Roof over two floors?

[pincorrect]

I have a cape style house. In one section the second floor is smaller than the ground floor. The floors are aligned in the front, but in the rear, the ground floor extends further. It has a gable roof with unequal angles. (The gables are on the side ends.) The front part of the roof rises at 43 degrees. The back side has a shallower 23 degree angle, and the back roof is much longer than the front, and spans both the second and ground floor. It actually meets the back wall below the ceiling level, so the back wall on the ground floor is shorter than the front wall.

How do I draw a roof that covers both floors?

[Allan Chesney]

Hi and welcome to the forum,

Before going any further, can please confirm which version you have. V16 has greater functionality for what you are doing  than earlier versions, while V17 and 2015 are a completely different program.

To get you started however, assuming V16 or earlier, you have to understand two basic concepts:

1. The roof sits at the wall height set in Building Location, rising from this height, so in your case you will have a roof on your ground floor and upper floor.

2.  If the walls on the upper floor slope with the roof, then the wall height setting  in Building Locations for that level, is the vertical part only.  In other words, if the upper floor has a wall only 2' or 600mm vertical before it slopes, then that is the wall height setting for that level. Make sure that the wall you draw is set to AutoExtend. When you draw the walls for that level they will extend as needed to reach the roof.

Work on those points first but no doubt you will have further questions, so just ask as they arise.

Allan

[pincorrect]

Thanks, Allan. Yes, I have V16. I understand your point about setting the building location wall heights for the ground and second floor.

Then, to proceed, should I start as follows?

• Set the location to second floor
• Insert a hip roof by picking points, picking the four corners on the second floor.
• Select the two side edges of the roof and convert to gable.
• Select the front and back edges individually and set their respective slopes. (This will move the peak of the roof forward.)

This would give me a roof over the second floor with the proper slopes. But then how would I extend the back section of the roof to continue over the back part of the first floor, which extends beyond the second floor? Can I extend the back edge of this roof, and would it join to the back wall on the first floor? Or would I need to change my location to the ground floor and draw a separate (shed style) roof that would have the correct angle to merge seamlessly into the back section of the second floor roof? Or, when I first drew the roof by picking points, could I have picked the two back corners of the rear ground floor wall, even though they were not on the currently selected location (second floor)?

[Allan Chesney]

Essentially your steps are correct, although By Perimeter insertion would be OK on the second floor since the roof obviously covers all of the second floor.. A single slope roof on the Ground floor is the easiest way to go - that is what a builder would do if you think about it.

The upper floor roof can be extended also but presumably it would a different pitch so would be very awkward to create. You would also find that the Ground Floor walls would not extend to an extended upper floor roof, as there would not be a roof on Ground Floor Location to extend to. Inserting the roof on the Ground Floor location overcomes that issue too.

Use a copy of your plan and give it a go. Let us know how you get on.

Allan

[pincorrect]

Very good, thank you Allan. I will try that when I get home tonight. But to clarify, when I insert the roof on the ground floor level, will TFP realize that, in the front of the house, the roof actually will need to sit on top of both the ground and second floor levels, and so it will automatically set the front edge support height to the height of the second floor wall?

By the way, while I just signed up to post threads, I have read the forum for quite some time. Thank you for all the detailed and excellent advice you have given everyone!

[Allan Chesney]

But to clarify, when I insert the roof on the ground floor level, will TFP realize that, in the front of the house, the roof actually will need to sit on top of both the ground and second floor levels, and so it will automatically set the front edge support height to the height of the second floor wall?

Simple answer - NO. Each Location is a separate entity, the vertical components of which are controlled in Building Locations. The lowest edge of the roof will sit at the wall height set for that location in Building Locations (even if there is no actual wall there) so the upper edge, in the case of a Shed style roof, is controlled by the pitch of the roof. The program does not know what is underneath the roof on a different location but will blend them together in 3D.

A trick you may not be aware of: you can extend a roof beyond the walls and make it go lower than the wall height setting, by right clicking the edge of the roof and choosing Move Edge. You have two options, to maintain the support height or adjust it. Choosing the latter will make the roof go lower, as for a verandah for example.

Been doing this about 20 years - it is always nice to hear it has been appreciated - thanks! 

Allan