailed. Like the british gypsum system I installed in my place 25 years ago.

 

[kingspandirect]

This is our standard recommendation for insulating a solid wall. With driven rain on the outside of a solid wall there can be potential issues with moisture ingress effecting the construction and boards performance. Therefore in line with our guarantees and testing this would be the preferred option.

Anna

 

[macadonald]

Hardly related, but thought I'd share my experience. I just removed all the plaster off of all the walls in my house and simply had new render and plaster put on, with no modern insulation (wasn't willing to make the rooms smaller). Never told BC and they'll never know.

At least I now have solid plaster as apposed to the 90 yr old crumbling stuff that was up there.

One day, I plan to remove the external render and may decide to insulate the outside. Not sure if BC would compromise on this?

 

[kingspandirect]

I can not comment on what your local BC will require from you, but generally speaking in line with current regulations if you make this type of alteration you would need to bring the walls up to current standard U Values.

For a render system externally we would recommend the use of our Kooltherm K5 External Wall Board.

Hope this helps.

Anna

 

[mointainwalker]

@ kingspandirect

there can be potential issues with moisture ingress effecting the construction and boards performance

Can you say how moisture can affect the boards performance because -to all extents and purposes outside precise laboratory measurement - they are impervious to moisture.