8 foot wide dormer require engineering?

[tharp]

Hello, I am planning to build an 8 foot wide dormer onto my roof. In general, does a dormer of this width always require engineering? If I can use the codebook only, what tables can I use to size the headers for this dormer? Thank you very very much!

 

[Mr. Inspector]

It depends on what codes, snow and wind load loads are in your area?

 

[ADAguy]

as usual the "it depends" will get you every time. Ask your AHJ.

 

[MACV]

For a shed dormer, if the main roof is steeply sloped and the front wall of the dormer aligns with the exterior wall below and the dormer rafters span from the top of that wall to a central ridge, you might be able to double the rafters under the side walls and use the rafter table in the code to size the dormer rafters (should be the same as the steep rafters) but its all up to the local inspector. If its set back or a gable dormer you will probably need professional assistance but its a simple task.