Tim S wrote:
coughed up some electrons that declared:
I realise you dont want to be bothered, but now is your opportunity to
dig it up and put insulation down that will save you n times the cost
of doing the job. Where n is an unknown number that someone else might
have more idea about.
Well, an interesting discussion came about at work today, between me and the
boss.
He's an engineer and as engineers do, he'd been doing a casual study of
flooring insulation, and I'm sure he won't mind me repeating it here.
He has a kitchen, tiled onto concrete with no insulation. Using an accurate
temperature meter, he'd noticed a 4 celcius difference between air just
above the floor (colder obviously) and air at about 1m above the floor.
Did the same at work and the difference was 0.5C.
We work in a converted apple shed, so teh subfloor is farmer's concrete onto
the ground.
Over that is 25mm Jablite and chipboard panels.
================
Observation - although not upto building regs for newbuilds, even 25mm
Jablite (I assume it would be Jabfloor 70) makes a massive difference.
So I priced it up for my house, 2 ways:
Method 1:
25mm Jabfloor 70 overlaid with 18mm water resistant T+G flooring chipboard
as recommended by Jabfloor's data sheet = (for 95m2 ish, whole ground
floor) �731 inc VAT.
Same with 25mm TB3000 Celotex and 18mm chipboard = �888
Both methods need additional materials such as DPC barrier, glue etc.
=================
The Celotex method looks like it would achieve a U-value of about 0.3 which
doesn't seem bad for a loss in room height of 43mm. Including final
flooring, door frame headroom would be reduced to 1.91m which seems
acceptable.
UFH isn't an option, but I could believe the cost of materials might
actually be recovered through less heating. I'd have to do some
calculations to prove it though.
The only thing that bothers me is having chip under my nice tiles and what
would happen with water ingress (it's going to be impossible to seal the
top layer 100% and hard for the substrate to dry out).
What do folk think?
Cheers
Tim
Do you really think a chipboard floor in wet conditions wont move or
rot in your lifetime? I wouldnt do it
There may be an easier & much cheaper way, thats to use an insulating
concrete slab. IOW the crete is made with a high percentage of
something like perlite, which insulates. So the slab itself is a
lattice of 3:1 mix and little air voids. Insulation wont be nearly as
good as polystyrene, but
a) it gets you a long lasting solid floor with no headroom loss
b) its cheap
c) its much less work/time to lay
I assume youre not wililng to dig out a few more inches.
I would also question whether if you've had concrete with no dpm for
years, you need a dpm now. I know its the fashion, but lets face it,
millions of us live in no dpm houses, and most are just fine. Your
risk, your choice.
NT