Structural Openings Explained: Lintels, Acrows & Strong Boys Made Simple
- Peter Samuels
- Aug 13
- 2 min read
Whether you’re creating a kitchen-diner or opening up for bifolds, if you’re knocking out part of a wall, you’re dealing with a structural opening.
And if that wall is load-bearing — you can’t just swing a sledgehammer and hope for the best.
In this post, ShellCo breaks down exactly what’s involved in making a safe structural opening, including when to use acrow props, strong boys, and steel lintels.
🧱 What Is a Structural Opening?
A structural opening is any planned gap in a load-bearing wall. This includes:
Doorways
Bifold openings
Open-plan layouts
New windows in brick/block walls
These walls are supporting weight from above (roof, floors, walls), so before any bricks come out, the load must be temporarily supported — then permanently transferred to a lintel or RSJ (steel beam).
🛠️ Key Tools Used:
🔹 Acrow Props
Vertical steel props that support weight while masonry is removed.
🔹 Strong Boys
Slide into the mortar joints and attach to the top of an Acrow. They hold the brickwork/joists laterally, letting you work underneath.
🔹 Needles
Used in major openings, needles transfer load deeper across longer spans, supported by Acrows or frames.
🔹 Lintels / RSJs
Once the opening is prepped, a steel lintel (precast or fabricated) or RSJ is inserted to carry the load long-term.
⚠️ Structural Opening Mistakes to Avoid
Removing bricks before propping ✅
Using too few Acrows
Cutting corners on padstones or bearings
Not using Building Control or a structural engineer
Letting inexperienced builders guess the span
One error here and you’re looking at serious structural failure.
🧱 How ShellCo Handles Structural Openings
We’ve done hundreds of structural openings across homes in Hertfordshire.
Our process:
Assess drawings + wall thickness
Mark out openings, check for services
Insert Acrows & strong boys safely
Remove brickwork
Install lintel or steel to spec
Make good — brick up ends, cement fill, prep for plaster
No shortcuts, no guesswork.
📍 Tool Hire for Builders & Self-Managed Projects
Running the job yourself?
We offer:
Fast pickup from Stevenage
Delivery available for larger orders
📞 Need a Structural Opening Done Properly?
Whether it’s a single door or a 6m bifold beam, ShellCo builds safe structural openings every week.
➡️ Contact us now for a site visit or quote.
Comments