Bodged roof insulation due to downlights

[Lindisfarne83]

Hi,

We had a small extension built last year, this all seemed fine until we came to the downlights. These were installed into our vaulted ceiling by the electrician who hacked out chunks of Celotex to fit them. I wasn't impressed at the time; I now realise how much of a no no this was as I believe the thermal efficiently of our extension is now very poor as a result. How could I go about resolving this as cheaply and effectively as possible? My first thought is swapping the downlights for insulation coverable ones and filling the voids with rockwool, alternatively I could (very carefully) try to build of a layer of expanding foam in the area above the fitting. Any helpful suggestions gratefully received. Thanks in advance!

 

[motorbiking]

It doesn't look like you have enough PIR in there anyway. How thick is it? Can you show a picture of the downlighter? Are they fire rated with hoods? Stuffing as much Rockwell as you can in will help. I suspect there is a draft driving warm air in to the void behind the insulation. Also make sure the downlighters all have their seals in place.

you need something like this if you are going to pack it.

LED Fire Rated Downlight - IP65

 

[Lindisfarne83]

I measured it at 120mm, which is not quite the 150mm that was stated on our drawings - will this make a big difference? There is a void behind the insulation our builder said this was necessary for ventilation of the roof space. Our current downlight is not fire rated and I would look to replace with one like you have linked but need them to be adjustable due to the angle of the ceiling.

 

[motorbiking]

See the link, they do adjustable and all are dimmable (with an LED compatible dimmer).

120mm should be OK. The easiest option is to try to make sure the current lights are sealed in to the plasterboard. Do they have silicon washers in place?

Unfortunately the lights you have must not be packed in insulation the way you want.

Are the holes too large?

 

[Lindisfarne83]

Yes they have silicone washers in place but because they are adjustable there is a bit of an air gap where they pivot. The plasterboard holes are also slightly larger than required which doesn't help.

I think I'll swap the lights out and try rockwool/sealing in the first instance but is it an awkward job working through the hole!

 

[motorbiking]

You could try a bead of silicon around the plasterboard hole to reduce it. Obviously let it dry before re-inserting.

 

[oldbutnotdead]

120mm instead of 150- so only 20% thinner insulation than was specified (and presumably quoted and paid for), might have some bearing on the thermal efficiency (the big holes for sure won't be helping)