# Rafter work on a barn



## Littyguy (Feb 10, 2019)

New here. I have never felt the need to join before as most topics are well covered. Now I have ventured into new territory and I am kind of stumped.

I am currently bidding a job to put solar shingles on a barn. 
The barn has significant sags in the rafters from being close to 100 years old, having been built with native timber (most likely insufficiently seasoned) and the extra weight of having two layers of asphalt over the cedar shakes.

The solar shingles require the deck to be a fairly flat plane--something this barn is not. At 68 ft long, the waves in this roof are substantial, possibly over a foot. It will be impossible to know for sure before removing the old roofing material.

My plan is to run string lines along the peak, gambrel transition, and eave, connect the lines with furring strips (will be more like rafters in places), and build a new roof deck with oversized facia to conceal the work. I am planning on putting bracing inside the peak to arrest any further sagging that might happen in the future.

The problem is that I have no idea how to bid the carpentry work. 
Materials should be fairly easy, but something like this can suck labor hours, especially if there is insufficient scaffolding and/or there are workers idle while the new surface is being sketched out. I'm not a fan of "time and materials" because it does not reward the contractor for efficiency, off-clock planning and innovation, and the client will often get sticker shock if complications are encountered.
Is there some standard for rafter repair and resheathing that can be applied?

There is visible staining on the rafters and support structure from leakage, so additional structural work may be necessary. How much +/-% is appropriate?

What drew me to this job is the fact that it is new and interesting. The work doesn't scare me, it's the possibility of underbidding that scares me.


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