Airtightness detail in attic conversion

Ush1 · 24-12-2015 11:22AM #1

I've done an attic conversion in my house using ballytherm foil backed boards for insulation. The rafters are 100mm so I left a 50mm gap and put 50mm boards between, then a 50mm insulated slap beneath.

The problem is that even with all this its very cold up there which I have put down to airtightness. There is a lot of draft coming from the led downlights I have fitted. My question is what would be the best way to draft proof around the downlights?

They basically pierce through both layers of insulation to the 50mm air flow gap and on a windy night so much cold air is getting in.

Calahonda52 · 24-12-2015 12:05PM

I don't think you can get a completely room sealed downlighter so I would guess that you need to rethink it.

you might check over in electrical
Where do the cables run?
Along the 50mm void?

Is the roof felt the old black stuff?

fred funk }{ · 24-12-2015 12:09PM

Ush1 wrote: »

I've done an attic conversion in my house using ballytherm foil backed boards for insulation. The rafters are 100mm so I left a 50mm gap and put 50mm boards between, then a 50mm insulated slap beneath.

The problem is that even with all this its very cold up there which I have put down to airtightness. There is a lot of draft coming from the led downlights I have fitted. My question is what would be the best way to draft proof around the downlights?

They basically pierce through both layers of insulation to the 50mm air flow gap and on a windy night so much cold air is getting in.

I recently converted our attic and knew that the downlighters would cause an issue so I went for a light fitting instead. Argos have a good selection of nice ones that take GU10 bulbs and are low profile in case headroom is a concern.

Ush1 · 24-12-2015 01:52PM

Calahonda52 wrote: »

I don't think you can get a completely room sealed downlighter so I would guess that you need to rethink it.

you might check over in electrical
Where do the cables run?
Along the 50mm void?

Is the roof felt the old black stuff?

Yes that's where the cables run and yes its the old style non breathable felt.

random.stranger · 26-12-2015 03:48PM

Looking for this type of thing op?
http://tenmatus.com/Content/Loft%20Covers

Available here:
https://www.build4less.ie/insulation-materials/downlighter-covers.html

fred funk }{ · 26-12-2015 06:37PM

random.stranger wrote: »

Looking for this type of thing op?
http://tenmatus.com/Content/Loft%20Covers

Available here:
https://www.build4less.ie/insulation-materials/downlighter-covers.html

Think they have to be fitted from above. That might not be possible in an attic conversion.

Airtightness detail in attic conversion

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