Steel BeamInstallers
Rear extension under construction with a steel beam over the opening into the house

Rear extension steels · March

Rear extension steels in March

Rear extension steels in March, from free survey to completion certificate.

  • Price fixed in writing once scope is agreed
  • Building control arranged
  • Temporary works and making good included

Free survey in March

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  • 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 March

We cover rear extension steels in March (PE15) and the streets around it. It sits about 14.2 miles from Peterborough, which we also cover. Each job is designed by a structural engineer and approved through local building control before work begins.

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.

Key points for your project

  • 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 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.
  • In older houses the rear wall may be solid brick in lime mortar, with timber lintels and shallow footings beneath. The engineer may ask for trial holes to see what the wall stands on before deciding where the steel will bear.
  • 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.
  • 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.

What happens, step by step

  1. Free visit

    A short visit to March to see the job, agree what you want and check the bearings, floors and services that affect the design.

  2. Calculations

    The engineer's calculations and a simple drawing are prepared for your opening and shared with you before anything is ordered.

  3. 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.

  4. Steel in, made good

    On site we prop, open up, fit and pack the steel, then fire protect, box in and plaster once the inspection is done.

How much should I budget in March?

As a guide, budget £2,650–£7,400 including VAT for opening into a rear extension in March, based on published UK cost guides adjusted for prices in the East of England (+6%).

JobTypical guide rangeWhat it usually covers
Opening into a rear extension£2,650–£7,400Original rear wall removed with a beam or goalpost, approvals and propping, coordinated with the extension build
Steel goalpost frame£2,100–£6,350Two posts and a beam bolted as a frame, pad foundations, base plates and fitting
Structural calculations for a beam£260–£800Site measure or photos, beam and padstone design and calculations for building control
Party wall surveyor (agreed surveyor, per neighbour)£950–£2,120 per neighbourSchedule 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 the East of England (+6%) and are rounded. How these figures are worked out.

Building rules for March

For March, 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.

Building rules in England

Rear extension steels near March

Rear extension steels in March: your questions

What happens at the survey visit in March?

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.

Do you cover March for rear extension steels?

Yes. We carry out rear extension steels in March and the PE15 postcode districts. Book a free survey visit and we will check the wall, arrange the engineer's calculations and send an itemised written quote.

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.

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.

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.

Planning to take a wall out?

Book a free survey visit. You get an itemised written quote covering calculations, building control, steel and making good.