# How Much Does a Rolled Steel Joist (RSJ) Cost?

Quick Cost Overview

• A standard RSJ installation typically costs between £800 and £2,500 in total.
• RSJ steel beams cost around £50 to £120 per metre for supply only.
• A structural engineer is required for all RSJ installations, so budget £300 to £500 for calculations.

RSJ Cost Guide Contents

1. RSJ Installation Cost Overview
2. RSJ Cost for Supply and Installation Per Metre
3. Different RSJ Types and Their Costs
4. What Affects the Cost of Fitting an RSJ?
5. The RSJ Installation Process
6. Avoid These Hidden RSJ Installation Costs
7. How to Calculate RSJ Costs
8. Find an RSJ Installer on MyBuilder
9. FAQs: Common Questions About RSJ Costs

RSJ Installation Cost Overview

The total cost of an RSJ installation in the UK depends on the size of the beam, the complexity of the work, and whether any associated structural work, such as wall removal or making good, is included in the quote.

For a straightforward single-storey residential installation, expect to pay in the region of £800 to £2,500 all in. This covers the beam itself, a structural engineer's calculations, and labour.

More complex projects, such as those requiring mechanical lifting equipment, longer spans, or work at height, will sit at the higher end or beyond.

Project Type	Typical Total Cost
Small opening (approx. 1m beam)	£500 – £900
Standard doorway or opening (approx. 2–3m beam)	£800 – £1,800
Larger span (approx. 4–5m beam)	£1,500 – £2,500
Complex installation (loft, multi-storey)	£2,500 – £5,000+
Full wall removal and RSJ installation	£2,500 – £6,500

These figures cover labour and the beam itself but exclude plastering, redecoration, and any structural modifications to surrounding walls or floors. Always ask for an itemised quote so you can compare like for like.

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RSJ Cost for Supply and Installation Per Metre

RSJ steel beam prices are typically calculated per metre of beam length, and the cost varies according to the weight and load-bearing capacity of the beam required, not just its length.

Supply-only RSJ costs (per metre):

Beam Type	Supply Cost Per Metre
Universal beam (I-beam)	£50 – £120
Universal column	£50 – £120
Double beam	£50 – £100
Parallel flange channel	£30 – £100
T-beam	£8 – £20
Steel lintel	£16 – £60

Steel beams are priced per kilogram at the merchant, with current UK rates averaging around £3.50 per kg. The total cost of the beam is therefore the beam's weight per metre multiplied by the length and the per-kg rate.

A structural engineer will calculate the exact specification required.

Supply and installation combined:

When you factor in labour, lifting equipment, and fixings, RSJ supply and installation combined typically runs £225 to £570 per metre. For a standard 3m beam with wall removal, the all-in cost including labour and materials is approximately £2,500.

For a broader view of what structural work costs, see our guide to structural engineer costs.

Different RSJ Types and Their Costs

The term RSJ is widely used as a catch-all for steel beams, but there are several distinct types. They are each suited to different applications and carrying different price points.

Universal Beams (I-Beams)

The most common type used in domestic projects. Universal beams have an I-shaped cross-section that provides excellent load distribution while using the minimum amount of steel. They are used horizontally to support walls, floors, and openings, the go-to choice for wall removals and extensions. Supply cost: £50 to £120 per metre.

Universal Columns

Similar in appearance to universal beams but used vertically rather than horizontally. Universal columns have a greater depth-to-width ratio and are used where high vertical load capacity is required, common in commercial buildings and larger structural projects. Supply cost: £50 to £120 per metre.

Parallel Flange Channels

Used in lattice girders and frameworks where a connecting profile is needed. Less common in standard domestic projects. Supply cost: £30 to £100 per metre.

T-Beams

The most affordable RSJ type, but also the least strong. T-beams do not have a bottom flange, which limits their load capacity. Suitable for lighter applications only. Supply cost: £8 to £20 per metre.

Steel Lintels

Used over smaller openings such as doors and windows rather than full wall spans. Standard rolled steel lintels cost approximately £16 to £22 per metre, while special or bespoke lintels run £40 to £60 per metre.

What Affects the Cost of Fitting an RSJ?

Two RSJ installations that look identical on paper can carry very different price tags depending on the specifics of the job. Here are the main variables:

• Beam size and weight: The heavier and longer the beam required, the more it costs to supply and install. A 1m lintel is a very different job to a 5m span beam requiring mechanical lifting equipment.
• Structural engineer fees: Every RSJ installation requires structural calculations before work begins. A structural engineer will specify the beam type, size, and padstone requirements. For a standard residential project, expect to pay £300 to £500 for calculations alone.
• Wall removal: If an RSJ is being installed as part of a load-bearing wall removal, demolition and rubble clearance will add to the overall cost. See our guide on house renovation costs for context on broader project costs.
• Access and location: Ground-floor installations are the most straightforward. RSJs being installed on an upper floor or in a loft space may require mechanical lifting, which adds significantly to labour time and cost.
• Supporting structure: The existing walls or columns that will support the RSJ ends may need padstones - blocks of dense concrete that distribute the beam's load. These are inexpensive to supply but add labour time.
• Making good: Plastering, plastering beads, and redecoration after the beam is in place are rarely included in an RSJ quote. Budget separately for these finishing costs.
• Location in the UK: Labour rates in London and the South East typically run 20 to 30% higher than national averages.

The RSJ Installation Process

Most homeowners are surprised by how many steps an RSJ installation involves - it is rarely a single-day job.

Here is how a standard installation typically unfolds, from the structural engineer's visit through to the finishing work.

Stage 1: Structural assessment and calculations

Before any work begins, a structural engineer surveys the site, calculates the required beam specification, and provides drawings for building regulations submission. This stage typically takes one to two weeks including the engineering calculations.

Stage 2: Preparation and temporary support

The existing structure above the opening must be supported using Acrow props and strongboys before any wall or structure is disturbed.

This is a critical safety step, the temporary supports carry the load while the permanent RSJ is installed.

Stage 3: Wall removal (if applicable)

Where a load-bearing wall is being removed, the masonry is carefully demolished and rubble cleared. At least two people are needed for this phase to work safely and efficiently.

Stage 4: RSJ installation

The beam is lifted into position, by hand for shorter, lighter beams, or by mechanical equipment for larger spans. Padstones are placed at each end to distribute the beam's load into the supporting structure. The beam is then positioned, levelled, and secured.

Stage 5: Making good

Once the RSJ is in place and the temporary supports removed, plastering, finishing, and redecoration complete the job.

A standard RSJ installation typically takes one to three days from start to finish, depending on complexity.

Avoid These Hidden RSJ Installation Costs

Beyond the beam and core labour, several additional costs are worth factoring into your budget:

Structural engineer fees: Required for every RSJ installation, budget £300 to £500 for a standard residential project. Some contractors include this in their overall quote; others do not. Always confirm upfront.

Building regulations: Structural work involving RSJs requires building regulations approval. Fees typically range from £200 to £500 depending on the local authority and scope of work.

Transport and delivery: RSJs are heavy and require specialist delivery. Delivery costs typically add £50 to £150 to the project depending on beam size and distance.

Plastering and making good: Filling and plastering after installation typically costs £20 to £30 per m². See our guide to plastering costs for a full breakdown.

How to Calculate RSJ Costs

Working out the likely cost of your RSJ installation before getting quotes gives you a useful benchmark and makes it easier to spot if a quote is significantly out of line.

• The starting point is the beam itself. Steel beams are priced per kilogram, with current UK rates averaging around £3.50 per kg.

• To calculate the material cost, you need three figures: the length of the beam in metres, the weight of the beam per metre (specified in kg/m, which varies by beam profile), and the price per kg.

Multiply these together to get the approximate supply cost.

Example: A 3m beam weighing 25kg/m at £3.50 per kg works out as: 3 × 25 × £3.50 = £262.50 for the beam alone

On top of that, add:

• Structural engineer fees: £300 - £500 for calculations and drawings
• Labour: £400 - £800 for a -straightforward installation. £1,000 - £1,400 for complex jobs
• Supporting materials (Acrow props, strongboys, padstones): £100 - £200
• Delivery: £50 - £150 depending on beam size and location
• Plastering and finishing: £20 - £30 per m²

Find an RSJ Installer on MyBuilder

It is easy to find a builder near you for your RSJ installation on MyBuilder. Post your job and available builders in your area can respond with their services and pricing. You can browse profiles, read reviews from local homeowners, and see photos of previous structural work before deciding who to contact.

All tradespeople on MyBuilder undergo checks at registration - such as ID documents, company details, certifications for regulated jobs and skill assessments - allowing you to hire with confidence.

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FAQs: Common Questions About RSJ Costs

Do I Need a Structural Engineer for an RSJ Installation?

Yes, always. A structural engineer must calculate the correct beam specification for your project before work begins, this is not optional. The calculations determine the beam type, size, weight, and padstone requirements based on the load the RSJ will carry. Attempting to specify a beam without engineering calculations is a serious structural risk. Structural engineer fees for a standard residential RSJ project typically run £300 to £500.

How Long Does an RSJ Installation Take?

Most standard RSJ installations take between one and three days from start to finish, including wall preparation and the installation itself. Larger beams requiring mechanical lifting, or projects involving significant wall removal and making good, will take longer. The structural engineer's calculations and building regulations approval add lead time before work can begin - typically one to three weeks.

Does an RSJ Need Fireproofing?

Yes. Under UK building regulations, RSJs must be protected from fire. In practice, this means either encasing the beam in at least two layers of plasterboard, or applying an intumescent fire-resistant coating.

An exposed steel beam that is not fireproofed will not comply with building regulations and could invalidate your home insurance. Your builder and structural engineer will advise on the appropriate method for your installation. You can browse photos of completed RSJ installations on MyBuilder to see how local builders have approached both boxed-in and exposed beam finishes.

What Size RSJ Do I Need for a 2.5m Span?

For a typical 2.5m span in a domestic property, a 152 x 89 x 16 universal beam is commonly used, though the exact specification depends on the load the beam needs to carry rather than the span alone.

A structural engineer will calculate the correct size based on what sits above the opening, whether that is a single floor, two storeys, or a roof, as well as the type of wall being removed and the bearing conditions at each end.

How Do I Know If I Have a Load-Bearing Wall?

The most reliable way to find out is to have a structural engineer or experienced builder assess the wall in person, but there are a few indicators that suggest a wall is likely load-bearing. Walls that run perpendicular to the floor joists are more likely to be load-bearing, as are walls that sit directly above or below other walls on different floors.

How Do I Know If I Have a Load-Bearing Wall?

The most reliable way to find out is to have a structural engineer or experienced builder assess the wall in person, but there are a few indicators that suggest a wall is likely load-bearing. Walls that run perpendicular to the floor joists are more likely to be load-bearing, as are walls that sit directly above or below other walls on different floors. External walls are almost always load-bearing.

Internal walls positioned in the centre of the house, running front to back, are also commonly load-bearing in traditional UK terraced and semi-detached properties.