Greater London · England
Swiss Cottage External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Swiss Cottage and across Greater London. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Panel joints letting water in
- Weathered mastic that no longer stretches
- Brick movement joints where the sealant has split
How the visit works
On the day, we start by going over the job with you, so there are no surprises. We protect the surfaces around the joints before any work begins. The work generally takes anything from a few hours to several days, depending on the building. In a London area like Swiss Cottage, the main things to plan are parking and access: let us know about parking, the floor we’ll be working on and any lift or shared entrance.
- We inspect the joints and agree which need resealing and how they’ll be reached.
- The old mastic and anything lodged in the joint is removed.
- The joint faces are cleaned and primed where the sealant needs it.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- We gun in a flexible exterior sealant in a colour that suits the wall and tool it neatly.
Preparing for the visit
- Mention any sign-in or site rules at work premises
- Mention any leaks or damp you’ve noticed
- Mention any tricky access
How to get a quote
Need a quote? Please ring 0345 464 0079 or drop us an email and tell us about the job. You will know what we plan to do, and what it will cost, before any work begins.
Advice
How we handle external mastic in Swiss Cottage
Ground-floor and low-level joints are straightforward to reach. Where joints are higher up, tell us about the building when you get in touch and we will confirm what access is needed. We work on joints between brick and frames, copings & trims and brickwork movement joints, and common reasons people get in touch are sealant pulling away from one side of the joint and joints pointed up with cement by mistake.
London’s terraces and conversions often share walls, gutters and downpipes with their neighbours, so a leaking gutter joint or failed wall joint can affect more than one home. For a flat in Swiss Cottage, check the lease for who looks after the outside.
You’re covered for a year from the day we finish. If anything is not right with it, call 0345 464 0079 or email us.
- Place
- Swiss Cottage (NW3, NW8, NW6)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Different surfaces, different methods
Concrete and blockwork
The face of concrete or block is often dusty, so cleaning and priming matter. A primer goes on where the product requires one before the bead.
Render joints
Water behind render can lead to blown patches. A sound joint keeps the render dry behind and helps it last.
Also near Swiss Cottage
Other services in Swiss Cottage
What sealant work cannot fix
Some problems need a builder, plumber or other trade rather than us:
- Cracking across the wall rather than at a joint
- Failed render or damaged cladding panels
- Subsidence or other structural problems
If you are not sure, just call 0345 464 0079 or email us and we will give you a straight answer before you book.
What we seal
- Joints between brick and frames
- Render & cladding joints
- Copings & trims
- Concrete & block
- Façade panels
- Brickwork movement joints
For landlords and businesses
Letting agents often deal with us directly. Tell us the address, the job and how access works.
Letting agents and landlords in Swiss Cottage can book us as well as homeowners. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
Common problems we fix in Swiss Cottage
If plants are growing out of a joint, the sealant has generally failed or was never there. Roots and dirt hold water against the wall and make things worse.
People usually contact us after spotting something like this:
- Rigid filler in a joint that should flex
- Joints with sealant missing in places
- Rain getting behind render or cladding at a joint
- Panel joints letting water in
For an older house near a landmark such as Church of All Souls, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Before you book anyone
- What the cure time is
- How the surfaces are prepared before sealing
- What product goes in the joint
- Who does the work, and how experienced they are
Swiss Cottage questions
I let a flat near South Hampstead station. Can you help?
Yes, we work for landlords and letting agents. Just phone 0345 464 0079 or email us and tell us about the property, and we will give you a clear quote.
Is parking a problem for a job in Swiss Cottage?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. That way the visit can be planned around it.
Will the new joint stand out?
The sealant colour is picked to suit the wall so the joint blends in. There’s a wide choice of exterior colours.
Can you seal joints between two different materials?
Yes. Materials like render, brick, metal and uPVC all move differently, so the joint between them must be flexible. The sealant is matched to both sides.
Do you work in Swiss Cottage?
Yes, we do. Swiss Cottage is part of the area we cover, and the service is the same as everywhere else.
Why do you put foam in the joint first?
Closed-cell backing rod sets the depth of the sealant and stops it sticking to the back of the joint. Then the sealant bonds to two faces and can move.
Can you do several jobs on one visit?
Yes. Just list everything you need and you’ll get one quote.
Where are you based?
We work from Crawley. Our applicators cover Swiss Cottage, along with the rest of our area.
How to look after the new joints
Good habits help new joints last longer. Our tips:
- Keep movement joints as flexible joints, not mortar
- Keep soil, plants and ivy away from the joints
- Check external joints each spring
- Keep high-pressure jets off the joints
Only paint over the joint if we have confirmed the sealant can take paint. Many exterior sealants aren’t designed to be painted and spoil the finish.
Gaps, plants or missing sealant in a joint are worth getting looked at. Earlier resealing means a smaller job and a better result.
External mastic in Swiss Cottage: local notes
London terraces and converted houses often share gutters, downpipes and walls, so it’s worth agreeing who is responsible before work starts. Historic houses like Winfield House (about 0.9 miles south-east) are a reminder that the area around Swiss Cottage has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
Managing a site like The UCL Academy? Then its movement joints, gutters and trims need looking after like any other building’s. Letting a property close to South Hampstead station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Swiss Cottage is about 1 mile south of Hampstead, in Greater London. Anywhere in NW3, we cover external mastic for homes and businesses. Our Greater London coverage runs to 764 places, and Swiss Cottage is one of them.
We cover every part of NW3, NW8 and NW6 for external mastic. Whether your property is on Avenue Road, Acacia Road and Harben Road or anywhere close by, our applicators can take on the job. Other places close to Swiss Cottage include South Hampstead (1 mile north), St John's Wood (1 mile south), Haverstock (1 mile east), Belsize Park (1 mile east) and Primrose Hill (1 mile east). We also work in nearby towns such as London (4 miles south-east), Kensington (3 miles south-west), St Pancras (3 miles south-east), Shoreditch (4 miles east), Walthamstow (7 miles north-east) and Hoxton (4 miles east).
Near you in Swiss Cottage
We work in homes and buildings around Cafe Med pub, Holy Trinity CofE Primary School and Primrose Hill. Nearby too are Cecil Sharp House (1.1 miles east) and St. Mary's Town and Country School (within half a mile north-east). Swiss Cottage has its own railway station: South Hampstead station. A little further out are Montfichet's Tower (3.7 miles south-east) and Isokon Gallery (0.8 miles north-east). For a walk, there’s The Long Water and Primrose Hill.
Why act early in Swiss Cottage
It often makes sense to reseal all the failing joints on an elevation together. Joints of the same age tend to fail together, and access only has to be arranged once. Damp from a failed joint spreads quietly in older London brickwork and timber, and by the time it shows on a wall or ceiling in Swiss Cottage, the repair is bigger than the sealant job would have been.
What it costs depends on the size of the job, how hard the old material is to remove and access to the work. You’ll have a clear quote before any work starts.
Why us?
- Every job guaranteed for a year
- Neat joints and a tidy finish
- ARBOMaster approved applicator
- Fully insured
Read our cost guide and customer reviews.