Greater London · England
Sand mastic for sash & case windows in Blackheath, Greater London
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homes and businesses in Blackheath and across Greater London. Fully insured, ARBOMaster approved and guaranteed for a year.
- Draughts and rain around sash boxes
- Gaps where the frame meets the masonry
- Mastic worn away on windows facing the weather
What the job involves on each surface
Tenement and terrace windows
Rows of sash windows on tenements and terraces often need renewing together. We work on single windows or whole elevations.
Brick reveals
Sand mastic is also used where timber frames meet brick. It suits older brickwork.
Sand mastic in Blackheath
If your home is listed or in a conservation area, check with your local planning authority whether consent is needed for work to windows. Like-for-like sand mastic is often the preferred finish. We work on brick reveals, stone surrounds and tenement windows, and people most often call us about mastic that needs renewing before redecorating and wind and rain getting in round a sash window.
From mansion-block windows to modern glazing in new flats, London has every kind of frame. Over the years, the sealant around them shrinks, cracks and pulls away, which is when draughts and damp patches appear in homes in Blackheath.
Each job carries a 12-month guarantee, large or small.
- Where
- Blackheath (SE3, SE13, SE10)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
What sand mastic looks like in Blackheath
Historic houses like Queen's House (about 0.9 miles north-west) are a reminder that the area around Blackheath 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 is traditional sand mastic. In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking.
For an older house near a landmark such as Church of All Saints, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall. Schools such as All Saints' Church of England Primary School Blackheath are buildings too, and larger buildings have plenty of frames, and the mastic around each one ages. For landlords with property near Blackheath station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
Blackheath is about 1 mile south-east of Greenwich, in Greater London. Homes, rented property, offices and hotels in Blackheath can book us for sand mastic, old or new, large or small. The work is guaranteed for a year. Blackheath is one of 764 towns and villages in Greater London where we work for sand mastic.
We work across SE3, SE13 and SE10 for sand mastic and the streets around it. That includes homes and businesses on Pond Road, Heath Lane and Wemyss Road. Close by, we work in Vanbrugh Park Estate (1 mile north), Greenwich (1 mile north-west), Maze Hill (1 mile north), Lewisham (1 mile south-west) and Westcombe Park (1 mile north-east). Within a short drive, we also cover London (5 miles north-west), City of Westminster (8 miles north-west), Marylebone (7 miles north-west), Kensington (9 miles west), St Pancras (7 miles north-west) and Shoreditch (5 miles north-west).
Landmarks near Blackheath
In Blackheath, that means homes and buildings near The Princess Of Wales Pub, Blackheath Proprietary School and Manor House Gardens and the streets around them. There’s a railway station in Blackheath itself: Blackheath station. Well-known places in the area include Lewisham Shopping Centre (1.1 miles south-west) and Royal Observatory (0.7 miles north-west). For a walk, there’s Tower Hill and Birdbrook Road Nature Reserve.
Aftercare tips
Good habits help new joints last longer. Our tips:
- Take care around the mastic when scraping paint
- Plan mastic work ahead of painting
- Get any rot dealt with first
- Inspect the joints round the windows every year or so
Make sure water drains away from the window surround. Water sitting against the mastic shortens its life.
Fine cracks show the mastic is starting to fail. It’s easier to renew it before it drops out.
Nearby places to Blackheath
Other services in Blackheath
What happens on the day
All our tools and materials come with us in the van, so you do not need to buy or prepare anything. After a quick look at the joints together, we protect the area and start. Most jobs take a few hours for a single window, longer for several. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Blackheath. A visitor permit or a nearby bay makes the visit run more smoothly.
- We look at the surrounds with you and agree the joints to renew.
- We remove the old, loose mastic.
- Deep gaps are packed so the mastic sits at the right depth.
- We apply the mastic by hand and shape it.
- We dress the finish so it sits neatly against the masonry.
Before we arrive
- Move anything stored near the joints
- Mention any sign-in or site rules at work premises
- Let us know if you’ve seen damp or leaks
Get a quote
Call for a quick quote, or email us if that’s easier. Tell us about the joints that need doing and we’ll talk you through the work before giving you a price.
Advice
Common questions in Blackheath
Can parking be tricky for a visit in Blackheath?
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.
Do you cover Blackheath for sand mastic?
Yes. Our work covers London and the South East, and Blackheath is part of that. Just ring 0345 464 0079 or email us with a few details of the job, and we’ll give you a clear quote.
Is consent needed for window work on a listed home?
Checking first is sensible. Ask your local planning authority whether consent is needed for listed or conservation-area properties.
How long does sand mastic take?
That depends on how much there is to do, but as a guide it takes a few hours for a single window, longer for several. We’ll tell you when we quote.
Can new sealant go over the old?
No, because it fails. The old sealant always comes out first, so the new joint bonds to clean surfaces.
Is it possible to take out silicone and use sand mastic instead?
Often, yes. Once the silicone is out and the joint prepared we point it with sand mastic.
Do you offer different sealant colours?
Generally, yes. White, clear and grey are common, and other colours are available for many products, and we will agree it with you first.
What exactly is sand mastic?
Sand plus a binder based on linseed oil. It’s applied by hand and shaped to suit the surround.
Should I try it myself first?
The biggest DIY mistake is sealing over old sealant. New silicone won’t bond to old, so it peels away and traps moisture behind it. All the old material has to come out first.
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and does not move well, and the joint depth matters as much as the finish.
What sealant work can’t fix
We’ll always be straight with you, so here’s what sealant can’t fix:
- Sash cords, weights and draught-proofing of the sashes
- Putty and glazing repairs
- 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.
Joints and surfaces we work on
- Timber door frames
- Sash and case windows
- Brick reveals
- Tenement windows
- Period & listed homes
- Stone surrounds
Landlords, agents and businesses in Blackheath
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Resealing at the right time is simple maintenance that we can handle for you.
In hotels, rooms out of use cost money, so we plan the work room by room. We have worked in hotels as well as homes and businesses.
Why it’s worth doing now in Blackheath
An open joint round the frame lets weather in. Left, water can reach the timber and the wall so renewing it early protects the window. Damp from a failed joint spreads quietly in older London brickwork and timber, and by the time it shows on a wall or ceiling in Blackheath, the repair is bigger than the sealant job would have been.
There are no prices on our website, because the cost depends so much on the job itself. For a quick quote, please phone 0345 464 0079 or drop us an email and we will talk you through it.
What you get with us
- 12-month guarantee on every job
- Trusted Arbo and Everbuild sealants
- 20+ years of sealant experience
- 4.9 on Google from 180+ five-star reviews