Lewisham · Greater London
Floor joist repairs in Lewisham
Floor joist repairs in Lewisham 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£310per joist inc VAT
- Postcodes
- BR3, SE4, SE6, SE12, SE13
- Population
- about 300,000
- Area
- Greater London
- Pricing region
- London
How do local ground conditions affect floor joist repairs in Lewisham?
Lewisham is one of the 32 London boroughs, with around 300,000 residents in districts such as BR3, SE4, SE6, SE12, SE13. Nearby, we also cover Southwark (3 miles), Greenwich (4 miles) and Lambeth (4 miles).
Shrinkable clay is widespread in Greater London. Ground movement here is more often linked to soils, drains and trees than to mining. What you mostly find across Greater London: Victorian and Edwardian terraces with shallow footings, inter-war semis in the outer boroughs, and converted flats and mansion blocks.
Symptoms that point to floor joist repairs
- Ceiling cracks below that follow the line of the joists
- Soft or spongy boards near outside walls, hearths or the bathroom
- A gap opening up between the skirting board and the floor
Guide prices for floor joist repairs in Lewisham
The ranges below reflect typical London 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 | £310 – £500 | per joist |
| Whole room of joists and boards | £2,500 – £7,500 | per room |
| Sleeper wall rebuild and ventilationest. | £500 – £1,900 | per room |
Methods for floor joist repairs
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
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
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.
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 Lewisham?
Guide prices for floor joist repairs in Lewisham start from about £310 per joist, including VAT, on London 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 Lewisham?
Yes, Lewisham is covered, along with postcode districts BR3, SE4, SE6, SE12. We also cover nearby Southwark and Greenwich.
Does the ground around Lewisham cause cracking?
Most of Greater London sits on London Clay, among the most shrinkage-prone ground in the UK, with river gravels along the Thames. Subsidence claims here are among the most frequent in the country, especially after dry summers and near street and garden trees. Only an investigation can say why a particular building has moved.
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.
More repairs we carry out in Lewisham
- Resin injection ground stabilisation
- Structural crack repairs
- Gable end wall repairs
- Subsidence repairs
- Wall tie replacement
Floor joist repairs near Lewisham
If a floor in Lewisham has dropped after plumbing or heating work, send photos of any lifted boards and notches, and we will price the strengthening.