I have a 1.5 story design that requires the roof rafters to birdsmouth onto 2x4 perimeter plates (1.5" tall walls). When I set the support height to 0, I cannot make any birdsmouth settings. Also, the roof will not go any lower than the top surface of the 1.5" tall wall. Actually it hovers a little over it. This makes the roof height and my coss sections wrong.
Any tricks to get the roof to lower into the correct position?
Here's the best I can do so far. This is with 0 support height. I need the rafter to drop down lower and cut a full birds mouth.
I recognize what you are trying to do and it seems reasonable but I have never seen it done in TFP.....but I have never tried, nor have I seen any questions about it.
If it were me, I'd try these 3 separate things....but they may not work and I doubt that TFP will actually cut out the bird's mouth:
- be sure you turn off "collision", it may be preventing the overlap you want
- try doing the roof on a separate location with its wall height very small and at elevation for roof you desire
- far harder= make a roof (maybe export from TFP as a start) and import it as an object, collision off, elevate to desired position. You could actually have bird's mouths cut out....but you may not need that detail in the assembled section view; only if you want to show the rafters as separate pieces.
I think you will need to experiment, but maybe Allan has done this before.
Doug.S
Hi Gerald,
Well I have not actually done this before as Doug thought, so the best person to answer the question is probably Jack. He has worked a lot with roofs of all types (mine have all been very similar) and he has produced some excellent rooof training videos that are well worth getting, especially if you are into any unusual roof types.
However, the question that comes to my mind, without seeing the design, is: Why are you using 1.5" walls? From what you have said, that is restricting the rafter length (which it will). Ìs it an attic space you are creating - hence the term you used "1.5 storey design"? Maybe we need to see the model (you could post it here or email it to me - alches AT iinet DOT net DOT au)
In the image I have assumed that is what you are doing, so, what I did was to select the roof, right click and Duplicate to Location and chose Ground floor but kept the Second floor roof and turned it off in the View filter. By keeping the second floor roof any walls you add on the second floor will follow the roof line - they won't follow the roof on the ground floor. I then switched to Ground Floor, Selected the duplicate roof (all edges) and changed the support height from 1.5" to lift the roof up to second floor level. You need to tell it to ignore the second floor, otherwise it will only be the overhang you will have, not the whole roof. You could alternatively create a new.location for this roof with the wall height set to the height you want the roof to be and Duplicate to that instead.
This was just a way to accomplish the appearance you want - Jack may have a better way to do it.
It is great to see someone using TFP for detail such as this! It is amazing the detail that is possible isn't it?
Welcome to the forum by the way! :)
Allan
Hi Gerald,
As a quick response, select the roof edge > right click and select > Move Edge > Adjust Support height.
I would have to test it to get exactly what you want, but the adjust option allows you to move the edge and have the roof drop following the pitch rather than stay 'level' following soffit height. Combining moved edge with overhang should get you what you need.
It is covered in my roof training videos, see link below.
Jack
Hi Jack,
I did try that before but could not get it to work. It works OK for a roof on a normal height wall but because of the low 1.5" wall it will not allow the support height to change to a level below the wall bottom - hence the use of a second location suggested before. Unless I am doing something wrong?
Allan
Thanks for the tips fellows. I did try previously duplicating the roof to the first floor (deleting the original), which allowed me to set its height to the right spot, but that broke the 2nd floor wall auto-extend results. I hadn't thought about keeping the original 2nd floor roof and making it "invisible." I'm going to give it a try.
This design has an attic 'bonus room' so the 2nd floor is totally within the roof space. The floor is constructed with 16" I-Joists and is a continous platform that sits on top of the first floor walls' top plate. I'm trying to build this model as close to actual construction as possible so that my drawings can easily be converted to construction detail drawings by the builder's draftsman.
Here's a sample rendering of the project. It's a new garage addition that attaches to the exisiting house. I had to model both the house and the addition at the correct terrain elevations to test the interface between the two for correct design and dimensions.
Quotethe low 1.5" wall it will not allow the support height to change to a level below the wall bottom
Hi Allan,
If you convert the roof to Surface and then use the move Edge option you can get it to fall below the bottom of the wall. This would require some adjusting when laid out , so I would agree that adding on a separate layer may be the best solution. It would also depend a lot on what is happening with the interior walls.
I try to keep a roof on the same level as the floor, so I can use Auto Extend for those 'short' attic type walls that need the roof to automatically 'end' them at a proper height.
One reason I need the auto extend to work for designs like this is that it's the only practical way to get the windows in the centers of the gable ends. Otherwise the gable wall has to be broken at the centerline which makes it no longer possible to place a window there.
Hi Gerald,
The Autoextend should still work, as long as you keep the original second floor roof, even if it is turned off.
Even with an ordinary single roof and where you have a level wall not extending into the gable, I think you should still be able to put a window in the gable, and use the Display Gable option in the roof properties to fill the gable end (with either the same material or a different one). As you said you probably would not be able to insert a window if you have two walls joined in the centre.
Allan
Well, I tried the approach of duplicating the 2nd floor roof to the first floor with the original roof turned off in the view filter, but it had the unexpected result of also turning off the roof of the dormer. So that idea won't work in this situation.
I did however find a workable, though tedious solution. I lowered the 2nd-floor level in the "Building Locations" menu by a few inches, then raised everything on that level back to its correct height with the "elevate" operation. This left the roof at the lower level of the Locations setting. Next I increased the support height of the roof edges to a large enough positive value so that I was able to enter the required birdsmouth/seat settings.
Hi Gerald,
Yes it seems you would have to create the dormer again on the duplicated roof as a dormer does not seem to duplicate to another location. You can Duplicate it on the same location (moving it to the side), and it will duplicate the dormer that way, but then you need to create new location and duplicate it to that but the dormer stays on the original location although it can still be dragged back with the roof to the correct postion but it all gets very complicated. Easier just to recreate the dormer on the 'ground floor' roof.
I gather your workaround has worked anyway so that is good.
Allan
Final result.
Now I can export this to xdf and just make minor edits in TurboCAD for working drawings.
That is great Gerald.
Good to see that you finally got it as you wanted it. :)
Allan