Eaves insulation - advice please!

jonnydeppiwish!

I have a chalet bungalow with 4 eaves as well as a loft. One eaves is v difficult to access but i have managed to lay 200mm of insulation inbetween the joists and another 100 over the top (9” joists).



the other 3 eaves have easy access but, unlike the most difficult one, they all have tongue and groove flooring. Given the joists run through the bedrooms, I’m assuming I’ll have to lift some of the boards in order to lay more insulation (can’t lay on top of the flooring as the joists are currently very well ventilated!).

Does anyone have any experience of this? Do I have any other options?

There is insulated plaster board between the eaves and the internal walls. 75mm iirc

Thanks in advance!

ThisIsWeird

Is that boarded for eaves storage? If so, then you do need to get under these boards in order to insulate the ceiling below.
You'll only be able to fill whatever joist gap is under these boards before replacing them, but that will be just as effective as thicker loose-laid insulation as it'll be enclosed, with no draught passing through the top layer.
You could add stilts to the boarding to allow more insulation under it, but I doubt it's worth it.
Then you have the dwarf wall between the habitable rooms and these eaves. They definitely need insulating, and the simplest would be to use rigid insulation, cut to fit snugly between the studs, any obvious gaps filled with foam.
Don't fill anything in between the sloping rafters - these need to be kept clear so they remain ventilated and dry.

jonnydeppiwish!

ThisIsWeird said:

Is that boarded for eaves storage? If so, then you do need to get under these boards in order to insulate the ceiling below.
You'll only be able to fill whatever joist gap is under these boards before replacing them, but that will be just as effective as thicker loose-laid insulation as it'll be enclosed, with no draught passing through the top layer.
You could add stilts to the boarding to allow more insulation under it, but I doubt it's worth it.
Then you have the dwarf wall between the habitable rooms and these eaves. They definitely need insulating, and the simplest would be to use rigid insulation, cut to fit snugly between the studs, any obvious gaps filled with foam.
Don't fill anything in between the sloping rafters - these need to be kept clear so they remain ventilated and dry.

Thanks - rigid would be very expensive as it would need to be 225mm deep!

ThisIsWeird

jonnydeppiwish! said:

ThisIsWeird said:

Is that boarded for eaves storage? If so, then you do need to get under these boards in order to insulate the ceiling below.
You'll only be able to fill whatever joist gap is under these boards before replacing them, but that will be just as effective as thicker loose-laid insulation as it'll be enclosed, with no draught passing through the top layer.
You could add stilts to the boarding to allow more insulation under it, but I doubt it's worth it.
Then you have the dwarf wall between the habitable rooms and these eaves. They definitely need insulating, and the simplest would be to use rigid insulation, cut to fit snugly between the studs, any obvious gaps filled with foam.
Don't fill anything in between the sloping rafters - these need to be kept clear so they remain ventilated and dry.

Thanks - rigid would be very expensive as it would need to be 225mm deep!

The rigid would only be for the backs of the dwarf walls - I thought you said these were 75mm timbers?

jonnydeppiwish!

Nope, no dwarf walls, just great big joists

ThisIsWeird

I was going by, "insulated plasterboard between the eaves and internal walls', so that's already insulated in any case. What thickness of insulation is used?
That boarded flooring in the pic, that's in the eaves storage areas? And there are rooms directly beneath them? In which case, yes, the boards need to come up, and the space between the ceilings below and the replaced boards should be filled with loft insulation.
You may find it's already been done?
Any cables running under there, lift them up and position them on top of the insulation as best you can.
See the slotted gaps between the underside of the roof and the edge of that boarded floor? Make sure you don't block these with insulation - they are needed for ventilation. That eaves storage area will be cold, but should also be dry.