Introduction to joint design and frame engineering

This intermediate level standard will provide the attendee with the knowledge and skills to design, identify and specify appropriate joints in a simple oak frame structure.

CITB has developed this standard in discussion with industry


Minimum 1 day of 6 learning hours


This training module will provide the attendee with the knowledge and skills to design, identify and specify appropriate joints in a simple oak frame structure.

The scope of this standard covers:

  • mortise and tenon
  • scarf joints
  • tension jointing
  • flooring joints
  • spline jointing
  • dovetails and cogs
  • structural features and processes
  • wooden pegs

Occupational relevance

Training delivered against this standard would be relevant to the following occupational groups:

  • operative and craft

Candidate pre-requisites

It is expected that the candidate will be employed within the oak frame industry or have significant relevant carpentry experience.


As a minimum, course instructors must be able to demonstrate that, in relation to this standard, they have:

  • a train the trainer or instructional techniques course certificate
  • successfully completed training to this standard
  • at least 10 years relevant industrial experience
  • a verifiable CV


Delivery may be in an on or off the job environment.

All materials and equipment must be of a suitable quality and quantity for candidates to achieve learning outcomes, and must comply with relevant legislation.

The class size and candidate/instructor ratio must allow training to be delivered in a safe manner and enable candidates to achieve the learning outcomes.

The following delivery methods may/may not be used in the delivery of this standard:

  • classroom
  • workshop

This standard is considered to contain 51% or more theoretical learning.

This standard is considered to be set at an intermediate level.


For the successful completion of training, candidates must complete an end of course practical assessment and knowledge test that measures the learning outcomes and has a pass or fail criteria.

Quality assurance

Quality assurance against this standard will require initial approval of the training organisation and their content mapped to the standard. 

CITB will also conduct an approval intervention, either desk-based or centre visit, to ensure the training organisation can meet the requirements of the Training Standard. 

Approved training organisations will be required to present information on records of training and assessment upon request to CITB for desk based analysis. They will also be visited annually by the CITB quality assurance team.


There is no mandatory renewal or recommended refreshment requirements for this standard.

Approval date

April 2019

Review cycle

Either on request or in 3 year(s) from approval date.

Learning outcomes

The candidate will be able to: Additional guidance to support learning outcome
Develop, create and describe the following joints, explain about their appropriate use, their strengths, limitations and special applications, the significance of proportion and position, material and context.
  • Mortise and tenon
  • Identify appropriate depth, proportion and position of mortise and tenon for a given application
  • Explain the relevance of different wood types/properties.
  • Describe the effect of shrinkage on the joint, pegging offset - direction and distance.
  • Scarf joints
  • Identify forces likely to act upon the scarf joint position.
  • Identify correct type of scarf joint according to application.
  • Explain the correct positioning of pegs, wedges, fixings in scarf joint.
  • Tension jointing
  • Identify location of tension joint within the frame.
  • Explain through-dovetail tenons.
  • Explain the use of pegs.
  • Explain the use of steelwork or other reinforcement.
  • Describe the effect of shrinkage.
  • Flooring joints
  • Explain the use of tusk tenons.
  • Describe soffit housing depth to allow for shrinkage.
  • Explain mortise removal in neutral zone
  • Describe the implications of “captured” timbers on erection process.
  • Spline jointing
  • Identify correct usage of spline joints.
  • Identify size and type of splines and correct peg placement.
  • Dovetails and cogs
  • Identify appropriate usage for dovetails and cogs.
  • Identify correct proportion and placement.
  • Demonstrate knowledge of the design significance of the following structural features and processes
  • materials properties
  • timber sizing and conversion
  • bay sizes
  • unsupported spans
  • cantilevered timbers
  • placement of braces to prevent racking and sway
  • placement of struts or braces to reduce deflection or sag
  • different designs for principal trusses
  • identifying tension and compression in frames
  • correct placement of joints for maximum strength and durability
  • the effect of material removed to form a joint on the strength of timbers
  • identify load paths in structural timber frames
  • understanding dynamic and static loads
  • Use of wooden pegs

Explain joint performance parameters with regards to:

  • peg position
  • peg timber type
  • size and number
  • peghole grain alignment
  • degree of offset or draw

Additional information

Recommended reading:


FRAMING ROOFS – The best of Fine Homebuilding

BARNS OF RURAL BRITAIN –Graham Hughes ISBN 0-906969-36-0

TIMBER FRAME – Ted Benson ISBN 1-56158-281-6

TIMBER FRAMED BUILDINGS – John Bailey Bed Bucks and Cam Historic Building Research Group