How to install insulation into ceiling cavity?

30 Apr 2009
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United Kingdom
I need to replace the plasterboard ceiling in one of my bedrooms. The property is a victorian end of terrace so suffers pretty badly due to lack of insulation.

The existing plasterboard appears to be fixed to timber battens with (what I presume was the original) lath and plaster ceiling above leaving a gap of about 200mm.

I was planning to insulate this space using a mineral wool insulation and add a vapour barrier whilst replacing the plasterboard ceiling. Although the loft is insulated there are areas such as the bay that are impossible to get insulation into and anything that can be done to improve the thermal performance will be worth it (I'm also thinking of insulating the walls using Thermaline plus).

Any suggestions on how to actually install the insulation as I've been reliably informed that sky hooks aren't readily available! I'd wondered about trying to install the vapour barrier at the same time and use this to hold up sections of a time (ie then stuff the insulation in) but worry about getting an effective installation for the vapour barrier.

Also - should I be aiming to try and provide some ventilation into the roof space to avoid condensation issues?

Any suggestions gratefully received.
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Insulation is made to fit joists set at the standard 400mm centres and will friction fit enough to stay up there for long enough to get your boards up.

However stapling up your Vapour check relatively tightly will make boarding it much easier.

Wear googles when working with mineral wool above your head as having it raining into your eyes is not that nice.
So how come neo, that all the roll insulation I see is perforated/marked at 600 mm :mrgreen: ?

Am I being discriminated against ?
As the void is basically a boxing out for a suspended ceiling I don't think the battens are at 400 or 600 centres. The existing plaster board is 900 x 1800mm and I suspect the battens are located to suit the boards (and provide a fixing). Shame as I liked the idea of friction fitting!

At the moment I haven't removed the ceiling (will happen at the weekend) but this is what I can work out.

I take the point about goggles (thanks for that).

Any other suggestions for the insulation?
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If you can't get the insulation to "friction fit" you have the option of using insulation support netting. You can buy it "Off the roll" by the metre for less than a £1 /m at any decent builder's merchant.

We tend to use 100mm dri-therm cavity batts when (acoustic) insulating ceiling voids as it is more rigid and stays up.
Suggest you use 200 mm roll insulation between joists holding in position with whatever you like ( netting, bits of string stapled to joists ) and then affix sheets of foil-backed plasterboard as your vapour-barrier.

You will improve the vapour-barrier by ensuring that the paper-side of the roll is facing down.

Your loft should be ventilated to prevent condensation, however by preventing moist, warm air getting into the loft, you are improving the current situation considerably.
how come neo, that all the roll insulation I see is perforated/marked at 600 mm ?

Am I being discriminated against ?

True when i said that i meant that 600 friction fits very nicely in 400 centres.

thanks for all the suggestions - greatly appreciated


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