Most manufacturers of fully adhered roofing underlayment or ice and water shield offer their product in two major categories.
Ice and water shield for metal roof.
Specifically designed to meet the challenges inherent in metal roof assemblies delivers all the advantages of grace ice and water shield with thermal stability up to 260 f seals around roofing nails resisting leakage caused by water back up ice dams or wind driven rain can be left exposed for up to 120 days.
Many metal roofs are attached using screws where ice and water shield prefers smooth fasteners for the best seal.
Grace ice water shield is supplied in 3 ft wide rolls of varying lengths.
Note that grace makes grace ice amp.
Grace ice water shield is a versatile underlayment material that may be used on sloped roofs under mechanically attached roof coverings such as asphalt shingles slate tile cedar and standing seam metal in many climate and assembly conditions see limitations for additional information.
These categories are regular and what s known as high temp i never really thought too much about the difference until a customer of mine had a problem with a black substance oozing out between the metal diamonds on his roof.
Ht specifically for use under metal roofing.
And also in southern climates it s put on the entire roof because even if the shingles blow off it keeps the water out.
If you have a metal roof you generally don t have that problem because even if you do get ice it s going to build up at the edge.