Katepal Oy > FAQ

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1. Roofs structures (vapour barrier, ventilation, sarking etc.)
2. Bitumen roofing shingles
3. Self-adhesive bitumen membranes
4. Bitumen felt roofing with triangular battens
5. Professional products
Most common mistakes
Difficult-to-shake false claims

1. Roofs structures (vapour barrier, ventilation, sarking etc.)

2. Bitumen roofing shingles

3. Self-adhesive bitumen membranes

4. Bitumen felt roofing with triangular battens
- Is an underlay felt used with bitumen roofing assembled over triangular battens?
  ANSWER: In a traditional bitumen roofing assembled with triangular battens to create upturn, an underlay felt is not needed except over valleys. Today roofs with triangular battens are also installed over an underlay, but in this case the battens are made of plastic and the membranes are of a weldable type (products for professional use requiring hot work installation). A wooden triangular batten will rot between the membranes before the end of the membrane life span.
- Can roofing shingles be installed on old bitumen roofing with triangular battens?
  ANSWER: It is not possible to install bitumen shingle roofing on old felt roofing with triangular battens. The triangular batten roofing should first be removed and the shingles installed after that. At the same time it is advisable to inspect the condition of the sarking boards and the rest of the structure. If necessary the rotted boards should be renewed. The old sheets of the old triangular batten bitumen roofing are under no circumstances acceptable as underlay, even if the battens are removed.

5. Professional products

Most common mistakes

Difficult-to-shake false claims