Greater London · England
External Mastic in St Mary Cray
External mastic in St Mary Cray from a team with over 20 years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Movement joints with cracked, split or missing sealant
- Failed sealant between panels on a façade
- Movement joints filled with mortar instead of sealant
How we handle external mastic in St Mary Cray
Movement joints let brickwork, render and cladding expand and shrink without cracking. Its sealant has to flex with the building, season after season, and when it fails, the wall takes the strain and water finds a way in. If you have gaps where render, brick and frames meet and joints with sealant missing in places, we can help, on joints between brick and frames, brickwork movement joints and render & cladding joints alike.
Outside work in London starts with access: side passages, upper floors and where to park. For a home in St Mary Cray, tell us how high the joints are and how to reach the back of the building.
We guarantee the work for a year. If something isn’t right with it in that time, tell us and we will put it right.
- Where
- St Mary Cray (BR5, BR6, BR7)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
What happens on the day
The work is kept neat and contained to the area we’re working on, so you can get on with your day. Expect the work to take a few hours for a handful of joints, longer for a whole elevation, and we tell you how long to leave it before we go. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in St Mary Cray. A visitor permit or a nearby bay makes the visit run more smoothly.
- We inspect the joints and agree which need resealing and how they’ll be reached.
- Old sealant and any debris are cut and raked out.
- The joint faces are cleaned and primed where the sealant needs it.
- Backing rod goes in next, setting the depth and keeping the sealant off the back of the joint.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
Before we arrive
- Mention any sign-in or site rules at work premises
- Clear items away from the joints we are working on
- Let us know about stairs, lifts or work at height
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 will talk you through what we’d do. Whenever you’re ready, ring 0345 464 0079 or drop us an email.
Related advice
How we quote for external mastic
For a quick quote, just ask. What matters most is:
- Mould in or behind the old joints
- The size of the job
- How easy the joints are to reach
- Whether old sealant or filler has to be cut out
Combining jobs into one visit is generally more efficient than separate visits. We’ll give you a clear quote for the lot.
Asking for a quote
A few details help us give you an accurate quote. When you get in contact, it helps to mention:
- Where the property is
- Access, such as stairs, a lift or height
- If it’s domestic, commercial or a hotel
- The problem you’ve noticed
Getting a quote is simple: let us know the job and the location and its rough size. Photos by email help us understand the job, and we will come back to you with a quote.
Leave it or put it right?
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. The correct repair is a flexible sealant with the right backing. 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.
The cost reflects the work involved, not guesswork. That is why we ask about the job first and send you a clear quote before we start.
What you get with us
- Trusted Arbo and Everbuild sealants
- White, clear, grey or coloured to suit, where the product allows
- Sanitary silicone with an anti-fungal additive in wet areas
- A 12-month guarantee on all work
Take a look at how sealant jobs are priced or customer reviews.
How to look after the new joints
How long the joints last depends on use and care. We suggest:
- Make sure movement joints aren’t pointed over
- Keep soil, plants and ivy away from the joints
- Avoid pressure-washing directly into sealant joints
- Have failed joints looked at early
Do not let soil, plants or ivy build up against the new joints. Anything that holds water against the joint wears it out sooner.
Water getting behind cladding or render can go unnoticed for a long time. By the time there’s a damp patch, the damage can be well established so early resealing is worth it.
Also near St Mary Cray
More services for St Mary Cray
For landlords and businesses
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
We work for landlords and letting agents as well as householders. Resealing between tenancies is a simple way to keep a property in good order before the next move-in.
Your questions about external mastic in St Mary Cray
Can parking be tricky for a visit in St Mary Cray?
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.
Do you work for landlords with property near St Mary Cray station?
Yes. We work for landlords and letting agents as well as householders, and several properties can be quoted together. Just ring 0345 464 0079 or send us an email with the address and what needs doing, and we will give you a clear price.
Will the old sealant be removed?
Yes. We cut out all the old sealant and clean the joint before applying anything new.
Can you quote for more than one area?
Of course. Doing several areas at once is usually more efficient.
Do you work for hotels and businesses?
Yes. Commercial and hotel work is a large part of what we do, as well as homes. We can talk about working times when we quote.
Will the new joint stand out?
We choose a sealant colour to suit the brick, stone or render, so the joint sits quietly in the wall. There’s a wide choice of exterior colours.
Where are you based?
Our base is Crawley. We work across South East England, London and Scotland.
Are you ARBOMaster approved?
Yes. We’re an ARBOMaster approved applicator, the approved applicator scheme for Arbo sealants.
Walls and rooflines in St Mary Cray
Historic houses like Bromley Palace (about 3.8 miles west) are a reminder that the area around St Mary Cray 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. In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts.
St Mary Cray is in London, so parking needs planning: let us know about parking bays, permits or a driveway. Schools such as Poverest Primary School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing. Homes close to Church of St Mary include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain.
St Mary Cray is about 11 miles south-east of London, in Greater London. Jobs in St Mary Cray get the same care as everywhere else we work: old sealant removed completely, careful preparation and a 12-month guarantee. St Mary Cray is one of 764 places in Greater London we cover. Our London page covers work nearby.
Here we cover the BR5, BR6 and BR7 postcode area for external mastic. We cover properties on New Road, Kent Road and Park Road. Being close to the A224, St Mary Cray is easy for our applicators to reach. We also cover Poverest (1 mile south-west), St Paul's Cray (1 mile north), Orpington (1 mile south), Derry Downs (1 mile south-east) and Kevington (1 mile east). Larger places within reach include London (11 miles north-west), City of Westminster (14 miles north-west), Marylebone (14 miles north-west), Kensington (15 miles north-west), St Pancras (13 miles north-west) and Shoreditch (12 miles north-west).
Landmarks near St Mary Cray
In St Mary Cray, that means homes and buildings near Harris Academy Orpington, The Blue Anchor Public House and Walsingham School and the streets around them. St Mary Cray has its own railway station: St Mary Cray station. A little further out are London Borough of Bromley Museum (0.9 miles south) and Lullingstone Castle (4.5 miles south-east). The countryside around St Mary Cray includes Summer Hill and The Warren.
DIY versus a professional finish
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
The biggest DIY mistake is sealing over old sealant. Silicone does not stick to old silicone, so it peels away and traps moisture behind it. Everything old must be removed first.
What the job involves on each surface
Copings and trims
Joints in copings, parapets and trims are exposed to the worst of the weather. Each is resealed with a weatherproof, flexible sealant.
Joints between dissimilar materials
Joints where frames, sills or panels meet the wall are common leak points. We cut out the old sealant and reseal with a product suited to both surfaces.