Greater London · England
External & façade joints in Downham, Greater London
Sealing brickwork movement joints, render, cladding and façade joints for householders, landlords and businesses in Downham. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Water getting into walls through failed joints
- Failed seals between different materials
- Moss and dirt in joints with no sealant left
External mastic in Downham
We cut out failed sealant, set the joint depth with closed-cell backing rod and reseal with a low-modulus exterior sealant. The colour is chosen to suit the brick or render so the joint does not stand out. If you are dealing with old sealant gone brittle and cracked and leaking joints around cladding and façade panels, 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 Downham, check the lease for who looks after the outside.
The work is covered for a year after we finish. If anything isn’t right with it, phone 0345 464 0079 or email us.
- Where
- Downham (BR1, SE6, SE12)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- A clear price before we start
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
FAQs for Downham
Is Downham in your area for external mastic?
Yes. Our work covers London and the South East, and Downham is part of that. You can ring 0345 464 0079 or send us an email and let us know what needs doing, and we’ll send you a clear quote.
I let a flat near Grove Park station. Can you help?
Yes, we work for landlords and letting agents. You can phone 0345 464 0079 or send us an email with the address and a few details, and we’ll give you a fixed price before any work starts.
Are you an approved applicator?
Yes. Mr Mastic is an ARBOMaster approved applicator.
Do I have to be there?
Access is agreed with you when the job is booked. Indoors, that normally means someone at home.
How long should I leave it?
That depends on the sealant used, so follow the cure time we give you.
Do you work for hotels and businesses?
Yes. We can plan bigger jobs in stages to suit the site.
Can I do it myself?
You can, for simple jobs. The key is preparation: remove all the old material and work on a clean, dry joint. If it doesn’t work out, we can redo it.
Do you guarantee your work?
Yes, for a year. If there’s a problem with our work in that time, tell us and we will put it right.
Nearby places to Downham
More services for Downham
Do you need external mastic in Downham?
Many joints fail because they were sealed too deep or with nothing behind them. If the sealant sticks to the back as well as the sides, it can’t stretch and rips as the joint opens.
Look out for any of the following:
- Cracked joints where brick meets render or frames
- Water getting into walls through failed joints
- Movement joints with cracked, split or missing sealant
- Weathered mastic that no longer stretches
Managing a site like Rangefield Primary School? Then movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
What your quote should include
- The length of the guarantee
- Are they insured?
- What product goes in the joint
- Whether they seal over old material or remove it
How the job changes by surface
Brickwork movement joints
People sometimes point up a brick movement joint by mistake. If that’s happened, we rake it out and reseal it properly.
Cladding and façade panels
Where a cladding system has its own specified sealant, we follow it or an approved alternative. Send us any details you have about the façade.
For landlords and businesses
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements.
Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. Hotel work is part of what we do, alongside homes and businesses.
What happens on the day
We bring everything the job needs with us. 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. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- We inspect the joints and agree which need resealing and how they’ll be reached.
- The old mastic and anything lodged in the joint is removed.
- Both sides are cleaned back to sound material and primed if needed.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
Getting ready for the visit
- Tell us about any water getting in
- Move anything stored near the joints
- Keep children and pets away from the work area
Ask for a quote
It all starts with a short chat. Describe the problem, the location and the size of the job, and we’ll explain how we’d tackle it. When it suits you, phone 0345 464 0079 or send us an email.
Related advice
Aftercare tips
Simple care keeps the joints in good condition. We recommend:
- Keep movement joints as flexible joints, not mortar
- Keep water from gutters off the wall
- Ask before painting over external sealant
- Walk round the building once a year and look at the joints
Do not paint over the new sealant unless we’ve said the product is paintable. Paint can crack on a flexible joint and spoil the finish.
Gaps, plants or missing sealant in a joint are worth getting looked at. Earlier resealing means a smaller job and a better result.
DIY versus a professional finish
The biggest DIY mistake is sealing over old sealant. Silicone does not stick to old silicone, so it lifts and traps water and mould underneath. Everything old must be removed first.
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Downham buildings and the weather
In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking. With historic houses such as Bromley Palace (about 1.7 miles south-east) nearby, there’s older building stock in the area around Downham as well as newer homes. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth.
For landlords with property near Grove Park station, failed wall and movement joints let damp in, so they’re worth checking between tenancies. Downham is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Downham is about 2 miles north of Bromley, in Greater London. Jobs in Downham get the same care as everywhere else we work: old sealant removed completely, careful preparation and a 12-month guarantee. Across Greater London, we cover 764 places, and Downham is one of them. There’s also a page for London, roughly 7 miles from Downham.
Every address in BR1, SE6 and SE12 is covered for external mastic, from the main roads to the quietest streets. Whether your property is on Shaw Road, Arcus Road and Brook Lane or anywhere close by, our applicators can take on the job. If you are just outside Downham, we cover Plaistow (1 mile south), Grove Park (1 mile north-east), Sundridge (1 mile south-east), Chinbrook (1 mile east) and Bellingham (1 mile west). Larger places within reach include London (7 miles north-west), City of Westminster (9 miles north-west), Marylebone (9 miles north-west), Kensington (10 miles north-west), St Pancras (9 miles north-west) and Shoreditch (8 miles north-west).
What’s near Downham
Locally, jobs take us to homes and businesses close to Holy Trinity College Bromley, Downham Fields and Bonus Pastor Catholic College and the streets around them. For rail, the closest station is Grove Park station, about 0.8 miles north-east. Well-known places in the area include The Glades (1.6 miles south) and Greenwich Castle (3.6 miles north). Green spaces nearby include Summer Hill and Downham Woodland Walk.
What affects the cost of external mastic
There’s no set price list. What we look at:
- The size of the job
- Access and height
- How many rooms, windows or areas are involved
- Any working-time requirements on site
No two jobs are quite the same, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all make a difference.
What to tell us for a quote
Photos by email are helpful but not essential. Please mention:
- The rough size of the job
- Where the job is, and your postcode
- Access, such as stairs, a lift or height
- Whether it’s a home or a business
Getting a quote is simple: tell us what needs doing and where and its rough size. Photos by email help us understand the job, and we’ll take it from there.