Some More About Joints
As well as the different types of joints used in oak framing, there is a wide variety of
forms within those types. Their shapes are often adapted to suit their individual positions and
roles within a frame and, although they can be grouped together by overall type, there is often
some commonality of shape and function between types.
Mortise & Tenon Joints
This is the most common joint used in oak framing, with variants in pretty much every frame.
In its simplest form, a tenon on the end of one timber will slot into a mortise cut into another,
fixed in place with one or more pegs, with the purpose of holding the timbers together tightly.
However, the shape of each part must account for the size and shape of the timbers, the position
of the joint and the forces acting upon it.
Very occasionally, we are asked to create a structure from reclaimed timbers of irregular shape,
where jointing can be very much complicated and often precludes the use of modern framing tools -
requiring reversion to more ancient methods.
Bridle Joints
A bridle joint is very similar to a mortise and tenon joint in many ways, but is open ended.
They are often found at the apex of a truss where a pair of principal rafters meet, though also
sometimes where they join with posts.
Dovetail Joints
The principle of a dovetail is that it widens within a joint to prevent it pulling apart.
As with other joints, there are may different forms.
Simple socketed dovetail.
Socketed clasp dovetail.
Dovetail tenons often secure collars to principal rafters, used in tension to resist roof spread and further secured with opposing wedges.
Housings, Sockets & Cogs
The purpose of a housing or socket is to carry the load of a timber from beneath without bearing that load upon the part of the joint securing it in place.
Scarf Joints
Longer frames often require longitudinal timbers such as ridge beams and wall plates to be joined end to end with scarf joints.
There are many forms of scarf joint, their use dependent upon their application and the nature of other joints nearby.
A simple mitred scarf.
A complex table scarf shaped to permit nearby housing and jointing of numerous other timbers from various directions and angles.