Sessile Oak
Sessile Oak workshop Intricate wooden carving

Green Oak Frame Carpentry

The bulk of the carpentry work is carried out in the workshop using mainly traditional specialist hand tools in addition to modern, state of the art machinery where applicable.

Skillful use of hand tools

All joints throughout a frame are fitted carefully, making use of classic pegged mortise and tenon joints of a range of shapes and types. This tried and tested method of fabrication is known for its strength and durability.

It can sometimes take a little persuasion

Whilst largely determined during the design stage, the finer carpentry details are often decided upon in response to the features of the timber to make best use of the particular strengths of every piece of wood - positioning, sizing and shaping accordingly.

Green oak, by its nature, is a dynamic material and, as such, demands a high standard of craftsmanship and a thorough understanding of the material. It can, at times, also be physically demanding so strength and durability are often as important in a framer as in the frames they make.

Building the Oak Frame in the Workshop

Sorting and grading delivered timbers for use

Sorting and Inspecting the Timber

With a design approved and a schedule established, the necessary timbers are ordered. Upon delivery to our workshop, they are sorted and inspected individually to ensure they are free of defects such as excessive knots, bowing, shake, sap-wood or cross-grain.

With each timber allocated a specific position in the frame, they are re-stacked to allow best access as the fabrication progresses.

Laying Out the Frame

Laid out oak doorway gable frame A structure will usually comprise a number of flat surfaces, or planes, representing sections along or through a structure. In the workshop, a plane is normally fabricated as a single frame.

A roof truss will typically be laid flat for working on trestles. A wall frame may be laid with its sole and wall plates positioned parallel to one another, with posts placed across them for marking. Accuracy is paramount. The joints are shaped and fitted, and the frame assembled on the trestles.

Laid out three-storey oak gable frame

Each component frame will often be assembled, dismantled and re-assembled two or three times as it progresses through the various stages of its fabrication.

Occasionally, we are commissioned to design and fabricate an innovative structure which requires its own individual approach to laying out, marking and working.

In such instances, techniques can be developed to accommodate the frame's features and allow us to mark and joint the timbers. Custom made brackets and even modified tools may be as novel as the structural design itself.

Laid out large oak truss

Some very large frames may be too big to fabricate in the workshop, whereupon carpentry is conducted in the yard, often in all sorts of weather conditions.

This doesn't harm the timbers in any way at all in wet weather since, being 'green' and of a high moisture content, they won't absorb any additional moisture. However, during prolonged periods of hot and dry weather, it may be necessary to protect them from drying too quickly.

Joints

Dovetailed socket and novel joints There are many different types of joints. Those most commonly used in timber framing include a variety of mortise and tenon joints, dovetails, bridles, scarfs and housings. On some frames, however, the design may require a number of novel and complex joints conceived and shaped for that single application.

Each is applied according to the eventual position of the joint within the structure and the forces acting upon it. In its shaping, precision is of the utmost importance. A loose fitting joint has the potential to shift the stresses it has been designed to withstand onto another part of the frame not necessarily designed to take it.

Carpenters marks

Carpenter's Marks

In Roman numerals, carpenter's marks ensure the correct positioning of each part of the structure. Whilst we like to keep them proportionate and decorative, they are essential as no two pieces in a frame are ever the same.

Braces

Marking and jointing curved braces Braces are fundamental to the rigidity of any frame. They can be cut to a variety of sizes and shapes, depending on their position within the frame. The deflection of their curves are marked and cut in line with the grain of the wood before being positioned across the laid out frame for marking, shaping and fitting.

Where braces are required to take additional load, such as arch or sling braces, their dimensions are increased accordingly - sometimes as large in section as any other timber in the frame.

Seasoned oak pegs

Pegs

All joints are secured with oak pegs, sized according to their position. Through off-set holes, they draw a joint tight when driven in.

Even a relatively small sun room can use as many as a hundred pegs - several hundred for larger projects. In the workshop, joints are held temporarily with podgers.

Timbers stacked ready for transport to site

Ready To Go

When all the timbers have been shaped and marked, they are carefully stacked to ensure their stability against warping and bowing, ready for transport to site and construction.

Tools of the Trade

Large framing chisels

A brief look at some of the traditional carpentry hand tools we use in our workshop.

Carpentry Tools
Carpentry Hand Tools

Health & Safety Kit

Respirator Example

Respirators

To prevent the inhalation of wood dust, a respirator is essential. Where possible, an "air-fed" respirator is recommended. Where machine tools are to be used in an enclosed space, a dust extraction and filtration system should be installed.

Ballistic Goggles

When using any machine tool that has a high speed component, such as a circular saw, eye protection is a must. Vented ballistic goggles will provide protection whilst retaining visibility.

Ear Defenders

Long term or continuous exposure to loud machinery can cause permanent hearing loss. The military style "Peltor" ear defenders are particularly useful because they are designed to be used in combination with a safety helmet or air-fed respirator.

Safety Boots

Where any heavy objects are to be maneuvered, safety boots should be worn. However, when operating on a timber frame construction, a high level of protection should be combined with high grip and light weight if possible. Boots incorporating non-slip soles with light-weight composite toe-caps and shanks are now becoming increasingly available.

Knee Pads

Whilst not usually considered an article of safety equipment, a good pair of knee pads will prevent unnecessary fatigue and aches.

Back/Lumbar Support

When maneuvering or lifting timbers, a flexible neoprene lumbar support can reduce fatigue and back strain. However, it should not be viewed as a substitute for safe lifting technique - bend the knees, not the back!

First Aid

In addition to being familiar with all workshop first aid equipment, it is recommended that everyone has a comprehensive personal first aid kit.

Types of Green Oak Frame
&
Glossary of Common Oak Framing Terms

Oak frame drawing.

Green oak frames come in numerous varieties. As an exceptionally adaptable material, it offers ample room for creative design expression, allowing for flexibility based on both aesthetic tastes and structural needs.

Frame Types & Glossary
Oak Frame Types & Glossary

Construction on Site

Green oak lofted barn.

Once the carpentry in the workshop is complete, the oak frame is transported to site and erected. Here's an overview of the process of constructing an oak frame on site, with links to details of subsequent works.

Frame Construction
Oak Frame Construction

Can We Use a Client's Own Timber?..

This is a question we are asked from time to time.
The answer is: "it depends."

Client timber
Client Sourced Timber

Oak Framed Building Projects

Mono-pitch Conservatory.

Look around our oak frame gallery to see the green oak building projects we've completed over the many years we've been crafting them. Whether it's a simple porch or a complex multi-storey extension, there's something that's sure to fire your imagination!

Green oak frame building gallery
Oak Frame Gallery

Project Slot Availability

Keep track of project workshop slot availability and times by referring to our News & Events page for the most recent schedule updates.

News & Updates
News & Events


This is a brief overview of workshop processes and tools used by Sessile Oak, rather than a guide to the science and art of timber framing. Structural timber framing should not be practised without proper training and experience or professional guidance.

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