floor insulation

[kitch0978]

Hi lads,

i`ve got stripped wooden floors in most of my rooms downstairs in my house. looks great but bloody draughty! was planning on insulating between the floor joists to resolve this problem. i have a crawlable void underneath and my plan was to put spaceblanket insulation battened up in between the joists..... wat depth insulation would u reccommend? If not space blanket wat other product would be easier/cheaper to install? thought about polystyrene slabs but reckon this would be a mare to fit...... wat do you reckon?

cheers

 

[arwalder]

Suspended timber floors are ventilated and need to be to ensure he timber does not rot. This in a roof is referred to as a cold deck system.. where the structure is ventilated. A warm deck situation is where the structure is on the warm side of the insulation. The same is true for floors. If it is a suspended floor over the ground (not between rooms) then your insulation should only be beneath the joists, and should ideally form a vapour barrier too. the best away of doing this is as a previous poster suggested to use Celotex Kingspan or Extratherm, which is a rigid PIR insulant which you can fix to the underside of the joists and batten beneath and fix through the batten and insulation to the joists for extra security. All joints should be taped from underneath if at all possible (not possible everywhere obviously due to access). If you have any airbricks between the joists these should be ducted underneath the insulation using periscope vents, particularly true if you arenot insulating the whole of the ground floor. This is strangely enough something that I have just done and hope to reap the benefits of. It was made relatively easy for me by the fact that I have a good 700mm under my floor boards for me to rent out to an immigrant family or Anne Frank!.. It also serves as a good crawl space to do the insulating. Additionally you should inform Building Control as you are upgrading an existing thermal element and need to make an application... but who is gonna know!

 

[freddiemercurystwin]

Insulation immediately beneath the boards not beneath the joists as the ill-informed arwalder has suggested //www.diynot.com/forums/viewtopic.php?p=1274527#1274527