Greater London · England
External Mastic in Walham Green
Movement joints in Walham Green need attention? We cut out the old, prepare the joints and apply the right sealant, and the work is guaranteed for a year.
- Gaps where render, brick and frames meet
- Damp patches traced to an open external joint
- Joints where the bead has come unstuck
How we handle external mastic in Walham Green
We cut out failed sealant, set the joint depth with closed-cell backing rod and reseal with a low-modulus exterior sealant. We pick a colour that sits well with the wall. Common call-outs are for damp patches traced to an open external joint and cracked joints where brick meets render or frames, on brickwork movement joints, joints between brick and frames and copings & trims.
Newer London blocks are built with movement joints in brick and render, and with cladding joints sealed with mastic. Period houses have different weak points, such as gutter joints, trims and the line where an extension meets the old wall, and both kinds of building are found across London.
A one-year guarantee comes as standard.
- Location
- Walham Green (SW6, SW10, SW11)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- A clear price before work begins
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Aftercare tips
Aftercare is simple:
- Keep soil, plants and ivy away from the joints
- Check the sealant is paintable before painting near it
- Keep movement joints as flexible joints, not mortar
- Avoid pressure-washing directly into sealant joints
Keep pressure washers away from the sealant. High-pressure water can lift the edges over time.
If you can see gaps, plants or bare sections in a joint, have it checked. Early work is quicker and leaves a better finish.
External mastic in Walham Green: local notes
In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking. Historic houses like Carlyle's House (about 1 mile north-east) are a reminder that the area around Walham Green has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
Homes close to Church of St John include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep. Rented homes near Imperial Wharf station change hands often, and failed wall and movement joints let damp in, so they’re worth checking between tenancies. As a London address, Walham Green can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Walham Green is about 2 miles south of Kensington, in Greater London. Jobs in Walham Green get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Walham Green is one of 764 places in Greater London we cover.
Every address in SW6, SW10 and SW11 is within our area for external mastic, from the main roads to the quietest streets. Whether your property is on Farm Lane, Lots Road and Epple Road or a nearby road, we can help. Being close to the A304, Walham Green is simple for us to get to. Close by, we work in Chelsea Harbour (1 mile south-east), Parsons Green (1 mile south-west), World's End (1 mile north-east), Sands End (1 mile south-east) and West Brompton (1 mile north). Further out, we also cover London (4 miles east), City of Westminster (3 miles north-east), Marylebone (3 miles north-east), St Pancras (5 miles north-east), Shoreditch (6 miles north-east) and Walthamstow (10 miles north-east).
Around Walham Green
Locally, jobs take us to homes and businesses close to Natural History Museum Library and Archives, Heatherley School of Fine Art and Langford Primary School, among other places. Also close by are William Parnell Park (within half a mile south) and The Rose pub (under half a mile south-east). There’s a railway station in Walham Green itself: Imperial Wharf station. Nearby you will also find Chelsea Stadium Tour And Museum (under half a mile north) and Chelsea and Westminster Hospital (0.5 miles north-east). For a walk, there’s Battersea Park Lake and WWT London Wetland Centre.
How it works
On the day, there’s very little for you to do. Show us the job and we will take it from there. The job generally takes a few hours for a handful of joints, longer for a whole elevation. In Walham Green, as in most of London, parking needs a little planning. A visitor permit or a nearby bay makes the visit run more smoothly.
- We start by walking round the building and agreeing the joints and the access.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs 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
- Mention any sign-in or site rules at work premises
- For indoor joints, keep the area dry beforehand if you can
- Tell us about any previous sealing or DIY attempts
How to get a quote
There’s no standard price list. Instead, your job gets its own clear quote. To get started, call 0345 464 0079 or drop us an email.
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FAQs for Walham Green
Is parking an issue for external mastic in Walham Green?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
Do you work for landlords with property near Imperial Wharf station?
Yes. We work for landlords and letting agents as well as homeowners. You can ring 0345 464 0079 or email us with the details for a clear quote.
Will there be a smell?
That depends on the sealant. Some smell for a while, some hardly at all.
How often do external joints need resealing?
It varies with how exposed the wall is and how much the joint moves. Look for splits, hardening or edges coming away and have them redone then.
Do you have insurance?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
Can new sealant go over the old?
No. The old sealant always comes out first, so the new joint bonds to clean surfaces.
Can you seal joints between render and window frames?
Yes. We cut out the old sealant, prepare both faces and reseal with a flexible exterior product. The colour is chosen to suit.
Do I have to be there?
Access is agreed with you when the job is booked. Indoors, that generally means someone at home.
DIY versus a professional finish
A DIY attempt does not rule out a professional job. We cut it out and start again, so tell us about it when you ask for a quote.
Too much sealant is as bad as too little. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
What happens if it’s left?
A properly done movement joint is an even line in a colour that suits the wall. A hurried job with smeared edges and no backing looks worse and fails sooner, so it pays to do it properly once. In a London flat, a failed joint rarely stays your problem alone: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
No two jobs are quite the same, so each one gets its own quote. Size, access and the product the joint needs all play a part, and we’ll explain the quote if you ask.
Why Walham Green clients choose us
- Neat joints and a tidy finish
- A choice of colours where the product allows
- An ARBOMaster approved applicator
- Arbo and Everbuild products
Take a look at how sealant jobs are priced or our reviews.
Places near Walham Green
More services for Walham Green
Landlords, agents and businesses in Walham Green
Landlords and agents in Walham Green can book us as well as householders. Resealing between tenancies keeps a property looking cared for before the next move-in.
Housing providers, facilities teams and property managers book us too. We can quote a run of properties together, and we’re fully insured for the work.
How the job changes by surface
Copings and trims
Joints in copings, parapets and trims are exposed to the worst of the weather. We reseal them with an exterior sealant suited to the material.
Concrete and blockwork
Big joints in concrete need careful depth control. Backing rod sized to the joint sets it and keep the sealant to the right depth.
How we quote for external mastic
Your quote is based on your job. We look at:
- The product the joint needs
- Whether old sealant or filler has to be cut out
- When we can work, for business premises
- The size of the job
Combining jobs into one visit is normally more efficient than separate visits, so it’s worth mentioning everything you’d like done. We will give you a clear price for the lot.
What we need to know
Photos by email are helpful but not essential. Please mention:
- What the problem is, such as mould, gaps, leaks or cracking
- Access, such as stairs, a lift or height
- How many joints, rooms or windows are involved
- Photos by email, if that is easy
Call for a quick quote, or email us if that’s easier. Describe what needs sealing and we will explain what’s involved before giving you a price.