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Modifying a truss roof for another floor

By Forrest M. Holly / July 3, 1980



Q. I have an attic crawl space with prefabricated self-supported roof trusses. Is it possible to put in a floor and dormer with this type of construction? The floor below the trusses is divided into rooms which would help to support the additional weight. Ken Vogel Liberty, Maine

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A. From Down East Maine to southern Arizona is too long a shot for me to answer a structural question such as this. The problem involves many other aspects which need some good analysis for a solid answer.

It sounds to me as though the floor and dormer may be possible. However, for a final say I suggest you call a local architect or engineer for a survey of the existing building, its condition, roof pitch, size and spacing of the trusses, the existing walls and their bearing ability, adequacy of the foundation, and so on.

Only then can you expect a good answer which will lead to working plans and specifications.

Design and construction mingle both art and science. Such a redesign as you propose is no job for an amateur. A professional trained in the business will develop on paper a scheme which combines both aesthetics as well as practicality.

You should be happy with the result -- and you'll have a safe building to boot.