West Sussex · England
Sand mastic for sash & case windows in Clapham, West Sussex
Window and door surrounds in Clapham need attention? We cut out the old, prepare the joints and apply the right sealant, with a one-year guarantee.
- Mastic worn away on windows facing the weather
- Silicone on a period window that looks wrong
- Old cement repairs round a window that have failed
How we handle sand mastic in Clapham
For a listed home or one in a conservation area, ask your local planning authority if consent is needed before window work. Like-for-like sand mastic is often the preferred finish. If you have tired mastic found when preparing windows for paint and mastic worn away on windows facing the weather, we can put it right, whatever the surface.
Homes in small places like Clapham often stand in the open, with little to shelter their windows from wind and rain. Exposed frames and sills lose their mastic sooner than sheltered ones.
Your job is guaranteed for a year, as with all our work.
- Place
- Clapham (BN13)
- Region
- West Sussex
- Cover
- 12 months on all our work
- Quote
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Work for landlords, hotels and businesses
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance that we can handle for you.
For anyone letting property in or around Clapham, several properties can go on one quote. Send us the addresses and the work at each.
More services for Clapham
Clapham questions
Do you cover smaller places like Clapham?
Yes. Clapham is within the area we cover, which takes in towns, villages and rural addresses. We work across London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
I let a flat near Goring-By-Sea station. Can you help?
Yes, landlords and agents are among the people we work for, and several properties can go on one quote. Just ring 0345 464 0079 or drop us an email with the address and what needs doing, and we’ll send you a clear quote.
Do you hold any approvals?
Yes. Mr Mastic is an ARBOMaster approved applicator and we’re fully insured too.
Can I add another job to the visit?
Yes, and it often makes sense. Doing several areas at once is usually more efficient.
Where is Mr Mastic based?
Our base is in Crawley, West Sussex, and we cover South East England, London and all of Scotland.
Is it OK to seal over old sealant?
No. Fresh sealant does not stick to old sealant, and it traps any mould or water underneath. It all has to come out first.
Do you do commercial work?
Yes. Commercial and hotel work is a large part of what we do. We can talk about working times when we quote.
What exactly is sand mastic?
It’s sand mixed with a linseed-oil-based binder for the joint between timber frames and masonry.
Common problems we fix in Clapham
Some old mastic was never deep enough. A thin layer does not hold well, which is why we pack deep voids first and get the depth right.
The problems people generally mention when they call are:
- Mastic dropping out of the joint
- Mastic that needs renewing before redecorating
- Gaps where the frame meets the masonry
- A silicone bead on a sash window that spoils the look
Letting a property close to Goring-By-Sea station? Then any sash windows need sound mastic to keep draughts and rain out.
What to look for in a quote
- Whether you can choose the colour
- Is the old sealant removed completely?
- What the quote includes, VAT included or not
- How the surfaces are prepared before sealing
What we do, step by step
You don’t need to clear the whole room or building before we come, only the area right around the joints. We protect the rest, and the job takes a few hours for a single window, longer for several in most cases. Somewhere like Clapham needs a little journey planning: tell us about narrow lanes, gates, long drives and where we can park. Everything for the job comes with us, so a second trip is avoided where possible.
- Each surround is checked first.
- The joint is raked out and cleaned.
- Large voids are packed out.
- New sand mastic is applied and shaped by hand.
- We finish the mastic to a tidy line.
How to prepare
- Try not to wet indoor joints just before the visit
- Let us know about earlier repairs to the joints
- Tell us about access, such as stairs, a lift or high-level joints
Get a quote
For a quick quote, get us on the phone, or email us if that’s easier. Tell us about the joints that need doing and we will explain what’s involved.
Read more
What sand mastic looks like in Clapham
Historic houses like Ecclesden Manor (about 1.5 miles south-west) are a reminder that the area around Clapham has older buildings as well as new. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic. Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
For site and facilities teams at buildings such as Clapham and Patching CofE Primary School, larger buildings have plenty of frames, and the mastic around each one ages. In the older streets around The Parish Church of St Mary, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Clapham is about 3 miles north-west of Worthing, in West Sussex. For sand mastic in and around Clapham, it’s easy to get a quote: please ring 0345 464 0079 or drop us an email. We cover West Sussex from our Crawley base. Clapham is one of 371 places in West Sussex where we work. Our Brighton page covers work nearby (14 miles or so).
Work in BN13 works the same way as everywhere else we cover. Whether your property is on The Street, Long Furlong and Church Close or a nearby road, our applicators can take on the job. Clapham is on the A280, which makes it straightforward to reach with everything needed for sand mastic. Other places close to Clapham include Patching (1 mile north-west), Cote (1 mile east), Hammerpot (2 miles west), Durrington (2 miles south-east) and Hangleton (2 miles south). Further out, we also cover Worthing (3 miles south-east), Bognor Regis (11 miles west), Chichester (14 miles west), Littlehampton (4 miles south-west), Shoreham-by-Sea (8 miles east) and Lancing (6 miles east).
Near you in Clapham
Locally, jobs take us to homes and businesses close to Clapham Wood, The Fox pub and Chatsmore Catholic High School, among other places. The closest station to Clapham is Goring-By-Sea station, roughly 2.1 miles south. A little further out are Museum of Sussex Folklore (2.9 miles south-east) and Old Castle (2.9 miles south-east). The countryside around Clapham includes WWT Arundel and Highdown Hill.
What we cannot put right
We’d rather tell you now than do work that won’t last, so these are the limits:
- Rotten sashes, sills or window boxes (a joiner’s job)
- Broken panes
- Whether work needs listed building consent
Not sure which it is? You can ring 0345 464 0079 or email us and we’ll tell you honestly before booking.
Surfaces we seal
- Tenement windows
- Timber door frames
- Brick reveals
- Period & listed homes
- Sash and case windows
- Stone surrounds
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions.
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it fails, we can still redo it.
Aftercare tips
How long the joints last depends on use and care. We suggest:
- Sort the mastic before the decorators arrive
- Keep sills and gutters clear so water drains away
- Leave the new mastic unpainted
- Keep modern sealant off the mastic
Don’t run silicone over the new mastic. If you see a crack, ask us to take a look before trying a quick fix.
Good mastic helps keep the frame dry. Once it fails, water can sit against the timber and timber that stays wet can rot.
Why deal with it now?
Cement-based fillers and modern sealants don’t always suit a period surround. Sand mastic matches what was there and that can be important for listed homes. Where a wall is exposed, as many are in small places like Clapham, wind-driven rain gets into any failed joint, and older walls, once damp, take a long time to dry.
What it costs depends on how much there is to do, how hard the old material is to remove and how easy the joints are to reach. You will have a clear quote before any work starts.
What you get with us
- Neat joints and a tidy finish
- Domestic, commercial and hotel work
- Rated 4.9 stars on Google
- Trusted Arbo and Everbuild sealants
Read what affects the cost or what customers say.