Fluorescent tube light fittings mounted on rockwool

9 Sep 2008
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United Kingdom
I am fitting 50mm of rockwool between my rafters (leaving a 45mm air gap between the felt for ventilation). This will leave it flush against the rafters and I will then add another 50mm across the entire roof for a total of 100mm.

At present, I have fluorescent tube light fittings screwed to a length of wood which is then screwed to the rafters. Once I have installed the insulation, this will need to sit on top of it. Should I just buy some 110mm+ screws and fix it back to the rafters through the insulation, or is there a better way?
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Fit wooden blocks to the rafters and stilt the fitting?

Have you any idea how daft fitting a fluo on to the existing rafters with longer screws would be?

It would compress the wool behind the fitting
It would push the felt
It would be wonky
It is a stupid idea

I would also suggest you give thought to the calble and make sure it is NOT buried under all that wool.
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That's why I asked. I have read that any gap in the insulation will cause significant heat loss so I was trying to avoid it wherever possible. I have not used rockwool before and have not bought it yet so I don't know how tough it is.

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