What are High Performance Felts ?

High performance felts are felts that have been modified in two major areas. The age hardening of the bitumen and the long term strength and elongation properties of the felt base. High performance felts also give cold weather flexibility and hot weather firmness, with excellent tear and puncture resistance.

There are two types of High Performance felt:

Atactic Polypropylene APP

APP (Atactic PolyPropylene)

APP is made out of modified bitumen with non-woven polyester or glass fiber reinforcements.

Styrene Butadiene Styrene SBS

SBS (Styrene Butadiene Styrene)

The SBS system has the greatest elasticity and elongation properties and provides the longest life span.  SBS membranes provide superior tensile strength while maintaining critical flexibility- even in the coldest environments.

High Performance felts generally need a carrier or ‘fleece’ to be produced in sheet form. This fleece is usually either glass fibre or polyester with the polyester being the better of the two. There is also another range of High Performance felts that do not have a fleece and therefore are not restricted by the properties of the fleece and are able to stretch up to 1000 percent.

What Are The Advantages of High Performance Felts ?

Regular Felts Crack Over Time.

The ageing and weathering characteristics of bitumen over a period of time are well documented. Bitumen will crack or craze in a crocodile skin formation from the combined effects of ultra-violet light, ozone and oxygen.

Overheating Can Damage Too

This ageing process leads to increasing hardness which can be expected to take place over a period of around 12 years. The rate of hardening is the greatest in the early years with significant hardening taking place in the first 3 to 5 years. This ageing process can be drastically accelerated by the overheating of the bitumen during the roofing operation.

The addition of polymers to the bitumen during manufacturing improves the properties of the felt as a roofing material in all aspects, and in particular flexibility, strength and fatigue resistance. These modified felts are called High Performance felts.


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