Larne · County Antrim
Floor joist repairs in Larne
If a plumber or electrician has recently had the boards up at your Larne home, the joists they worked around are worth a look. Deep notches and holes in the wrong place weaken joists quickly, and sistering them is usually a short, tidy job.
Guide price from£220per joist inc VAT

- Postcodes
- BT40
- Population
- about 18,000
- Area
- County Antrim
- Pricing region
- Northern Ireland
What should you know about the ground under Larne?
Postcode districts BT40 cover Larne, a County Antrim town of about 18,000 people. Nearby, we also cover Carrickfergus (9 miles), Newtownabbey (14 miles) and Belfast (18 miles).
Most of County Antrim is on firmer ground than the clay belts of the south-east. Historic brine and salt working has caused ground movement in parts of County Antrim in the past. Housing stock in County Antrim: Red-brick terraces in Belfast, Victorian villas, and post-war and newer estates.
Signs you may need floor joist repairs
- A gap opening up between the skirting board and the floor
- Floor bouncing, or ornaments rattling, when someone walks across
- Ceiling cracks below that follow the line of the joists
How much will floor joist repairs cost in Larne?
These are guide prices for Larne, using Northern Ireland rates and including VAT. Your written quote follows photos or a survey, and is fixed once the repair is specified.
| Item | Guide price | Per |
|---|---|---|
| Splicing or sistering a damaged joist | £220 – £350 | per joist |
| Whole room of joists and boards | £1,750 – £5,300 | per room |
| Sleeper wall rebuild and ventilationest. | £350 – £1,300 | per room |
Which repair method suits a home in Larne?
Replacing joists and boards
When rot or woodworm runs through most of a floor, it is usually cheaper to replace the joists, strutting and boards together. Where joists run parallel to an outside wall, restraint straps tie the new floor back to it so the wall keeps its lateral support.
Best for: Widespread rot, or a whole floor that has dropped
Sistering a joist
A new length of treated timber, the same depth as the original, is bolted or screwed alongside the damaged joist so the two share the load. It is the quickest fix for a notched, cracked or sagging joist that is otherwise sound, usually after lifting a few boards.
Best for: Cut, cracked or sagging joists with sound ends
What happens when we carry out floor joist repairs in Larne?
Photos and a call
Send photos of the dip or soft area, the outside wall at ground level and any air bricks. A short call about when it started, and any recent plumbing or heating work, tells us whether the problem is local or widespread.
Repair the structure
Boards are lifted and numbered if they are going back, and rotten timber is cut out. New treated timber is fixed and checked with a level before strutting, hangers and any restraint straps go in.
Relay and ventilate
Boards are relaid or replaced, skirting refitted and air bricks cleared or added outside. We point out anything that would let damp back in, such as soil heaped against the wall, so the repair lasts.
Rules for floor joist repairs in Northern Ireland
In Northern Ireland, minor repairs usually need no approval, but structural work comes under the Building Regulations (Northern Ireland) 2012 and council building control. There is no Party Wall Act in Northern Ireland.
Floor joist repairs in Larne: questions and answers
What is the price of floor joist repairs in Larne?
Guide prices for floor joist repairs in Larne start from about £220 per joist, including VAT, on Northern Ireland rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Do you carry out floor joist repairs in Larne?
Yes, Larne is covered, along with postcode districts BT40. We also cover nearby Carrickfergus and Newtownabbey.
Does the ground around Larne cause cracking?
County Antrim is largely basalt over chalk, with soft estuarine 'sleech' along Belfast Lough that is notorious for settlement. Historic salt mining is recorded near Carrickfergus. Only an investigation can say why a particular building has moved.
Can floor joists be repaired without taking up the whole floor?
Yes, in most cases only the boards over the affected joists need lifting, and three or four boards are often enough to sister a joist or splice a rotten end. Widespread rot is the exception, because the whole floor must come up to remove the decay.
What causes rot in floor joists?
Damp causes almost all joist rot. Joist ends in damp walls, voids with blocked air bricks, leaking pipes and high outside ground levels keep timber wet enough for fungi to grow. Replacing timber without fixing the damp usually means the rot returns.
More repairs we carry out in Larne
- Boundary and garden wall repairs
- Bowing wall repairs
- Structural crack repairs
- Subsidence repairs
- Retaining wall repairs
Floor joist repairs near Larne
For a guide price on floor joist repairs in Larne, use the quote tool or send photos of the dip, any soft boards and the air bricks.