Bi-fold & sliding door openings · Cornwall
Bi-fold & sliding door openings in Cornwall
Bi-fold & sliding door openings across Cornwall, designed by a structural engineer and signed off by building control.
- Survey, design and installation in one
- Covering EX23, PL10, PL11, PL12
- Inspected before it is covered
- 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 Cornwall
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.
Across Cornwall, bi-fold & sliding door openings usually come up when people want more light, a better layout or a way through to a new extension. We work in Redruth, Newquay and Truro and the surrounding villages. Whatever the reason, the beam is sized from calculations and the work is inspected before anything is covered.
Worth knowing before you start
- New glazed doors must meet the energy efficiency requirements of the building regulations, and a wide opening adds a large area of glazing to the house. The door supplier normally provides the performance data that building control needs.
- The house is open to the weather between taking out the wall and fitting the doors. Temporary sheeting or a boarded frame keeps rain out and the house secure, so the gap between the structural work and door fitting should be kept short.
- 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.
- 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.
From survey to sign-off in Cornwall
Survey in Cornwall
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 Cornwall?
As a guide, budget £2,600–£7,200 including VAT for rear wall opening for bi-fold or sliding doors in Cornwall, based on published UK cost guides adjusted for prices in the South West (+3%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| Rear wall opening for bi-fold or sliding doors | £2,600–£7,200 | External wall opened up to about 5 m with steel, propping, cavity tray and making good (doors supplied separately) |
| Steel goalpost frame | £2,050–£6,200 | Two posts and a beam bolted as a frame, pad foundations, base plates and fitting |
| Lintel replacement | £410–£1,240 per lintel | Propping, removing the old lintel, new lintel set on beds and brickwork made good |
| Structural calculations for a beam | £260–£770 | Site measure or photos, beam and padstone design and calculations for building control |
Figures include our approximate regional adjustment for prices in the South West (+3%) and are rounded. How these figures are worked out.
Building rules for Cornwall
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 in Cornwall: your questions
Who approves bi-fold & sliding door openings in Cornwall?
Structural work in Cornwall needs a building notice or full plans application to the local council's building control team or a registered building control approver. We prepare and submit it with the structural engineer's calculations and arrange the inspections, so the completion paperwork follows the job.
How much do bi-fold & sliding door openings cost in Cornwall?
As a guide, budget £2,600–£7,200 including VAT for rear wall opening for bi-fold or sliding doors in Cornwall, based on published UK cost guides adjusted for prices in the South West (+3%). 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.
Can I have a level threshold with bi-fold doors?
Often yes, but it has to be designed. The inside floor, outside paving and drainage all need to work together so water cannot run in, usually with a drainage channel outside and the right damp-proof detail under the door frame. We look at levels at the survey and plan the threshold with the door supplier.
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.
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.
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.
Can I stay at home while the work is done in Cornwall?
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.