Extend rafters - is this something possible, and how does it work?

There are many reasons for extending existing rafters. However, this is not necessarily an easy task, and in some cases quite a tricky task, where then even with experts opinions often go far apart. To extend the basics of rafters, see this post.

Rafters are statically relevant components

And that fact is extremely important. Extensions must be planned carefully, and in many cases statically recalculated. With a sense of proportion and thumb width, nothing is to be done here.

As a result, rafter extensions are certainly not in the range home improvement could handle. And even carpenters usually do not plan a rafter extension, not all alone, at least not in the more complicated cases.

Reasons that can make rafter lengthening necessary

One of the most common reasons for a rafter extension is the installation of an ETICS. In order to be able to carry out the installation of the facade correctly, the roof overhang of some houses must be extended accordingly.

However, this changes the statics of the entire roof, and that's just a potential problem. A thermal bridge on the wall crown as a result of the extension of the roof must usually be remedied with an additional rafter insulation. Here, the effort is relatively high.

The same is true even if only for better weather protection of the roof overhang should be increased to better protect the facade.

In some old houses also moisture damage can often make a repair of the rafters and an extension necessary, but there are also plenty of alternative options.

Technical possibilities for rafter extension

  • so-called Aufschieblinge, but mostly only for relatively short lengths used
  • Lugs on the original rafter, mostly laterally
  • Attachment of a stub

Roof extension as an alternative

In some cases - at least on the gable side - also easier ways to extend a roof, for example, to obtain a better shade. There are approved extension elements that can usually be used quite easily.

On the eaves side, a roof extension is usually a complicated procedure, but here again a rafter extension solution is often needed.

Tips & Tricks

Rafter extensions must always be carried out by experienced carpenters - this is definitely not a field of application for DIY enthusiasts, and the static issues are too precarious.

Video Board: Extending Rafter Depth for Insulation | Loft Conversion Project 2.0