Shed Dormer Framing Question

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Nate R

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My house had one dormer put in at the time it was built, from what I can tell anyway. There's another dormer that was added later.

Anyway, the original dormer is framed as shown in the picture below
SiteLines5.jpg


Take a look at the ceiling joists shown in the picture. Am I right in assuming that there needs to be an interior wall on the other end of those joists all along the width of the dormer? (Or some sort of support; beam, etc) And thus some of the ceiling (not roof) load would be transferred to that interior wall, and thus loading the floor joists that the wall sits on?
 

Leejosepho

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Am I right in assuming that there needs to be an interior wall on the other end of those joists all along the width of the dormer? (Or some sort of support; beam, etc)

Those joists should attach to the regular roof rafters on the other side of the ridge (somewhat like the bottom chord of a truss) to help keep the ridge triangulated after the normal rafters have been cut out, and no wall or support beam would be necessary as long as those joists are properly sized for their span.

And thus [with an interior wall or support beam] some of the ceiling (not roof) load would be transferred to that interior wall, and thus loading the floor joists that the wall sits on?

Yes, to the point of their own weight plus ceiling board and insulation, but not in any structural way.
 

Nate R

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Gotcha, OK. It appears my house's dormer has those joists just end over an interior wall. But things were done differently in 1922, and my house is FAR from perfect in the framing department. Just trying to figure out where the load normally goes.


I was looking at removing the end stud from that interior wall, so this will change my plans a bit.
 

Leejosepho

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Gotcha, OK. It appears my house's dormer has those joists just end over an interior wall. But things were done differently in 1922, and my house is FAR from perfect in the framing department.

While I believe it best for them to go to the other side, what you have there is no big deal if the dormer is relatively short along the ridge. The longer the dormer, however, the fewer rafters there are to keep the ridge from sagging.
 

hj

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dormer

I am not sure what you are asking, but the joists over the "opening" have to have the same support that the room's joists, which should also be resting on it, need over any open space, such as a window, door, etc.
 

Toolaholic

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Naterrrrr

I'm and old Cape cod carpenter . This is very typical const. on The Cape and New ENGLAND. The answer is No. Normally We frame in a full length Knee wall
with openings for storage. Also I would do a number of drawer sets in these
walls for clothing. Load comes down on outside double plate , on ridge
[ opposing rafters carry this load ] , and double trimmers shown. Collar ties carry load as well!
This advice is not free, I expect You and family to pull for My

BOSTON RED SOX :D
 
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