Loose fill insulation for DIY use?

12 Jun 2014
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United Kingdom
Quick query,

We have a garage conversion on internal garage in house, and the inside of garage walls are timber studs, with foil backed plasterboard attached to the studs. There is no celotex/kingspan or any other type of insulation between the plasterboard and the internal garage brick walls, as the builder advised the garage is part of the house so has brick cavity walls and this no internal insulation is necessary. Looking back however, it has always bugged me why I did not insist the builder to insulate between the P/board and the brick internal walls of the original garage at the time of the conversion. I wish I had got a second opinion now.

Two sides of this rectangular garage room are on outside walls, (as the garage was on the corner of the house) and I wondered if it worthwhile (or even if there is such a loose-fill product?) that can be retrospectively injected into the cavity between the plasterboard and the original internal garage brickwalls as a DIY job?

The room is not that cold and is heated with radiator, but I just wanted some opinions on the energy saving that I could achieve by adding some loose fill polystyrene or cellulose beads into the cavity between plasterboard and garage brick walls. Is it worth it? was the builder correct to not insulate? Just looking for advice really !

Many thanks.
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If those brick cavity walls are uninsulated they will indeed be acting 'somewhat' like an external wall, as the cavity acts like a thermal chimney. This is why party walls in new builds now have to be insulated according to building regs.

If the wall is in fact insulated, don't bother, if it isnt then look at having blown in cavity insulation.

If the latter is unpallatable, then yes you could blow insulation behind the plasterboard. Not quite sure it is something I would call a DIY job, you would need equipment, and you would need to drill holes into the plasterboard at the top.

Given the time and hassle of doing it DIY, it might just be cheaper to rip of the plasterboard and do it again properly (plasterboard is cheap).

Can't say it is something I have done, so may be wrong on which is easier or cheaper.

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