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Building Homes or Extensions/Dormers with attic truss options



My attached garage is 30 in length by 26 wide. It is is built with attic trusses. This create a space that is about 12-15 feet wide upstairs. We would like to make the room wider. I could build small dormers (6 feet or so) without any issues, but we would like more space that what this offers. We would really like to put in a shed dormer that could span almost the whole length. 3 questions:

What are the consequences of adding a shed dormer? Would i have to redo the roof?

Usually, is the bottom cord of an attic truss the same height as an i-joist lets say that could span the same length?

Any other options to adding space when the roof is built with attic trusses?

Stephane- You will find that the best option is the shed dormer. A skilled builder can do this without having to redo the roof. The bearing plane (truss chord) would be the same height as the new bearing beams required.
Trusses; though fast and inexpensive for a new build, do not lend themselves for very many future options. From your description this project seems pretty simple.
Please feel free to contact me for any reason.

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Glen W


I can answer questions about the whole home building, additions and renovation processes. I am able to talk about finite hands on skills to budget and management areas.


I have been a General Contractor for over 25 yrs. and in 10 States

BA - Architecture

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