What actually happens when a wall is opened up?
Design, needle and prop, cut, beam onto padstones, pin up. Why the propping is the designed part, what building control inspects, and why this is the one job where the sequence matters more than the components.
- Difficulty
- advanced
- Time
- 11 min
- Read
- 5 min
- Safety
- restricted
Short answer
The wall above the opening is supported first, on needles passed through the wall onto props each side standing on something that can carry them. Only then is the masonry removed. A calculated beam goes in on calculated padstones, the masonry above is pinned tight to it so it bears rather than hangs, and the props come out last. Every stage is designed and the middle stages are inspected.
This is the job householders most often underestimate, because the finished result is a hole and a beam and looks straightforward. What you are paying for is the sequence and the temporary works, and those are the parts that are invisible afterwards and dangerous when done badly.
Safety
Step by step
- Establish what the wall is doing first.Whether it is loadbearing, what lands on it, and what is above it — floor joists, a roof, another wall, a chimney breast. GuideHQ has a guide on identifying a loadbearing wall, and the honest answer is that the consequences of guessing wrong are severe enough that this gets checked properly.
- Get the design before anything else.A structural engineer calculates the loads, sizes the beam, sizes the padstones, and specifies the temporary support. That document is what the builder works to and what building control assesses.
- Notify building control.Removing part of a loadbearing wall is controlled work in England and Wales, under the Building Standards in Scotland and the Building Regulations in Northern Ireland. It is inspected at defined stages and it ends in a completion certificate you will need when you sell.
- Deal with the party wall question.In England and Wales, cutting into a party wall to take a beam bearing is notifiable under the Party Wall etc. Act 1996, and the notice period is set by statute. Scotland and Northern Ireland have no equivalent statute and the position is governed by common law and the title deeds.
- Needle and prop before cutting anything.Slots are cut high in the wall, steel needles are passed through, and adjustable props are set under each end on both sides of the wall, standing on spreaders. The props have to bear onto something that can carry the load, which frequently means propping down through a floor to the ground as well.
- Cut, place the beam, and pin up.The masonry is removed, the padstones are bedded, the beam is placed and levelled, and the gap between the beam and the wall above is packed solid — pinned up — with slate or dry-packed mortar so the wall bears on the beam instead of settling onto it later.
- Deal with fire and services before it is closed up.An exposed steel beam usually needs protecting to achieve its fire resistance, which is why beams are boarded rather than left bare. Cables, pipes and any flue in the wall have to be dealt with as part of the design, not discovered during the cut.
- Strike the props last, and in order.The props come out only when the beam is bearing properly and the pinning up has gained strength. Removing them early transfers the load into a joint that has not set.
Tips
- Ask to see the engineer's calculations and the building control application before work starts. A builder who has them will produce them immediately.
- The cost is in the temporary works, the beam and the making good — not in the hole. A quote that looks cheap is usually cheap on the first of those three.
- Removing a chimney breast is the same problem with an extra question: what supports the stack above the part you removed. It is a common and serious omission.
Common mistakes
- Cutting a hole and then propping — The support has to be in place before the wall is weakened. Cutting first is how walls come down, and the collapse takes the ceiling and floor above with it.
- Propping onto a suspended timber floor without spreading the load — A prop concentrates several tonnes onto one point of a floor that was designed for people and furniture. Props need spreaders, and often need propping through to solid ground below.
- Not pinning up between the beam and the wall above — The wall then settles onto the beam over months, opening a crack along the line and dropping everything above it slightly. It is a visible, avoidable defect.
- Doing the work and not registering it — An unregistered structural alteration is found by the buyer's solicitor and stops the sale until it is regularised, which is far harder and more expensive afterwards.
If it doesn't work
A crack has opened along the top of a beam some months after the work
Cause: Inadequate pinning up, so the wall above has settled onto the beam — Fix: Report it to the builder while any guarantee stands, and to the engineer. It usually needs cutting out and dry packing properly rather than filling.
Doors and windows nearby have started to bind since the opening was made
Cause: Movement associated with the alteration — Fix: Stop and get the engineer back. New distortion near a new opening is a structural signal, not settling in.
You have bought a house with an obvious opening and no paperwork
Cause: Structural work done without building control approval — Fix: It can be regularised retrospectively, which involves an application, exposure of the bearings for inspection, and possibly an engineer's report. Indemnity insurance covers enforcement risk but not the structural question, so do not treat it as a substitute for knowing the beam is adequate.
Questions people ask
Can I take out a small section of a loadbearing wall without a beam?
No. Any permanent opening in a loadbearing wall needs something spanning it, and that something needs sizing. The size of the opening changes the beam, not whether one is needed.
How long does the work take?
The cutting and beam installation is often only a day or two. The design, approvals, party wall notices and making good take far longer, and the notice periods in the party wall legislation are fixed by statute.
What is a goalpost frame?
A beam with steel posts each side, used where the masonry beneath the bearings cannot carry the load down or where a very wide opening is wanted. It is one of the standard answers when a padstone alone is not enough.
Does this apply to a stud wall?
A non-loadbearing stud partition is a different job, and GuideHQ covers forming a doorway in one. The crucial word is non-loadbearing, and establishing that is the first step in both cases.