Greater London · England
External Mastic in Westerham
Professional external mastic in and around Westerham, with old sealant always removed completely and a 12-month guarantee.
- Failed sealant between panels on a façade
- Movement joints with cracked, split or missing sealant
- Sealant pulling away from one side of the joint
Work for landlords, hotels and businesses
We also work for businesses, from offices to washrooms and kitchens. On commercial sites, working times can be discussed when we quote.
Housing providers, facilities teams and property managers book us too in Westerham and across Greater London. We can quote a run of properties together.
About our external mastic in Westerham
A movement joint is only as good as its depth. Backing rod controls how deep the sealant goes and keeps it off the back of the joint, so it bonds to the two sides only and can stretch. We work on render & cladding joints, concrete & block and façade panels, and people most often call us about leaking joints around cladding and façade panels and hard, crazed mastic that has stopped moving.
Modern London flats rely on sealed movement joints and cladding joints. Period houses have different weak points, such as gutter joints, trims and the line where an extension meets the old wall, and both kinds of building are found across London.
You’re 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
- Westerham (TN16)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Quote
- A clear price before work begins
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Honest limits
Some problems need a builder, plumber or other trade rather than us:
- Render that’s blown, hollow or coming away
- Rising or penetrating damp from elsewhere in the wall
- Cracked brickwork or render that needs a builder or plasterer
Not sure which it is? You can phone 0345 464 0079 or email us and we will tell you honestly before booking.
Where we work in Westerham
- Façade panels
- Joints between brick and frames
- Render & cladding joints
- Concrete & block
- Brickwork movement joints
- Copings & trims
Outside joints around Westerham
Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts.
Westerham is in London, so parking needs planning: let us know about parking bays, permits or a driveway. In the older streets around Church of St Mary the Virgin, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Westerham is about 5 miles west of Sevenoaks, in Greater London. Jobs in Westerham get the same care as everywhere else we work: old sealant removed completely, careful preparation and a 12-month guarantee. Westerham is one of 764 towns and villages in Greater London where we work. You can also see our page for Crawley, about 16 miles away.
Our applicators cover all of TN16 for external mastic and the streets around it. That includes homes and businesses on Market Square, London Road and High Street. Westerham is on the A25 and B2024, which makes it straightforward to reach with everything needed for external mastic. We also cover the places around Westerham: Force Green (1 mile north), Moorhouse Bank (1 mile south-west), Goodley Stock (2 miles south), The Chart (2 miles south-west) and South Street (2 miles north-west). Larger places within reach include Orpington (8 miles north), New Cross (15 miles north), Thornton Heath (12 miles north-west), Croydon (10 miles north-west), East Dulwich (15 miles north-west) and Plumstead (15 miles north).
Local landmarks in Westerham
In Westerham, that means homes and buildings near The Olde House At Home Public House and the streets around them. The nearest railway station is Hurst Green station, roughly 3.4 miles south-west. Nearby you will also find Tandridge Priory (2.2 miles south-west). The countryside around Westerham includes Betsom's Hill and Dryhill Nature Reserve.
What happens if it’s left?
Pointing a movement joint with mortar might seem a neat fix, but it stops the joint moving. The movement then cracks the brickwork or render nearby. A flexible sealant over backing rod is what the joint needs. In a London flat, a failed joint rarely stays your problem alone: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
Commercial jobs are quoted on the same basis as homes: the amount of work, how we reach it and what it needs, along with when we can work on site. Call for a quick quote and we’ll explain what it covers.
Why us?
- We agree the colour with you first
- Domestic, commercial and hotel work
- A choice of colours where the product allows
- A 12-month guarantee on all work
Take a look at how sealant jobs are priced or what customers say.
Common questions in Westerham
Is parking an issue for external mastic in Westerham?
Parking in Westerham, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Do you work for landlords with property near Hurst Green station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or send us an email and tell us about the property, and we’ll send you a clear quote.
When is the sealant fully cured?
That depends on the sealant used, so follow the cure time we give you when we finish.
Do you seal joints where cladding meets other materials?
Yes. We cut out the old sealant, prepare both faces and reseal with a flexible exterior product. The colour is chosen to suit.
Is it OK to seal over old sealant?
No, it will not last. It can look neat for a few weeks, but the new bead soon lifts. Removing the old sealant completely is the only lasting way.
Can you quote for more than one area?
Yes, and it often makes sense. Doing several areas at once is usually more efficient.
Do you have insurance?
Yes. Mr Mastic is fully insured, and we have been doing sealant work for more than 20 years.
Will there be a smell?
There can be a smell while the sealant cures, which fades as it sets. Opening a window helps.
How to look after the new joints
A little care helps the new joints last. Our advice:
- Make sure movement joints are not pointed over
- Tell anyone working on the walls about the movement joints
- Look over the joints every year, ideally after winter
- Fix overflowing gutters above sealed joints
Look over the joints once a year, ideally after winter. Watch for splits, edges coming away or growth in the joint.
A joint that has stopped moving pushes the movement elsewhere, often as cracks near the joint. Resealing it early helps prevent that.
Nearby places to Westerham
More services for Westerham
How the visit works
Our applicators work methodically: protection first, then preparation, sealing and a tidy-up. Typically it takes anything from a few hours to several days, depending on the building and we leave things clean and tidy. 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, the joints are inspected and the access agreed.
- We cut out the old mastic and rake out anything in the joint.
- The faces are brushed clean and primed where the product requires 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
- Keep pets and children clear of the area while we work
- Mention any sign-in or site rules at work premises
- Tell us if parking is tricky
Get a quote
For a quote, ring 0345 464 0079 or drop us an email with the location and a short description of the problem. We’ll give you a clear price before any work starts.
Related advice
Do you need external mastic in Westerham?
Every building moves. Clay bricks expand slightly over their life, concrete and block shrink, and everything moves with temperature and wet. All of that ends up in the joint sealant.
Most people get in touch when they notice one of these:
- Rigid filler in a joint that should flex
- Old sealant gone brittle and cracked
- Sealant pulling away from one side of the joint
- Cracked joints where brick meets render or frames
If you let a flat or house near Hurst Green station, outside joints that have cracked can let damp into a rental, so check them between lets.
Comparing quotes
- Whether you can choose the colour
- Are they insured?
- How the joint is cleaned and prepared
- What guarantee comes with the work
Surface by surface
Render joints
Render is weaker at the surface than brick, so a sealant that stretches easily protects the edges. Priming is done where the sealant calls for it.
Joints between dissimilar materials
Joints where frames, sills or panels meet the wall are common leak points. The old joint is removed and a sealant that bonds to both sides goes in.