Greater London · England
Keston Sand Mastic
Sand mastic in Keston from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Draughts and rain around sash boxes
- Mastic dropping out of the joint
- Silicone on a period window that looks wrong
How the visit works
The work is kept neat and contained to the area we’re working on, so you can get on with your day. Expect the work to take a few hours per window, depending on the condition of the joints, and we tell you how long to leave it before we go. For a job in Keston, 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.
- We check the window surrounds and agree which joints need renewing.
- The loose and crumbling mastic is raked out and the joint cleaned.
- Deep voids are packed so the mastic is the right thickness.
- We mix the sand mastic and apply it by hand, shaping it to the joint.
- The finish is dressed so it sits neatly against the stone or brick.
Before we arrive
- Mention any parking rules near the property
- Tell us about access, such as stairs, a lift or high-level joints
- Tell us about any water getting in
Ask for a quote
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is, and we’ll explain how we’d tackle it. When it suits you, ring 0345 464 0079 or drop us an email.
Advice
Sand mastic in Keston, done properly
Sand mastic suits most period window surrounds. Newer frames normally get a flexible sealant instead, and we will talk through which suits your home. Typical jobs include a silicone bead on a sash window that spoils the look and mastic round period door frames that has failed, across timber door frames, brick reveals and period & listed homes.
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 Keston is something to talk through when you book.
Big or small, it’s backed by our one-year guarantee.
- Location
- Keston (BR2)
- Region
- Greater London
- Cover
- A year, on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
What we’re called out for in Keston
Most of it is simply age. Even well-laid mastic needs renewing in time and how long it lasts depends on the weather it faces.
These are the problems we’re asked about most:
- Gaps round a timber door in stone or brick
- Failed mastic on an exposed elevation
- Draughts and rain around sash boxes
- Window mastic to renew ahead of painting
Homes close to Keston Parish Church include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Comparing quotes
- Whether you can choose the colour
- How hidden problems are handled
- When the joint can take water or movement
- Whether they seal over old material or remove it
Also in Keston
What the job involves on each surface
Stone surrounds
Old stone surrounds are often uneven, so the gap isn’t the same all the way round. Sand mastic is shaped by hand to suit.
Tenement and terrace windows
In shared buildings, the windows may be part of a wider repair so it’s worth checking responsibilities.
Your questions about sand mastic in Keston
I let a flat near Hayes (Kent) station. Can you help?
Yes, we work for landlords and letting agents. Just call 0345 464 0079 or send us an email and tell us about the property, and we will give you a clear quote.
Is parking a problem for a job in Keston?
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 you do several jobs on one visit?
Yes. More than one area can go on one quote.
Is it worth trying it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. Most DIY failures come from sealing over old material, wet joints or too much sealant.
What exactly is sand mastic?
It’s a mix of sand and a linseed-oil-based binder. It’s applied by hand and shaped to suit the surround.
Can new sealant go over the old?
No, it will not last. It may look fine at first, but the new layer lifts away from the old one. Removing the old sealant completely is the only lasting way.
Is it possible to paint over sand mastic?
Sand mastic is normally left unpainted, as guidance on traditional windows advises. Ask us before decorating.
Which is right for my windows, sand mastic or modern sealant?
We will help you decide. Period homes often look best with sand mastic and newer frames suit modern sealant.
How we quote for sand mastic
For a quick quote, just ask. What matters most is:
- When we can work, for business premises
- Whether old sealant or filler has to be cut out
- Any mould that needs treating
- Whether the work is at height
A few things move the cost up or down: how much old sealant there is and how stubborn it is, whether mould needs treating, and whether we need extra access for height. We take all of that into account in your quote.
Helping us quote
The more you tell us, the more accurate the quote. When you get in contact, it helps to mention:
- Whether it has been sealed before
- How many joints, rooms or windows are involved
- How we’d reach the joints
- The type of property
To get a quote, call 0345 464 0079 or send us an email and tell us where the job is and what the problem looks like. You’ll have a clear quote before work begins.
Landlord and commercial work in Keston
Whether it’s one flat or a portfolio, you get the same standard of work: the old material taken out, careful preparation and a 12-month guarantee.
We also work for businesses, from offices to washrooms and kitchens. On commercial sites, working times can be discussed when we quote.
Looking after it afterwards
How long the joints last depends on use and care. Here’s what we suggest:
- Get any rot dealt with first
- Check the mastic when you check the paintwork
- Keep modern sealant off the mastic
- Sort the mastic before the decorators arrive
Leave the new mastic alone while it firms up. It forms a skin fairly soon, but takes longer to harden fully.
An open joint round the box lets weather through. The longer it’s left, the more the joint opens as more mastic falls out.
Sand mastic in Keston: local notes
In a converted house or block, who looks after the windows depends on the lease, so it’s worth checking before booking. Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
For site and facilities teams at buildings such as Keston Church of England Primary School, its window and door frames need their mastic kept sound, just like a home’s. If you let a flat or house near Hayes (Kent) station, any sash windows need sound mastic to keep draughts and rain out.
Keston is about 3 miles south of Bromley, in Greater London. Anywhere in BR2, we cover sand mastic for homes and businesses. Keston is one of 764 places in Greater London where we work for sand mastic. There’s also a page for London, roughly 11 miles from Keston.
Here we cover the BR2 postcode area for sand mastic. Sand mastic is available to properties on Church Road, Greys Park Close and Heathfield Road. Nearby, we also carry out sand mastic in Nash (1 mile west), Farthing Street (1 mile south-east), Locksbottom (1 mile north-east), Leaves Green (2 miles south) and Hayes (2 miles north-west). We also work in nearby towns such as London (11 miles north-west), City of Westminster (13 miles north-west), Marylebone (13 miles north-west), Kensington (14 miles north-west), St Pancras (13 miles north-west) and Shoreditch (12 miles north).
Landmarks near Keston
Typical jobs here are in homes near South Park, Ravens Wood School and The Greyhound pub and the streets around them. The closest station to Keston is Hayes (Kent) station, about 1.5 miles north-west. Well-known places in the area include Princess Royal University Hospital (1.1 miles east) and Bethlem Museum of the Mind (1.5 miles north). Open spaces near Keston include West Kent Golf Course nature reserve and Summer Hill.
What sealant work cannot fix
Some problems need a builder, plumber or other trade rather than us:
- Masonry that needs repairing
- Rotten sashes, sills or window boxes (a joiner’s job)
- Planning or listed building consent (your local planning authority decides)
If in doubt, phone 0345 464 0079 or email us and we will say what we think.
Surfaces we seal
- Period & listed homes
- Timber door frames
- Stone surrounds
- Tenement windows
- Brick reveals
- Sash and case windows