Greater London · England
External Mastic in Belsize Park
Sealing brickwork movement joints, render, cladding and façade joints for householders, landlords and businesses in Belsize Park. Fully insured, ARBOMaster approved and guaranteed for a year.
- Joints where the bead has come unstuck
- Water getting into walls through failed joints
- Failed sealant between panels on a façade
How the visit works
You don’t need to clear the whole room or building before we come, only the area right around the joints. We protect the rest, and the work takes a few hours for a handful of joints, longer for a whole elevation for a typical job. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Belsize Park. It helps if you can point us to a visitor permit or a bay close to the door.
- We start by walking round the building and agreeing the joints and the access.
- We cut out the old mastic and rake out anything in the joint.
- Joint faces are cleaned back and primed if the sealant needs it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
Getting ready for the visit
- Clear items away from the joints we’re working on
- Where the joints are inside, avoid wetting them before we arrive
- Let us know about stairs, lifts or work at height
Getting a quote
To get a quote, ring 0345 464 0079 or drop us an email with the location and a short description of the problem. You’ll have a clear quote before any work starts.
Advice
External mastic in Belsize Park, done properly
Joints in render and cladding are easy to overlook until a damp patch appears. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a matching colour. We work on render & cladding joints, joints between brick and frames and façade panels, and the jobs we see most are rain getting behind render or cladding at a joint and cracked joints where brick meets render or frames.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. For a home in Belsize Park, tell us how high the joints are and how to reach the back of the building.
We stand behind the work with a one-year guarantee, so you’re not left on your own once the job is done.
- Location
- Belsize Park (NW3, NW5, NW1)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear price before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Common problems we fix in Belsize Park
UV, rain and frost all age exterior sealant. In time it goes hard, crazes on the surface and stops stretching, so the next time the wall moves, it splits or pulls away.
It’s worth asking for a quote if you see:
- Brick movement joints where the sealant has split
- Hard, crazed mastic that has stopped moving
- Failed sealant between panels on a façade
- Rain getting behind render or cladding at a joint
If you let a flat or house near South Hampstead station, split movement joints are easy to miss on a rental until damp shows inside.
What to look for in a quote
- Is the old sealant removed completely?
- How the joint is cleaned and prepared
- Whether VAT is included
- When the joint can take water or movement
What happens if it’s left?
Pointing a movement joint with mortar might seem a neat fix, but it locks the joint solid. The movement then cracks the brickwork or render nearby. The correct repair is a flexible sealant with the right backing. In London conversions, one flat’s bathroom is often above another flat’s ceiling, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble for homes in Belsize Park.
Some things make a job bigger or smaller: the old material and how easily it comes out, whether mould needs treating, and whether the work is at height. Your quote takes all of that into account.
Why us?
- Arbo and Everbuild products
- We never seal over old sealant
- 180+ five-star Google reviews
- Tidy, careful work
See our cost guide or our reviews.
Landlords, agents and businesses in Belsize Park
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Keeping joints in good order is simple maintenance.
Mouldy or split sealant often shows up at the end of a tenancy, and it’s quick to put right between tenancies. We can quote for more than one property at once.
Questions from Belsize Park
Can you help a landlord with a rental near South Hampstead station?
Yes, landlords and agents are among the people we work for, and several properties can be quoted together. You can phone 0345 464 0079 or send us an email with the details for a clear quote.
Can parking be tricky for a visit in Belsize Park?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot, so mention what’s available when you book.
Is there any odour?
Sometimes, a little. It fades as the sealant cures.
What does external mastic cost?
The cost depends on the size of the job, access and how much old sealant has to come out. Call for a quick quote.
Will it make a mess?
No. The area is protected while we work and cleaned up afterwards.
Can you seal joints between render and window frames?
Yes. The old joint is removed, both surfaces cleaned and primed where needed, and a flexible sealant applied. The colour is chosen to suit.
Do you do commercial work?
Yes. Hotels, offices and other businesses use us, and we are fully insured.
Can a movement joint be filled with mortar?
No. A mortar-filled joint cannot move, so the wall cracks somewhere else instead. It needs a flexible sealant over backing rod.
Belsize Park buildings and the weather
Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. With historic houses such as Keats House (about 0.8 miles north) nearby, there’s older building stock in the area around Belsize Park as well as newer homes. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth.
Belsize Park is in London, so parking needs planning: let us know about parking bays, permits or a driveway. If you look after a building such as Fine Arts College, larger buildings have long runs of movement joint that eventually need resealing.
Belsize Park is about 1 mile south-east of Hampstead, in Greater London. We provide external mastic to householders, landlords and businesses in Belsize Park and nearby. Across Greater London, we cover 764 places, Belsize Park among them.
Here we cover the NW3, NW5 and NW1 postcode area for external mastic. Whether your property is on Eton Road, Lawn Road and Ornan Road or anywhere close by, we can help. Other places close to Belsize Park include Haverstock (1 mile north), Primrose Hill (1 mile south), South Hampstead (1 mile west), Swiss Cottage (1 mile west) and Chalk Farm (1 mile east). Larger places within reach include London (4 miles south-east), Kensington (4 miles south-west), Shoreditch (4 miles east), Walthamstow (7 miles north-east), Hoxton (3 miles east) and Whitechapel (4 miles south-east).
What’s near Belsize Park
We work in homes and buildings around The Washington pub, Primrose Hill and St. Mary's Town and Country School and the streets around them. You’ll also find Cecil Sharp House (0.8 miles south-east) and St Paul's Church of England Primary School (under half a mile south). For rail, the closest station is South Hampstead station, roughly 0.7 miles west. Nearby you will also find Wellington Hospital (0.9 miles south-west) and O2 Centre (0.8 miles west). Open spaces near Belsize Park include Adelaide Nature Reserve and The Long Water.
What the job involves on each surface
Concrete and blockwork
Wide joints in concrete need the depth controlling carefully. Backing rod sized to the joint sets it and keep the sealant to the right depth.
Joints between dissimilar materials
Where a frame or panel meets masonry, water often finds a way in. The old joint is removed and a sealant that bonds to both sides goes in.
Also near Belsize Park
What else we do in Belsize Park
How to look after the new joints
Once the sealant has cured, a few habits help it last:
- Wash walls gently around the sealant
- Keep water from gutters off the wall
- Clear growth from the base of walls and joints
- Check external joints each spring
Have a quick look at the joints each spring. Splits, gaps at the edges or plants in the joint are early warning signs.
Once a joint cannot move, the wall finds another way, often as cracks near the joint. Catch it early and you reduce the risk.
Quotes for external mastic in Belsize Park
Your quote is based on your job. We look at:
- The number and length of the joints
- The product the joint needs
- Any mould that needs treating
- The number of rooms or windows
The cost depends on the size of the job, how much old material has to come out and how easy the joints are to reach. We give a clear quote before any work starts, so you know where you stand.
What to tell us for a quote
What to tell us when you ask for a quote:
- How many joints, rooms or windows are involved
- Pictures of the joints, sent by email
- Where the property is
- What the problem is, such as mould, gaps, leaks or cracking
We quote each job on its own, so start by telling us what you need. Just phone 0345 464 0079 or email us with the details.