Tips on insulating old floor

07734

hi

i have an edwardian house, the ground floor in on a raised floor, with a 2 foot void underneath. it's pretty drafty, and i was going to insulate it. i was wondering if anyone has any pointers or recommendations as to the best way to do it.

i was going to use kingspan between the joists, supported with some nails. i've read of other people using rockwool supported by netting, but this seems a bit fiddlier.

am i right that it needs to be in direct contact with the underside of the floorboards? are there any moisture issues i need to be alert to? it's bone dry in the void, with some airbricks.

thanks

07734

cnocbui

I put 100mm Polystyrene foam sheets under the floor of my shed. Cut them accurately and friction fitted between the joists.

aujopimur

You can use Kingspan that's self supporting, I can't remember the proper name for the product, but your local builders providers will know what you need.

07734

Thanks guys

MicktheMan

Don't forget to also include an air tightness membrane and tape this to the walls.

What I would do is:
1. remove skirting and floor boards.
2. Fit insulation between joists and ensure no gaps and the top of the insulation is flush with the top of the joists. Use the full depth of the joists.
3. Fit airtightness membrane over entire area, tape overlaps and also tape edges to walls. Use proprietry air tightness membranes/tapes/mastics.
4. re-instate floorboards and skirting.
This will ensure you have an insulated and airtight floor.

07734

Hi mick,

is that for vapour control, or to stop air movement?

(I thought kingspan didn't require a vapour control barrier?)

MicktheMan

air movement aka draughts

07734

Great, thanks for the advice

BryanF

07734 wrote: »

hi
edwardian house, the ground floor in on a raised floor, with a 2 foot void underneath. it's pretty drafty, and i was going to insulate it. i was wondering if anyone has any pointers or recommendations as to the best way to do it.

i was going to use kingspan between the joists, supported with some nails. i've read of other people using rockwool supported by netting, but this seems a bit fiddlier.

am i right that it needs to be in direct contact with the underside of the floorboards? are there any moisture issues i need to be alert to? it's bone dry in the void, with some airbricks.

thanks

07734

do not use kingspan or any poly based insulation. this is an old house. use a natural insulation like hemp, wood, cellulose, sheepswool or at least mineral wool and be sensitive to the materials your removing and carefully to replace with appropriate materials that will not reduce the houses ability to expel internal moisture. use a natural fleece or similar to hold the insulation. do not block up the airbricks and get a natural floor underlay to reduce draughts.

is this house listed or in a conservation area? - you may be best to check its status or seek a consultation with a professional before starting any works..

best of luck

07734

Thanks bryan!!!

BryanF

MicktheMan wrote: »

include an air tightness membrane

Mick have you used this stuff
http://www.idevelop.ie/iproducts/prd/2159/timber_frame_products/actiroll_vapour_check/

I'm looking for the most natural recyclable here (I aware of the intellegent options etc;))

MicktheMan

BryanF wrote: »

Mick have you used this stuff
http://www.idevelop.ie/iproducts/prd/2159/timber_frame_products/actiroll_vapour_check/

I'm looking for the most natural recyclable here (I aware of the intellegent options etc;))

No, never used it, but would be interested in finding out more about it though.

antoinolachtnai

BryanF:

what would you think if he used this:

http://www.draughtex.co.uk/

I have used this on some upper floors in an Edwardian building. It does make a difference, and is pretty straightforward to install. This will reduce or eliminate the draughts.

I think it would be very difficult to effectively insulate the void with any sort of filling material. Any positive effect is mostly going to be because of blocking airflow. That will obviously have an implication for ventilation.

BryanF

antoinolachtnai wrote: »

BryanF:

what would you think if he used this:

http://www.draughtex.co.uk/

I have used this on some upper floors in an Edwardian building. It does make a difference, and is pretty straightforward to install. This will reduce or eliminate the draughts.

I think it would be very difficult to effectively insulate the void with any sort of filling material. Any positive effect is mostly going to be because of blocking airflow. That will obviously have an implication for ventilation.

It seems like a remedial measure, could be an interesting application for around the skirting though. I suppose its a non-evasive Air-tightness option (the add is BS though - how can they call it an insulation!) I also wonder if this product is used can the floor still expand and contract - which is what the gaps between the joints are for..

I think both AT and ins (+ maybe niose) should be considered and therefore an underlay would be better

antoinolachtnai

It is basically a neoprene foam. Everything will be able to expand and contract just fine.

It helps noise a good bit between floors in my experience.

An underlay would definitely be better, if you don't want the look of the exposed floorboards.

BryanF

antoinolachtnai wrote: »

It is basically a neoprene foam. Everything will be able to expand and contract just fine.

It helps noise a good bit between floors in my experience.

An underlay would definitely be better, if you don't want the look of the exposed floorboards.

sorry when I wrote 'underlay'. I should have said AT membrane under the floor boards. the tubing is definitely a non-evasive option:)