The gutter is built into the wall, and that single design decision is behind the cold bridging, the damp and the mould — which is also why sealing, painting or lining the trough only ever buys you a bit of time.
Do you have Finlock? A quick check
- The gutter is deep, square and unmistakably concrete, not plastic or metal
- It sits as part of the wall rather than hanging on brackets below the tiles
- There is a visible joint line every few feet along its length
- Upstairs walls feel cold in a band just below the ceiling
- Mould reappears in bedroom corners however often it is cleaned
- Wallpaper or paint blisters along the top of the wall in winter
Why the damp appears indoors
Two things can be going on — water ingress and thermal bridging — and they can happen separately or together. Water can get in through deteriorated joints, failed linings or defects in the concrete, and track into the wall construction. The continuous concrete also forms a thermal bridge, making the upper internal wall colder than the surfaces around it. In the right conditions, moisture in the indoor air then condenses on that colder surface.
Ventilation and redecoration might ease the symptoms, but they won't remove the underlying thermal bridge or fix water ingress. The right remedy really depends on the condition and construction of the Finlock system in front of us.
- 1Finlock concrete trough spanning the wall head
- 2Rain reaches the gutter from above
- 3Water can enter through joints or defects in the concrete
- 4Thermal bridge — the concrete chills the upper internal wall
- 5Cold band forms on the internal wall
- 6Condensation and mould can follow
Removal and rebuild
We scaffold the elevation, cut out and remove the concrete blocks, then rebuild the eaves in timber with insulation at the wall head to break the cold bridge. The roof edge is made good, new underlay is taken over a drip into the new gutter, and a new fascia, soffit and rainwater system is fitted and falled to the outlets.
It's a structural piece of work on the wall head, not just a gutter swap, and it should be priced and programmed as such.
Existing Finlock
The concrete trough built into the wall head, with joints starting to open up.
Removal & rebuild
Blocks cut out, eaves rebuilt in timber, and the wall head insulated properly.
New roofline
New fascia, soffit and guttering, falling correctly to the outlets.
The alternatives, honestly assessed
Lining stops the immediate ingress and costs less, but it leaves the cold bridge behind, and every liner has a service life of its own. Overfitting a plastic gutter beneath the concrete hides the block without actually removing it. Both are reasonable choices if you plan to move soon, but neither really solves the problem for someone staying put.
Repair
Seals a joint and buys some time, but the cold bridge and the damp are still there underneath.
Line
Stops water getting in for less money, but every liner has a service life and will need doing again.
Remove & replace
Ventilation and redecoration can ease the symptoms, but they won't remove the thermal bridge or fix water getting in. What's right depends on the condition of the Finlock system and how it's built.
Common questions
What homeowners in Hampshire usually want to know about finlock concrete gutter removal.
Ask us anything