Q:
While replacing some roof tiles recently, I had to remove the roof ridge vent. When I did so, I noticed that the rafters had separated from the ridge beam (1/2 in. on one side and a full inch on the other). The rafters had been only toenailed to the ridge beam. Is it necessary or even possible to pull the rafters back tight with the ridge beam?
Gregg Palmer, Silver Spring, MD
A:
Contributing editor Scott McBride, of Sperryville, Virginia, replies: The situation you describe may have been caused by radical shrinkage of framing members, perhaps compounded by sloppy workmanship in the first place. In any event, I don’t think the situation needs to be remedied, provided that the roof in question is an ordinary gable.
The reason is that in a rafter/ceiling-joist roof system, the ridge represents the apex of a truss. As such, the ridge and the adjoining rafter ends are entirely in compression. If anything has the ability to force the rafter ends up tight against the ridge, it would be the formidable weight of the roof itself, especially a tile roof.
So the question becomes what exactly is holding the rafters away from the ridge. My guess would be the crossed toenails. Beginning carpenters get a vexing lesson in this subject when they learn to toenail studs. When the first toenail fails to draw the stud tight to the plate, a second toenail is driven from the opposite side. The toenails cross, leaving a permanent gap between the stud and plate. No amount of bludgeoning will tighten up the joint. The crossed toenails form a sort of spring capable of withstanding tremendous pressure.
If the roof in question is over a cathedral ceiling, I would be more leery. These roofs typically have no ceiling joists to counter the outward thrust of the rafters. Consequently, the ridge may be structural, meaning that it is acting as a beam to carry the rafters. (By contrast, an ordinary ridge acts strictly as a compression member that ties the tops of the rafters together.) Some kind of differential settlement in your walls could conceivably cause rafters to draw away from a structural ridge. If that is the case or if you have any doubts at all, you should consult an engineer who may be able to prescribe a remedy involving metal framing connectors or plywood gussets that will keep the rafters from separating further.
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