Greater London · England
Eltham Sand Mastic
Sand mastic across Eltham and nearby, with every bit of old sealant taken out first.
- Tired mastic found when preparing windows for paint
- Mastic worn away on windows facing the weather
- Open joints round the window box
About our sand mastic in Eltham
Burnt sand mastic is a traditional material blends with stone and brick surrounds. It’s a good fit for period properties, where modern sealant can look out of place. We’re often asked to deal with mastic worn away on windows facing the weather and old sand mastic that has cracked, crumbled or fallen out, across stone surrounds, period & listed homes and sash and case windows.
London’s Victorian and Edwardian terraces were built with timber sash windows, and many still have them or their replacements. Whatever is in the opening now, the joint between frame and wall is what keeps the weather out.
All of our work is guaranteed for twelve months, and the guarantee is the same wherever you are.
- Place
- Eltham (SE9, SE12, DA15, BR7)
- Wider area
- Greater London
- Cover
- One year on every job
- Price
- A clear quote up front
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Keeping the joints in good condition
How long the joints last depends on use and care. We suggest:
- Clear gutters so water doesn’t pour onto the windows
- Inspect the joints round the windows every year or so
- Have rotten timber repaired before new mastic goes in
- Don’t run silicone over sand mastic
Leave the new mastic unpainted, which is the traditional advice. If you are redecorating, ask us first.
Good mastic helps keep the frame dry. Once it fails, water can sit against the timber and timber that stays wet can rot.
Signs you need sand mastic in Eltham
Timber frames move with the seasons. The movement cracks the mastic little by little.
Look out for these signs:
- Old sand mastic that has cracked, crumbled or fallen out
- Patchy fillers round a sash window
- Gaps where the frame meets the masonry
- Weathered mastic on the most exposed windows
If you look after a building such as St Thomas More Catholic Comprehensive School, larger buildings have plenty of frames, and the mastic around each one ages.
What your quote should include
- What guarantee comes with the work
- Which sealant they’ll use, and why
- How the colour is chosen
- Who does the work, and how experienced they are
What affects the cost of sand mastic
You’ll get a clear quote before any work starts. It takes into account:
- The number of rooms or windows
- Whether there’s mould to deal with
- Which sealant suits the joint
- Access and height
There are no prices on our website, because the cost depends so much on the job itself. For a quick quote, please call 0345 464 0079 or email us.
What to tell us for a quote
When you contact us, it’s useful to know:
- The problem you’ve noticed
- The address or postcode of the job
- A few photos by email, if you can
- Any previous sealing or DIY work
Want a quote for sand mastic? Please call 0345 464 0079 or send us an email and tell us about the job. You’ll know what we plan to do, and what it will cost, before any work begins.
Should I try it myself first?
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
What we cannot put right
Before booking, it’s worth knowing the limits too:
- Masonry that needs repairing
- Planning or listed building consent (your local planning authority decides)
- Putty and glazing repairs
If you’re not sure, just call 0345 464 0079 or email us and we will give you a straight answer.
Where we work in Eltham
- Period & listed homes
- Timber door frames
- Stone surrounds
- Tenement windows
- Brick reveals
- Sash and case windows
Sand mastic in Eltham: local notes
Historic houses like Eltham Palace (about 0.4 miles north-west) are a reminder that the area around Eltham has older buildings as well as new. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic. In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking.
If you let a flat or house near Mottingham station, any sash windows need sound mastic to keep draughts and rain out. For an older house near a landmark such as Church of Holy Trinity, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Eltham is about 7 miles west of Dartford, in Greater London. Jobs in Eltham get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. Across Greater London, we cover 764 places, and Eltham is one of them. London is on our list too, about 8 miles from Eltham.
Work in SE9, SE12, DA15 and BR7 is quoted and booked the same way as anywhere else. Whether your property is on Eltham High Street, Tarnwood Park and Elmslie Court or anywhere close by, our applicators can take on the job. With the A20 and B263 close by, Eltham is easy for our applicators to reach for sand mastic. We also cover the places around Eltham: Middle Park (1 mile west), New Eltham (1 mile south-east), Well Hall (1 mile north), Coldharbour (1 mile south) and Avery Hill (1 mile north-east). Within a short drive, we also cover London (8 miles north-west), City of Westminster (10 miles north-west), Marylebone (10 miles north-west), Kensington (12 miles west), St Pancras (9 miles north-west) and Shoreditch (8 miles north-west).
Around Eltham
In Eltham, that means homes and buildings near Horn Park, Eltham Church of England Primary School and The Greyhound Public House and the streets around them. Eltham has its own railway station: Mottingham station. Nearby you’ll also find Eltham Community Hospital (within half a mile north) and Metropolitan Police Museum (2.1 miles east). The countryside around Eltham includes The Tarn and Summer Hill.
Eltham: your questions answered
Do you work for landlords with property near Mottingham station?
Yes, landlords and agents are among the people we work for. Just call 0345 464 0079 or drop us an email with the address and what needs doing, and we’ll give you a clear quote.
Is parking an issue for sand mastic in Eltham?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. That way the visit can be planned around it.
How long does sand mastic take to go off?
The surface skins quite quickly, then hardens over a longer period. Timing depends on the weather and the joint.
Which products do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. We use products from Arbo and Everbuild.
Can new sealant go over the old?
No. Fresh sealant does not stick to old sealant, and it traps any mould or water underneath. We remove it all first.
How much does sand mastic cost in Eltham?
Every job is different, so each one gets its own quote. For a quick quote, call 0345 464 0079 or email us with a short description of the job.
How long does sand mastic take?
It depends on the size of the job, but as a guide it takes a few hours for a single window, longer for several. We will give you a better idea when we quote.
Is it possible to take out silicone and use sand mastic instead?
Usually, yes. Once the silicone is out and the joint prepared, sand mastic is applied by hand.
Other services in Eltham
Why deal with it now?
Silicone might seem the quicker option, but on period stone or brick it often looks out of place. Sand mastic suits the building and blends with the stone or brick. 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.
The cost reflects the work involved, not guesswork. That’s why we ask about the job first.
Why book with us
- Tidy, careful work
- Full insurance on every job
- Rated 4.9 stars on Google
- We never seal over old sealant
Read our cost guide or what customers say.
How the visit works
Once we are on site, we check the joints match what you told us. If we find something unexpected, we talk it through with you first. After that, the work takes a few hours for a single window, longer for several. In a London area like Eltham, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- We check each window surround and the condition of the joint.
- The joint is raked out and cleaned.
- Large voids are packed out.
- New sand mastic is applied and shaped by hand.
- The finish is dressed neatly.
How to prepare
- Keep children and pets away from the work area
- Tell us about any water getting in
- Move anything stored near the joints
Ask for a quote
To get a quote, phone 0345 464 0079 or send us an email with the location and a short description of the problem. You will have a clear quote before work begins.