Greater London · England
Sand mastic for sash & case windows in Clapham Junction, Greater London
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for householders, landlords and businesses in Clapham Junction. Fully insured, ARBOMaster approved and guaranteed for a year.
- Cement or filler used on old window joints that has cracked
- Old sand mastic that has cracked, crumbled or fallen out
- Wind and rain getting in round a sash window
What happens if it’s left?
Cement-based fillers and modern sealants do not always suit a period surround. Sand mastic is the like-for-like choice and that can be important for listed homes. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in Clapham Junction, the repair is bigger than a sealant job.
The cost depends on the amount of work, how much old material has to come out and how easy the joints are to reach. You’ll have a clear quote before any work starts.
Why choose Mr Mastic in Clapham Junction
- Domestic, commercial and hotel work
- Quality sealants from Arbo and Everbuild
- We are fully insured
- We leave the area clean and tidy
Read how sealant jobs are priced or our reviews.
Sand mastic in Clapham Junction
A silicone bead around a sash window can look out of place and isn’t always the right material. Sand mastic gives a finish that matches the age of the house and we can swap the silicone for it. If you have weathered mastic on the most exposed windows and old cement repairs round a window that have failed, we can put it right, whatever the surface.
Many London homes are flats, with windows high above the street. Who looks after the outside of the frames can depend on the lease, so check that first, and access in Clapham Junction is something to talk through when you book.
There’s a 12-month guarantee on every job, whatever its size.
- Place
- Clapham Junction (SW11, SW18, SW4)
- Wider area
- Greater London
- Cover
- A year, on every job
- Quote
- A clear quote up front
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
What happens on the day
You don’t need to clear the whole room or building, only the area right around the joints. We protect the rest, and the job takes a few hours per window, depending on the condition of the joints in most cases. For a job in Clapham Junction, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- First we agree which joints need doing.
- We remove the old, loose mastic.
- We pack any deep voids first.
- We apply the mastic by hand and shape it.
- The surface is finished to suit the stone or brick.
Getting ready for the visit
- For business premises, tell us about site rules or sign-in
- Keep pets and children clear of the area while we work
- Tell us about any previous sealing or DIY attempts
Ask for a quote
We do not publish a price list. Instead, your job gets its own clear quote. To get started, ring 0345 464 0079 or drop us an email.
Read more
Honest limits
To be straight with you, some problems need a different trade:
- Broken panes
- Sashes that rattle, stick or won’t open
- Masonry that needs repairing
If in doubt, ring 0345 464 0079 or email us and we will say what we think.
Surfaces we seal
- Sash and case windows
- Timber door frames
- Stone surrounds
- Tenement windows
- Brick reveals
- Period & listed homes
How the job changes by surface
Tenement and terrace windows
In shared buildings, the windows may be part of a wider repair so it’s worth checking responsibilities.
Timber door frames
A neat sand mastic joint round a front door suits a period home.
What sand mastic looks like in Clapham Junction
In London conversions and blocks, the lease decides who is responsible for the frames, so check that before you book. The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
For landlords with property near Clapham Junction station, older sash windows in a rental need their mastic kept sound to keep the weather out. If you look after a building such as Christ Church CofE Primary School, the mastic around its windows and doors needs looking after like any other building’s.
Clapham Junction is about 3 miles south-east of Kensington, in Greater London. Whether you are in the middle of Clapham Junction or further out, we cover sand mastic for every kind of property, from flats and houses to offices and hotels. Across Greater London, we cover 764 places, Clapham Junction among them.
Every address in SW11, SW18 and SW4 is within our area for sand mastic. We cover properties on York Road, Este Road and Home Road. Being close to the A3207, Clapham Junction is simple for us to get to for sand mastic. If you’re just outside Clapham Junction, we cover Battersea (1 mile south-east), Sands End (1 mile north-west), Chelsea Harbour (1 mile north-west), Wandsworth (1 mile south-west) and Clapham (1 mile east). Further out, we also cover London (4 miles north-east), City of Westminster (4 miles north), Marylebone (4 miles north), Kensington (3 miles north-west), St Pancras (5 miles north-east) and Shoreditch (6 miles north-east).
Around Clapham Junction
Locally, jobs take us to homes and businesses close to Imperial Park, The Falcon pub and Thames Christian College and the streets around them. There’s a railway station in Clapham Junction itself: Clapham Junction station. Nearby you’ll also find Baynard's Castle (4.4 miles north-east) and Battersea General Hospital (0.8 miles north). Open spaces near Clapham Junction include Battersea Park Lake and Wandle Meadow Nature Park.
Do you need sand mastic in Clapham Junction?
Rain on the window surround works into any crack and pushes it out. Windows facing the weather tend to go first.
It’s worth asking for a quote if you see:
- Cement or filler used on old window joints that has cracked
- Window mastic to renew ahead of painting
- Gaps between timber frames and stone or brick
- A silicone bead on a sash window that spoils the look
If you live in an older home near Clapham Welsh Presbyterian Church, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Comparing quotes
- Which sealant they’ll use, and why
- The length of the guarantee
- When the joint can take water or movement
- Is VAT in the price?
What affects the cost of sand mastic
Every job gets its own quote. This is what makes a difference:
- The number and length of the joints
- Working hours on commercial sites
- How many areas need sealing
- Whether the work is at height
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.
Asking for a quote
You don’t need to know the technical terms. It helps if you can tell us:
- If it’s domestic, commercial or a hotel
- A few photos by email, if you can
- If someone has resealed it before
- What the problem is, such as mould, gaps, leaks or cracking
Getting a quote is simple: let us know what needs doing and where, and roughly how big it is. Photos by email help us understand the job, and we will come back to you with a quote.
Landlords, agents and businesses in Clapham Junction
Landlords and agents in Clapham Junction can book us as well as householders. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance.
Clapham Junction: your questions answered
Do you work for landlords with property near Clapham Junction station?
Yes, rental work is part of what we do. You can ring 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.
Is parking an issue for sand mastic in Clapham Junction?
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.
Can new sealant go over the old?
No. New silicone will not bond to old silicone, and anything trapped underneath, including mould and water, stays there. We remove it all first.
Can sand mastic be painted?
Traditional guidance is not to paint over sand mastic. If you’re redecorating the window, ask us first and we’ll advise.
Do you guarantee sand mastic work?
Our 12-month guarantee applies on every job.
Can you work on commercial sites?
Yes. We’ve worked for hotels, offices and other businesses and we are fully insured.
Do I need permission for sand mastic on a listed building?
It’s best to ask your local planning authority first. Sand mastic is often favoured as like for like, but they decide.
Will there be a smell?
It depends on the product. Some smell for a while, some hardly at all, and any smell fades as they cure.