to insulate or not to insulate, that is the question

evosteo

hi all,

im currently in the middle of doing the main bedroom and box room up in the house,

72.5mm insulated plasterboard on all the external walls,

i was also planning on maybe installing either 200mm fiber glass or ballytherm 50mm aeroboard under the bedroom floors, the main bedroom which is above the sitting room and is open plan,
and the box room which is above the porch and is probably the coldest room in the house,

is it a waste of time and money installing the extra insulation under the floorboards or would there be good reason to? i think the box room will benefit from it the most


cant have too much insulation???????

cheers

steve

Calahonda52

Yes you can have too much insulation, especially if you don't address uncontrolled air ingress, otherwise known as airtightness, in the house.

Insulation that allows cold air to pass through it is useless

whizbang

+1 above. But too much insulation is only wrong if its in the wrong place, or wrongly placed..or wrong type..or ..

In your case, under the floorboards, make sure there is zero air flow around the floor joists where they meet the external wall.
insulate here with 100mm Aerobord, cut a few mm bigger than the gap, so it self seals. It can be difficult to get perfect cuts though.

Ideally continue the insulated plasterboard right down to below floorboard level.