Greater London · England
Croydon External Mastic
External mastic for Croydon and the surrounding area: careful preparation, the right product and tidy work. Call for a quick quote.
- Joints where the bead has come unstuck
- Damp patches traced to an open external joint
- Joints pointed up with cement by mistake
External mastic in Croydon, done properly
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 moss and dirt in joints with no sealant left, we can put it right.
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 Croydon, check the lease for who looks after the outside.
All our work comes with our one-year guarantee, wherever you are in Greater London.
- Place
- Croydon (CR0, CR2, CR9, CR8)
- Region
- Greater London
- Cover
- 12 months on all our work
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
How the visit works
Every visit runs the same way: we look at the joints together, protect the area around them, carry out the job and tidy away. Most jobs take a few hours for a handful of joints, longer for a whole elevation. For a job in Croydon, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- 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.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- We apply the sealant, tool it and check the whole run.
Before we arrive
- Where the joints are inside, avoid wetting them before we arrive
- Clear the area around the work
- Tell us about access, such as stairs, a lift or high-level joints
How to get a quote
To get a quote, call 0345 464 0079 or send us an email with the location and a short description of the problem. You will have a clear quote before we start.
Related advice
DIY versus a professional finish
Sealing over old silicone is the commonest DIY error. Silicone doesn’t stick to old silicone, so it peels away and traps moisture behind it. All the old material has to come out first.
A careful DIYer can reseal a simple joint, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
What the job involves on each surface
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.
Brickwork movement joints
Vertical joints in long brick walls let the brickwork expand without cracking. They’re resealed over backing rod with a low-modulus sealant.
Nearby places to Croydon
What else we do in Croydon
Outside joints around Croydon
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. London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking.
Homes close to St Andrew's include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep. For landlords with property near South Croydon station, outside joints that have cracked can let damp into a rental, so check them between lets.
Croydon is about 9 miles south of London, in Greater London. Jobs in Croydon get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. Across Greater London, we cover 764 places, Croydon among them. You can also see our page for London, roughly 9 miles from Croydon.
Work in CR0, CR2, CR9 and CR8 works the same way as everywhere else we cover. That includes homes and businesses on High Street, Church Road and Ruskin Square. Main roads around Croydon include the A235 and B243, which makes travel easy. Neighbouring places we cover for external mastic include South Croydon (1 mile south), Coombe (1 mile east), Addiscombe (2 miles north-east), Ashburton (2 miles north-east) and Woodside (2 miles north-east). Larger places within reach include London (9 miles north), City of Westminster (10 miles north), Marylebone (11 miles north), Kensington (10 miles north-west), St Pancras (11 miles north) and Shoreditch (11 miles north).
Near you in Croydon
In Croydon, that means homes and buildings near Cambridge Tutors College, Rutherford School and Keg & Grill pub and the streets around them. There’s a railway station in Croydon itself: South Croydon station. Other landmarks nearby include Croydon Airport Visitor Centre (1.2 miles south-west) and Croydon University Hospital (1.7 miles north). Not far away are Roundshaw Downs and Duppas Hill.
Croydon questions
Can you do external mastic in Croydon?
Yes. We work across London and the South East, and Croydon is part of that. Just phone 0345 464 0079 or drop us an email with a few details of the job, and we’ll give you a clear price.
Is parking a problem for a job in Croydon?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly.
Do you use backing rod?
Backing rod goes into deeper joints as a matter of course. It sets the sealant depth and prevents three-sided bonding so the bead can stretch.
Which products do you use?
It depends on the joint: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. Brands we use include Arbo and Everbuild.
Does someone need to be in?
That depends on where the joints are. Inside work needs someone to give us access, while outside work can sometimes be arranged differently.
Is there a guarantee?
Yes, for a year. If anything is not right with the work within the year, let us know and we’ll sort it.
Why is there a gap in my brick wall?
Most straight vertical gaps in brickwork are movement joints. It lets the bricks expand without cracking and needs a flexible seal, not mortar.
How often do external joints need resealing?
That varies with the weather the wall faces, how much it moves and the sealant used. Treat it as a maintenance item and look at it yearly.
When to call us in Croydon
Joints sealed without backing rod, or far too deep, rarely last. If the sealant sticks to the back as well as the sides, it can’t stretch and tears as soon as the joint widens.
Common reasons people contact us include:
- Failed seals between different materials
- Failed sealant between panels on a façade
- Weathered mastic that no longer stretches
- Rain getting behind render or cladding at a joint
As a London address, Croydon can be tricky for parking: let us know about parking bays, permits or a driveway.
What to look for in a quote
- Which colour the sealant will be
- What the cure time is
- Which sealant they’ll use, and why
- Whether VAT is included
Work for landlords, hotels and businesses
Hotels need rooms back in use, so the work can be planned room by room. Hotel work is part of what we do, alongside homes and businesses.
We also work for property managers and facilities teams in Croydon and across Greater London. We can quote a run of properties together, and we are fully insured for the work.
Keeping the joints in good condition
Joint life depends on how it’s used and looked after. Here’s what we suggest:
- Have failed joints looked at early
- Clear growth from the base of walls and joints
- Keep high-pressure jets off the joints
- Keep movement joints as flexible joints, not mortar
Don’t paint over the new sealant unless we have said the product is paintable. Many exterior sealants aren’t designed to be painted, and paint can crack as the joint moves.
Once a joint can’t move, the wall finds another way, often as cracks near the joint. Resealing it early helps prevent that.
Why deal with it now?
Running new sealant over the old bead rarely lasts. The new layer cannot bond properly to old, weathered material, so we always take the old sealant out. In older London homes, water behind a failed joint soaks into brick and timber without much sign, and by the time it shows on a wall or ceiling in Croydon, the repair is bigger than the sealant job would have been.
There are no prices on our website, because the cost depends so much on the job itself. For a quick quote, please ring 0345 464 0079 or drop us an email.
Why book with us
- We’re fully insured
- Arbo and Everbuild products
- Approved under the ARBOMaster scheme
- 20+ years of sealant experience