New roof recently

[jaotguy]

I think shingle companies have pretty much switched to fiberglass mat for the base layer of shingles. There is still asphalt in the upper layer for water proofing, but it doesn't contact the roof.

up here in Canada , they still prefer to use the asphalt shingles ( supposed to take the cold and flex better )
you can get fiberglass mat but you pay a premium for the installation ... nobody like the "slivers" you get when installing them.

I installed the glass style myself the last time I re-shingled and can vouch for the slivers :laughing:

 

[quicksandfarmer]

Tyvek is slippery, you'd fall right off the roof. There are similar underlayments though.

I did several roofs last summer and I used TriFlex, I liked that I could carry a 10-square roll in each hand. It goes on a lot easier than felt and is a lot tougher. The 30# felt was $10/square and the TriFlex was $11/square, definitely worth the money.

 

[Rustyiron]

Quicksand is right! The last I looked, it's printed right on the Tyvek that you do not want to stand on it! Perhaps your roofer was trying to say that it (modern synthetic underlayment) is like tyvek.
It's (felt/underlayment) purpose besides a secondary protection layer is for condensation between the layers.

 

[PAGUY]

Rustyiron - It said right on it that it was Tyvek.

quicksandfarmer - They walked all over it -up and down the roof - and never slipped while piling shingles on peak of the roof.

I liked what I read at the website and I do now remember the contractor saying it would help in energy conservation.