Trying to get roof rafters for addition running perpendicular to slope

[DanWEC]

Hello,

 

I'm trying to do permit drawings for an addition off the gable end of a basic 2 story wartime house. Just extending the house by 6 feet on one side, it also extends past the rear of the house, and wraps around the rear by a few feet, so there will be a second roof plane on the rear of the house. The problem is it's sensible from a construction standpoint to run the joists and roof rafters perpendicular to the existing house, and while I can change the joist directions without a problem as shown I can't get roof rafters to run perpendicular to the slope. 

 

The attached picture, (Showing the rear of the house with the addition roof plane required) shows the rafters on the front plane populated (just by stretching the current front roof plane over the addition) but they need to change direction 90* just for the 6 foot addition section to match the joists below). The rear roof plane is blank, not sure how to proceed. Will I have to draw them all manually?

 

 

(Ignore what looks like the second floor joists on the addition pocketting into the existing house, that just happened when I was playing with the roof and having it generate framing, it's now deleted, they hang off the outside of the existing rim joist)

 

Thanks very much for any help!

[solver]

Start a new plan. Draw a roof plane. Open it and look at the Baseline settings on the General panel. Experiment with the settings.

 

You can enter pitch as 3 in 12 instead of degrees.

[DanWEC]

Thanks Eric, I saw this solution mentioned before by you in the Chief Architect forum, but I couldn't find the baseline angle in HDP so I didn't think it was an option, found it! Thanks. 

 

I set the pitch to zero, changed the baseline angle to what the actual roof pitch is (26.57* for 6 in 12), then rotated the plane 90*. Worked great, but with one small issue,

 

Any suggestions on rotating the rafters so that they're not vertical? If I click on one all I can seem to do is rotate them along the x axis. Angles are mostly shaded out if I try selecting the ends via an elevation view.

 

 

 

 

 

[AlpineGeoff]

Answering this from a construction perspective: No it does not make sense to run rafter perpendicular to the existing. Running rafters this way, you will have to beef up the existing rafter to carry the load of the new perpendicular rafters, and also need to post under the new barge to carry the new rafters. You would also need a collar tie, and a structural engineer to figure this out. I would run rafters parallel and either have a different pitch on the side that bumps out 6', or run an eyebrow roof off the new main roof to cover the bump out.

[DanWEC]

3 hours ago, AlpineGeoff said:

Answering this from a construction perspective: No it does not make sense to run rafter perpendicular to the existing. Running rafters this way, you will have to beef up the existing rafter to carry the load of the new perpendicular rafters, and also need to post under the new barge to carry the new rafters. You would also need a collar tie, and a structural engineer to figure this out. I would run rafters parallel and either have a different pitch on the side that bumps out 6', or run an eyebrow roof off the new main roof to cover the bump out.

 

Geoff, I'm a builder first, attempted Home Design Pro user second. I already use this program as a tool for renovation renderings, but I'm doing a bit of a pet project to figure if I can get good enough at this program to integrate into my business instead of outsourcing all drafting, but not too promising so far. I'll likely leave it to the pros after this.  As for the framing, given that it's only a 6' bump out from the existing foundation it doesn't make sense to me to run 4 members parallel, approx 16' span, with a knee wall and collar ties, with when all they need to do is span 6' instead. The existing gable end rafter is already supported by the existing gable end wall, which I inspected and is framed appropriately.  I will be leaving all the existing wall framing in place except for 2 passages w/lintels.  I know where you're coming from, you probably assumed I was removing the support framing on the existing gable end wall which would leave a suspended rafter as the header for the perpendicular rafters, but the wall below it is staying. I see that my WIP framing image doesn't show the existing gable studs, they're only showing only on the opposite end as the addition.  

My initial plan was parallel rafters, which would put most of the roof load on the front and rear walls, with 1/3rd on the sides transferring down through the knee wall, but in this config with 2 load bearing walls only 6' apart I feel like this makes more sense. I'd love to hear if you have more input though, always happy to hear opinions!