Bi-fold & sliding door openings · Mitcham
Bi-fold & sliding door openings in Mitcham
Bi-fold & sliding door openings for homes in CR4, SM1, SM4, designed by a structural engineer.
- Free survey visit in Mitcham
- 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
About our bi-fold & sliding door openings service in Mitcham
For homes in Mitcham and the CR4, SM1, SM4, SM5 and SW16 districts, we handle bi-fold & sliding door openings from survey to sign-off. We also cover the surrounding towns and villages in London. The beam is sized by a structural engineer and inspected before it is boxed in.
Replacing a window or narrow patio door with a full run of bi-fold or sliding doors opens a room to the garden. Because it is an external wall, the opening usually carries the first floor, the wall above and sometimes roof loads, and the new steel has to work with the doors as well as hold the house up.
Things to plan for
- Door suppliers quote a structural opening size, which allows for the frame and fixing tolerances. Agreeing that size before the steel is designed avoids reveals that are too tight or gaps that have to be packed out later.
- Very wide openings, or ones that run close to the corner of the house, may leave too little wall for the beam to bear on. In that case the engineer may specify steel columns or a goalpost frame standing on its own foundations.
- Replacing a rear window with doors in a house is usually permitted development, but front elevations, listed buildings, flats and homes where permitted development rights have been removed may need planning permission or another consent.
- New brickwork at the reveals and above the opening should match the existing in colour, size and bond. Sound bricks from the wall being removed are often cleaned and reused, and the mortar colour is matched as closely as possible.
- A wide glazed opening changes the security of the back of the house. During the works the opening is boarded at night if the doors are not yet fitted, and it is worth checking the locking and glass specification of the doors you choose.
Four stages, one team
Survey in Mitcham
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 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.
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.
What do bi-fold & sliding door openings cost in Mitcham?
As a guide, budget £3,200–£8,950 including VAT for rear wall opening for bi-fold or sliding doors in Mitcham, based on published UK cost guides adjusted for London prices (+28%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| Rear wall opening for bi-fold or sliding doors | £3,200–£8,950 | External wall opened up to about 5 m with steel, propping, cavity tray and making good (doors supplied separately) |
| Lintel replacement | £510–£1,540 per lintel | Propping, removing the old lintel, new lintel set on beds and brickwork made good |
| Widening an internal doorway | £1,300–£3,200 | Opening widened with a new lintel or short beam, approval where structural, and making good |
| Structural calculations for a beam | £320–£960 | Site measure or photos, beam and padstone design and calculations for building control |
Figures include our approximate regional adjustment for London prices (+28%) and are rounded. How these figures are worked out.
Approvals in Mitcham
In England, taking out a load-bearing wall or putting in a beam is building work under the Building Regulations 2010. It needs approval from building control, either the local council's building control team or a registered building control approver, through a full plans application or a building notice. Part A covers the structure and Part B covers fire safety, which is why steel in homes is usually fire protected.
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.
Bi-fold & sliding door openings near Mitcham
- Morden 1.3 mi
- Wimbledon 2.2 mi
- Streatham 2.4 mi
- Carshalton 2.4 mi
- Wallington 2.8 mi
- Croydon 3.2 mi
Local questions answered
Can I stay at home while the work is done in Mitcham?
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.
Do you also work near Mitcham?
Yes. We also cover nearby towns including Morden, Wimbledon, Streatham and Carshalton.
How long does it take to make an opening for bi-fold doors?
The structural opening usually takes three to five working days, including propping, cutting out the wall, fitting the steel and outer leaf support, and forming the reveals. The doors can then be fitted, with inside making good and outside brickwork finishing following on. Lead times on made-to-order doors affect the overall timeline more than the steelwork.
How wide can a bi-fold door opening be?
There is no fixed limit, as it depends on the loads above and what the beam can bear on. The engineer designs the steel and, for very wide openings or ones near a corner, may specify columns or a goalpost frame. The door system's own maximum panel sizes and configurations also need checking.
Do I need a steel beam for bi-fold doors?
Usually, yes. Bi-fold and sliding doors need wide openings, and in a load-bearing external wall that span is normally carried on steel. The engineer designs it for strength and stiffness, because glazed doors can stick or be damaged if the beam deflects. A small opening under light loads might only need a lintel, but that is the engineer's call.