Understanding Oak Frame Terminology and Its Importance in Construction

This blog covers the essential Oak Frame terminology and its role in the construction of an Oak building. We will describe how our Oak Frame structures are crafted with precision and expertise.

We explain to each customer we meet the construction techniques used to create our beautiful Oak frame designs but, thought it would be useful to detail all the information in a blog as a point of reference and make it available to those people that we do not get to meet.

To avoid information overload we will split the terminology into three blogs. . This first blog will focus on the construction techniques for the Oak frame and our Oak frame garages with the second blog describing roof details and stud work with Larch weatherboard, then the third describing the features more often used in our Oak gazebos, pavilions and Oak cookhouses.

The Oak Frame

The Oak frame is the structural element of the building, made from solid green Oak timber. Cheshire Oak Structures use 175mm x 175mm fresh sawn constructional grade Oak for the principle Oak frame, posts, eaves beams and tie beams. Being green Oak means that the Oak is fairly recently felled and that there is around 10 to 20% moisture still in the Oak. Kiln dried draw pegs are used in the construction and this allows the green Oak to shrink when drying out, therefore clamping down onto the draw pegs, making them like a steel connection.

Traditional Oak frames are manufactured using time honoured joinery techniques which allow the timber to expand, contract and age over time. The posts and beams are jointed together with draw pegs, there are no screws nor nails in the Oak frame.

A mortice and tenon joint in an Oak frame is a strong, classic joint that joins two pieces of Oak. The simplest way to explain a mortise and tenon joint is to imagine “the Tenon being inserted into the slot Mortice.

Mortices are sockets, recesses, or holes cut into the Oak in order to connect it with the tenon (or “tongue”). Tenons are projections on the end of a piece of timber, designed for insertion into a mortise. The tenon slides into the mortice, creating a tight, secure connection, reinforced with oak draw pegs.

Draw pegs that we use are kiln dried Oak pegs, that when knocked into the off-set holes in the mortice, they pull the tenon firmly into the joint. The pegs are generally left sticking out on either side of the joint for aesthetic purposes. 

Oak Knee Braces.  Cheshire Oak Structures use knee braces which are gently curved to achieve maximum structural stability and to retain structural integrity no matter the weather conditions and create an attractive traditional appearance. These also feature mortice and tenon joints, which are pegged.

Scarf joints are used on long eaves beams where the length of Oak is scarcer to source and not easily managed. Therefore two or three or more pieces of Oak are manageable and can be jointed by a scarf joint. We usually use lengths of Oak that are 6.5m long, before being worked on, on a two bay garage this is sufficient for our 6.2m wide two bay garage. On a three bay, as in this case at 9.3m wide, the beam would be in two parts with a scarf joint.

Cog joints are mainly used on the tie beams where the tie beam is jointed to the eaves beam, to help stop the roof spread. Tie beams do what they say, they tie the eaves beams together.

The Oak posts and Oak beams are fitted together using the mortice and tenon joints, the Oak knee braces give structural support and the Oak pegs secure all the different sections together to form the principle Oak frame, as shown in the image below. This Oak frame is known as “a ring beam construction” meaning that the whole of the frame is tied together thru’ the numerous joints and Oak timbers.

This Oak frame is the basis for every Oak garage we design and build.

Once the principle Oak frame is constructed we "cut on" the roof timbers and then fit the wind bracing and Larch weatherboard to give the finished Oak framed garage as the three bay garage below.

The final result

The next blog in this series will cover further features that make up our Oak Frame Garages

If you would like more information on our Oak garages complete the enquiry form or if you are more traditional in outlook (like our Oak frames) please call the office on 01829 250919.