Timber Framing Moment of Zen: Scarf Joint

by ziggy on May 27, 2012 -- 2 comments -- Follow

sillbeam-scarf

When two timbers join to become one unit, they are mated with a so-called “scarf joint”. Scarf joints come in many different styles, some more elaborate than others. This sill beam scarf joint is a rather simple one, as far as layout and cutting, goes and it is wisely located directly above a support pier.

This photo was taken before pegs were driven into each tenon, but if you look carefully you can see on the upper half of the scarf where the peg hole is marked.

Scarf joints were developed when taller trees became scarce and long spans had to be created with shorter pieces of timber. I think that timber framing is beautiful for its ingenuity and effective use of materials.

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  • I couldn’t agree more that timber framing is an art and a craft and an inspiration.
    Yes, it may use more wood, but it is building to last, and I think that is the true definition of sustainable.
    We are building an unmilled timber frame house this summer using trees from our own land that would be considered weeds by the lumber industry. I am finding that there is a lot more labor upfront when you have to fit trunks and limbs together as nature formed them, but it is very satisfying.
    Timber frame always feels good!

  • While scarf joints have their place in connecting timbers, they also have limitations. Depending upon your loads, you could have a beam failure here, especially to the right of the bearing point. On the right, you effectively now have 1/2 the beam depth in strength & perhaps a bit more on the left. One has to spread the bearing out past the joint. Options: a 3-4′ piece of beam material directly under the joint to spread your bearing; sister some structural material on each side of the joint; or add piers to either side of the joint. Do your load calcs; perhaps your timbers are oversized enough to make this work as it is.

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