Greater London · England
Balham External Mastic
Sealing brickwork movement joints, render, cladding and façade joints in Balham, with a 12-month guarantee on every job. Call for a quick quote.
- Water getting into walls through failed joints
- Movement joints filled with mortar instead of sealant
- Joints where the bead has come unstuck
Walls and rooflines in Balham
London and the South East are among the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Historic houses like Carlyle's House (about 2.9 miles north) are a reminder that the area around Balham 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.
Rented homes near Balham station change hands often, and split movement joints are easy to miss on a rental until damp shows inside. Homes close to Church of St Mary include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain.
Balham is about 2 miles south-west of Stockwell, in Greater London. Whether you’re in the middle of Balham or further out, we cover external mastic for every kind of property, from flats and houses to offices and hotels. Our Greater London coverage runs to 764 places, Balham among them.
Postcode districts we cover here for external mastic: SW12, SW17 and SW4. If you need external mastic at a property on Lynn Road, Weir Road and Byrne Road or a nearby road, our applicators can take on the job. We also cover the places around Balham: Grange Mills (1 mile north-east), Hyde farm estate (1 mile east), Clapham Park (1 mile north-east), Streatham Park (1 mile south-east) and Tooting Bec (1 mile south-west). Within a short drive, we also cover London (5 miles north-east), City of Westminster (5 miles north), Marylebone (5 miles north), Kensington (4 miles north-west), St Pancras (6 miles north) and Shoreditch (7 miles north-east).
What’s near Balham
In Balham, that means homes and buildings near Oak Lodge School, Wandsworth Common and The Bedford pub. Balham has its own railway station: Balham station. Nearby you will also find St James' Hospital (0.5 miles west) and London Sewing Machine Museum (0.6 miles south-west). For a walk, there’s Knight's Hill and Battersea Park Lake.
External mastic in Balham
Ground-floor and low-level joints are straightforward to reach. For joints higher up, give us some details of the building and we will confirm what access is needed. If you have weathered mastic that no longer stretches and movement joints with cracked, split or missing sealant, we can put it right, whatever the surface.
Modern London flats rely on sealed movement joints and cladding joints. Period houses have different weak points, such as gutter joints, trims and the line where an extension meets the old wall.
There’s a 12-month guarantee on every job, large or small.
- Location
- Balham (SW12, SW17, SW4)
- Region
- Greater London
- Cover
- One year on every job
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
What we are called out for in Balham
Many joints fail because they were sealed too deep or with nothing behind them. Sealant bonded to three sides has nowhere to go and rips as the joint opens.
Common reasons people contact us include:
- Panel joints letting water in
- Water getting into walls through failed joints
- Sealant pulling away from one side of the joint
- Old sealant gone brittle and cracked
As a London address, Balham can be tricky for parking: let us know about parking bays, permits or a driveway.
Before you book anyone
- Is VAT in the price?
- Are they insured?
- How long to leave it before use
- How long the guarantee is
Nearby places to Balham
Also in Balham
Keeping the joints in good condition
Aftercare is simple, and it makes a real difference:
- Ask before painting over external sealant
- Avoid pressure-washing directly into sealant joints
- Show decorators and builders where the movement joints are
- Walk round the building once a year and look at the joints
Follow the cure time we give you before the joint is knocked or disturbed. Most exterior sealants skin fast but take longer to cure right through.
An open movement joint lets rain into the wall every time it pours. That can lead to damp patches, staining and frost damage which cost more to put right than the joint.
Your questions about external mastic in Balham
Is parking an issue for external mastic in Balham?
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 Balham station?
Yes, landlords and agents are among the people we work for, and several properties can be quoted together. Just call 0345 464 0079 or send us an email with the address and what needs doing, and we will send you a clear quote.
Is it OK to fill a movement joint with cement?
No, not where the gap is a movement joint. Pointing it stops it working, and the wall may crack nearby. A flexible sealant is the right fill.
Which products do you use?
We choose the sealant for the joint, not the other way round. Movement, water and weather all affect the choice, and we will explain our choice.
What information do you need?
Just the basics: where it is, what you’ve noticed and how we reach it. Then call 0345 464 0079 or send us an email.
Should I try DIY first?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
Where do you work from?
Our base is in Crawley, and we work across South East England, London and Scotland.
Do you guarantee your work?
Yes. All our work carries a one-year guarantee.
Why it’s worth doing now in Balham
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 doesn’t last so it’s worth doing right. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble for homes in Balham.
Some things make a job bigger or smaller: the old material and how easily it comes out, whether mould needs treating, and whether we need extra access for height. Your quote takes all of that into account.
What you get with us
- Any old sealant cut out fully, not covered over
- Approved under the ARBOMaster scheme
- A 12-month guarantee on all work
- Colour picked to suit the job
Read what affects the cost and customer reviews.
Landlord and commercial work in Balham
Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Failed sealant is one of the commonest items on a check-out report, and it’s easy to sort out between tenants. We can quote for more than one property at once.
What the job involves on each surface
Joints between dissimilar materials
Each side of the joint may need its own preparation. We prepare both faces so the sealant bonds properly.
Cladding and façade panels
Cladding and façade panels are normally separated by sealed joints. Each joint gets a sealant that suits the panel and its movement.
How the visit works
On the day, there’s very little for you to do. Show us the job and we will take it from there. The work itself takes a few hours to a few days, depending on the length of joint and the access. In Balham, flats, stairs and shared entrances are part of the routine. Mention any building rules, key holders or managing agents when you book.
- Each joint is checked and the colour of the new sealant agreed.
- We take out the old sealant until the faces are sound.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
How to prepare
- Tell us if parking is tricky
- Let us know about earlier repairs to the joints
- Let us know about stairs, lifts or work at height
Getting a quote
The more we know about the job, the more useful the quote. Let us know the location, the problem and roughly how many joints.
Related advice
What affects the quote in Balham
Every job gets its own quote. These are the things that affect it:
- Access and height
- How many areas need sealing
- The old material and how stubborn it is
- Which sealant suits the joint
Doing several joints on one visit is normally more efficient than separate visits, so it’s worth mentioning everything you’d like done. You’ll get one clear quote for the whole job.
Asking for a quote
To help us quote quickly, please include:
- If it’s domestic, commercial or a hotel
- Where the property is
- How we’d reach the joints
- The rough size of the job
For a quote, call 0345 464 0079 or drop us an email with the location and a short description of the problem. You’ll have a clear quote before any work starts.