Greater London · England
Merton Park External Mastic
Specialist external mastic for Merton Park: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Movement joints filled with mortar instead of sealant
- Damp patches traced to an open external joint
- Hard, crazed mastic that has stopped moving
Why deal with it now?
A properly done movement joint is an even line in a colour that suits the wall. A rushed bead with no backing looks untidy and does not last, so it pays to do it properly once. In older London homes, water behind a failed joint soaks into brick and timber without much sign, and once it shows in Merton Park, the repair is bigger than a sealant job.
What you pay reflects the work, not a rough estimate. That is why we ask about the job first and send you a clear quote before work begins.
Why book with us
- Over 20 years’ experience
- Homes, businesses and hotels
- Arbo and Everbuild products
- We agree the colour with you first
External mastic in Merton Park, done properly
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. The colour is chosen to suit the brick or render. We work on façade panels, joints between brick and frames and copings & trims, and people most often call us about brick movement joints where the sealant has split and sealant pulling away from one side of the joint.
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 Merton Park, check the lease for who looks after the outside.
All our work is covered by a 12-month guarantee, wherever you are in Greater London.
- Place
- Merton Park (SW19, SW20, SM4)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
DIY sealant or a professional job?
The difference is mostly in the preparation and the product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, and the work is guaranteed for a year.
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.
Keeping the joints in good condition
Once the sealant has cured, a few habits help it last:
- Keep water from gutters off the wall
- Ask before painting over external sealant
- Keep soil, plants and ivy away from the joints
- Show decorators and builders where the movement joints are
Avoid pressure-washing straight into the joints. A strong jet can damage the edges of the bead.
Small splits are the time to act. Then it’s a straightforward cut-out and reseal before water has had years to get in.
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What we cannot put right
New sealant cannot fix everything, and we’d rather say so up front. Sealant won’t put right:
- Structural movement, which needs a surveyor or engineer
- Cracks in the bricks or render themselves, away from the joints
- Rising or penetrating damp from elsewhere in the wall
Not sure which it is? You can ring 0345 464 0079 or drop us an email and we will tell you honestly.
What we seal
- Concrete & block
- Façade panels
- Render & cladding joints
- Joints between brick and frames
- Copings & trims
- Brickwork movement joints
What we are called out for in Merton Park
Sometimes a movement joint was filled with mortar or a rigid filler by mistake. The joint can’t move, so the wall cracks somewhere else instead.
Common reasons people contact us are:
- Rain getting behind render or cladding at a joint
- Hard, crazed mastic that has stopped moving
- Moss and dirt in joints with no sealant left
- Leaking joints around cladding and façade panels
For landlords with property near South Merton station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
What to look for in a quote
- Who does the work, and how experienced they are
- Is the old sealant removed completely?
- Whether they’re fully insured
- What the quote includes, VAT included or not
Your questions about external mastic in Merton Park
Do you cover Merton Park for external mastic?
Yes. Our work covers London and the South East, and Merton Park is part of that. Just ring 0345 464 0079 or drop us an email with a few details of the job.
Can you help a landlord with a rental near South Merton station?
Yes, landlords and agents are among the people we work for. You can phone 0345 464 0079 or email us with the details for a clear quote.
Do I have to be there?
It depends on the job. Inside work needs someone to give us access, while outside work can sometimes be arranged differently.
Do you take out the old sealant first?
Yes, always, and completely. New silicone does not stick to old silicone, so the joint is cleaned back first.
Where are you based?
Our base is in Crawley, and we work across South East England, London and Scotland.
Is it OK to fill a movement joint with cement?
No. Cement or mortar cannot stretch. If it has already been filled, we can generally cut it out and reseal it.
Are you ARBOMaster approved?
Yes. We are an ARBOMaster approved applicator.
How do you reach high-level joints?
That depends on the building and the joints. We work on joints that can be reached safely. Give us some details and we will confirm the access.
External mastic in Merton Park: local notes
In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts. Historic houses like Southside House (about 1.4 miles west) are a reminder that the area around Merton Park has older buildings as well as new. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
Homes close to St Mary's Church include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain. Merton Park is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Merton Park is about 1 mile south-east of Wimbledon, in Greater London. If you need external mastic in Merton Park, it’s easy to get a quote: please call 0345 464 0079 or drop us an email. We cover Greater London from our Crawley base, Merton Park included. Our Greater London coverage runs to 764 places, and Merton Park is one of them. Our London page covers work nearby (8 miles or so).
Our applicators cover all of the SW19, SW20 and SM4 postcode area for external mastic and the streets around it. We cover properties on Mina Road, Manor Road and Cecil Road. Other places close to Merton Park include Wimbledon Chase (1 mile west), Bushey Mead (1 mile west), Cannon Hill (1 mile south-west), Wimbledon (1 mile north-west) and Crooked Billet (1 mile north-west). We also work in nearby towns such as London (8 miles north-east), City of Westminster (7 miles north), Marylebone (8 miles north), Kensington (6 miles north), St Pancras (9 miles north-east) and Shoreditch (10 miles north-east).
Local landmarks in Merton Park
Typical jobs here are in homes near Wibbas Down Inn, Morden Hall Park and Wimbledon School of Art, among other places. The nearest railway station is South Merton station, about 0.5 miles south. Other landmarks nearby include St George's Hospital (1.6 miles north-east) and Southside Wandsworth (3.1 miles north). Green spaces nearby include Merton Park Green Walks and Henman Hill.
What affects the quote in Merton Park
Some jobs are bigger than they look, and some smaller. What affects the quote:
- Any mould that needs treating
- The size of the job
- How easy the joints are to reach
- The number of rooms or windows
No two jobs are quite the same, so each one gets its own quote. Size, access and the product the joint needs all make a difference, and we’ll explain the quote if you ask.
Asking for a quote
When you call or email, it’s useful to know:
- Where the job is, and your postcode
- How we’d reach the joints
- If it’s domestic, commercial or a hotel
- A few pictures by email, if you can
There’s no standard price list. Instead, your job gets its own clear quote. To get started, phone 0345 464 0079 or send us an email.
What we do, step by step
On the day, we look over the joints with you first. We protect the surfaces around the joints before we start. The work usually takes a few hours to a few days, depending on the length of joint and the access. For a job in Merton Park, parking and access are the things to plan: let us know about parking, the floor we will be working on and any lift or shared entrance.
- 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.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
How to prepare
- Let us know if you’ve seen damp or leaks
- For indoor joints, keep the area dry beforehand if you can
- Plan for the work area to be out of bounds to pets and children
Getting a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints.