Greater London · England
External & façade joints in Roundshaw, Greater London
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Roundshaw and across Greater London. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Damp patches traced to an open external joint
- Sealant pulling away from one side of the joint
- Weathered mastic that no longer stretches
Should I try it myself first?
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and does not move well, and the joint depth matters as much as the finish.
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
How we handle external mastic in Roundshaw
Failed sealant is cut out, the depth set with closed-cell backing rod, and the joint resealed with a low-modulus sealant made for outside. We pick a colour that sits well with the wall so the line blends in. We work on façade panels, brickwork movement joints and concrete & block, and the jobs we see most are movement joints filled with mortar instead of sealant and brick movement joints where the sealant has split.
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 Roundshaw, check the lease for who looks after the outside.
Our work is backed for twelve months, and the guarantee is the same wherever you are.
- Place
- Roundshaw (SM6, CR8, CR0)
- Region
- Greater London
- Cover
- A year, on every job
- Price
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Also near Roundshaw
More services for Roundshaw
When it isn’t the sealant
We’ll always be straight with you, so here’s what sealant can’t fix:
- Cracks in the bricks or render themselves, away from the joints
- Walls that need new movement joints cut into them
- Damp that is not coming from the joint
Not sure which it is? You can ring 0345 464 0079 or email us and we will tell you honestly before booking.
Where we work in Roundshaw
- Render & cladding joints
- Concrete & block
- Copings & trims
- Brickwork movement joints
- Façade panels
- Joints between brick and frames
Landlords, agents and businesses in Roundshaw
Housing providers, facilities teams and property managers book us too in Roundshaw and across Greater London. We can quote a run of properties together, and we’re fully insured.
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.
Keeping the joints in good condition
A little care helps the new joints last. Our advice:
- Leave the joints unpainted unless we’ve said otherwise
- Look over the joints every year, ideally after winter
- Never let anyone fill a movement joint with mortar
- Point out the joints to other trades
Look over the joints once a year, ideally after winter. Splits, gaps at the edges or plants in the joint are early warning signs.
Leave a failed movement joint and water keeps getting into the wall. That can lead to damp patches, staining and frost damage.
Different surfaces, different methods
Copings and trims
Coping joints that leak let water straight down into the wall. Sealing them early saves the wall below.
Render joints
The face of render can be soft, so a low-modulus sealant is kinder to the joint edges. We prime where the product needs it.
What affects the cost of external mastic
The price is agreed before any work begins. It’s based on:
- Any working-time requirements on site
- The amount of work
- Whether the work is at height
- The type of sealant required
Doing several joints on one visit normally makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. We’ll give you a clear quote for the lot.
What we need to know
When you contact us, these details help:
- Photos by email, if that is easy
- What the problem is, such as mould, gaps, leaks or cracking
- The type of property
- Access, such as stairs, a lift or height
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we’ll explain how we’d tackle it. Whenever you’re ready, call 0345 464 0079 or email us.
FAQs for Roundshaw
Can parking be tricky for a visit in Roundshaw?
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.
Can you help a landlord with a rental near Wallington station?
Yes. We work for landlords and agents as well as homeowners, and several properties can go on one quote. Just phone 0345 464 0079 or send us an email with the address and what needs doing, and we’ll give you a clear quote.
Will it make a mess?
Not at all. We work neatly, protect the area around the joints and tidy up afterwards.
Will the old sealant be removed?
Yes, every time. New silicone does not stick to old silicone, so the joint is cleaned back first.
What is a movement joint?
A vertical gap in a long brick wall is usually a movement joint. It gives the wall room to move, and it should be sealed with a flexible sealant.
Should I point up the gap in my brickwork?
No. Cement or mortar cannot stretch. If it has already been filled, we can usually cut it out and reseal it.
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. More than one area can be quoted together.
What external mastic looks like in Roundshaw
London terraces and converted houses often share gutters, downpipes and walls, so it’s worth agreeing who is responsible before work starts. Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
If you let a flat or house near Wallington station, failed wall and movement joints let damp in, so they’re worth checking between tenancies. As a London address, Roundshaw can be tricky for parking: tell us about permits, visitor bays or off-street space when you book. Homes close to St. Paul's include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain.
Roundshaw is about 2 miles south-west of Croydon, in Greater London. Wherever you are in the SM6 postcode area, our applicators can take on external mastic. Across Greater London, we cover 764 places, Roundshaw among them. For nearby work, see our London page, about 10 miles away.
We cover every part of the SM6, CR8 and CR0 postcode area for external mastic. You’ll find streets such as Link Lane, Milton Road and Redwing Road. Neighbouring places we cover for external mastic include Russell Hill (1 mile east), Bandonhill (1 mile north), Peaks Hill (1 mile south), Waddon (1 mile north-east) and Wallington (1 mile north-west). Further out, we also cover London (10 miles north), City of Westminster (11 miles north), Marylebone (11 miles north), Kensington (11 miles north), St Pancras (12 miles north) and Shoreditch (12 miles north).
Landmarks near Roundshaw
Locally, jobs take us to homes and businesses close to Wilson's School, Waddon Ponds and The John Fisher School. The nearest railway station is Wallington station, roughly 0.9 miles north-west of the centre. A little further out are Purley War Memorial Hospital (1.2 miles south-east) and Croydon Airport Visitor Centre (0.6 miles east). Not far away are Roundshaw Downs and Duppas Hill.
How the visit works
We bring everything the job needs with us, so there’s nothing for you to buy. Once we’ve agreed what’s being done, we protect the area and start. Most jobs take a few hours to a few days, depending on the length of joint and the access. In a London area like Roundshaw, the main things to plan are parking and access: let us know about parking, the floor we will be working on and any lift or shared entrance.
- We look at every joint and agree a colour to suit the wall.
- We take out the old sealant until the faces are sound.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- We prime the faces where required.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- Let us know if you’ve seen damp or leaks
- On commercial sites, let us know about site rules
- Where the joints are inside, avoid wetting them before we arrive
Get a quote
Asking for a quote is easy: let us know the job and the location, and roughly how big it is. Photos by email help us understand the job, and we’ll come back to you with a quote.