insulating floors

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Nicky cigreen

Joined: 25 Jun 2007
Posts: 9868
Location: Devon, uk

Posted: Tue Aug 01, 23 11:15 am Post subject: insulating floors

As part of my ongoing efforts to increase the insulation in this house, thoughts now turn to the floors. Downstairs floors are all concrete. They are cold. I've read 20% of heat can be lost through floors.

My budget and headspace will not stretch to anything that involves digging up the floors, so solutions will have to be on top, and underneath any flooring - carpets in some rooms - other flooring in kitchen and bathroom.

Any opinions on what to use? Any experience?

Slim

Joined: 05 Mar 2006
Posts: 6612
Location: New England (In the US of A)

Posted: Tue Aug 01, 23 11:32 am Post subject:

Is the concrete insulated from the outside at all? If not, is there a possibility of burying foam board around its perimeter?
Can also put a thin foam underlayment over the concrete and raise the level of the floor inside with new flooring over that, but pay mind to vapor permeability... If the concrete is the coldest area, then that is where vapor will condense.... And that cost will probably be more in supplies than only trying to further isolate the concrete from the cold air around it outdoors.

dpack

Joined: 02 Jul 2005
Posts: 46192
Location: yes

Posted: Tue Aug 01, 23 12:09 pm Post subject:
decent underlay seems to work on our ones

tahir

Joined: 28 Oct 2004
Posts: 45665
Location: Essex

Posted: Tue Aug 01, 23 1:55 pm Post subject:
To make a real difference you'd need probaby 100mm of insulation on top of your floors PLUS insulation around the perimeter to the depth of the slab as Slim suggests. I think do as dpack says, any gain in performance will in real terms be neglible but it should be more comfortable underfoot.

dpack

Joined: 02 Jul 2005
Posts: 46192
Location: yes

Posted: Tue Aug 01, 23 2:45 pm Post subject:

this might be irrelevant but, daughter's house was a bit shaken and eroded

the kitchen needed robust more than insulated, the slab is direct onto packed hardcore and ballast, then sand and DPM averages about 300mm deep nowt less than 200mm or over 500mm,it had to deal with levels as well
i reckoned i had put enough metal in the walls not to need it in that floor

they report it as rather pleasant after it dried for a year as it takes heat in summer and gives heat in winter, it never feels hot or cold, which surprised me

it does stop the rather bounced foundations from moving into the kitchen which was the prime motive

re cold concrete, if you have it replacing it would be daft money unless you need to replace for other reasons

do you know anyone with a "damp"meter, if it is very dry there is little need to worry about impermeable floor coverings, if it is damp find out why

dry concrete in a house never seems to feel cold, damp stuff can be very unpleasant

another thought, is this an old house or on an old site? Or maybe not quite as one would hope after "our Kevin" mended it?

try bumping it at 300mm centres with a stout stick, does anything sound different/hollow? is any of it wonky?
try not to think why i suggested those, i have come across "reasons" for cold floors/cold spots etc, if there are none it is a good and comforting start

tahir

Joined: 28 Oct 2004
Posts: 45665
Location: Essex

Posted: Tue Aug 01, 23 3:09 pm Post subject:
Damp is a whole nother issue, and will definitely make the slab feel colder

dpack

Joined: 02 Jul 2005
Posts: 46192
Location: yes

Posted: Tue Aug 01, 23 3:55 pm Post subject:

i recon damp should be first check when the current surface is rolled back to assess the situation

heath and alex's one is dry because of the gully drains we put around the perimeter of it(and fixing the broken old drain and pipes) although the yard surface slopes towards the house on 3 elevations in one yard( that was an "our kevin" job as well) it would have been daft costly to remedy directly

re damp easy mk one eyeball for starters, is the dust/muck dry and floaty or stuck to the concrete?

Nicky cigreen

Joined: 25 Jun 2007
Posts: 9868
Location: Devon, uk

Posted: Tue Aug 01, 23 4:42 pm Post subject:

thanks all.
Damp is definitely an issue for this house, as previously described, but not in the floors. They are dry, the dust is dusty! and I have even tried that test where you tape down an area of plastic and leave it overnight to see if there is condensation - no.
I have no idea if any insulation was included in the floors, as they are before my time, but I doubt it. I'll consider the perimeter thing.

Increasing the comfort factor will make a big difference, I think.

tahir

Joined: 28 Oct 2004
Posts: 45665
Location: Essex

Posted: Tue Aug 01, 23 4:46 pm Post subject:
Really unlikely that there was insulation under the slab. Insulating the perimeter will only make a marginal difference unless you whack on loads of insulation to the floor.

dpack

Joined: 02 Jul 2005
Posts: 46192
Location: yes

Posted: Tue Aug 01, 23 5:43 pm Post subject:

if the floors are dry the visqueen or whatever is doing its job, that is good

insulation, good fleece membrane(it looks a bit like the stuff for plants) to separate concrete from good underlay to suit the top surface(ask pro flooring folk, not our kevin, as to specs and prices etc for the situation)

probably best easiest comfort per Â£ rather than more dramatic options

hunt yer damp and kill it, again it is often the correct and quite inexpensive thing that sorts another bit of it

kill it, drive a stake through its heart and then kill again and steal its assets
damp is the biggest font of all problems in most house type buildings

----------------------------------------

if i can i will try to help with the damp stuff, it was a trauma for some clients but "yes we can at a fair price", "its dry rot to you but(don't tell them that bit) it can be mended"

damp best fettled and prevented

i have no idea what your home is made of, what condition it is in, or the surrounding landscape especially the 20 m around it, generic damp advice is not much use. it is very site specific

each half of a semi can have similar symptoms with different causes

quite often a quick look at ground level compared to original ground level gives means of remedy, bridges (bridges are easy) dropping the surface to where it should be is pick and barrow stuff, some things are a 5 min zero or minimal cost job, some need robust interdiction

make it dry will help loads with make it warmer in winter, and it won't fall to bits or get eaten which is always good.

show tell ask

we will try to assist

NorthernMonkeyGirl

Joined: 10 Apr 2011
Posts: 4627
Location: Peeping over your shoulder

Posted: Tue Aug 01, 23 7:38 pm Post subject: Re: insulating floors

Nicky cigreen wrote:

If any grants come through for heatpumps / upgraded heating, I gather that using the concrete as a store for underfloor heating can be pretty handy. In which case you want insulation NOT between you and concrete, but between concrete and outside.

However, in the meantime, and as long as it doesn't create changes that cause damp, it sounds like anything to separate you from concrete would be best. You can search various underlays by thermal rating (sometimes, on some websites) and there are also ones that include foil etc to reflect heat around. Confusingly, a lot of "above the slab" insulation is intended to THEN be covered by e.g. plywood then e.g. carpeting.

I think I would be looking for underlays, carpets, and rugs made of mainly natural fibres so I'm not tempting fate re. damp!
I've put new floor in the bathroom over the top of - essentially - polystyrene with a silver foil backing. I think the most obvious change is that the vinyl tiles themselves are not cold to the touch.

How is everything for draughts? An icy blast at ankle height can be very striking and not in a fun way.

Anything relevant here? https://www.engineshed.scot/building-advice/

I currently work with historic building experts, they recoil in horror at the mention of spray foam, and seem to be keen on reverting / understanding the original processes of the building - often including breathability, NOT fully sealing off from outside...

dpack

Joined: 02 Jul 2005
Posts: 46192
Location: yes

Posted: Tue Aug 01, 23 9:26 pm Post subject:
ace advice ankle wind, bad and often an easy fix

Nicky cigreen

Joined: 25 Jun 2007
Posts: 9868
Location: Devon, uk

Posted: Tue Aug 01, 23 9:52 pm Post subject:

dpack wrote:

if i can i will try to help with the damp stuff, ...

thanks Dpack - we have covered this a few times - the main issue is the house is about 4 foot lower than the ground level outside which A I do not own and B has some buildings on it. This house is a lot older than the surrounding buildings and the ground levels have been built up,then built on. So French drains etc are out. The standard advice - and the advice you have given before - is to tank the walls on the inside. Whilst this will contain the damp, historic building experts have advised against the idea as it does push the problems into the original walls which then develop their own problems, including destroying the lime and well.. mud.. holding the stones together. We have already pulled some dodgy cement off the inside walls at their suggestion, and that considerably helped reduce the damp , so I am unlikely to go the tanking route.

indeed the concrete floors are frowned upon, as again these push the damp issues to the walls. It has been suggested the floors be lifted so they can breathe. But I am not about to do that - because budget and headspace.

I also have identified water coming in in another area and am in the process of having that fixed. it does take a long while for these thick walls to dry out after each fix, so it is an ongoing project.

Last edited by Nicky cigreen on Tue Aug 01, 23 10:30 pm; edited 1 time in total

Nicky cigreen

Joined: 25 Jun 2007
Posts: 9868
Location: Devon, uk

Posted: Tue Aug 01, 23 10:28 pm Post subject: Re: insulating floors

NorthernMonkeyGirl wrote:

thanks NMG - useful advice. it can be hard to find the balance between breathability and insulation - yes that website agrees with a lot of things I have already been advised, which I find encouraging - I will read further - my house is old and definitely built to let things breathe and have had to learn to work with the house as it was intended - unfortunately in more recent years all sorts of remedies were put in that caused more problems than they solved and I am gradually undoing them.

how did you get on with the vinyl tiles - were they the kind that clicked together? I gather these can handle insulation underneath, and I might put some in the downstairs loo. (well not the actual loo... )

at the moment, for long winded reasons, two downstairs rooms have no covering at all, so anything will be better, but it would be nice to make it cosier

I'll do some research of natural materials. re rugs I am a fan of the thickly woven rag rugs made from cotton - it's recycling of sorts, natural offers some comfort, and most importantly wool moths don't eat them.

You are right about drafts - I am working my way through fixing them all.

Mistress Rose

Joined: 21 Jul 2011
Posts: 15950

Posted: Wed Aug 02, 23 7:53 am Post subject:

As far as rugs are concerned, unless the moths are really a problem, you can make your own. I made one for our lounge using wool/nylon rug yarn and special canvas using only a bit of wood for a length cutting guide for the wool, a pair of scissors to cut said lengths and a rugging hook. Even more 'green' is cutting lengths of old cloth into strips and pushing them through hessian. Another way is to weave them using cotton string warp and lengths of old cloth with a loom as illustrated in 'Scouting for Boys' and various other books, which could be easily set up in your barn.

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