Insulation between suspended ceiling & hollowcore.

LowOdour

I have a 3 inch space between my suspended ceiling and hollowcore, and am looking for insulation to fill it with. I had considered putting foilback plasterboard up instead but the floor upstairs will not have any insulation so would like to have some insulation between ceiling and floor.

I have looked at the 25mm moy acoustic, but not sure if it will give enough of a u-value. (Would really need to be some form of fiberglass/glasswool though).
Also considered insulated plasterboard but that would require re inforcing the suspended ceiling which I dont really want to tackle.

Suggestions welcomed.

PaleRider

Insulation is really not necessary under Concrete slab, as any heat will rise to the upper floor and benefit the first floor rooms. It would be best to channel your efforts to the External Walls etc. This is a tricky area to insulate, foil backed plasterboard would do fine. However fibreglass would be fine also.

FesterBeatty

PaleRider wrote: »

Insulation is really not necessary under Concrete slab, as any heat will rise to the upper floor and benefit the first floor rooms. It would be best to channel your efforts to the External Walls etc. This is a tricky area to insulate, foil backed plasterboard would do fine. However fibreglass would be fine also.

Agreed - I dont understand why you would want to insulate between internal rooms. What are you trying to achieve?

LowOdour

Ok, maybe I should give more detail about the insulation spec so far. I have 60mm TW50 in the cavity.

Downstairs I have 38mm drylining on the wall. Upstairs, in the slope of the roof I have 100mm kingspan rigid board with 38mm drylining board underneath. In the ceiling i'll have 300mm glass wool.

I wont have any insulation in the floor upstairs because I wont have the depth. So is it best to allow the heath to travel up? What affect will that have downstairs? will i end up losing alot of heat?
Id rather keep the heat downstairs if it wont have a major inpact upstairs if i let the heat rise.

tred

LowOdour wrote: »

Ok, maybe I should give more detail about the insulation spec so far. I have 60mm TW50 in the cavity.

Downstairs I have 38mm drylining on the wall. Upstairs, in the slope of the roof I have 100mm kingspan rigid board with 38mm drylining board underneath. In the ceiling i'll have 300mm glass wool.

I wont have any insulation in the floor upstairs because I wont have the depth. So is it best to allow the heath to travel up? What affect will that have downstairs? will i end up losing alot of heat?
Id rather keep the heat downstairs if it wont have a major inpact upstairs if i let the heat rise.

I agree your going overboard. I doubt your gaining much for the cost involved. Its not as if you have a big draugty area dragging heat upstairs. most of it will absorb into the slab.

LowOdour

tred wrote: »

I agree your going overboard. I doubt your gaining much for the cost involved. Its not as if you have a big draugty area dragging heat upstairs. most of it will absorb into the slab.

If i dont put insulation in the suspended ceiling, is it then worth putting foil back plasterbaords on?
In theroy , I would prefer to retain more heat downstairs than allow it go up through the concrete floor and not get much heat upstairs and downstairs.

tred

LowOdour wrote: »

If i dont put insulation in the suspended ceiling, is it then worth putting foil back plasterbaords on?
In theroy , I would prefer to retain more heat downstairs than allow it go up through the concrete floor and not get much heat upstairs and downstairs.

I guess you could. but if you talk to your engineer, or ber accessor, hell be looking at the build from a unit, not room by room.

MicktheMan

LowOdour wrote: »

If i dont put insulation in the suspended ceiling, is it then worth putting foil back plasterbaords on?
In theroy , I would prefer to retain more heat downstairs than allow it go up through the concrete floor and not get much heat upstairs and downstairs.

@OP: I agree with the other posters. Concentrate on the building envelope and not internal partitions. What I mean here is to reduce or eliminate thermal bridging and don't forget about workmanship & air tightness. I have seen too many new houses using way too much energy to keep the house warm even though the insulation spec was good but where is was installed badly and no thought was given over to air tightness. This last point (airtightness) is especially true where the house has internal insulation slabs fixed to the external walls such as yours.

turnfan

+1. Also consider all that insulation bought and installed and the heat will go up the stairs opening anyways!

archtech

be sure an continue the insulated plasterboard up to the underside of the conc floor and not stop it at or just above the suspended ceiling line, otherwise you will increase the risk of condensation.

Bitten & Hisses

I put in rockwool between the concrete slab and ceiling, but it was intended mainly as accoustic insulation rather than thermal.