Is it UV resistant? How stiff or rigid is it? I need to use it on the roof of the RV.

It is vinyl, so it should be reasonably UV resistant, like vinyl siding. It is fairly stiff too. More so than standard siding. You won't be able to bend and form it, if that is what you are thinking. It is sturdy, somewhat depending on how well you fasten it. I would say you are good.

It is flexible, but still stiff. I believe the company states it is UV protected. Check with the company: http://www.monosystems.com/products/item/cablehider-fwhfcl-pvc-raceway/118/10005 Product I used is: CH12 -W Or at Lowe's: http://www.lowes.com/ProductDisplay?catalogId=10051&productId=3611814&cmRelshp=req&langId=-1&cId=PDIO1&storeId=10151&partNumber=298084-35681-CH12-W&rel=nofollow&rememberMe=true Might not be suitable for outdoors??? Probably not good for outdoors.