Bay Roof Bump Out No Hips

[Joe Carola]

I figured I would start another thread about Bay Roofs since the other thread was such a good one. This one is a simple one, but the only problem that I see ALL THE TIME when guys frame these is that they put the last front wall common on even with the end of the top plate. For example in my drawing I used a 6' front wall and a 2' bump out for the bay making the bay 10' wide with an 1' equal overhang all three sides.


When guys frame it like this, the side walls overhangs smaller than the front wall. If you shift the first common over on each side including the overhang where the fascia points meet 4.97053" out past the 6' front wall making them 6' 9-15/16", that will make the side wall rafters overhang the same. If you keep them on the corner of the 6' front wall, the side wall overhang is 8.485281".

On the left side of the drawing I used 5/12 as the front pitch and it's also the 5/12 pitch for the rafter up against the wall, therefore the small side wall rafter becomes a 30.51° or 7-1/16/12 Pitch.


On the right side of the drawing the front 5/12 common and the wall 5/12 remain the same and the side wall common stays the same 7-1/16/12 because your just shifting everything over and not changing any plan view runs or rises, just the overhang and birdsmouth location.

[JMS BUILDERS]

Re: Bay Roof Bump Out No Hips

I agree with the method, nice sketch by the way What program?

[Joe Carola]

Re: Bay Roof Bump Out No Hips

I agree with the method, nice sketch by the way What program?

Jason,

Have you seen them framed with the commons on the wall corner and shorter side overhangs like I see everywhere?

I used Sketchup, the free version.

[sbebuilders]

Re: Bay Roof Bump Out No Hips

This one is a simple one, but the only problem that I see ALL THE TIME when guys frame these is that they put the last front wall common on even with the end of the top plate.

Joe,

I've stacked this baywindow with no over hang and it looks ok, but not great. I've never stacked this type of baywindow with overhang. However I seen a couple hundred of these stacked with the common at the end of the wall and every single one of them looked wrong and the 45 wall fascia always looks like it's running up hill. I guessing this was the way the architect drew it, except for the out of level fascia. Never even thought of placing the last common rafter off the wall. Does it look correct when it's stacked.



Sim

[Joe Carola]

Re: Bay Roof Bump Out No Hips

However I seen a couple hundred of these stacked with the common at the end of the wall and every single one of them looked wrong and the 45 wall fascia always looks like it's running up hill.

I've seen that also many times. It seems like they framed the wall rafter wrong and the overhang is to long along with the HAP cut being to high.

Never even thought of placing the last common rafter off the wall. Does it look correct when it's stacked.

Yes, it looks great. I just extend the front wall top plate on both sides to catch the rafters.

[sbebuilders]

Re: Bay Roof Bump Out No Hips

Yes, it looks great. I just extend the front wall top plate on both sides to catch the rafters.

That is such a good idea...extend the front wall top plate on both sides.

We need to put that idea in a baywindow cheat sheet, so we don't have to drive around looking at out of level fascia anymore. Need to post it on a architectual forum as well. Maybe even the autocad website/forum .

[kpatrix]

Re: Bay Roof Bump Out No Hips

Hey Joe,

I don't wanna hijack this thread, it made me think of the bump out bays with hips.

I prefer to do it this way because I like symmetry. Equal overhangs and equal HAPs. When I see them without hips, it looks a little off to me. Maybe it's because I like my plan angles to match up with the soffit angles. I"ve reframed lot's of bays because it looked "off" to me and I couldn't just let it slide, even on my own dime.

That's why I pay so much attention to them now. Frame a bay with a 12" overhang on one side and a 10" overhang on the other two, then run equal brick frieze, and the closed soffit angles from the fascia dont intersect the mitres on the brick frieze. It's not symmetrical.

I will take the main run, from the front wall in the example, minus ledger = 22 1/2"

I get a hip run of 31 13/16". subtract the run from this and multiply by 2 and subtract this sum from the 6' wall and minus 3" to get a ridge length.

In this case it's 53 1/8"

Cut the two true hips, which are nailed to the wall, at 33 3/16"

The bay corner hips are 26 1/8.

Cut 3 commons, 24 3/8"

Tack the true hips on the wall where they belong, drop the ridge in between them and nail it off.

Find the center of the bump wall and pop in a common. pop all the other commons off of this. Set the bay hips. Measure in the jacks and fill it in.

There won't be any commons on the bay walls, they are all jacks.

Anyway, you can use the same pattern for all the rafters, except for the hips against the wall. It's a true octagonal solution. With closed soffits, all the corners are bisected.

It's symmetrical.

John

[Joe Carola]

Re: Bay Roof Bump Out No Hips

John,

I don't like these bays without the hips either, but when they're on the plans and the Architect's don't want to change them I have to frame them this way.

[kpatrix]

Re: Bay Roof Bump Out No Hips

John,

I don't like these bays without the hips either, but when they're on the plans and the Architect's don't want to change them I have to frame them this way.

On a contemporary, I like them. On a french or victorian, it just doesn't look right.

The way you have it, it would look right at the soffit, and that's where it matters. Equal overhangs, bissected soffit, level.

[Joe Carola]

Re: Bay Roof Bump Out No Hips

That is such a good idea...extend the front wall top plate on both sides.

Sim,

It's just another example of why I figure these types of roofs including the overhang and simplfying the framing and why you can get any roof with no matter how many different picthes there are to have equal overhangs and where the hip and valley offsets will cross the plate lines.

We need to put that idea in a baywindow cheat sheet, so we don't have to drive around looking at out of level fascia anymore.

I think that I saw one the other day out of the corner of my eye. I will drive by tommorrow and see. If so,I will take pictures and post them here.

Need to post it on a architectual forum as well. Maybe even the autocad website/forum .

I've never been on an Architectural forum before. You think they'll let us Framers in?..........;-)

[Joe Carola]

Re: Bay Roof Bump Out No Hips

The way you have it, it would look right at the soffit, and that's where it matters. Equal overhangs, bissected soffit, level.

John,

Years ago I used to frame them the wrong way. I would always maintain equal overhangs, but what I did was the ledger was cut the same size as the front wall, for this example would be 6'. I would just stick the last rafter/hip off the plate line out to the overhang.

That way was wrong because it changed the wall rafter pitch. The hip wasn't a true Octagon hip either. It was a GOON hip....;-)

I changed the drawing on the right side to show you how I used to do it which is the wrong way, but worked. I think what made me realize how to frame it the way I showed in the beginning of this thread was that one time the bay roof had to have copper. So the way I did it was that the top of the front roof was smaller than the bottom width. That's what made me think to make the top ledger the same as the fascia width so everything was equal top and bottom.

Look at the right side of the drawing.

[Joe Bartok]

Re: Bay Roof Bump Out No Hips

That way was wrong because it changed the wall rafter pitch. The hip wasn't a true Octagon hip either. It was a GOON hip....;-)

I've never heard of this kind of Hip before. Is this something we should know more about? :)

Seriously, good drawing Joe. Sometimes it seems like a lot of work to do the geometry and math and it's tempting to fudge it and take the easy way out. The "easy way" usually turns out to be more work and often ends up making a mess. There were times when I've had to fix framing and/or joints that were based on wrong assumptions by others. And I have a file with sketches similar to your drawing where I made mistakes of my own. (Like the one recently in a BT post ... treating the fence meeting the sloped wall like a regular Valley rafter).

Anyway, I have something for all to consider that goes back to the other hipped bays as well. It hasn't been talked about or maybe I missed it - when we offset to create equal soffits one of the the plates also has to be raised or lowered.

[Joe Carola]

Re: Bay Roof Bump Out No Hips

I've never heard of this kind of Hip before. Is this something we should know more about? :)

Maybe Sim can name it, "Joe Carola Goon Hip".......;-) I don't mind making fun of myself or showing something that I did wrong. Sometimes you learn things on your own.

If you look at the drawing on the right side with the Goon Hip, you will see that the hip in plan view is only running at 36.34153" or 36-15/16" when the common is running at 36". It makes that hip pitch a 22.43° or 4-15/16/12 pitch instead of the 5/12 common. Not that big of a difference.

It also changes the wall rafter pitch to 20.11° or 4-3/8/12 pitch.

Anyway, I have something for all to consider that goes back to the other hipped bays as well. It hasn't been talked about or maybe I missed it - when we offset to create equal soffits one of the the plates also has to be raised or lowered.

I thought that I mentioned it somewhere, maybe not, but either you raise the plates or adjust the birdsmouths according to the pitch. Or, you raise the plates and adjust the birdsmouth so that for example, if you have to add 2-1/4" to the side wall plate, you can use a 2x and a piece of 3/4" plywood and cut the birdsmouth to fit that. I hope that makes sense.

[Joe Bartok]

Re: Bay Roof Bump Out No Hips

Yes, that makes sense. I didn't time today but tonight (if I get a chance) I want to try something else and test drive those formulas in the Fixed Ridge Height threads. I should be possible to pick any point along the 5/12 wall rafter, make that the working point or fixed height and get the same answers as changing the plate height or bird's mouth.
It seems like a lot of trouble to go to but it never hurts to have more than one solution to a problem.

[JMS BUILDERS]

Re: Bay Roof Bump Out No Hips

Jason,

Have you seen them framed with the commons on the wall corner and shorter side overhangs like I see everywhere?

I used Sketchup, the free version.

jOE yes see them wrong on 95% I look at (of course the other 5% are the ones i do lol) In the first year I opened I was framing them wrong thinking I was right, long story short I hired an old timer pt 69! still going strong till this day at 78! he taught me the right way and showed me I still always need to be open to different ideas and it also told me WHAT A GREAT HUMAN RESOURCES GUY I AM ! jk lol