A scab board is a short piece of lumber that is typically used for the purpose of joining two adjacent pieces of timber together with the intention of causing the two pieces of timber to shore-up one another thereby increasing their overall strength.
When do you use a Scab?
A number of situations exist where a scab board can and should be used to improve the overall strength of any wood-framed structure. The most common place a scab board will be seen is in the construction of a door frame, and in-between wall studs. Generally, a door frame is constructed using two outer studs on either side held together at the top by a scab board on each set with two studs forming the top of the door frame.
Another popular place that scab boards are frequently used is in the roof structure in-between the trusses. A scab board will frequently be used where two or more pieces of timber are used directly next to each other to form the truss. A scab board is usually placed on the underside of the truss to increase the overall strength of the truss itself.