Replacing the landing to loft skylight, what material is best?

6 Oct 2010
Reaction score
United Kingdom

We are finally after 8 years, wanting to replace the (piece of crap), draughty perspex sheet that is our landing skylight (sitting in line of sight under the roof velux window in our loft).

I have always wondered just how much heat gets lost through it into the roof space, not to mention noise that can get in the house, e.g. from helicopters (we live in the centre of a City).

We were just going to order a direct replacement of perspex, though I'm not sure what thickness to go for. I was thinking about 4mm?

Our aperture measures 517mm x 855mm

I found a local company that can do an unpolished edge perspex sheet, cut to size for £13.68 inc VAT and I can collect.

But then I saw they do double glazed units and it says that would only be £15.91! The problem is, I know nothing of installing double glazed and wonder if my measurement would still be for the glass only, or incl the aluminium silver frame around it, and then if it did include it, would it be visible looking up from the landing?

I guess I'll need to ring the company tomorrow but does anyone think going double glazed is going to make a significant difference to preventing heat loss and sound insulation?
Sponsored Links
I would presume they mean the glazed panel with the narrow black seal/trim around the outside. If you look at the rebate in your existing frame that holds the perspex, then you should be able to see if it is wide enough to hide such a trim. (You won't have a problem with the extra weight of glass, right?).

Double glazing probably would improve heat loss. Although I live in a house with a leaky Victorian glass skylight and I've not really been aware of serious heat loss through it. But maybe that's just because the whole of the loft is just as leaky!
Last edited:
From the visible line of spacer bar ( the bit the that holds the two panes of glass apart ) to the edge of the glass on a sealed unit will normally be 10-12mm on each side. I would also recommend you have it toughened , as it is above your head , and then if you added 'low e ' glass you will save a bit more heat BUT it will all depend on how well the framing is put in...

Hope this helps

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links