Bi-fold & sliding door openings · Purley
Bi-fold & sliding door openings in Purley
Bi-fold & sliding door openings for homes in CR0, CR2, CR5, designed by a structural engineer.
- Itemised written quote
- Beam sized by a structural engineer
- Covering Purley and nearby
- Free survey visit
- Engineer's calculations arranged
- Building control handled
- Fixed written price once scope is agreed
- England, Wales, mainland Scotland & NI
Planning bi-fold & sliding door openings in Purley
We cover bi-fold & sliding door openings in Purley (CR0, CR2, CR5) and the streets around it. The wider London area is covered as well. Each job is designed by a structural engineer and approved through local building control before work begins.
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.
Worth knowing before you start
- Both leaves of a cavity wall need support over the opening. Depending on the design, the outer brickwork may sit on a plate fixed to the beam or on a separate external lintel, and the engineer specifies which suits the loads and the look.
- External walls can have gas meters, boiler flues, soil pipes, outside taps or cables near the new opening. These are found at survey and moved by the right trade, with any gas pipework done by a Gas Safe registered engineer as the law requires.
- Glazed doors need a stiffer beam than a plain opening of the same width. If the steel bends even slightly under load, folding panels can bind, sliders can stick and glass can be stressed, so the engineer sets a tighter deflection limit for door openings.
- In cavity walls a cavity tray above the new head directs any water in the cavity out through weep vents. Without it, damp can show inside above the doors, so the tray is lapped and sealed correctly as the brickwork is rebuilt.
- The structural work for a typical bi-fold opening usually takes three to five working days. Doors are often made to order, so the steel goes in once opening sizes are confirmed and the doors are fitted soon after.
From survey to sign-off in Purley
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.
What do bi-fold & sliding door openings cost in Purley?
As a guide, budget £3,200–£8,950 including VAT for rear wall opening for bi-fold or sliding doors in Purley, 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) |
| RSJ supply and fit (single beam) | £1,000–£3,200 per beam | Beam supplied, delivered, lifted and packed on padstones, with propping (calculations and approval priced separately) |
| Lintel replacement | £510–£1,540 per lintel | Propping, removing the old lintel, new lintel set on beds and brickwork made good |
| Opening into a rear extension | £3,200–£8,950 | Original rear wall removed with a beam or goalpost, approvals and propping, coordinated with the extension build |
Figures include our approximate regional adjustment for London prices (+28%) and are rounded. How these figures are worked out.
Building control and neighbours in Purley
For Purley, 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.
If the beam bears into a wall you share with a neighbour, the Party Wall etc. Act 1996 applies, and a party structure notice must be served at least two months before that work starts. We arrange this through a party wall surveyor.
Bi-fold & sliding door openings near Purley
- Coulsdon 1.7 mi
- South Croydon 1.9 mi
- Wallington 2.6 mi
- Carshalton 3.2 mi
- Croydon 3.3 mi
- Sutton 3.9 mi
Questions about bi-fold & sliding door openings in Purley
Do you also work near Purley?
Yes. We also cover nearby towns including Coulsdon, South Croydon, Wallington and Carshalton.
Can I stay at home while the work is done in Purley?
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.
What does a bi-fold opening quote include?
Our itemised written quote covers the survey, calculations, building control, propping, removing the wall, steel and padstones, outer leaf support, cavity trays and closers, temporary weather protection and making good. Doors, threshold drainage and patio work are shown separately unless agreed. The price is fixed in writing once the opening size and specification are agreed.
Why does the beam need to be stiffer for glazed doors?
Because glazed doors tolerate very little movement. Every beam bends slightly under load, and with bi-folds or sliders that movement can make panels bind, tracks drag or glass crack. The engineer sets a stricter deflection limit for these openings, which often means a heavier section than strength alone would need.
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.
What happens at the survey visit in Purley?
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.