How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
Does a ridge board need to be supported?
Monday, October 22, 2018
The only purpose of a ridge board is to provide a stable bearing surface for the tops of paired rafters to meet. It does not carry any load. The ridge board is usually just a nominal one inch or two inches wide (1x or 2x lumber) and must be tall enough so that the ends of the joists make full contact with it along their face. An example of one is shown above. The bearing walls that are parallel with to a ridge beam must have the stiffness to resist the the outward pressure exerted on the walls by the joists. This can be provided by horizontal ceiling rafters that connect between the walls or a concrete block wall with a tie beam. So a ridge board does not have to be supported.
A ridge beam, on the other hand, is a thicker board that looks like a structural beam (because it is) and needs support at both ends and possibly in-between. It carries the center half of the roof’s live and dead loads. To learn more about the difference between them and the ways that lateral pressure can be controlled when using a ridge beam, see our blog post Is a ridge board/beam required for a roof framed with rafters?
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To learn more about roofs and attics, see these other blog posts:
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