Bi-fold & sliding door openings · West Sussex
Bi-fold & sliding door openings in West Sussex
Survey, engineer's design and installation of bi-fold & sliding door openings anywhere in West Sussex.
- Free survey visit in West Sussex
- 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 West Sussex
Bi-fold and sliding door openings are wide gaps formed in an external wall, usually at the back of the house, to take a run of folding or sliding glazed doors. A steel beam carries the wall, floor and roof loads above, and it is designed stiff enough that its movement does not press on the glass or stop the doors running.
If you are planning bi-fold & sliding door openings in West Sussex, the order of work matters as much as the steel: survey, calculations, approval, propping, installation, inspection and making good. Towns we cover include Worthing, Horsham and Littlehampton, among other places in the area. We run that sequence for you as one job with one point of contact.
Key points for your project
- 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.
- 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.
- Level or flush thresholds are popular with bi-fold doors, but the floor inside and the patio outside need planning together. Drainage at the threshold and a proper damp-proof detail stop water running in when the outside is close to floor level.
- 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.
- 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.
Four stages, one team
Survey in West Sussex
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.
Guide prices for bi-fold & sliding door openings in West Sussex
As a guide, budget £2,800–£7,850 including VAT for rear wall opening for bi-fold or sliding doors in West Sussex, based on published UK cost guides adjusted for prices in the South East (+12%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| Rear wall opening for bi-fold or sliding doors | £2,800–£7,850 | External wall opened up to about 5 m with steel, propping, cavity tray and making good (doors supplied separately) |
| Steel goalpost frame | £2,250–£6,700 | Two posts and a beam bolted as a frame, pad foundations, base plates and fitting |
| Opening into a rear extension | £2,800–£7,850 | Original rear wall removed with a beam or goalpost, approvals and propping, coordinated with the extension build |
| RSJ supply and fit (single beam) | £900–£2,800 per beam | Beam supplied, delivered, lifted and packed on padstones, with propping (calculations and approval priced separately) |
Figures include our approximate regional adjustment for prices in the South East (+12%) and are rounded. How these figures are worked out.
Building control and neighbours in West Sussex
For West Sussex, 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.
Bi-fold & sliding door openings by town
Bi-fold & sliding door openings in West Sussex: your questions
Which towns in West Sussex do you cover?
We cover towns including Crawley, Worthing, Bognor Regis and Littlehampton, plus the villages and smaller towns around them.
How much do bi-fold & sliding door openings cost in West Sussex?
As a guide, budget £2,800–£7,850 including VAT for rear wall opening for bi-fold or sliding doors in West Sussex, based on published UK cost guides adjusted for prices in the South East (+12%). 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.
Should I order my doors before the opening is made?
It helps to choose them first. The supplier's structural opening size and threshold detail feed into the steel design, so the opening is formed to suit the doors exactly. Many people order once the engineer has confirmed the opening, then time the structural work so the gap is weathered for as short a time as possible.
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.
Will the house be open to the weather while the wall is out?
Only briefly, and it is protected throughout. Once the wall is out, the opening is sheeted or boarded so it stays weathertight and secure until the doors arrive. Timing the structural work close to the door delivery date keeps that period as short as possible.
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.
What happens at the survey visit in West Sussex?
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.