Cobham · Surrey
Floor joist repairs in Cobham
Floor joist repairs in Cobham 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£280per joist inc VAT

- Postcodes
- KT11
- Population
- about 17,000
- Area
- Surrey
- Pricing region
- South East
What is the ground like in Surrey?
Cobham, Surrey: about 17,000 residents across postcode districts KT11. We also take enquiries from nearby Esher (3 miles), Weybridge (4 miles) and Leatherhead (4 miles).
Shrinkable clay is widespread in Surrey. Ground movement here is more often linked to soils, drains and trees than to mining. Housing stock in Surrey: Victorian and Edwardian villas, 1930s semis and detached houses in the commuter towns, and post-war estates.
Guide prices for floor joist repairs in Cobham
Prices in Cobham are worked out on South East rates. They include VAT and are a starting point: access, the extent of the damage and whether an engineer or building control is involved all move the figure.
| Item | Guide price | Per |
|---|---|---|
| Splicing or sistering a damaged joist | £280 – £450 | per joist |
| Whole room of joists and boards | £2,250 – £6,700 | per room |
| Sleeper wall rebuild and ventilationest. | £450 – £1,700 | per room |
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.
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.
Symptoms that point to floor joist repairs
- Ceiling cracks below that follow the line of the joists
- A gap opening up between the skirting board and the floor
- Soft or spongy boards near outside walls, hearths or the bathroom
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 Cobham?
Guide prices for floor joist repairs in Cobham start from about £280 per joist, including VAT, on South 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 Cobham?
Yes. We take enquiries from across Cobham, including KT11, and from nearby places such as Esher and Weybridge. Send photos for a free initial view and we will tell you what happens next.
Does the ground around Cobham cause cracking?
North Surrey sits on London Clay, the south on Weald Clay, with chalk along the North Downs and sands in the west. Large gardens with mature trees on clay make seasonal subsidence a familiar problem. Only an investigation can say why a particular building has moved.
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.
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 Cobham
- Structural surveys and crack monitoring
- Brick arch repairs
- Bay window subsidence repairs
- Resin injection ground stabilisation
- Underpinning
Floor joist repairs near Cobham
Send photos of the floor and the outside wall at your Cobham property for a free initial assessment and a no-obligation written quote.