Swanley · Kent
Floor joist repairs in Swanley
If your floor in Swanley dips by a wall or bounces in the middle of the room, the joists are worth checking. Send photos of the floor, the outside wall at ground level and any air bricks, and we will tell you what the pattern suggests.
Guide price from£280per joist inc VAT

- Postcodes
- BR8
- Population
- about 22,000
- Area
- Kent
- Pricing region
- South East
Why does the ground in Kent matter for floor joist repairs?
With roughly 22,000 people, Swanley spans postcode districts BR8 in Kent. Nearby, we also cover Dartford (4 miles), Bexley (4 miles) and Bromley (5 miles).
Much of Kent sits on clay that shrinks in dry summers and swells in wet winters. Parts of Kent lie on a former coalfield, so a coal mining search is worth checking if movement has no obvious cause. Across Kent, most homes are Victorian terraces in the Medway towns, weatherboarded and Wealden houses, 1930s semis and seaside bungalows.
Repair options we may recommend
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
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
What to expect when we carry out floor joist repairs
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.
Is it time for floor joist repairs? Common signs
- Floor dipping towards an outside wall or in the middle of the room
- A musty smell, or fungal strands showing between the boards
- Ceiling cracks below that follow the line of the joists
What should you budget for floor joist repairs in Swanley?
For Swanley we use South 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 | £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 |
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.
Your floor joist repairs questions
How much should I budget for floor joist repairs in Swanley?
Guide prices for floor joist repairs in Swanley 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.
Can you survey a property in Swanley?
Yes. We take enquiries from across Swanley, including BR8, and from nearby places such as Dartford and Bexley. Send photos for a free initial view and we will tell you what happens next.
Why do houses in Kent crack?
North Kent sits on London Clay, central Kent on Gault and Weald Clays and the Downs on chalk, so shrinkable clay is widespread. East Kent around Deal and Dover had a small deep coalfield, worked until the late 1980s. 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.
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.
Related work in Swanley
- Brick arch repairs
- Mining subsidence repairs
- Bowing wall repairs
- Underpinning
- Structural surveys and crack monitoring
Floor joist repairs near Swanley
If a floor in Swanley has dropped after plumbing or heating work, send photos of any lifted boards and notches, and we will price the strengthening.