Rear extension steels · Harpenden
Rear extension steels in Harpenden
Steelwork, approvals and making good for rear extension steels in Harpenden and nearby.
- Free survey visit in Harpenden
- 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
What rear extension steels involve in Harpenden
Need rear extension steels in Harpenden? We also work in nearby Luton, roughly 5.0 miles away. We survey the property, arrange the engineer's design, deal with local building control, fit the steel and make good, all under one quote for AL3 and AL5 addresses.
We work alongside your builder or as the steel package within the wider build. We arrange the engineer's design, coordinate building control, prop and open the rear wall at the right stage of the programme, and fit and pack the steels so the extension can be finished around them.
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.
- The steelwork forms part of the extension's building regulations approval, and the engineer's calculations go in with it. Planning for the extension itself is separate; many rear extensions to houses in England fall within permitted development, subject to size limits and conditions.
- When bi-fold or sliding doors sit directly beneath the new steel, the beam has to stay stiff enough not to bind the door panels. The engineer sets a tighter deflection limit, which can mean a deeper or heavier section than strength alone would need.
- 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.
What happens, step by step
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 a building notice or full plans application to the local council's building control team, so approval is in place before the wall is touched.
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 Harpenden
As a guide, budget £2,650–£7,400 including VAT for opening into a rear extension in Harpenden, based on published UK cost guides adjusted for prices in the East of England (+6%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| Opening into a rear extension | £2,650–£7,400 | Original rear wall removed with a beam or goalpost, approvals and propping, coordinated with the extension build |
| Rear wall opening for bi-fold or sliding doors | £2,650–£7,400 | External wall opened up to about 5 m with steel, propping, cavity tray and making good (doors supplied separately) |
| Side return extension steelwork | £3,700–£9,000 | Beams and posts along the old side wall line, propping and approvals (extension build extra) |
| Steel goalpost frame | £2,100–£6,350 | Two posts and a beam bolted as a frame, pad foundations, base plates and fitting |
Figures include our approximate regional adjustment for prices in the East of England (+6%) and are rounded. How these figures are worked out.
Building control and neighbours in Harpenden
For Harpenden, building control is provided by the local council's building control team, or by a registered building control approver if preferred. We send them the engineer's calculations with a building notice or full plans application and book the inspections. Work done without approval can cause problems at sale and is far dearer to put right later.
Terraced and semi-detached homes often need party wall notices, because cutting into a shared wall to take a beam end is notifiable under the Party Wall etc. Act 1996. Allow at least two months for the notice period unless your neighbour agrees sooner.
Rear extension steels near Harpenden
- St Albans 4.7 mi
- Luton 5.0 mi
- Hemel Hempstead 5.9 mi
- Welwyn Garden City 6.5 mi
- Hatfield 6.8 mi
- Dunstable 8.5 mi
Rear extension steels in Harpenden: your questions
Can you work on older or listed homes in Harpenden?
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.
Do you also work near Harpenden?
Yes. We also cover nearby towns including St Albans, Luton, Hemel Hempstead and Welwyn Garden City.
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.
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.
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.
What happens at the survey visit in Harpenden?
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.