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Is it possible to extend existing roof line for addition work?

9 years ago

Hi, I'd like to enlarge the front of my house by just continuing and extending the existing roof by 3 to 6 feet and then building additional space underneath the new roof.

My house is a 45 by 28 foot one story, split level, tuck-under garage house, with 28 foot long, 4x12 slope engineered common trusses running perpendicular to the front of the house. The heel of the trusses are at the front of the house.

Because the edge of the front roof is 16 feet above the driveway and 12 feet above the front yard, I would just like to extend the existing roof down and forward, maintaining the 4/12 roof slope. I would then be able to enlarge my garage and the bedrooms over it, add a 6 by 12 foot entrance foyer and closet and add to the living room.

The existing front wall I would remove and replace with a line of double 12 foot 14 inch lvl beams to support the existing roof. I would stick frame the new 3 to 6 feet of new roof and ceiling joists. The rooms on the inside of the front of the house would have sloped ceiling that would drop 2 to 3 feet at the front wall. I'm OK with the look of the sloped ceiling and lowered front windows. I'm also sloping the ceiling so much for a deep energy retrofit, as I live in the Minneapolis area with very cold winters.

I have a full two volume set of the 2000 International Residential Building Code, and sectional updates of it, so I have checked my plans for downward loads but I don't know about lateral, shear and uplift loads on this unusual roof remodel. I'm wondering if my house could fall over.

My concern is the 3 to 6 feet of new sloped roof drops one to two feet below the existing roof and lvl supporting it below. I'm afraid lateral and shear forces could cause the roof to buckle and collapse where the new roof meets the old roof.

Does anyone have experience with this kind of roof extension? I'd like to know if this kind of roof extension is possible before I hire a structural engineer to check my plans.
I've considered other roofing designs for the front of my house, including cross gables, but I feel they go too high and are a lot more work. My existing roof is just 4 years old so I'd rather leave as much of it alone as possible. I'd also like to add to the sides and back of the house, so I would like to economize where I can. I'll be doing the work myself this spring and summer.


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