Advice re insulating over boarded loft

BUFF

grumbler said:

Yes, you can.

And mineral wool is no less breathable than sheep wool, but, I think, much cheaper.

Not hygroscopic though - wool is. fwiw Historic Environment Scotland prefer sheep's wool to mineral, certainly for older (e.g. pre-WW1) buildings. 

plumb1_2

Better to insulate the walls.

ic

Does the bedroom have a bay window?  If it does and the bay has its own little bit of roof, you might find its ceiling is inaccessible from the loft, so won't have been insulated.  I've just had to rip down an original lath and plaster ceiling above a bay in order to install insulation.  It was a very messy job, but I'm hoping will prove its worth in the coming weeks.

Bendy_House

ic said:

Does the bedroom have a bay window?  If it does and the bay has its own little bit of roof, you might find its ceiling is inaccessible from the loft, so won't have been insulated.  I've just had to rip down an original lath and plaster ceiling above a bay in order to install insulation.  It was a very messy job, but I'm hoping will prove its worth in the coming weeks.

If there is/was headroom - eg between the bay ceiling and the top of the window frame - then adding a 35mm sheet of Thermal Laminate Board (insulated plasterboard) to the underside would almost certainly have been easier, and would be very effective.

ic

Bendy_House said:

ic said:

Does the bedroom have a bay window?  If it does and the bay has its own little bit of roof, you might find its ceiling is inaccessible from the loft, so won't have been insulated.  I've just had to rip down an original lath and plaster ceiling above a bay in order to install insulation.  It was a very messy job, but I'm hoping will prove its worth in the coming weeks.

If there is/was headroom - eg between the bay ceiling and the top of the window frame - then adding a 35mm sheet of Thermal Laminate Board (insulated plasterboard) to the underside would almost certainly have been easier, and would be very effective.

That's exactly what I've done downstairs in another bay that had the space (was actually able to sneak in 100mm PIR plus plasterboard).  In the bedroom the bay window was lower, and we already had expensive made to measure curtains so couldn't reduce the height without incurring the cost of having the curtains adjusted.  As it is we now have 100mm PIR above the ceiling - it also allowed access to add insulation to the edge of the main ceiling bordering the the bay.