Greater London · England
External & façade joints in Merton, Greater London
Specialist external mastic for Merton: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Joints pointed up with cement by mistake
- Old sealant gone brittle and cracked
- Brick movement joints where the sealant has split
Aftercare tips
How long the joints last depends on use and care. We suggest:
- Keep soil, plants and ivy away from the joints
- Keep high-pressure jets off the joints
- Walk round the building once a year and look at the joints
- Show decorators and builders where the movement joints are
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They should be kept open and resealed, not filled.
Leaks behind façade panels and render often go unseen. When it finally shows inside, the joint may have been open for years.
About our external mastic in Merton
Where two different materials meet, such as brick and render or blockwork and metal, they move at different rates. A flexible exterior sealant takes up that movement. If you’re dealing with movement joints with cracked, split or missing sealant and hard, crazed mastic that has stopped moving, we can put it right.
Modern London flats rely on sealed movement joints and cladding joints. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall, and both kinds of building are found across London.
Whatever the size of the job, you get the same 12-month guarantee.
- Location
- Merton (SW19)
- Region
- Greater London
- Guarantee
- A year, on every job
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Also in Merton
FAQs for Merton
Do you cover Merton for external mastic?
Yes, Merton is within the area we cover. We work across London and the South East. You can ring 0345 464 0079 or drop us an email and let us know what needs doing.
Can you help a landlord with a rental near Haydons Road station?
Yes. We work for landlords and agents as well as householders, and several properties can go on one quote. Just ring 0345 464 0079 or send us an email with the address and what needs doing, and we’ll send you a clear quote.
Do you work for hotels and businesses?
Yes. We work in offices, washrooms, hotels and other commercial premises, as well as homes. Working times can be discussed when we quote.
Can you seal joints between two different materials?
Yes. We cut out the old sealant, prepare both faces and reseal with a flexible exterior product. The colour is chosen to suit.
Do you hold any approvals?
Yes. We hold ARBOMaster approved applicator status.
When will the joints need doing again?
That depends on the wall, the weather and the movement. Signs to watch for are cracking, hardening and gaps at the edges.
Do you remove the old sealant?
Yes, always, and completely. New sealant will not bond properly to old, so any old material comes out before anything new goes in.
Can you quote for more than one area?
Yes, and it often makes sense. Doing several areas at once is normally more efficient.
How it works
Good joint work is mostly preparation, so that’s where we spend the time. Joints are cleaned back and dried before anything new goes in. All told, the work takes anything from a few hours to several days, depending on the building. In Merton, flats, stairs and shared entrances are part of the routine. Mention any building rules, key holders or managing agents when you book.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Preparing for the visit
- Where the joints are inside, avoid wetting them before we arrive
- Tell us about access, such as stairs, a lift or high-level joints
- Let us know if you’ve seen damp or leaks
Getting a quote
Need a quote? Please ring 0345 464 0079 or email us with a few details. You’ll know what we plan to do, and what it will cost, before any work begins.
Read more
DIY sealant or a professional job?
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
If you’ve already had a go yourself, that is fine. We cut it out and start again, so just mention it when you contact us.
Outside joints around Merton
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 Southside House (about 1.8 miles west) nearby, there’s older building stock in the area around Merton as well as newer homes. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
If you live in an older home near St John The Divine, the joints between older walls, newer extensions and the roofline need a sealant that can move. Merton is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Merton is about 1 mile south-east of Wimbledon, in Greater London. Every kind of property in Merton can book us for external mastic, old or new, large or small. Every job comes with our one-year guarantee. Our area takes in 764 places across Greater London. There’s also a page for London, roughly 7 miles from Merton.
We work across the SW19 postcode area for external mastic and the streets around it. You will find streets such as High Path, Pincott Road and Hayward Close, all of which we cover. Merton sits on or near the A24, which makes travel easy. We also cover the places around Merton: Merton Abbey (1 mile east), South Wimbledon (1 mile north-west), Colliers Wood (1 mile east), Tooting Bec (1 mile north-east) and Summerstown (1 mile north). Further out, we also cover London (7 miles north-east), City of Westminster (7 miles north), Marylebone (7 miles north), Kensington (6 miles north), St Pancras (8 miles north) and Shoreditch (9 miles north-east).
Around Merton
In Merton, that means homes and buildings near The Nelson Arms, Wimbledon School of Art and Wandle Park. For rail, the closest station is Haydons Road station, roughly 0.8 miles north of the centre. Other landmarks nearby include Southside Wandsworth (2.8 miles north) and St George's Hospital (1.1 miles north-east). The countryside around Merton includes Henman Hill and Merton Park Green Walks.
Different surfaces, different methods
Render joints
Rendered walls have joints at beads, openings and changes of material. We reseal them with a flexible exterior sealant that suits the render colour.
Brickwork movement joints
People sometimes point up a brick movement joint by mistake. Where one has been mortared, we cut it out and reseal it with sealant.
Why it’s worth doing now in Merton
Done well, a resealed joint is a neat, straight line that suits the wall. A hurried job with smeared edges and no backing looks worse and fails sooner. Damp from a failed joint spreads quietly in older London brickwork and timber, and by the time it shows on a wall or ceiling in Merton, the repair is bigger than the sealant job would have been.
The cost reflects the work involved, not a rough estimate. That is why we ask about the job first and agree the price before starting.
Why book with us
- A sealant colour to suit the surroundings
- Anti-fungal sanitary silicone in wet areas
- We agree the colour with you first
- Neat joints and a tidy finish
See what affects the cost and customer reviews.
What we’re called out for in Merton
A lot of failed joints come down to preparation: joint faces that were dusty or damp, unprimed where they needed it, or still carrying old sealant. The sealant never bonds properly.
These are the problems we are asked about most:
- Panel joints letting water in
- Damp patches traced to an open external joint
- Plants rooting in failed movement joints
- Weathered mastic that no longer stretches
If you let a flat or house near Haydons Road station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Before you book anyone
- Whether they’re fully insured
- How the colour is chosen
- What the quote includes, VAT included or not
- How long to leave it before use
Landlords, agents and businesses in Merton
If you manage several properties in or around Merton, several properties can go on one quote. Send us the addresses and the work at each.
Whether it’s one flat or a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a one-year guarantee.