Caernarfon · Gwynedd
Floor joist repairs in Caernarfon
Houses in Caernarfon and across Gwynedd with suspended timber ground floors rely on dry walls and a ventilated void to stay sound. When either fails, rot usually starts at the edges of the room long before anything shows in the middle.
Guide price from£230per joist inc VAT
- Postcodes
- LL55
- Population
- about 10,000
- Area
- Gwynedd
- Pricing region
- Wales
How do local ground conditions affect floor joist repairs in Caernarfon?
Caernarfon (LL55) has around 10,000 residents and sits in Gwynedd. Nearby places we cover include Llangefni (8 miles), Bangor (9 miles) and Pwllheli (18 miles).
Most of Gwynedd is on firmer ground than the clay belts of the south-east. Old metal-mine shafts and workings are recorded in places, so mining searches are routine for some properties. Housing stock in Gwynedd: Slate and stone terraces, chapels and cottages, Victorian seaside houses and post-war estates.
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.
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.
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
- Floor bouncing, or ornaments rattling, when someone walks across
- Ceiling cracks below that follow the line of the joists
- Floor dipping towards an outside wall or in the middle of the room
Guide prices for floor joist repairs in Caernarfon
Prices in Caernarfon are worked out on Wales 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 | £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 |
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
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
Rules 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.
Frequently asked questions
How much will floor joist repairs cost in Caernarfon?
Guide prices for floor joist repairs in Caernarfon start from about £230 per joist, including VAT, on Wales rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Do you cover Caernarfon?
We do. Caernarfon and the surrounding area are covered, including nearby Llangefni and Bangor. A free initial assessment from your photos is the first step.
Is the ground in Gwynedd prone to subsidence?
Gwynedd and Anglesey are mostly hard rock with glacial deposits, so clay shrinkage is uncommon. Historic slate quarrying and metal mining have left tips and workings in places. Only an investigation can say why a particular building has moved.
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.
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.
Other structural repairs in Caernarfon
Floor joist repairs near Caernarfon
Send photos of the floor and the outside wall at your Caernarfon property for a free initial assessment and a no-obligation written quote.