Help with auto roof plane


BeeoHat
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Go to solution Solved by Rich_Winsor,

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Those could be call crickets too, that was just an example I found online, but I was referring to this particular case where I don't see them in the Pic provided, and his images were labelling Valleys as Crickets.....

M.

It's actually hard to tell if his Sketchup #1 or #2 image is the correct one from that grainy photo.....

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Yes, I was glad that you pointed out the incorrect notation. You posted soon enough that I didn't respond right away. Then there were all kinds of interpretations, so I didn't get involved. Without crickets, some roof lines would not work for remodels.

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Bill:

 

This is an interesting exercise in changing the shape of a roof by altering roof pitches of the three outer roof planes.  When I say changing the "shape", I am talking about moving the point of intersection of the two side roof planes (that actually connect with the brick wall) for the bay with the three triangular shaped bay roof planes.  All 5 of those roof planes have one common point of intersection.  I am under the assumption that the two side roof planes will be at the 4:12 roof pitch shown in your plan (although they don't have to be).

 

I was playing around with your plan and if I make the ridge length of the two side roof planes 77-79/128" (pitch at 4:12 and fascia top at 112-1/4"), then the center triangular roof plane for the bay ends up having a pitch of 7-9/16:12 while the two triangular roof planes on either side have a pitch of ~ 5-3/8:12.  If you want to move point of intersection back towards the house to flatten the pitch of those three triangular shaped roof planes then you have to "manually" shorten the length of the flat ridge (i.e., move outer the point of intersection of the two side roof planes (the distance from the brick wall to the point of intersection) and then "manually" matching (moving) the top points of intersection of the three triangular roof planes and then "manually" changing the ridge heights in the dialog box for each of the three roof planes while keeping the fascia top at 112-1/4".  If you try to get Chief to join any of those roof planes to fix all the lines of intersection, you will probably get a "shooting" roof plane.

 

post-191-0-00866800-1399237526_thumb.jpg          post-191-0-26607300-1399237499_thumb.jpg

 

If you are unfamiliar with manually manipulating roof planes, trying to explain this so you can understand it isn't super easy.  I am not sure that you can get Chief to auto build this part of the roof unless you have pre-determined with Trig or CAD what the roof pitches should be.  If you haven't totally figured this out yet, give me a call at (208) 935-1521 and I will try to talk you through it.

 

I didn't watch Scott's video.  To simplify the design, I don't think you need to have those extra short lines of intersection Scott shows in the image he posted.  I think Gene's and Rich's 3D images are the way you want to go.  Rich's plan image looks like it needs to be cleaned up ... I think he has overlapping roof planes.  As I said, there are many possible solutions you can have with this roof design.  The geometry of the walls of the bay and the porch and the corresponding roof pitches are what make this exercise a good one for learning how to manually manipulate roof planes.

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Think you got it CJ , that was what I thought was there ,it is just hard to see if there is a Hip in line with the Gutter line of the porch roof or not in the photo...

Many different ways to build it.

Try building with no eave and see what you get.

Now add the eave on see the configuration. You will get the little legs I have. Without the funny legs I have, imagine how the rafters will intersect the roof porch beam.

Many different ways, pick your poison.

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Well, thanks to all the input, I finally got up the nerve to try this manual roof plane construction, and somehow managed to pull it off!! It took a bit of work, but as Gene noted, it was a "very worthwhile exercise".

 

Again, thanks to all for the commentary, and especially Scott's videos, which really got me to try my hand. :)  :)

post-567-0-40515800-1399324362_thumb.jpg

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Well, thanks to all the input, I finally got up the nerve to try this manual roof plane construction, and somehow managed to pull it off!! It took a bit of work, but as Gene noted, it was a "very worthwhile exercise".

Again, thanks to all for the commentary, and especially Scott's videos, which really got me to try my hand. :):)

I hate to be a kill joy, but you did not watch close enough. Some of your rafters and a couple of valley rafters will have extra deep bird mouth. .

Build able as shown but I bet they did not build it like that.

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I tried my hand at making a video demonstrating how I build this bay roof.

https://www.youtube.com/watch?v=PZ4ZQBdliLA

Very nice Jim,  thanks for that.  I think you and I are on the same page with essentially the same result,

 

The difference between your method and my method is very minor.  Because the two angled roofs have a different pitch,  this result is either a different eave overhang,  or a different roof baseline height.

 

My method results in a variation in the eave overhang,  (about a 2-1/2" variation in the eave overhang).

 

You method results in a variation in the roof baseline height for the angled roofs,  (very minor but it is there).  Also I think your valleys and hip for the angled roofs will not meet exactly at the the angled intersection of the top plates.  again a very minor variation.

 

I would think my method might be easier to build in the field (maybe),  but I would have to live with the fact that the eaves are slightly different.  Out here with the way are eaves are (sans fancy eaves and friezes),  it is not a problem.  I think where you guys are you deal with a lot more fancy eaves and friezes so it may be more of an issue.

 

So pick your poison.

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