Rear extension steels · Denbighshire
Rear extension steels in Denbighshire
Calculations, approvals, propping, steel and making good for rear extension steels across Denbighshire.
- Survey, design and installation in one
- Covering LL15, LL16, LL17, LL18
- Inspected before it is covered
- Free survey visit
- Engineer's calculations arranged
- Building control handled
- Fixed written price once scope is agreed
- England, Wales, mainland Scotland & NI
What rear extension steels involve in Denbighshire
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.
We carry out rear extension steels throughout Denbighshire, for homeowners, landlords and builders who need the structural part done properly. We can survey in places such as Prestatyn, Rhyl and Ruthin and the villages around them. You get an itemised written quote that shows the calculations, approvals, steel, labour and finishing as separate lines.
Key points for your project
- 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.
- Soil stacks, waste pipes, boiler flues and gas meters are often fixed to the back wall. These are moved before the wall opens, and any work on gas pipework must by law be carried out by a Gas Safe registered engineer.
- 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.
- 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.
- 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.
Four stages, one team
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 Denbighshire 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 Denbighshire
As a guide, budget £2,300–£6,350 including VAT for opening into a rear extension in Denbighshire, 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 |
| 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) |
| Steel column or post | £460–£1,360 per column | Column supplied and fitted with base and cap plates on a pad foundation |
| Side return extension steelwork | £3,200–£7,750 | Beams and posts along the old side wall line, propping and approvals (extension build extra) |
Figures include our approximate regional adjustment for prices in Wales (-9%) and are rounded. How these figures are worked out.
Approvals in Denbighshire
In Wales, structural alterations come under the Building Regulations 2010 as they apply in Wales. Denbighshire County Council handles building control for Denbighshire. For work started or approved from 1 July 2026, the Welsh system uses an application to building control, dutyholders appointed in writing, a commencement notice before work starts and a compliance statement at the end.
Where the steel bears into a wall shared with next door, notice must be served under the Party Wall etc. Act 1996. If your neighbour dissents, surveyors agree how the work is done before it starts.
Rear extension steels by town
Questions about rear extension steels in Denbighshire
How soon can rear extension steels start in Denbighshire?
Start dates depend on the engineer's calculations, the building control approval and, where needed, party wall notice periods. We give you a realistic timetable after the survey and keep you updated as each approval comes through.
What happens at the survey visit in Denbighshire?
We look at the wall, the floor and ceiling either side and what sits above, measure the opening you want, and note cables, pipes and access for the steel. It usually takes under an hour and there is no charge.
Can I use my own builder for the extension and you for the steels?
Yes. We can supply and fit the steel package while another builder handles the extension shell and finishes. Dates are agreed with them so the rear wall is opened at the right stage, and the engineer's details are shared so levels, padstones and foundations line up.
How wide can a rear extension opening be?
There is no fixed limit, and openings across the full width of a house are common with the right steel. The engineer sizes the beam or frame for the span and the loads above. Wider spans need deeper or heavier steel and possibly columns, which affects headroom and cost.
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.
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.
How much do rear extension steels cost in Denbighshire?
As a guide, budget £2,300–£6,350 including VAT for opening into a rear extension in Denbighshire, 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.