Quality criteria for the roofing felt: what holds the most tight

Depending on the application, the requirements for roofing felt are often very different. Either they form only one of several layers, or they are used under other materials - in other cases, they are in turn sole roofing. Which criteria are decisive for the required quality, this article reveals.

Location and location of the roofing felt

Roofing felt alone as a covering

For covering a small wooden shed in the garden or a very small garden shed you can also attach roofing felt alone. In this case, the roofing felt is applied in two layers to ensure adequate protection against moisture.

The upper layer should consist of sanded roofing felt, the lower layer should be "naked" - ie unbesandet. Thus, a corresponding protection on the surface is ensured, damage to the upper layer by the grain of the underlying layer but at the same time excluded.

For better protection you can also delete the roofing felt. For a better UV protection (less weathering), a coat of paint is worthwhile, the roofing felt on the scales will then be more durable. Additional sprinkling with gravel or a special covering layer can extend the durability of the roofing felt.

Possible here are:

  • Roofing felt R333 as lower layer (not sanded)
  • Roofing felt R500 as lower layer
  • Roofing board R333 sanded as upper layer

Roofing felt R333 is particularly cost-effective compared to other types and especially compared to bitumen roofing membranes.

Roofing felt as a lower layer under a bitumen roofing membrane

Roofing felt can also be used as a lower layer for a higher-quality covering and a welded bituminous roofing membrane as an upper layer. Also in this case, the uppermost layer should be sanded as possible.

The combination with a welded web results in a higher water resistance. Below, a more stable track should also be used. It is recommended to place on higher-quality roofing felt or a roofing felt V13.

In this case, the covering is indeed more efficient, but also significantly more expensive. For the welding of a bituminous roofing membrane, it also requires some skill and practice, in most cases, a helper is highly recommended.

Roofing felt under bitumen shingles

Even when laying bitumen shingles, for example on the roof of a garden shed, roofing felt comes into play as a lower layer. Here can be used in garden sheds ordinary roofing felt R333, as the bitumen shingles ensure a very dense roofing.

But if the bitumen cover is done on a residential building, you should use higher quality roofing felt or bituminous membranes as the lower layer. Such a covering is standard in the USA and also with us more and more frequently - because of the low weight of the covering and the advantages of the full formwork with the heat protection.

Basic rules

The use of the individual types of roofing depends mainly on the desired degree of tightness and the durability of the roofing, but also on your own budget. In principle, however, upper layers should be sanded, but lower layers should not. Heavier webs or paperboards usually also allow a smoother laying without dents and folds.

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