We are building a roof over garden table: sort of like a pergola with roofing. We are using OSB panels for insulation and fiberglass roofing sheets for weather protection. We already chose translucent roofing for availability and price, but we started to wonder whether a dark opaque roofing would offer a better heat protection from the sun.
Dark opaque roofing would become way hotter than a translucent one, but would also protect the underlying OSB panels from direct sunlight. Hot air between the roofing and OSB panels is free to circulate and convey the heat away, but some heat would nevertheless be transferred to OSB panels including with heat radiation from the roofing.
Translucent roofing enables most of the sunshine to be reflected from the bright OSB panels, but I guess a greenhouse effect comes into play and traps some heat, again heating the panels.
So more out of theoretical curiosity than out of need for actual advice I ask: Which roofing would offer cooler environment under the roof: translucent or opaque?
Best Answer
Technically speaking, the coolest thing to do is to have an opaque roofing surface that's a perfect mirror. Short of that, it should be painted somewhere in the red spectrum, reflecting the infra-red range. Beyond that, lighter colors are better.
Personally, I'd avoid the translucent, since I don't know whether long-term exposure to UV rays will damage the OSB.