I have a large shed with a shallow angled roof made from 9mm OSB board and supported by wooden beams every 3ft approx, and covered with standard shed roofing felt.

I want to put a few sky-lights made from double-walled polycarbonate plastic in the roof (EG 2x6ft)

What would be a good method to do this, and keep it water-tight?

Climate - England so rain, wind, some snow, and on the odd occasion SUN!

  • Apart from dedicated products, that would be a little broad to answer (for me, at least). In any case, You may want to put in Your question infos about climate (location) and desired materials (what You got in shops nearby). Jul 23, 2015 at 11:20
  • Do you have snow?
    – bib
    Jul 23, 2015 at 11:43

2 Answers 2


Homemade skylights are a bit tough. But, you basically want to have the top & sides under the roofing & the bottom on top of the roofing. Set the panels in a thick bead of caulk, silicone or not & screw down either through the panels or with brackets.

The polycarbonate's channels would be best run horizontal to the pitch rather than downward with it. Membrane tape or even just aluminum tape the sides first then the top. Finally, caulk the roofing down to the sides & top of the panel & do a final caulking at the bottom of the panels to stop any capillary action or ice damming.


If you place the top edge of the skylight at the ridgeline then you won't have to deal with flowing water from higher on the roof.

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