Truss Plugin/Extension

First look at a gutter fully wrapping a complex (hip) roof:

Note the 3/4" offset from the sub-fascia since I have soffit and fascia enabled. The 3/4" thick fascia is not drawn yet, hence the gap.

I’ve also set my vertical offset to 1" for the gutter.

Version 2.5.6 - 10.11.2019

  • Added gutters for complex roofs.

View model here:

On this particular model I’ve employed a vertical offset of 1" and a gutter extension of 1.5" with a K5 style gutter, other gutter styles available.

I have not enabled downspouts yet as I need to come up with a better system for handling these. I think I have a new system figured out but I need to work on the details before I’m ready to implement it.

The problem with complex roofs is that I am only scratching the surface right now. There are quite a few permutations that are possible that are quite common with many residential designs that I still cannot handle with the current complex roof module.

Consider this relatively simple example:

With this case the fascia is at two levels. At the back corner on roof plane A you have what I call a 3/4 Hip (kind of hybrid between a half hip and a hip, one side is a hip and the other is technically a half hip). This causes the fascia line to rise by 24".

Where roof plane E meets roof plane D, you have one roof plane dying into the other and creating a “Flying Valley” and the other roof plane terminates at the wall below (a partial gable end?).

I guess I was wrong there are “flying valleys” after all.

The problem with trying to construct this particular example with my proposed secondary roof module is that its a little more complicated than that. Rather than two separate roof assemblies the roofs are technically merged. Also the 3/4 Hip configuration kind of requires that the roof assemblies are one construct.

This example really has me scratching my head right now.

What does jump out at me is that when you are dealing with an inside corner (angle between walls is greater than 180 deg.) the roof planes die into each other creating a partial gable and a flying or hanging valley.

When you have an outside corner (angle between the walls is less than 180 deg.) you then end up with a 3/4 hip. Two additional solutions might be a gable or half hip with unequal legs. If you were to keep making the setback of the half hip larger eventually it would degenerate into the 3/4 hip where one leg is now a hip roof.

My original restrictions on the placement of gable ends are too tight. In order to created roofs where you may have a gable on a gable we need to relax things a bit or at least change up the conditionals:

This further complicates each building element or at least opens up possibilities which did not exist before so I will need to add additional logic for sheathing, cladding, sub-fascia and gutters.

Who said complex roofs were going to be easy.

Another variation of the gable roof study:

Gables ad infinitum…

The one thing that jumps out here is that gable roof planes cannot be adjacent to each other (or other variants like dutch gable or half hip configurations), gable roof planes are separated by hip planes. Additionally, I will limit the gable option to orthogonal roof planes only (corners must be 90 or 270 degrees).

There is always on more thing to add, at some point I hope to have conquered this beast.

The gable on gable scenarios are proving to be a real challenge. Not only do I have to detect adjacent roof planes but as you can see in the image above the sub-fascia might die into the adjacent roof plane or continue on to the eave. A lot of additional logic here to make this work properly. This will easily add another week or two onto my ETA of Nov. 15th.

When you raise the fascia line along a segment of the roof inevitably it must return to same level since a roof is a closed loop. See model here:

I think I can make this work but I’m going to have to drastically change my algorithms to allow for unequal fascia/gutter lines.

The other interesting thing with all of this is that the fascia line could step up and down multiple times around a roof.

Another observation is that only hip roof planes technically step up or down, gable roof planes/edges are controlled by the adjacent hips.

A couple of interesting gable roofs:

Looks like I have the roof primitive working for “interior” gables. Now I just need to sort out the details for sheathing, cladding, sub-fascia and gutters. An interior gable is defined as a gable roof plane with one or more corner angles of 270 degrees (orthogonal inside corner), hence an interior gable.

For now I’m not going to allow interior dutch gables or half hips. As long as the angles, at both corners, are 90 degrees then you will be able to place a dutch gable or half hip on that roof plane. However, the gable is a little more flexible and will allow some interesting configurations, as shown.

Notice how the sheathing is now projecting underneath the gable overhangs:

Now I just need to get the cladding to behave similarly and then a few adjustments to the sub-fascia and gutters.

First look at cladding correctly displaying for interior gables:

The sub-fascia for interior gables is interesting because in most cases one or both side will die into another roof plane, however this is not always the case as can be seen in the example to the far left. Logic to include all of these possibilities now must be constructed.

Unlike the much simpler exterior gable the position of the peak of the interior gable roof has no direct relation to the perimeter points that define this gable’s edge. Due to this inconvenience I cannot (easily) mathematically calculate the sub-fascia, I must use the roof primitive geometry to derive the correct points and position, again more emergent behavior. In short, the roof primitive is smarter than I am.

First look at sub-fascia for interior gables:

Bit of a struggle to consider all of the possible permutations for this type of roof but I think I have finally arrived at a robust solution.

I just need to consider gutters and then we can proceed with the actual framing of the roofs.

I’ve also heavily modified my error checking code for the roof primitive to make the overall performance more robust. With the addition of interior gables there is more probability that the designer can create roof design that does not have valid geometry. Further testing will be required to try and eliminate these scenarios or further augment the areas that are having trouble with these situations.