Greater London · England
Sand mastic for sash & case windows in St Mary Cray, Greater London
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homes and businesses in St Mary Cray and across Greater London. Fully insured, ARBOMaster approved and guaranteed for a year.
- Cracked mastic round a front door frame
- Crumbling sand mastic round a window
- Old cement repairs round a window that have failed
St Mary Cray questions
Is parking an issue for sand mastic in St Mary Cray?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. That way the visit can be planned around it.
Can you do sand mastic in St Mary Cray?
Yes. We work across London and the South East, and St Mary Cray is part of that. Just call 0345 464 0079 or drop us an email with a few details of the job, and we’ll send you a clear quote.
Do you work for letting agents?
Yes. We work for homeowners, landlords, letting agents, businesses and hotels.
Is it worth trying it myself?
It depends on the job. Work at height, movement joints, fire-rated gaps and large areas are best left to a professional.
Can I paint the new mastic?
The usual advice is to leave sand mastic unpainted. Ask us before you decorate around it and we will talk you through it.
Are you fully insured?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
Do I need to be at home?
For indoor joints, yes, someone needs to let us in. Once we have agreed the job, you don’t need to watch us work.
Is it possible to take out silicone and use sand mastic instead?
Yes. We remove the silicone and clean the joint before the sand mastic goes in.
How we handle sand mastic in St Mary Cray
Across St Mary Cray, we renew sand mastic around sash and case windows. Every joint is cleaned out and filled by hand, finished to suit the masonry. Common call-outs are for window mastic to renew ahead of painting and old sand mastic that has cracked, crumbled or fallen out, on stone surrounds, tenement windows and period & listed homes.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. The mastic around them dries out and cracks with age, which is when draughts and damp patches appear in homes in St Mary Cray.
Each job carries a 12-month guarantee, large or small.
- Location
- St Mary Cray (BR5, BR6, BR7)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
The process
Before we leave, we go over the finished joints with you and explain the cure time. The visit itself normally takes a few hours for a single window, longer for several, depending on how much there is to do. In St Mary Cray, flats, stairs and shared entrances are part of the routine. If the building has a concierge, managing agent or access rules, tell us when you book.
- We look at the surrounds with you and agree the joints to renew.
- We remove the old, loose mastic.
- We pack any deep voids first.
- The sand mastic is mixed and pressed into the joint by hand.
- We dress the finish so it sits neatly against the masonry.
Before we arrive
- Tell us about any previous sealing or DIY attempts
- Where the joints are inside, avoid wetting them before we arrive
- Move anything stored near the joints
Ask for a quote
We quote each job on its own, so the first step is telling us about yours. Simply call 0345 464 0079 or send us an email and describe the job and send pictures if you have them.
Advice
Looking after it afterwards
No joint lasts for ever, but care makes a real difference. A few tips:
- Don’t run silicone over sand mastic
- Check with your local planning authority if your home is listed
- Renew mastic before redecorating the windows
- Clear gutters so water does not pour onto the windows
Avoid sealing over the mastic with silicone. If you see a crack, ask us to take a look before trying a quick fix.
Fine cracks show the mastic is starting to fail. It’s easier to renew it before it drops out.
Leave it or put it right?
Replacing sash windows is a big decision for a period home, and in listed buildings it may need consent. If the frames are sound, renewing the mastic deals with gaps and draughts at the surround. In a flat in St Mary Cray, failed sealant seldom stays inside your own four walls: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
Combining jobs into one visit generally makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. You will get one clear quote for the whole job.
Why us?
- We are fully insured
- Every job guaranteed for a year
- 180+ five-star Google reviews
- Neat joints and a tidy finish
Read what affects the cost or our reviews.
When something else is needed
We won’t take on work that will not last, so here’s what sealant cannot put right:
- Rotten sashes, sills or window boxes (a joiner’s job)
- Masonry that needs repairing
- Cracked or broken glass
If in doubt, phone 0345 464 0079 or send us an email and we will say what we think before booking.
Surfaces we seal
- Period & listed homes
- Tenement windows
- Brick reveals
- Stone surrounds
- Sash and case windows
- Timber door frames
Towns and villages near St Mary Cray
What else we do in St Mary Cray
Should I try it myself first?
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
Surface by surface
Timber door frames
Period doors in stone or brick openings are often pointed with sand mastic. We renew it the same way as on windows.
Brick reveals
Gaps between frame and brick let in rain and draughts. New mastic seals the gap.
When to call us in St Mary Cray
Over the years, sand mastic weathers. It hardens, cracks and starts to come away from the frame or the masonry.
People normally contact us after spotting something like this:
- Window mastic to renew ahead of painting
- Draughts and rain around sash boxes
- Gaps round a timber door in stone or brick
- Weathered mastic on the most exposed windows
For an older house near a landmark such as Church of St Mary, the joint between an old wall and a newer frame is generally the first place rain gets in.
What your quote should include
- Whether they seal over old material or remove it
- What guarantee comes with the work
- Who turns up on the day
- Whether VAT is included
St Mary Cray homes and the weather
With historic houses such as Bromley Palace (about 3.8 miles west) nearby, there’s older building stock in the area around St Mary Cray as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
If you look after a building such as Poverest 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 St Mary Cray station, any sash windows need sound mastic to keep draughts and rain out.
St Mary Cray is about 11 miles south-east of London, in Greater London. Every kind of property in St Mary Cray is covered for sand mastic. Every job comes with our 12-month guarantee. We cover 764 towns and villages across Greater London. There’s also a page for London, about 11 miles away.
We work across the BR5, BR6 and BR7 postcode area for sand mastic. Local streets include New Road, Kent Road and Park Road. Being close to the A224, St Mary Cray is easy for our applicators to reach. Neighbouring places we cover for sand mastic include Poverest (1 mile south-west), St Paul's Cray (1 mile north), Orpington (1 mile south), Derry Downs (1 mile south-east) and Kevington (1 mile east). Further out, we also cover London (11 miles north-west), City of Westminster (14 miles north-west), Marylebone (14 miles north-west), Kensington (15 miles north-west), St Pancras (13 miles north-west) and Shoreditch (12 miles north-west).
Landmarks near St Mary Cray
Typical jobs here are in homes near Harris Academy Orpington, The Blue Anchor Public House and Walsingham School. There’s a railway station in St Mary Cray itself: St Mary Cray station. Well-known places in the area include London Borough of Bromley Museum (0.9 miles south) and Lullingstone Castle (4.5 miles south-east). Open spaces near St Mary Cray include Summer Hill and The Warren.