I'm trying to create a 3d model of the house which should resemble medieval one. It's not aiming to be perfectly aligned nor have strict measures; I'd like to learn how roof would be constructed if the mentioned house was real one.

I'm searching for a correct way of creating its roof. The house walls form some corners which prevent roof to have perfect forms. Here is a screenshot of the house without the roof:


There is a corner on the near side, however there aren't any on the other side (the wall is straight there). And this is its plan without roof:


house plan is highlighted

I don't have decent references and not aware of principles as to how are roofs constructed to cover that form. Should it be like this example ? (it is only a schematic representation of forms)



roof is highlighted

However its is now curved which is not something I saw on the ridges of the roof. What is the principle of constructing roof for similar case and how roof for that house could look like ?


First, there is no standard rule of thumb for resolving roof conditions. There may be as many possible solutions as there are people trying to solve the roof challenge you have.

Let's start by identifying the roof sections. I count 6 roof segments and will label the upper left section as 1 with 2 & 3 to the right of it. Similarly the lower sections are 4 thru 6 with 4 below one, 5 below 2, and 6 below 3 on the plan. (It would be helpful to others if you place those section numbers on your plan image).

Roof sections 1, 3, 4, &6 are straight forward. They individually have the same lengths on each side and are straightforward slopes. Sections 1 & 4 mirror each other as do 3 & 6. Since their horizontal lengths from base to peak lines differ they will not have the same slope which is often very desirable for aesthetic reasons. If you maintain the same slope either the eave line or ridge will not be at the same height for roof pair sections 1-4 and 3-6. The usual way of resolving this is to let the ridge in 4-6 be higher than 1-3 and I will assume that keeping the base line even is your bottom line for the design since it maintains a simple roof bearing condition for the entire roof system.

The real design challenge is in resolving the differences between 1-4 and 3-6 in sections 2 & 5. Section 2 has parallel base and ridge lines resulting in a horizontal level bases and ridges. Section 5 has unequal side lengths which result in either an unlevel base or ridge line. So the two ridge lines will not meet each other. That means that the 3D drawing you provided cannot work without warping roof sections 2 or 5, a very undesirable solution for construction purposes and aesthetics.

Possible solutions

  1. Create one ridge line based upon the slopes of 3-6 and carry those base and ridge lines across the entire plan . That would result in the roof overhanging sections 1 & 2 further, but that may not be a bad thing. Certainly and truss fabricator would be able to design the trusses to cantilever the additional length. Conventional framing for that condition would either require an exterior column at the upper left corner or some cantilever framing at the base line of the side of section 1.

  2. Extend the ridge line of sections 1-4 over to the left side line of roof section 3-6 creating a flat triangular roof area between sections 2 & 5. This is doable but will result in exposed triangular side walls along the adjacent edge of 3-6 and 2-5 to close off the gap between roof slope angles. It will also require some well done flashing to prevent water penetration at the junction. Especially if there is a winter season with snow build-up.

  3. Create a raised structure at sections 2 & 5 that raise their roofs higher and allow you to resolve that roof section independent of the other sections.

  4. Modify the design. Often in architectural design if things are not resolving well the designer must re-examine the initial assumptions and attempts change one or more of them to see what comes out of it. This approach often leads to a better, more interesting and more construct-able solution.

  • Thank you for your answer and plan proposal; I didn't think about that for some reason and edited the question. I tried to follow your plan while naming sections for better clarity. Fortunately this house isn't going to be in winter conditions (nor in any ones) as it will remain being 3d. As for now I ended up with this design which is, I guess, your 2-nd way. The design is most likely not good one, although I can't change its base unfortunately. – Mr Zak Mar 20 '17 at 19:44
  • Your proposed design from the comment link will work. I suggest aligning the roofs across the back in the same plane rather than the little offset shown in your image. – Ashlar Mar 20 '17 at 21:05
  • Thank you for your suggestion, I thought of that but wasn't sure whether it's done like that or not; now I will stick with that way. – Mr Zak Mar 20 '17 at 22:02

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