What is the this roof style? Can it even be done with timber! Its not Mansard or Gambrel.

Though similar to Gambrel notice the extra pitch.

Any pictures, design, sketches of where this has been implemented would be good plus its name of course!

I've updated the question to emphasive that the diagram shows the shape not the design as I thought that was obvious but just in case!

I am not intending to actually design one I just want to know if its done and preferably a picture or design example like one can easily find for a Gambrel roof with a simple search. roof


3 Answers 3


As you add more facets it comes to resemble a bow (or bowstring) truss. Those, of course, have internal triangular structure to make them a truss, so they are (very) stable, and their "ultimate" form is to actually have curved top members, rather than straight-line segments.


I still consider it a gambrel. The word simply means "leg" or "forked leg", describing the interior supporting timbers.

The inherent flaw in the design as you've shown it is potential lack of rigidity at the upper angles. Unless they're robustly gusseted there and at the lower angles they're in danger of inverting at those points. There isn't enough arch to prevent outward splay and maintain compression.

  • I'm inclined to agree, but I still need more information on the actual internal design even if its a simple diagram - no problem finding this for the usual Gambrel or Mansard. I've searched quite a bit but I cannot find a diagram and even less a picture of a house with the extra pitch so maybe it is not possible to do with wood.
    – onepound
    Commented Jan 10, 2019 at 14:26
  • I'm not sure you'll find a single canonical design. You could simply add legs under the new angles as with the lower angles and call it done, assuming there's support for those legs in the floor system. The request is borderline off-topic considering the importance of good engineering.
    – isherwood
    Commented Jan 10, 2019 at 14:30
  • Thanks for the info. I was not asking to design it (I'll update the question to remove doubt), I just want to know if its done and any examples especially photo's of houses using it because I have a feeling that it is not.
    – onepound
    Commented Jan 10, 2019 at 14:35

Its called a structural failure. Depending on where you are, local building regulations or codes would almost certainly require an engineer to design such a structure and it would probably need to be a complex truss or geodesic barrel vault.

  • A fair point, but not an answer to the question.
    – isherwood
    Commented Jan 10, 2019 at 15:09

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