Bi-fold & sliding door openings · Lisburn and Castlereagh
Bi-fold & sliding door openings in Lisburn and Castlereagh
Survey, engineer's design and installation of bi-fold & sliding door openings anywhere in Lisburn and Castlereagh.
- Itemised written quote
- Beam sized by a structural engineer
- Covering Lisburn and Castlereagh and nearby
- 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 Lisburn and Castlereagh
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.
Bi-fold & sliding door openings in Lisburn and Castlereagh follows the same careful process wherever the property is: a survey, an engineer's design, the right approval and safe temporary works. Coverage takes in Lisburn and everywhere in between. We price it all up front so there are no surprises once the wall is open.
Key points for your project
- Width, what sits above, whether columns or a goalpost are needed, outer leaf support, threshold works and how much brickwork needs matching all affect the price. The doors themselves are normally supplied separately unless agreed otherwise.
- 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.
- 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.
- 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.
- 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.
What happens, step by step
Survey in Lisburn and Castlereagh
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
A full plans application or building notice goes to Lisburn and Castlereagh City Council under the Building Regulations (Northern Ireland) 2012 before work begins.
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 Lisburn and Castlereagh
As a guide, budget £2,150–£6,000 including VAT for rear wall opening for bi-fold or sliding doors in Lisburn and Castlereagh, based on published UK cost guides adjusted for prices in Northern Ireland (-14%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| Rear wall opening for bi-fold or sliding doors | £2,150–£6,000 | External wall opened up to about 5 m with steel, propping, cavity tray and making good (doors supplied separately) |
| Structural calculations for a beam | £220–£640 | Site measure or photos, beam and padstone design and calculations for building control |
| RSJ supply and fit (single beam) | £690–£2,150 per beam | Beam supplied, delivered, lifted and packed on padstones, with propping (calculations and approval priced separately) |
| Lintel replacement | £340–£1,030 per lintel | Propping, removing the old lintel, new lintel set on beds and brickwork made good |
Figures include our approximate regional adjustment for prices in Northern Ireland (-14%) and are rounded. How these figures are worked out.
Approvals in Lisburn and Castlereagh
Building control in Lisburn and Castlereagh is run by Lisburn and Castlereagh City Council. Beams and new openings are controlled work under the Northern Ireland regulations, so we apply before anything is removed and the steel is inspected before it is covered.
The Party Wall etc. Act does not extend to Northern Ireland. Shared walls are dealt with under your title and the general law, so we recommend agreeing access and the work with your neighbour before it starts.
Bi-fold & sliding door openings by town
Bi-fold & sliding door openings in Lisburn and Castlereagh: your questions
What happens at the survey visit in Lisburn and Castlereagh?
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 I need a party wall agreement for bi-fold & sliding door openings in Lisburn and Castlereagh?
There is no Party Wall Act in Northern Ireland. Your title deeds and the general law apply instead, so agree the work with your neighbour in writing before it starts.
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.
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.
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.
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.
Who approves bi-fold & sliding door openings in Lisburn and Castlereagh?
Structural work in Lisburn and Castlereagh needs a full plans application or building notice to Lisburn and Castlereagh City Council. We prepare and submit it with the structural engineer's calculations and arrange the inspections, so the completion paperwork follows the job.