If an RSJ will support a structural alteration, arrange a project-specific design before ordering it. For the work discussed on RSJ.info, use a chartered structural engineer. A calculator result or the size used in a neighbour’s house cannot establish what your building needs.
The useful question is what the engineering appointment will include. A fee described as “beam calculations” may cover less than you expect. Ask for the scope in writing, particularly where a survey, connection design, temporary works or responses to Building Control are separate services.
What the engineer needs to find out
A beam carries load into supports, and those supports carry it further through the building. The design therefore needs more than an opening width. Existing wall construction, members above, support positions and the proposed changes all affect the solution.
Send any existing drawings and measured plans with your enquiry. Mark the proposed opening, floor and roof arrangement, joist directions if known, storeys above, and locations of chimneys or other concentrated loads. Photographs help explain the proposal but may not reveal concealed construction. State what is unknown instead of guessing.
Explain the practical constraints too: a flush ceiling, limited headroom, a narrow access route or a visible steel finish can affect the options. These are easier to discuss before a design is issued than after steel has been fabricated.
Ask for defined deliverables
Use this as an enquiry checklist rather than assuming every appointment includes every item.
| Item to clarify | Question for the appointment |
|---|---|
| Existing structure | Is a site visit included, and who arranges any opening-up investigation? |
| Calculations | Which members, supports and connections are within the design scope? |
| Drawings | Will the issued detail identify sections, grades, lengths, bearings and connections? |
| Temporary condition | Who designs temporary support and coordinates its use? |
| Approvals | Who submits information and answers technical queries? |
| Site changes | How are unexpected conditions or proposed substitutions referred back? |
| Inspections | Which visits or checks are included, and which are additional? |
Keep the agreed scope with the quotation. If two engineers offer different services, comparing only the total fee can be misleading. The same applies when an installer says engineering is “included”: establish who supplies the design and what the package covers.
Permanent design and temporary works are different tasks
The finished beam arrangement does not describe every stage while the opening is formed. Ask who is responsible for the temporary condition and how the contractor will obtain the information needed for it.
HSE’s temporary-works guidance explains why temporary works need design and management appropriate to the task. A general guide cannot specify prop positions, capacities or a removal sequence for an unseen building. Do not treat those details as something to improvise after work has begun.
Building Control and planning
Building Regulations approval and planning permission are separate matters. In England and Wales, GOV.UK’s approval guidance explains when Building Regulations approval may be needed and points to different arrangements in Scotland and Northern Ireland. Confirm the route for the actual building and jurisdiction.
Do not assume that a calculation document is itself an approval or completion record. Agree who makes the application, who coordinates notifications and inspections, and which documents the owner should retain at handover. Questions about a listed building or other consents also need to be resolved through the appropriate authority.
What to do when the site differs from the drawings
An unexpectedly thin wall, an existing member in the way or a changed opening can invalidate an assumption. Record the difference and obtain the responsible designer’s instruction before altering the agreed structural arrangement. A larger beam is not a universal remedy for a changed support or connection.
When requesting a revision, include the drawing reference, photographs, measurements and the contractor’s question. Keep the revised issue with the order and site documents so that the fabricator and installer use the same information.
Our calculators can explain mass, units and simplified elastic behaviour. They do not provide a signed structural design. Structural work must be designed by a chartered structural engineer and receive the applicable Building Control approval. This article has not received an independent engineering review.