Greater London · England
Sand mastic for sash & case windows in Clapham, Greater London
Window and door surrounds in Clapham need attention? We remove the old material, prepare the joints and seal them properly, and the work is guaranteed for a year.
- Mastic round period door frames that has failed
- Open joints round the window box
- Crumbling sand mastic round a window
Keeping the joints in good condition
So the new joints stay in good condition:
- Look over the window mastic once a year
- Leave the new mastic unpainted
- Avoid heavy scraping on the mastic joint
- Ask the planning authority about consent for listed or conservation-area homes
Make sure water drains away from the window surround. Water sitting against the mastic shortens its life.
Good mastic helps keep the frame dry. Once it fails, water can sit against the timber and timber that stays wet can rot.
Sand mastic for homes and businesses in Clapham
We work across Clapham renewing sand mastic on sash windows and doors. Every joint is cleaned out and filled by hand, finished to suit the masonry. Typical jobs include gaps where the frame meets the masonry and wind and rain getting in round a sash window, on tenement windows, period & listed homes and sash and case windows.
London has a lot of flats and conversions, where windows are often on upper floors. Who looks after the outside of the frames can depend on the lease, so check that first, and access in Clapham is something to talk through when you book.
Every job comes with our 12-month guarantee, wherever you are in Greater London.
- Place
- Clapham (SW4, SW8, SW9)
- Wider area
- Greater London
- Guarantee
- One year on every job
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Honest limits
It helps to know what we cannot do too:
- Putty and glazing repairs
- Timber that has rotted
- Decisions on consent for listed homes
If you’re not sure, just ring 0345 464 0079 or drop us an email and we’ll give you a straight answer before booking.
Surfaces we seal
- Timber door frames
- Tenement windows
- Period & listed homes
- Sash and case windows
- Brick reveals
- Stone surrounds
Leave it or put it right?
Silicone might seem the quicker option, but on period stone or brick it often looks out of place. Sand mastic is the traditional material and blends with the stone or brick. In London conversions, one flat’s bathroom is often above another flat’s ceiling, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Dealing with it early is far simpler.
Every job is a little different, so we quote each one individually. Size, access and the product the joint needs all make a difference.
Why us?
- Over 20 years’ experience
- Trusted Arbo and Everbuild sealants
- ARBOMaster approved applicator
- Anti-fungal sanitary silicone in wet areas
See what affects the cost and our reviews.
Places near Clapham
Other services in Clapham
Surface by surface
Stone surrounds
Stone openings are rarely perfectly straight, so the joint varies in width. Sand mastic is shaped by hand to suit.
Timber door frames
A neat sand mastic joint round a front door suits a period home.
Landlord and commercial work in Clapham
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Housing providers, facilities teams and property managers book us too in Clapham and across Greater London. Several sites can go on one quote.
Should I try it myself first?
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
If you’re set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it fails, we can still redo it.
Clapham questions
Do you work for landlords with property near Clapham High Street station?
Yes. We work for letting agents and landlords as well as householders. You can ring 0345 464 0079 or send us an email with the details for a clear quote.
Do you cover Clapham for sand mastic?
Yes, Clapham is within the area we cover. We work across London and the South East. Just phone 0345 464 0079 or drop us an email with a few details of the job, and we’ll give you a clear quote.
Can I paint the new mastic?
It’s traditionally left unpainted, which is what traditional guidance recommends. Ask us before decorating.
When will the new mastic be hard?
Not straight away. It skins first and hardens fully later, and we will tell you what to expect.
Is the work guaranteed?
All our work has a 12-month guarantee.
Is there any odour?
Possibly a little. Any smell clears as the sealant cures.
How do I get a quote for sand mastic in Clapham?
There’s no set price, as it depends on the job: how much there is, what’s there now, how we reach it and what it needs. You’ll get a clear quote before we start.
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.
How it works
We bring everything the job needs with us, so there’s nothing for you to buy. After a quick look at the joints together, we protect the area and start. It normally takes a few hours for a single window, longer for several. For a job in Clapham, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- Each surround is checked first.
- We rake out the old mastic and clean the joint.
- We fill deep gaps so the new mastic isn’t too thick.
- We point the joint with sand mastic by hand.
- We finish the mastic to a tidy line.
Getting ready for the visit
- Plan for the work area to be out of bounds to pets and children
- Mention any parking rules near the property
- Try not to wet indoor joints just before the visit
Get a quote
Want a quote for sand mastic? Please call 0345 464 0079 or email us and tell us about the job. We will explain what we’d do and give you a clear quote before we start.
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Frames and glazing around Clapham
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. In London conversions and blocks, the lease decides who is responsible for the frames, so check that before you book.
For an older house near a landmark such as St Paul's Church, the joint between an old wall and a newer frame is normally the first place rain gets in. If you let a flat or house near Clapham High Street station, older sash windows in a rental need their mastic kept sound to keep the weather out. For site and facilities teams at buildings such as Clapham Manor Primary School, its window and door frames need their mastic kept sound, just like a home’s.
Clapham is about 3 miles north of Streatham, in Greater London. Anywhere in SW4, we cover sand mastic for homes and businesses. We cover 764 towns and villages across Greater London, large and small.
Jobs for sand mastic in SW4, SW8 and SW9 works the same way as everywhere else we cover. Sand mastic is available to properties on Grafton Square, Clapham High Street and Houghton Square. With the B224 and B303 close by, Clapham is simple for us to get to. Close by, we work in Stockwell (1 mile east), Little Portugal (1 mile north-east), Clapham Park (1 mile south), South Lambeth (1 mile north-east) and Brixton (1 mile south-east). Within a short drive, we also cover London (3 miles north-east), City of Westminster (3 miles north), Marylebone (4 miles north), Kensington (4 miles north-west), St Pancras (4 miles north) and Shoreditch (5 miles north-east).
Landmarks near Clapham
Around Clapham, our work takes us to homes and buildings near Lambeth Academy, Larkhall Park and Trinity Academy. Clapham has its own railway station: Clapham High Street station. Well-known places in the area include Baynard's Castle (3.5 miles north-east) and Harrods (2.6 miles north-west). Green spaces nearby include Battersea Park Lake and Knight's Hill.