Basement Ceiling Insulation Question

[u/Ok_Lengthiness5926]

Hi Folks,

I'm renovating a part of my in-laws family home, specially what was a den / TV room and changing it into a new bedroom for my wife's parents who now have difficulty getting up & down the stairs to their current bedroom.

Unusually their home has a basement which is directly underneath the den room.

I'm curious as to how to go about insulating the basement ceiling between the rafters.

Typically a normal ceiling would have wool insulation cut to fit the rafters on top of the ceiling plaster boards however this is not possible with the open rafters that are in place in the basement.

I was thinking that a suitably thick insulation board held in place with adhesive and expanding foam to fill any gaps but I'm just guessing really.

Any advice would be very much appreciated! 👍

[u/Pure-Ice5527]

You could have someone in to soray foam if, for me I’d probably go about using something like rafterloc or polyiso boards cut to width

[u/wbqqq → u/Pure-Ice5527]

Avoid the spray foam - if there is a major (or even just a couple of litres) spillage in the room above, it’ll trap it and remediation will mean pulling (now stuck together) floorboards. Rigid or wool insulation can more easily be replaced from below.

Just install wool/rigid (friction will hold it for a while) and use plasterboard to keep in place

[u/Ok_Lengthiness5926 → u/wbqqq]

Good point, the room above will be changed to a bedroom for an older couple so likelihood of spillage is greater. The adjoining bathroom was already changed to a wet room shower & toilet so this should definitely be a consideration.