Mid Glamorgan · Wales
Floor joist repairs in Mid Glamorgan
Floor joist repairs in Mid Glamorgan starts with the ground. Parts of Mid Glamorgan have clay that can shrink near trees in dry spells, and the buildings here are mostly long stone and brick terraces on valley sides, so the repair has to suit both.
Guide price from£230per joist inc VAT

- Area
- Mid Glamorgan
- Pricing region
- Wales
- Ground
- Clay in parts
- Towns listed
- 12
Why does the ground in Mid Glamorgan matter for floor joist repairs?
Mid Glamorgan lies on the South Wales coalfield, with dense historic workings, spoil tips and steep valley sides. Landslip, retaining walls and mining legacy are all live issues in the valleys.
Historic coal workings are recorded beneath parts of Mid Glamorgan, and a coal mining search is worth checking where movement is unexplained. Typical buildings in Mid Glamorgan: Long stone and brick terraces on valley sides, Victorian houses in Bridgend and post-war estates.
Which repair method suits a home in Mid Glamorgan?
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
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
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 happens when we carry out floor joist repairs in Mid Glamorgan?
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.
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.
Signs you may need floor joist repairs
- Floor bouncing, or ornaments rattling, when someone walks across
- Ceiling cracks below that follow the line of the joists
- A gap opening up between the skirting board and the floor
- Floor dipping towards an outside wall or in the middle of the room
How much will floor joist repairs cost in Mid Glamorgan?
The ranges below reflect typical Wales 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 | £230 – £370 | per joist |
| Whole room of joists and boards | £1,850 – £5,500 | per room |
| Sleeper wall rebuild and ventilationest. | £370 – £1,400 | per room |
Do you need approval for floor joist repairs in Wales?
In Wales, small like-for-like repairs do not usually need approval, but work that alters or strengthens the structure needs building control under the Welsh Building Regulations, and the Party Wall etc. Act 1996 can apply to shared walls.
Towns in Mid Glamorgan we cover for floor joist repairs
- Rhondda
- Tonypandy
- Bridgend
- Merthyr Tydfil
- Pontypridd
- Aberdare
- Caerphilly
- Maesteg
- Porthcawl
- Llantrisant
- Nelson
- Mountain Ash
Floor joist repairs in Mid Glamorgan: questions and answers
Is the ground in Mid Glamorgan prone to subsidence?
Mid Glamorgan lies on the South Wales coalfield, with dense historic workings, spoil tips and steep valley sides. Landslip, retaining walls and mining legacy are all live issues in the valleys. Historic coal workings are recorded beneath parts of Mid Glamorgan, and a coal mining search is worth checking where movement is unexplained. Only an investigation on site can say why a particular building has moved.
How much will floor joist repairs cost in Mid Glamorgan?
On Wales rates, floor joist repairs starts from about £230 per joist, including VAT. The written price depends on the extent of the damage, access and whether an engineer or building control is needed.
Why is my floor bouncy?
A bouncy floor usually means the joists are deflecting too much, often because they span too far, have lost their strutting or have been weakened by notches. It rarely means imminent failure, but it is worth checking, especially if the bounce appeared after work in the room.
Will my insurance pay for rotten floor joists?
Usually not, because rot, woodworm and gradual wear are standard exclusions. Damage from a sudden escape of water, or a floor that dropped through subsidence, may be treated differently. Check your policy, and tell your insurer before permanent repairs start if either applies.
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.