Rear extension steels · Caernarfon
Rear extension steels in Caernarfon
Rear extension steels for homes in LL55, designed by a structural engineer.
- Free survey visit in Caernarfon
- Engineer's calculations arranged
- Building control handled for you
- Free survey visit
- Engineer's calculations arranged
- Building control handled
- Fixed written price once scope is agreed
- England, Wales, mainland Scotland & NI
Planning rear extension steels in Caernarfon
Rear extension steels in Caernarfon are planned around the house, not a standard kit. Our coverage runs across Gwynedd, so nearby villages are included too. We visit, measure and check what the wall carries, then arrange calculations and building control approval before any steel is ordered.
Building a rear extension is only half of the open-plan result. The original back wall still holds up the first floor and the rear wall of the bedrooms above, so opening it needs steel. Depending on the width and what is left to bear on, that could be a single beam on padstones, a beam on columns, or a full goalpost frame.
Things to plan for
- Two-storey rear extensions add a second level of loads to think about. Steels at first-floor level may carry the existing rear wall of the bedrooms or tie the new roof into the old one, so the engineer looks at both floors together.
- 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.
- During the opening, props stand both inside the house and within the extension footprint. Where props bear on a newly laid slab, the propping plan checks that the slab can take those point loads, using spreaders where needed.
- The original rear wall of most houses is load-bearing because it supports first-floor joists and the bedroom wall above. Even where the joists run parallel to it, the masonry overhead still needs carrying, so steel is almost always part of opening it up.
- Where the extension ceiling and the house ceiling should run through at one level, the steel may need setting higher into the floor zone or tying in with the extension roof structure. That choice changes the steel design, so it is settled before calculations.
From survey to sign-off in Caernarfon
Survey in Caernarfon
We visit, look at the wall and what sits above it, measure the opening and note services, access and how the steel can be brought in.
Engineer's design
A structural engineer sizes the beam, padstones and any posts, and sets out the temporary support needed while the wall is out.
Building control
We submit the application or notice to Cyngor Gwynedd under the Building Regulations as they apply in Wales, before work starts.
Install and sign-off
Props go in, the opening is formed, the steel is set and packed, building control inspects it, and we make good.
How much should I budget in Caernarfon?
As a guide, budget £2,300–£6,350 including VAT for opening into a rear extension in Caernarfon, 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 |
| Side return extension steelwork | £3,200–£7,750 | Beams and posts along the old side wall line, propping and approvals (extension build extra) |
| Steel goalpost frame | £1,800–£5,450 | Two posts and a beam bolted as a frame, pad foundations, base plates and fitting |
| Structural calculations for a beam | £230–£680 | Site measure or photos, beam and padstone design and calculations for building control |
Figures include our approximate regional adjustment for prices in Wales (-9%) and are rounded. How these figures are worked out.
Building control and neighbours in Caernarfon
Removing a load-bearing wall in Wales needs approval under the Welsh building regulations before work starts. For Caernarfon the application goes to Cyngor Gwynedd or a registered building control approver, with the engineer's calculations, and a completion certificate follows the final inspection.
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 near Caernarfon
- Menai Bridge 7.6 mi
- Llangefni 8.1 mi
- Bangor 8.6 mi
- Porthmadog 15.8 mi
- Pwllheli 18.4 mi
- Holyhead 18.8 mi
Questions about rear extension steels in Caernarfon
Can I stay at home while the work is done in Caernarfon?
Usually, yes. The work area is screened and floors are protected. The rooms either side of the opening are out of action for a few days, and there is some noise and dust while the masonry comes out.
How much do rear extension steels cost in Caernarfon?
As a guide, budget £2,300–£6,350 including VAT for opening into a rear extension in Caernarfon, 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.
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.
When does the back wall come out during an extension build?
Usually once the extension walls and roof are up and the new space is weathertight. That keeps the house secure and dry while the opening is formed. The steel goes in, building control inspects it, and the builder then carries the floors and ceilings through.