Does anyone out there have any experience framing an eyebrow dormer into a trussed roof?
I’ve got a remodel where we’re looking at adding an eliptical window over an entrance with an eyebrow dormer on top. The window will sit on the top plate. The problem is that the current roof is framed with scissor trusses and there aren’t any nearby interior walls. The window would cut through two of the trusses. We’re already ripping part of the roof deck off but I’d like to minimize the interior work.
Any ideas? I’d like to know my options before we call the engineer in.
Replies
Since you talk about interior work, I assume this is an existing house?
What you want to do is probably possible, but a major pain in the keester to do right. If you have really high snow loading or if the trusses are long spans it may not work at all.
Typically a repair calls for cutting off the 2 trusses and hanging them on a header. The header is then hung off of the adjacent undisturbed trusses.
The problem is that these adjacent trusses have to be beefed up a great deal. This will likely involve adding a bunch of lumber and plywood gussets across the ENTIRE length of the truss. And I doubt you can do it all without ripping out the ceiling and/or roof.
A couple of ideas come to mind. First would be to leave the existing trusses undisturbed and drywall them. That way you'd still have the light shaft, but no major structural modifications. But the customer may not go for that.
The second idea is to have new scissor girder trusses built and slip them in place to support the header. If you have to tear into the structure anyway, this might be easier than trying to do the repairs to the existing trusses.
How about some more info? Like the span, pitches, loading, and age of the structure? And your geographical location? That may help some.
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Boss,
Thanks for your feedback. Yeah, this is a remodel of a twelve-year-old ranch. The entrance opens into the great room which has a span of 26'. This area of the house wasn't being touched other than the entry way. Due to the owner's budget, the girder-truss option probably won't fly.
The roof / ceiling pitches of the existing truss' are 9/12 and 4.5/12 and again the span is 26'. We're located north of Detroit, so the snow load is a consideration (especially lately!).
I ran the exposed truss idea by the owners last night (the architect being long out of the picture) and they were receptive. We're adding some exposed timber elements to the front elevation so we could even possibly veneer them and have that fit in. I suppose then that I'd build up a sill with cripples over the heel and then go from there with the dormer. This will be my first eyebrow dormer but I'm welcoming the challenge.
Thanks again for the advice!
Glad to know something I said/did was useful.
With the high outside pitch, that would have made it easier to do the repairs, if you'd gone that route. But the high snow loads you have up there (40 PSF?) would have made it difficult.
Glad to hear the owners went along with leaving the trusses in place. That should make things considerably easier for you.
Any chance you'll be posting before and after pics? A project like that one would be neat to see.The only English words I saw in Japan were Sony and Mitsubishi [Bill Gullickson]