Flat Roofing Advice Required

Hi there, I hope someone can help.

I've got a small flat roof to the rear of my property which needs replacing and have been given 2 quotes from the same roofer the first offering a 10 year guarantee the second a 15 year guarantee. Both are for a 3 layer torch on felt roof. The only difference between the 2 quotes being the first layer.

The 10 year guarantee being "Layer one will consist of a 3B underlay felt"

The 15 year guarantee being "Layer one will consist of an Evermore 2mm underlay felt"

Can anyone tell what the differences between the 2 are?

Many thanks
Ben

I have just been searching for products that you can foit yourself and avoid expense of fitters...there are a number of products out ther but i'm going to pos the question on a new thread so look out. A guarantee means nothing anyway.....

There is no torch on 3B. Not heard of the other stuff.

Most HT Torch ons will give 20 years if falls are good.