Greater London · England
External Mastic in Kensington
External mastic in Kensington from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Movement joints with cracked, split or missing sealant
- Weeds or debris growing in open joints
- Old sealant gone brittle and cracked
About our external mastic in Kensington
On houses, flats and commercial buildings across Kensington, we reseal joints in brickwork, render, cladding and façade panels. The preparation is the same whatever the wall: clean, sound faces and a controlled depth. We work on brickwork movement joints, copings & trims and joints between brick and frames, and the jobs we see most are movement joints filled with mortar instead of sealant and hard, crazed mastic that has stopped moving.
Newer London blocks are built with movement joints in brick and render, and with cladding joints sealed with mastic. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall.
You are covered for a year from the day we finish. If anything isn’t right with it, phone 0345 464 0079 or send us an email.
- Location
- Kensington (W11, W8, W14, SW7)
- Region
- Greater London
- Cover
- One year on every job
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
What affects the cost of external mastic
Your quote is based on your job. We look at:
- Whether old sealant or filler has to be cut out
- How many rooms, windows or areas are involved
- The type of sealant required
- The number and length of the joints
We do not show prices on the website, because the cost depends so much on the job itself. For a quick quote, please call 0345 464 0079 or send us an email.
What to tell us for a quote
The more you tell us, the more accurate the quote. When you get in contact, it helps to mention:
- If it’s domestic, commercial or a hotel
- The address or postcode of the job
- Pictures of the joints, sent by email
- How many joints, rooms or windows are involved
To get a quote, ring 0345 464 0079 or email us and tell us where the job is and what the problem looks like. We will give you a clear quote before any work starts.
Landlords, agents and businesses in Kensington
Mouldy or split sealant often shows up at the end of a tenancy, and it’s quick to put right between tenancies. Several properties can go on one quote.
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
What the job involves on each surface
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.
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. We reseal their joints with backing rod and a flexible product.
Kensington: your questions answered
Is Kensington in your area for external mastic?
Yes. We work across London and the South East, and Kensington is part of that. You can call 0345 464 0079 or send us an email and let us know what needs doing.
Can parking be tricky for a visit in Kensington?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. The visit is then planned around what’s available.
Where are you based?
We are a Crawley-based firm, with over 20 years’ experience. Our area covers South East England, London and Scotland.
What should I tell you?
Where the job is, what the problem is and roughly how big it is. If you can, email a few photos.
How long will you be here?
It depends on the size of the job, but most jobs take a few hours for a handful of joints, longer for a whole elevation. We will tell you when we quote.
Are you ARBOMaster approved?
Yes. We are approved under the ARBOMaster scheme, which is run for the Arbo sealant brand.
Should I try DIY first?
Sometimes. Preparation is everything: all the old sealant out, and a clean, dry joint. We can always put it right if it fails.
Can you seal over the old sealant?
No, and we never do. It can look neat for a few weeks, but the new bead soon lifts. The old sealant has to come out completely.
What we do, step by step
We keep the work tidy and contained to the area we’re working on. The job usually takes anything from a few hours to several days, depending on the building. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. If the building has a concierge, managing agent or access rules, tell us when you book.
- First we look over the joints with you, agree which to renew and talk through access.
- Old sealant and any debris are cut and raked out.
- Both sides are cleaned back to sound material and primed if needed.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
Getting ready for the visit
- Let us know about stairs, lifts or work at height
- Plan for the work area to be out of bounds to pets and children
- Clear the area around the work
How to get a quote
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is, and we’ll talk you through what we’d do. When it suits you, call 0345 464 0079 or send us an email.
Read more
Honest limits
We’ll always be straight with you, so here’s what sealant cannot fix:
- Adding movement joints to masonry that has none
- Subsidence or other structural problems
- Failed render or damaged cladding panels
Not sure which it is? You can phone 0345 464 0079 or send us an email and we will tell you honestly.
Surfaces we seal
- Façade panels
- Joints between brick and frames
- Copings & trims
- Brickwork movement joints
- Render & cladding joints
- Concrete & block
Signs you need external mastic in Kensington
Every building moves. Brickwork grows a little over the years, blockwork and concrete shrink, and all of it moves with heat and moisture. All of that ends up in the joint sealant.
If you can see any of these, it’s time to have the joints looked at:
- Rigid filler in a joint that should flex
- Failed seals between different materials
- Sealant that has lost its bond to the brick or render
- Moss and dirt in joints with no sealant left
Letting a property close to Kensington Olympia station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
What to look for in a quote
- What the cure time is
- Who does the work, and how experienced they are
- Which sealant they’ll use, and why
- Whether all the old sealant comes out first
Kensington buildings and the weather
In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts. London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Schools such as St Barnabas and St Philip's CofE Primary School are buildings too, and movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. Homes close to Church of St Barnabas include some older properties, and the joints between older walls, newer extensions and the roofline need a sealant that can move.
Kensington is about 5 miles west of London, in Greater London. Jobs in Kensington get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. We cover 764 towns and villages across Greater London, from the larger towns to small villages.
Every address in W11, W8, W14 and SW7 is within our area for external mastic. We cover properties on Kensington High Street, Edwardes Square and Somerset Square. Main roads around Kensington include the A402 and B316. We also cover the places around Kensington: Holland Park (1 mile north), Notting Hill (1 mile north), Shepherd's Bush (1 mile west), Notting Dale (1 mile north) and White City (1 mile north-west). We also work in nearby towns such as London (5 miles east), Marylebone (3 miles north-east), St Pancras (4 miles north-east), Shoreditch (6 miles east), Walthamstow (10 miles north-east) and Hoxton (6 miles north-east). Kensington is one of the larger places we cover in Greater London.
Landmarks near Kensington
Around Kensington, our work takes us to homes and buildings near Holland Park, Scarsdale Tavern and Holland Park School. Other local landmarks include Kensington School (0.5 miles east) and Abdus Salam Library (1 mile east). Kensington has its own railway station: Kensington Olympia station. A little further out are Kensington Arcade (less than half a mile east) and London Museum (0.7 miles north-east). Open spaces near Kensington include WWT London Wetland Centre and The Long Water.
Also near Kensington
Other services in Kensington
How to look after the new joints
Looking after new joints is easy, and it makes a real difference:
- Point out the joints to other trades
- Leave the joints unpainted unless we’ve said otherwise
- Check external joints each spring
- Don’t let climbing plants root in the sealant
Follow the cure time we give you before the joint is knocked or disturbed. Most exterior sealants skin fast but take longer to cure right through.
Once a joint cannot move, the wall finds another way, often as cracks near the joint. Catch it early and you reduce the risk.