Super shed felt vs polyester cap sheet

[yorkshirelad]

Hi,

What is the difference between polyester reinforced shed felt (sometimes called super shed felt) and polyester cap sheet? I am re-roofing some garden buildings and wondered if they are really the same thing?

Plan is to :

- nail 1st layer
- stick the 2nd layer with cold bitumen adhesive.

Should i just use 2 layers of cap sheet/ super shed felt or is it better to use the felt underlay?

Any particularly good bitumen adhesives you can recommend?

Any advice appreciated.

Thank you

 

[alan333]

Your cap sheet will probably have mineral granules on it's surface so it needs a really good bond if you use it as underlay. Underlay has a more bitumen-like surface for the bitumen of the next layer to bond with, so use underlay for layer one and cap sheet for layer two. Alternatively use mineral cap sheet upside down as underlay (even tho it's more expensive), but beware you might get mineral granules on your head inside the shed for a while.

I can't comment on cold adhesive cos I've only used it once about 30 years ago (and it was crap), but for better results use torch-on cap sheet, torched on.