Floor insulation

sja360

sja360

sja360

Soldato
Joined
28 Jul 2003
Posts
4,189
Location
Dundee
Looking for some advice on anyone that's carried out installing insulation for a suspended timber floor.

Currently I've got no insulation underneath and we are taking back one of the rooms to the original pine boards, the joists are 150mm in height and its roughly 400mm between centres.

I've read old buildings it's better to use natural but at the same time I read up some people have just used mineral wool as its a lot cheaper and thermally almost the same.

Issue is what thickness and type of insulation, I did think the full 150mm but I believe my insulation and joists would block ventilation to the sub floor as the joists are sitting on sleeper walls. The house has good ventilation currently underneath with several vent bricks.

The room is about 25m2 however I'm considering doing the full ground floor at around 65m2 as I've read the benefits can be substantial.

If anyone can shed light on this it would be helpful.
 
I stuck 200mm knauf loft roll in mine, should still allow passage of water vapour to prevent rot

I filled the gaps with draughtX and it worked quite well
 
eviled said:
I stuck 200mm knauf loft roll in mine, should still allow passage of water vapour to prevent rot

I filled the gaps with draughtX and it worked quite well
Click to expand...

Did you notice a difference in the warmth of the room after all that insulation? Do you have any worries about future issues having used knauf wool? All I read about is having everything being breathable etc and as usual expensive wool is suggested.

Hedge said:

I thought these videos were a good watch.
Click to expand...

I'm not willing to rip up the floorboards, in fact I've just removed carpet and sanded back one of the rooms with plans to do more rooms. The boards are in great condition so I don't fancy the upheaval. I've got a crawl space of about 40-50cm in the subfloor.
 
It's an awful job handling insulation, I couldnt imagine doing it in a tight crawl space :eek: good luck!

I did notice the room warmer after, but we did fit new carpet/underlay so that probably contributed too.
 
have a look for underfloor insulation installers in your area - I was looking at doing this myself previously and found a company who did it for less that I could buy the insulation for! and it's a horrible job
 
my rule of thumb is there has to be zero damp issues before putting any form of insulation anywhere in an old house
I used small hygrometers to monitor temps and humidity behind the insulation and its not shown cause for concern so far.

Its not as bad a DIY job as everyone is making out, and if you do it yourself you know you've used the right materials and not left any cold spots
(just get a throw away boiler suit)
 
sja360 said:
I'm not willing to rip up the floorboards, in fact I've just removed carpet and sanded back one of the rooms with plans to do more rooms. The boards are in great condition so I don't fancy the upheaval. I've got a crawl space of about 40-50cm in the subfloor.
Click to expand...

I doubt that you will get a contractor (who is not a cowboy) to work in a 500mm crawl space to fit insulation. It would be classed as confined space working any would require a 'top man', confined space risk assessments, rescue plans, and given that space, probably forced air ventilation. Either DIY it or be prepared to lift those floor boards.
 
SimonR said:
I doubt that you will get a contractor (who is not a cowboy) to work in a 500mm crawl space to fit insulation. It would be classed as confined space working any would require a 'top man', confined space risk assessments, rescue plans, and given that space, probably forced air ventilation. Either DIY it or be prepared to lift those floor boards.
Click to expand...

I realise it would be classed as a confined space. Chances are I'm going with the DIY route tbh. I'll probably curse and swear doing it but atleast it'll be done cheaply and it should contribute to a warmer house come winter.
 
Hi sja, I might be able to help a bit here.

I live in a G2 listed building and previously my 5x5m living room was VERY cold in the winter; ~13 dec with lots of draughts. Draughtex just didn't cut it. I also had downstairs neighbors going at it like rabbits all day every day; It was beyond embarrassing when my parents came over. I couldn't look at my neighbors in the eye knowing what she had been through. Some sort of insulation was a must.

I first read the listed buildings guide for insulation guide (below) so I knew what options I had to play with and chose Natuwool in the end; Natuwool was/even stated in their own guide. Getting the wrong product could have bad condensation issues and that ins't something that I/anyone wants, so I would avoid products where condensation control isn't #1. All in all, it cost about £600 for everything I needed (delivered).

It took about 2 days to install. One to lift up the floor boards & clean and another day to install and re-fix. I didn't fill every nook and cranny - I left some strategic parts exposed (like power cable runs, central heating piping etc) so that rising air has plenty of options to escape; I probably filled about 4/5 of the room I guess. Natuwool can be handled without gloves/masks, so it's dead easy to pull apart and push where it's needed if places are awkward.

The difference before/after is vast and well worth the time and effort; the room is quieter and warmer. One thing that I would change is how I got the old nails out - I should have cut them clean with a angle grinder but I ended up hitting them out with a hammer. The floor needs a sand and re-varnish anyway so any places that need filling i'll sort it out then.


https://historicengland.org.uk/advi...ings/insulating-floors-in-historic-buildings/
https://historicengland.org.uk/images-books/publications/eehb-insulation-suspended-timber-floors/


https://www.blackmountaininsulation.com/products/natuwool
 
I was worried someone would suggest natuwool :o

Is it cheaper if you go direct to black mountain instead of 3rd party suppliers? I assume there is some form of discount on bulk buying 50+m2?
 
sja360 said:
I was worried someone would suggest natuwool :o

Is it cheaper if you go direct to black mountain instead of 3rd party suppliers? I assume there is some form of discount on bulk buying 50+m2?
Click to expand...

No idea sja. If I recall correctly, I just asked for a quote on the blackmountain website and got a response from a 3rd party supplier (Intpetro / IPP); who I think owns blackmountain anyway.
No harm in asking...and you want to make sure you get the right product for the place you are in; which sounds very similar to mine. Have you spoken to any pro's at all?
 
kiteloopy said:
No idea sja. If I recall correctly, I just asked for a quote on the blackmountain website and got a response from a 3rd party supplier (Intpetro / IPP); who I think owns blackmountain anyway.
No harm in asking...and you want to make sure you get the right product for the place you are in; which sounds very similar to mine. Have you spoken to any pro's at all?
Click to expand...

I haven't checked the cost with a professional outfit. Main reason is I'm not sure it would be cheaper, fitted properly or be the correct insulation for the house. I'm fairly set on doing it myself.
 
sja360 said:
I haven't checked the cost with a professional outfit. Main reason is I'm not sure it would be cheaper, fitted properly or be the correct insulation for the house. I'm fairly set on doing it myself.
Click to expand...

yea same. I guessed that all quotes to do my place would be in the 2-3k or above category.
 
You must log in or register to reply here.
Back
Top Bottom