A scab is a short piece of wood used for the purpose of joining two adjacent pieces of timber together with the intention of causing the two pieces of timber to counterbalance each other increasing their overall strength.

When do you use a Scab?

A number of situations exist where a scab should be used to improve the overall strength of a framed structure. The most common place a scab will be seen is in the construction of a door frame. Generally, a door frame is constructed using two outer studs on either side held together at the top by a scab on each set with two studs forming the top of the door frame.

The other location a scab is frequently used is in the attic structure for the trusses. A scab will frequently be used where two or more pieces of timber are used directly next to each other to form the truss. A scab will be placed on the underside of the truss to increase the overall strength of this truss.