County Antrim · Northern Ireland
Floor joist repairs in County Antrim
Across County Antrim, requests for floor joist repairs usually begin with a crack someone has noticed getting wider. Most of County Antrim is on firmer ground than the clay belts of the south-east. A repair only lasts if the reason for the movement has stopped.
Guide price from£220per joist inc VAT
- Area
- County Antrim
- Pricing region
- Northern Ireland
- Ground
- Mostly firmer ground
- Towns listed
- 8
Is County Antrim prone to ground movement?
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.
Historic brine and salt working has caused ground movement in parts of County Antrim in the past. What you mostly find across County Antrim: red-brick terraces in Belfast, Victorian villas, and post-war and newer estates.
What should you budget for floor joist repairs in County Antrim?
The ranges below reflect typical Northern Ireland costs for floor joist repairs, including VAT. Scaffold, access and making good can push a job to the top of the range.
| 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 |
Repair options we may recommend
Splicing ends and fitting hangers
Where only the end has rotted, it is cut back to sound timber and a new piece is fixed alongside, bearing on the wall or on a new joist hanger. Missing or under-nailed hangers elsewhere are replaced at the same time. The damp in the wall must be fixed too.
Best for: Rotten joist ends in damp solid walls
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
Sleeper walls and ventilation
Settled or damp sleeper walls are rebuilt on a sound base with a damp-proof course under new timber plates. Blocked air bricks are cleared, extra ones added where the void has dead spots, and soil or paving heaped against the outside wall is lowered.
Best for: Damp ground floor voids or joists on poor supports
What to expect when we carry out floor joist repairs
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.
Lift boards and inspect
On site we lift a few boards where the floor is worst and check the joist ends, sleeper walls and void with a moisture meter. Outside, we look for high ground, blocked vents and leaks keeping the timber wet.
Written quote
You get a no-obligation written quote listing which joists are sistered, spliced or replaced and any sleeper wall or ventilation work. It becomes a fixed price in writing once the repair is specified.
Is it time for floor joist repairs? Common signs
- A gap opening up between the skirting board and the floor
- Floor dipping towards an outside wall or in the middle of the room
- Ceiling cracks below that follow the line of the joists
- Soft or spongy boards near outside walls, hearths or the bathroom
Do you need approval 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 near you in County Antrim
Your floor joist repairs questions
Does the ground around Belfast 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. Historic brine and salt working has caused ground movement in parts of County Antrim in the past. Only an investigation on site can say why a particular building has moved.
How much will floor joist repairs cost in County Antrim?
On Northern Ireland rates, floor joist repairs starts from about £220 per joist, including VAT. The written price depends on the extent of the damage, access and whether an engineer or building control is needed.
Do I need building control for floor joist repairs?
Usually not for like-for-like repairs to a few joists, but replacing a whole floor structure can be building work. In Scotland that generally needs a building warrant, and in Northern Ireland council building control applies. We deal with building control where the work needs it.
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.
Is a sagging floor dangerous?
A gentle, long-standing sag is usually not dangerous, and many older floors have moved slightly over a century. A sag that is getting worse, soft boards or a floor dropping near a wall needs checking soon, because rotten joist ends can lose their bearing.