Seaham · County Durham
Floor joist repairs in Seaham
Floor joist repairs in Seaham start underneath the boards, not on top of them. We look at the joist ends, the sleeper walls and the ventilated void before suggesting sistering, splicing or replacement, so the price reflects the timber you actually have.
Guide price from£230per joist inc VAT

- Postcodes
- SR7
- Population
- about 22,000
- Area
- County Durham
- Pricing region
- North East
What should you know about the ground under Seaham?
Seaham (SR7) has around 22,000 residents and sits in County Durham. We also take enquiries from nearby Houghton-le-Spring (5 miles), Sunderland (5 miles) and Peterlee (5 miles).
Parts of County Durham have clay that can shrink near trees in dry spells. Historic coal workings are recorded beneath parts of County Durham, and a coal mining search is worth checking where movement is unexplained. Across County Durham, most homes are colliery terraces, stone and brick villas in Durham and Darlington, and post-war council estates.
Methods for floor joist repairs
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
From first photo to finished repair
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.
Symptoms that point to floor joist repairs
- Floor dipping towards an outside wall or in the middle of the room
- Floor bouncing, or ornaments rattling, when someone walks across
- Soft or spongy boards near outside walls, hearths or the bathroom
Guide prices for floor joist repairs in Seaham
For Seaham we use North East rates. Treat the table as a budget guide, inc VAT; the price you pay is the one on your written quote.
| 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 |
Rules for floor joist repairs in England
Like-for-like repairs such as crack stitching and repointing do not usually need building control approval in England, but anything that changes or strengthens the structure, such as underpinning or rebuilding a wall, does. If the work touches a party wall, the Party Wall etc. Act 1996 may apply.
Frequently asked questions
What is the price of floor joist repairs in Seaham?
Guide prices for floor joist repairs in Seaham start from about £230 per joist, including VAT, on North East 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 Seaham?
Yes, Seaham is covered, along with postcode districts SR7. We also cover nearby Houghton-le-Spring and Sunderland.
Does the ground around Seaham cause cracking?
Much of County Durham sits on the Durham Coalfield, worked for centuries, often under a cover of glacial clay. Many former pit villages have recorded mine workings, and coal mining searches are standard for property here. Only an investigation can say why a particular building has moved.
What is sistering a floor joist?
Sistering is fixing a new length of timber alongside an existing joist so the two share the load. It strengthens a notched, cracked or sagging joist without removing it, so it is quicker and less disruptive than replacement.
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.
More repairs we carry out in Seaham
- Structural crack repairs
- Subsidence repairs
- Roof structure repairs
- Gable end wall repairs
- Structural surveys and crack monitoring
Floor joist repairs near Seaham
Got a bouncy or sinking floor in Seaham? Send a short video of someone walking across it, and we will tell you what it is likely to need.