Greater London · England
Sand Mastic in Downe
Problem with your window and door surrounds in Downe? We remove the old material, prepare the joints and seal them properly, with a one-year guarantee.
- Mastic dropping out of the joint
- Gaps round a timber door in stone or brick
- Mastic that needs renewing before redecorating
How we handle sand mastic in Downe
Our applicators renew the sand mastic around sash and case windows and doors in stone and brick. Out comes the old, loose mastic, the joint is prepared and new mastic is shaped by hand. Common call-outs are for window mastic to renew ahead of painting and mastic dropping out of the joint, across stone surrounds, timber door frames and period & listed homes.
Many London homes are flats, with windows high above the street. In a converted house or block, the lease normally says who is responsible for the windows, so it’s worth checking before booking, and access in Downe is something to talk through when you book.
We guarantee the work for a year. If something is not right with it in that time, tell us and we will put it right.
- Location
- Downe (BR6)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Quotes
- A clear price before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Different surfaces, different methods
Brick reveals
Brick reveals round timber windows are often pointed with sand mastic. It gives a traditional finish.
Timber door frames
Doors face weather and wear, so their mastic can fail sooner. It’s renewed by hand.
How to look after the new joints
Simple care keeps the joints in good condition. We recommend:
- Avoid patching sand mastic with silicone
- Check with your local planning authority if your home is listed
- Ask us before painting near the mastic
- Have rotten timber repaired before new mastic goes in
Do not touch or press the mastic while it hardens. It skins over quickly, but takes longer to harden fully.
Once mastic starts to crumble, rain gets in. It can soak into the frame and the surrounding masonry so early renewal protects both.
Downe: your questions answered
Is parking a problem for a job in Downe?
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.
Do you work for landlords with property near Chelsfield station?
Yes, we work for letting agents and landlords. You can phone 0345 464 0079 or email us with the address and a few details, and we’ll give you a fixed price before work begins.
Is consent needed for window work on a listed home?
Your local planning authority is the one to ask. They’ll tell you if consent is needed for work to your windows.
Do you have insurance?
Yes. We’re fully insured, and we can confirm the details when we quote.
Do you come to Downe?
Yes. From our base in Crawley, we cover South East England, London and all of Scotland.
Do you do commercial work?
Yes. Larger jobs can be planned room by room or area by area.
Is it OK to seal over old sealant?
No, and we never do. It can look neat for a few weeks, but the new bead soon lifts. Removing the old sealant completely is the only lasting way.
How do I get a quote for sand mastic in Downe?
It depends on the job, so we quote each one individually. For a quick quote, call 0345 464 0079 or email us with a short description of the job.
When to call us in Downe
Rain on the window surround works into any crack and loosens it further. Windows facing the weather tend to go first.
Signs it’s time to call us include:
- Window mastic to renew ahead of painting
- Modern sealant on a period surround
- Gaps round a timber door in stone or brick
- Crumbling sand mastic round a window
If you look after a building such as Downe Primary School, its window and door frames need their mastic kept sound, just like a home’s.
Comparing quotes
- How the joint is cleaned and prepared
- How hidden problems are handled
- Who turns up on the day
- Whether all the old sealant comes out first
DIY sealant or a professional job?
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 a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, then guaranteed for a year.
What sealant work cannot fix
We’d rather tell you now than do work that will not last, so these are the limits:
- Sashes that need overhauling
- Cracked or broken glass
- Planning or listed building consent (your local planning authority decides)
Not sure which it is? You can phone 0345 464 0079 or drop us an email and we’ll tell you honestly before booking.
Joints and surfaces we work on
- Tenement windows
- Period & listed homes
- Stone surrounds
- Brick reveals
- Timber door frames
- Sash and case windows
Downe homes and the weather
In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking. With historic houses such as Down House (about 0.6 miles south) nearby, there’s older building stock in the area around Downe 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.
As a London address, Downe can be tricky for parking: let us know about parking bays, permits or a driveway. Rented homes near Chelsfield station change hands often, and any sash windows need sound mastic to keep draughts and rain out.
Downe is about 4 miles south-west of Orpington, in Greater London. Across the BR6 area, we cover sand mastic for homes and businesses. Downe is one of 764 places in Greater London we cover. We also work in London, about 13 miles from Downe.
We work across the BR6 postcode area for sand mastic. If you need sand mastic at a property on High Street, North End Lane and Belle Vue Road or anywhere close by, we can help. We also cover the places around Downe: Farthing Street (1 mile north-west), Hazelwood (1 mile east), Luxted (1 mile south), Leaves Green (1 mile west) and Single Street (2 miles south). Larger places within reach include London (13 miles north-west), City of Westminster (15 miles north-west), Marylebone (15 miles north-west), St Pancras (15 miles north-west), Shoreditch (14 miles north-west) and Hoxton (15 miles north-west).
Around Downe
Typical jobs here are in homes near The Queens Head pub, Charles Darwin School and South Park. For rail, the closest station is Chelsfield station, roughly 2.6 miles north-east. Well-known places in the area include Crofton Roman Villa (2.7 miles north-east) and Princess Royal University Hospital (1.8 miles north). Open spaces near Downe include Downe Bank Nature Reserve and Betsom's Hill.
What we do, step by step
Our applicators work methodically: protect, prepare, seal, tidy. Typically it takes anything from a few hours to a full day, depending on how many windows. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- First we agree which joints need doing.
- We remove the old, loose mastic.
- Deep gaps are packed so the mastic sits at the right depth.
- The sand mastic is mixed and pressed into the joint by hand.
- We dress the finish so it sits neatly against the masonry.
Preparing for the visit
- Mention any parking rules near the property
- Let us know about stairs, lifts or work at height
- Try not to wet indoor joints just before the visit
Get a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and add pictures by email if you can.
Read more
Nearby places to Downe
What else we do in Downe
Why deal with it now?
New sash windows are a major, costly change, and in listed buildings it may need consent. Where the frames are in good order, new mastic seals the surround. In a flat in Downe, 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.
Leaving a failed joint generally makes the job bigger, not smaller. If you’re not sure whether it needs doing, call 0345 464 0079 or send us an email for an honest opinion and a quote.
What you get with us
- We never seal over old sealant
- Sanitary silicone with an anti-fungal additive in wet areas
- Experience in homes, commercial sites and hotels
- Full insurance on every job
Take a look at how sealant jobs are priced and our reviews.