www.ultimatehandyman.co.uk

Hi guys,

I'm thinking of using 50mm kingspan sheets for under my suspended flooring secured by 25 x 25 batons the floorboards are already fitted some have been removed for re-wiring purposes.

What I'm asking is 50mm thick enough or not enough. Or is their an alternative that might do the job better.

Thanks in advance

R0nin

100mm rigid insulation is standard now,or use 150mm mineral wool draped on netting. 50mm is better than nothing but 150 mineral wool is way cheaper and will be much better.

Sorry to bump an old topic but I have suspended floor on the ground level and I can access half of the kitchen and hallway as theres a hatchway built into the floor.

If I wanted to add insulation under the floor is it as simple as adding it to inbetween the joists?

It looks like the PO used thin polystyrene sheets simply wedged up between the joists in the past, but these were removed during renovation work.

Wouldn't airflow between the joists be effected promoting rot?

wet rot is caused by timber being constantly for several weeks around 19% moisture content more or less it doesnt happen
this is why sheds and posts rot around ground level as below it will probably be more and above less

if your floor timbers can breath on one or more surfaces they will shed excess moisture