RSJ & Steel Beam Cost 2026 — Calculation Fees from £450

How much does an RSJ cost in 2026?

The cost of an RSJ project breaks down into three parts:

• Structural calculations and drawings (what we provide): £450 + VAT for one beam, +£96 for each additional beam in the same project
• The steel beam itself: £200–£800 depending on size and length
• Builder labour to install (temporary propping, lifting, bearing, making good): £1,000–£3,000

For a typical single-wall removal in a 1930s semi, the total project cost (engineer + steel + builder) is usually £3,000–£5,000 inclusive. Our £450 fee is the engineering portion — the calculations and drawings your builder needs to order the correct steel and do the work safely.

Why does the RSJ engineer fee start at £450?

The £450 fee covers a chartered structural engineer visiting your property, confirming the wall is load-bearing, calculating the loads from the floors / walls / roof above, designing the correct steel section (size, weight, length and grade), specifying padstones and bearing details, producing builder-ready drawings and a Building Control-ready calculation pack. This is what makes the work legally compliant and safe — and what Building Control will look for before signing off the project.

Do I need an engineer or can the builder just put a beam in?

Building Regulations require structural calculations from a qualified engineer for any load-bearing wall removal. A builder can install the beam, but the calculations must be signed by a chartered engineer (CEng MICE) and submitted to Building Control before work starts. Skipping this step is a notifiable offence under the Building Regulations and creates serious problems when you come to sell — solicitors will require the Building Control completion certificate, and without engineer-signed calculations no completion certificate is issued.

What size RSJ do I need for a typical wall?

There is no single answer — the correct beam size depends on the span (length of the opening), the loads from above (single storey, two storeys, roof type), the bearing conditions and the deflection limits in the British Standards. As a very rough guide, a 3-metre opening in a typical two-storey house often needs a 152x89x16 UB or larger; a 4-metre opening often needs a 203x133x25 UB or larger. Anyone telling you the beam size without doing the calculations is guessing — and that is what creates problems with Building Control later.

Is there a cheaper way to remove a wall?

If the wall is genuinely non-load-bearing, you do not need a structural beam at all — and our £285 non-load-bearing wall check confirms this in writing for you and your builder. If the wall is load-bearing, the cheapest legal option is a standard fixed-price calculation pack (£450) and a properly sized steel beam. Trying to save money by skipping the engineer often results in a beam that is undersized, the wrong section, or installed without proper bearing — which then has to be replaced or strengthened later at much higher cost.

Can you tell me the cost before I commit?

Yes. Tell us what you are planning — which wall, what room, what you want to achieve — and we will confirm whether the £450 fixed price applies before you book anything. In most residential cases it does. For more complex projects (multiple beams, very large openings, unusual structures) we provide a custom quote free of charge after a brief consultation, and you only proceed when you are happy with the price.