thinest external wall to meet building regs

[RobertL]

Can anyone suggest how to make the thinnest wall that will meet building regulations (especially part L) for an external wall?

I am building a oen ground floor side extension along part of the gable end of my terraced house, but the available plot is only 700mm wide at its narrowest. I want to lose as little internal width as possible.

any suggestions?

Robert

[Bob Minchin]

Presumably you can virtually do away with the inner skin if you have arrange for all load bearing needs to be catered for about head height. So from the inside. Plasterboard, vapour barrier/insulation in a metal studding system, minimal damp gap cavity with the stud supported on the exterior brickwork skin. Might get you to 200mm overall with skim coat?

Provide the length of this wall construction is kept to a couple metres only then you should get away without piers.

Will poss be a job for an architect though I guess to prove to the BCO that all requirements are met.

Bob

[Owain]

You can use a double glazed window wall system, similar to that used for shop fronts, if you can support the roof above (cantilever slab?) and use compensatory insulation elsewhere to meet Part L. Should get you down to about 100mm for the framework and the thickness of the glass for the infill. Glass can be frosted/etched for privacy.

Owain

[js.b1]

Render over Expermet (metal mesh) attached to Knauf cement panel, celotex on inside.

I think it is Knauf cement panel, there are many, they come in planks for cladding to sheets. The only note is they are very heavy, something like 1.2 tons per metre-cubed. I think insulation-direct or somewhere similar has several of them, they range from about =A325 per sheet up to something ridiculous if you go for very fancy advanced materials.

I recall there are 2 figures for BR, #1 is the overall figure, #2 is the minimum figure. You just need to meet the minimum figure with a little extra elsewhere to compensate.

Any architect should be able to solve this one off the top of their head. Glass is the other suggestion, and a floor to ceiling window is quite attractive if that area inside can be used as a play area for children to sit and watch the rain outside.

[Lee Nowell]

I seem to remember that when I had a similar issue, working with BC, we agreed on...

100mm stud wall filled with Cellotex Insulated plasterboard on the inside (25mm)

I guess overall thickness would then depend on your prefered exterior finish. We did 18mm ply then EML and render so probably around 150/

160mm in total.

[Tabby]

Vacuum insulation panels have by far the greatest insualtion per inch, so might be of interest. They don't come cheap though.

NT

[The Natural Philosopher]

Con the bco by making that part a double glazed window.

[Paul R]

I am working on the same problem. My verbal discussions with BCO (not been on site) suggest that I can use plasterboard, vapour barrier, 120mm stud (with 100mm Celotex or equivalent infill)external board, breather membrane and am planning to use Delta-PT membrane with screed to finish.

I await to hear other suggestions.

Paul R

[Martin Bonner]

You might be able to make things thinner with aerogel insulation rather than Celotex.

you only need half the thickness.

Of course, you probably need to budget for twice the bank balance ...