Rear extension steels · Powys
Rear extension steels in Powys
Rear extension steels across Powys, designed by a structural engineer and signed off by building control.
- Price fixed in writing once scope is agreed
- Building control arranged
- Temporary works and making good included
- Free survey visit
- Engineer's calculations arranged
- Building control handled
- Fixed written price once scope is agreed
- England, Wales, mainland Scotland & NI
About our rear extension steels service in Powys
Rear extension steels are the beams, columns and frames that let the original back wall of a house be opened up into a new extension. Sized by a structural engineer, they pick up the floor, wall and roof loads that the old wall carried and pass them into bearings or foundations, so the new and old spaces join as one open room.
Looking for rear extension steels in Powys? Towns we cover include Brecon, Ystradgynlais and Welshpool, among other places in the area. Our teams handle the calculations, the building control approval, the propping and the steel itself, and leave the opening ready for plastering and decoration.
Things to plan for
- The building control completion certificate for the extension covers the steelwork to the old rear wall. Keep it with the engineer's calculations and drawings, as a buyer's solicitor will expect to see the structural paperwork for the extension.
- Opening the rear wall is usually the dustiest stage of an extension project. The work face is sheeted off from the rest of the house, and the kitchen is often out of use for a few days while the opening is formed and the steel goes in.
- Columns carry concentrated loads, so each normally sits on a pad foundation designed by the engineer. Digging these inside an existing kitchen or through a solid concrete floor takes planning, especially where drains run close to the back wall.
- A single beam works where solid masonry is left at both ends of the opening. Where the opening runs nearly the full width or the corners are weak, the engineer may use columns or a goalpost frame, which is two posts and a beam bolted together.
- The opening is usually formed once the extension walls and roof are up, so the house stays secure and dry. Leaving it too late can hold up plastering and floor screeding, so the steel date is agreed with the builder early on.
How the job runs in Powys
Look and measure
We check the wall, the span you want and what the wall is carrying, and photograph anything the engineer needs to see.
Design and price
Calculations come back from the engineer and we confirm your fixed written price, line by line.
Building control
We submit the application or notice to Powys County Council under the Building Regulations as they apply in Wales, before work starts.
Fit, inspect, finish
The work is propped and the steel installed and packed tight. After inspection the opening is boxed, plastered and left clean.
Guide prices for rear extension steels in Powys
As a guide, budget £2,300–£6,350 including VAT for opening into a rear extension in Powys, based on published UK cost guides adjusted for prices in Wales (-9%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| Opening into a rear extension | £2,300–£6,350 | Original rear wall removed with a beam or goalpost, approvals and propping, coordinated with the extension build |
| Steel goalpost frame | £1,800–£5,450 | Two posts and a beam bolted as a frame, pad foundations, base plates and fitting |
| Rear wall opening for bi-fold or sliding doors | £2,300–£6,350 | External wall opened up to about 5 m with steel, propping, cavity tray and making good (doors supplied separately) |
| Party wall surveyor (agreed surveyor, per neighbour) | £820–£1,820 per neighbour | Schedule of condition and award where a neighbour dissents; serving notice alone, where the neighbour consents, costs far less (England and Wales only) |
Figures include our approximate regional adjustment for prices in Wales (-9%) and are rounded. How these figures are worked out.
Building rules for Powys
Welsh building regulations treat beams and new openings as controlled building work. We apply to Powys County Council on your behalf before anything is removed, give the commencement notice the 2026 Welsh rules require, and the steel is checked before it is boxed in.
The Party Wall etc. Act 1996 applies in Wales as well as England, so a beam bearing into a shared wall needs a party structure notice at least two months before work starts. We arrange notices through a party wall surveyor.
Rear extension steels by town
Rear extension steels in Powys: your questions
Do I need a party wall agreement for rear extension steels in Powys?
Yes, if the beam bears into a shared wall: the Party Wall etc. Act 1996 applies in England and Wales, and a party structure notice must be served at least two months before that work starts. We arrange it through a party wall surveyor.
Can you work on older or listed homes in Powys?
Yes. Older homes often have lime mortar, timber lintels or shallow footings, which the engineer allows for. Listed buildings need listed building consent for internal structural changes as well as building regulations approval, and that must be in place first.
Is the steel included in the extension's building regulations?
Yes. The steelwork is part of the extension, so the engineer's calculations go to building control with the extension application and the steel is inspected before it is covered. The completion certificate issued for the extension then covers the structural work to the rear wall.
What is a goalpost frame in an extension?
A goalpost frame is two steel columns with a beam across the top, bolted together and standing on their own foundations. It is used where the opening is so wide that little masonry is left to bear on, or where the existing corners cannot take the load. The engineer decides whether one is needed.
Who designs the steels for a rear extension?
A structural engineer. Your architect's drawings show the layout, but the engineer calculates the beams, columns, connections and foundations. We arrange those calculations, or work from an engineer's design you already have, and make sure the details suit the builder's programme.
Do I need a steel beam for my rear extension?
If the original back wall is being opened up into the extension, almost certainly yes. That wall normally carries the first floor and the wall above, so a beam, columns or a goalpost frame takes over the job. A structural engineer confirms exactly what is needed once the opening width and loads are known.
How much do rear extension steels cost in Powys?
As a guide, budget £2,300–£6,350 including VAT for opening into a rear extension in Powys, based on published UK cost guides adjusted for prices in Wales (-9%). The exact figure depends on the span, what the wall carries, access and the finish, and is fixed in writing once the scope is agreed.