Professionally extend a roof overhang

There are many reasons to extend a roof overhang. However, in many cases you should only make the extension if conditions are to be observed, for example, by the energy laws, but not only for purely optical reasons. Below we explain the background.

Roof overhang and roof overhang

First of all, a distinction must be made between the roof overhang and the roof overhang so that there can be no misunderstandings.

  • Roof overhang: laterally, the distance from the facade to the respective eaves (drip edge)
  • Roof overhang: at the ridge ends (verge), the overhang beyond the facade

Reasons for a roof overhang extension

Especially older houses have no roof overhang. The roof usually ends flush with the ridge stone. However, there are many reasons why homeowners want to extend the overhang.

  • as weather protection
  • in a facade insulation
  • optical reasons

While the extension of the roof overhang is relatively easy, static calculations are mandatory when extending the roof overhang. Basically, if you want to extend the purlins, the overhang should make up a third of the purlin length. Two thirds of the purlin are bladed with the old purlin.

However, it may be useful again to shorten the old purlins accordingly. This is not a problem with the foot purlin, but it gets more complicated with the ridge purlin (the top purlin). If necessary, you must support the entire roof truss completely safely. Decisive here are above all the positions of the last, final supports.

Overhang extension due to facade insulation with ETICS

In particular, in the roof overhang extension due to the insulation with a thermal insulation composite system (ETICS), the extension of the verge is necessary because the ETICS is too much oversize gets - especially in older houses, the verge is flush with the facade. At the same time, however, you must remember that neither plaster nor ETICS are suitable for carrying the purlins. Hence the procedure described above.

Roof overhang extension as weather protection

When weather protection different requirements come into play.

  • as a sunscreen against the heating of the facade and for shading
  • as rain protection for the facade

As stated previously, the roof overhang extension can be very complicated and complicated. While in case of an extension, especially for shading and as sun protection, the individual circumstances have to be considered, you should consider the following with a protrusion extension of the verge: a protrusion of approx. 0.5 m protects a façade area downwards of approx. 1.5 m.

Depending on the height of the façade, this may be 25% or less of the façade surface. Finally, rain falls only in very few cases vertically. The effort associated with the extension of the supernatant can therefore not be in many cases in relation to the massive workload. It is therefore always advisable to consult a structural engineer, ie a carpenter, structural engineer or architect.

Optical reasons for the extension of the roof overhang

For the reasons already mentioned, a roof extension on the verge has to be considered much more thoroughly.

To the effort but also comes the regulatory background. When extending the roof overhang at the verge you will need to obtain a building permit. In addition, there may be minimum distance measures to neighboring properties and also to the street. Last but not least, in many cases neighbors will have to confirm their agreement in writing.

But that also means that you need a structural engineer or an architect who can design and sign the appropriate blueprints before submitting them to the Building Authority for approval.

Tips & Tricks

The extension of the roof overhang at the eaves is much easier. Although statics also play a major role here, there are special metal profiles that are laid out with the rafters. This allows you to extend the overhang by one or two tile rows.

On the other hand, roof extensions should only be carried out if an absolute must, such as the fulfillment of the energy laws, is behind it.

Video Board: Roof Overhang Building Design Tips - Construction and Architecture