Gambrel dormer into a gable roof

[Chaz..]

I will be building a garage 24x25 gable with a 8 or 9 inch pitch, with two dormers , one on each side,the question is the owner wants a gambrel dormer on one of the sides ,feels he will get more usable space, dormer width about 18 feet ,can that work,also if it can be done I was going to built trusses for the rafters,also I am trying to wrap my head around how the valley will work ,if it could can that also be a truss , how will it work with the gable roof on that side with a different pitch 8 or 9 pitch then the gambrel. Thanks in advance

[dlhunter]

If you are going with trusses your truss manufacturer will take care of all of that for you. All you need to do is send them a check and schedule delivery.
It is doable but I would probably just stick frame something like that.

[Lavrans]

Hmm... Just imagining what a gambrel dormer will look like.

Of course you can do it- the valley is going to have a crook to it. I would be inclined to frame the rough opening as you would a shed dormer to avoid getting into all the issues of load & spread. Then you can set in a valley rafter that will catch the shallow Gambrel pitch with another intersecting it to catch the steeper pitch. I suppose that what's going on it could be built as trusses.

Otherwise you choose the steeper gambrel pitch and run the valley at that angle, whatever it is, as the primary valley and add in a second valley wherever the top pitch dies into the roof... Seems like a lot of odd framing and extra cash to the guy who's going to have to calculate the load paths for you.

Gambrel.jpg

Note- drawing assumes the dormer would start below the ridge- if it's tying into the ridge everything is a little easier, but the look changes a bit...

[Chaz..]

Darrel,I am going to stick frame it,and plan on making the trusses(with plywood gussets myself do not plan on building a wall at the knuckle,plan on attaching gambrel rafters to the valley, if that could be done, ,I am just trying to wrap my head around it, never did a gambrel roof plus trying to visualize how the gable roof will tie into the gambrel dormer roof with the valley,since there will be three pitches trying to make sure it work and how the common rafters from the gable roof works with the gambrel valley, thanks again

[Chaz..]

Lavrans, talk to engineer ,will be using structural ridges on main roof and dormers,ridges will be all the same height,I was not going to use cheek wall, but it will probably make it easier , I was going to make trusses and attach to gambrel valley but never seen that done and wonder if it could since it will be two piece valley ,my concern is strength will need a leg under valley ,thanks again for imput

[Lavrans]

Lavrans, talk to engineer ,will be using structural ridges on main roof and dormers,ridges will be all the same height,I was not going to use cheek wall, but it will probably make it easier , I was going to make trusses and attach to gambrel valley but never seen that done and wonder if it could since it will be two piece valley ,my concern is strength will need a leg under valley ,thanks again for imput

You shouldn't need a leg under the valley. You will probably have to have a custom hanger welded up, but that's pretty cheap all things considered. Looks like fun, even though I'm not sold on the look. Why not do a huge eyebrow? :)

[AndyGump]

O.K. that just looks weird.

Andy.Gambrel Dormer.jpg

[Chaz..]

Andy , thanks for the picture, I agree with you, but that is what the owner wants to do, can you draw the framing,I am trying to visualize how the valley will work with the three different pitches ,main roof ,the top pitch of gambrel the bottom of gambrel all tying in to the gambrel valleys, I was not going to have a wall for the gambrel ,plan on building a truss, top of it attached
into the ridge and bottom cut of truss rafter gets nailed to the valley, never seen it done, wondering if that is possible thanks again for the help

[jimAKAblue]

O.K. that just looks weird.

Andy.Attachment 27052

It will look much weirder if you draw it in proportion.

He's talking about an 18' wingspan on a 25' building. That will leave only 3.5' on each side of the wings.

Without drawing it I know it's something that I'd be ashamed to frame LOL!

[jimAKAblue]

The obvious solution is to make the entire roof a gambrel and if that isn't enough top floor space, then add a few small dormers.