insulating single skin brickwork

[Eleanor]

John, thanks. I really should pay better attention! 

[pb]

For interest:

Spacetherm k = 0.013W/mK, so for a 10mm sheet you'd be looking at something on the order of 1.3W/m2K.

To get the same insulating effect with Celotex (k = 0.022W/mK or so) you'd need about a 17mm thickness.  In practice that would probably mean a 20mm board at a cost of maybe £2.50/m2.

Using Rockwool (k = 0.038W/mK) you'd be looking at 30mm, costing perhaps £1.40/m2.

Or, to put it another way, the Spacetherm is nearly twice as effective as Celotex for a given thickness, but costs something around ten times as much (perhaps a bit more).  For a couple of dormers that might be fine since, in absolute terms, it still won't be all that much money.  But you definitely wouldn't want to do a large area that way if there was any alternative.

[chasfromnorfolk]

Thanks for all extra and usefully detailed garage info... and a potential slimline cure for some chilly dormer cheeks too as a bonus.

By way of a quid pro quo, I've just finished a conversation with Sheffield Insulation re a product I'd used in several "solid floor" jobs, called, as far as I can remember Styrofloor - high density foam backed flooring grade chipboard.

They don't have that any more, being replaced by Kingspan TF73, but that is only available by the palletload. They have (but don't list) what I am told is a comparable:Cellecta Xchip board, and that is a stock item available by the board.

Job goes live in February, I'll report back.

Chas

[biff]

good luck chas,
               sometimes the simplest ,is best, but its good to know what you could have missed before you missed it,
    merry chrissers and a happy new year, to one and all, from donegal.
                                                                                         biff

[chasfromnorfolk]

good luck chas,
               sometimes the simplest ,is best, but its good to know what you could have missed before you missed it...
                                                                                         biff

My problem (or, rather, one of them) is having a wealth of information largely obsolete due to occasional use. Things (not least the Building Regs) move on so fast - and there's a danger of overlooking a neat modern solution to an age-old problem that arrived in the meantime.
40 years ago I was still specifying concrete 'boot' lintels when a patient builder asked if I'd never heard of Catnics.

With insulation (pretty well non existent when I started taking an interest in building) it's a matter of degree and characteristic. At one time - and Biff will remember this - you'd be considered pretty Tomorrow's World to put an inch of something fluffy behind plasterboard. or a stack of egg trays in the loft to make the lovenest cosier...

MC and HNY to one and all too, and particularly you, Biff.

Chas