Will I cause damp?

Thomas1993

New Member
I have around a 5ft cellar underneath my living room, the cold it lets through is bad and quickly kills the heating once off, I have been advised to put 50mm thick insulation boards underneath the floorboards between the joists (by a handyman) my damp course is roughly 3 foot high in what must be the cellar. Will I cause damp by completing this DIY work I.e will I stop cold air from being able to rise too much. Any professional advice would be much appreciated, cheers in advance
 

ChrispyUK

Well-Known Member
I have around a 5ft cellar underneath my living room, the cold it lets through is bad and quickly kills the heating once off, I have been advised to put 50mm thick insulation boards underneath the floorboards between the joists (by a handyman) my damp course is roughly 3 foot high in what must be the cellar. Will I cause damp by completing this DIY work I.e will I stop cold air from being able to rise too much. Any professional advice would be much appreciated, cheers in advance

put in 100mm if you can. You could also put in a decoupled ceiling and tie up a friend for the night and no one will be any the wiser
 

Smudger1

Well-Known Member
Floor boards up get down there and fix kingspan/celotex ins boards up to bottom of joists tight jointed no air gaps then sit more inbetween joists., reboard. Ventilation air bricks front and back for air flow under there, and be snug as a bug.
 

Thomas1993

New Member
Update I have physically entered the basement and it is smaller than expected 3.5-4 foot at best. My damn course is mills beneath my joists, will I still be good to seal up nice and tight insulation boards?
 

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Thomas1993

New Member
The damp proof course sits on top of the bricks supporting the joists
 

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Thomas1993

New Member
Update, I have physically been down and it’s actually only 3.5/4 foot at best the damp course also sits on top of the bricks supporting the joists, there is a small gap beneath the joists where you can see the start of the air bricks. Can I still insulate as planned? Cheers
 

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ChrispyUK

Well-Known Member
Update, I have physically been down and it’s actually only 3.5/4 foot at best the damp course also sits on top of the bricks supporting the joists, there is a small gap beneath the joists where you can see the start of the air bricks. Can I still insulate as planned? Cheers

You need as much ventilation as possible so don’t block them off. If you can get more in then do so. You can also replace the clay ones with the newer plastic type that are more efficient. You could insulate the majority of the floor as long as you don’t block the air flow.
 
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