Greater London · England
Sand Mastic in Beckenham
Sand mastic in Beckenham from a team with over 20 years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Open joints round the window box
- Tired mastic found when preparing windows for paint
- Failed mastic on an exposed elevation
Keeping the joints in good condition
Joint life depends on how it’s used and looked after. We suggest:
- Leave the new mastic unpainted
- Ask the planning authority about consent for listed or conservation-area homes
- Look over the window mastic once a year
- Sort the mastic before the decorators arrive
Check the mastic when you check the paintwork. Small cracks are easier to deal with early.
An open joint round the box lets weather through. The longer it’s left, the more the joint opens as more mastic falls out.
About our sand mastic in Beckenham
Our applicators renew the sand mastic around sash and case windows and doors in stone and brick. Out comes the old, loose mastic, and new mastic is applied and shaped by hand. We are often asked to deal with gaps where the frame meets the masonry and draughty sash windows at the surround, on sash and case windows, stone surrounds and timber door frames.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. Over the years, the sealant around them shrinks, cracks and pulls away, letting in draughts and water.
The work is covered for a year after we finish. If there’s a problem with it, please ring 0345 464 0079 or email us.
- Location
- Beckenham (BR3, SE26, BR4, SE20)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
How the visit works
On the day, we look over the joints with you first, so you know exactly what we’re doing. We protect the surfaces around the joints before any work begins. The work usually takes a few hours per window, depending on the condition of the joints. 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.
- We check each window surround and the condition of the joint.
- We rake out the old mastic and clean the joint.
- Large voids are packed out.
- We point the joint with sand mastic by hand.
- We finish the mastic to a tidy line.
Preparing for the visit
- Mention any leaks or damp you’ve noticed
- Plan for the work area to be out of bounds to pets and children
- Clear items away from the joints we are working on
How to get a quote
We quote each job on its own, so start by telling us what you need. Simply ring 0345 464 0079 or send us an email and describe the job and send pictures if you have them.
Read more
Different surfaces, different methods
Stone surrounds
Sand mastic sits naturally against stone. The finish blends with the masonry.
Sash and case windows
Most of our sand mastic work is on sash windows. We renew the mastic round each box.
Common problems we fix in Beckenham
Previous repairs in cement or silicone often trap water or crack away. They don’t move with the timber, and they generally need raking out.
Signs it’s time to call us include:
- Weathered mastic on the most exposed windows
- Tired mastic found when preparing windows for paint
- Silicone on a period window that looks wrong
- Cement or filler used on old window joints that has cracked
In the older streets around Christ Church, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Questions to ask before booking
- Whether they’re fully insured
- Which sealant they’ll use, and why
- Is VAT in the price?
- What happens if the job turns out different
What affects the cost of sand mastic
Every job gets its own quote. These are the things that affect it:
- Whether old sealant or filler has to be cut out
- When we can work, for business premises
- How much there is to do
- How many areas need sealing
A failed joint rarely gets cheaper to fix by waiting. If you’re not sure whether it needs doing, ring 0345 464 0079 or email us and we’ll give you an honest view and a quote.
What to tell us for a quote
You do not need to know the technical terms. Just tell us:
- What the problem is, such as mould, gaps, leaks or cracking
- Where the property is
- Any access issues, like height or stairs
- If someone has resealed it before
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is, and we will explain how we’d tackle it. Whenever you’re ready, ring 0345 464 0079 or email us.
Towns and villages near Beckenham
Other services in Beckenham
Beckenham: your questions answered
Can parking be tricky for a visit in Beckenham?
Parking in Beckenham, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Do you work for landlords with property near Beckenham Junction station?
Yes, landlords and agents are among the people we work for, and several properties can go on one quote. You can phone 0345 464 0079 or send us an email with the details for a clear quote.
Is it worth trying it myself?
You can, for simple jobs. Preparation is everything: all the old sealant out, and a clean, dry joint. If it doesn’t work out, we can redo it.
Do you do commercial work?
Yes. We’ve worked for hotels, offices and other businesses, and we’re fully insured.
What do you need from me for a quote?
Just the basics: where it is, what you’ve noticed and how we reach it. Then phone 0345 464 0079 or drop us an email.
Can you replace silicone on a period window with sand mastic?
Yes, we do this often. The old silicone has to come out completely so the mastic beds in well.
Do you offer different sealant colours?
Usually, yes. White, clear and grey are common, and other colours are available for many products, and we agree the colour with you before we start.
Where is Mr Mastic based?
We work from Crawley. Our applicators cover Beckenham.
Why act early in Beckenham
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. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in Beckenham, the repair is bigger than a sealant job.
There are no prices on our website, because each job is priced on what it involves. For a quick quote, please call 0345 464 0079 or drop us an email.
What you get with us
- 4.9 on Google from 180+ five-star reviews
- Any old sealant cut out fully, not covered over
- Neat joints and a tidy finish
- ARBOMaster approved applicator
See our cost guide or our reviews.
Frames and glazing around Beckenham
In a converted house or block, who looks after the windows depends on the lease, so check that before booking. The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
As a London address, Beckenham can be tricky for parking: tell us about permits, visitor bays or off-street space when you book. If you look after a building such as Harris Primary Academy Beckenham Green, larger buildings have plenty of frames, and the mastic around each one ages.
Beckenham is about 7 miles south-east of London, in Greater London. Beckenham gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a 12-month guarantee. Our Greater London coverage runs to 764 places, and Beckenham is one of them. There’s also a page for London, roughly 7 miles from Beckenham.
Our applicators cover all of BR3, SE26, BR4 and SE20 for sand mastic. Sand mastic is available to properties on High Street, The Drive and Stanmore Terrace and the roads around them. Being close to the B230 and B251, Beckenham is easy for our applicators to reach for sand mastic. If you are just outside Beckenham, we cover Penge (1 mile west), Bell Green (2 miles north), Bellingham (2 miles north), Southend (2 miles north) and Sydenham (2 miles north-west). Further out, we also cover London (7 miles north-west), City of Westminster (9 miles north-west), Marylebone (9 miles north-west), Kensington (10 miles north-west), St Pancras (9 miles north-west) and Shoreditch (8 miles north).
Landmarks near Beckenham
Typical jobs here are in homes near Harris Academy Beckenham, Beckenham Place Park and The George Inn and the streets around them. Beckenham has its own railway station: Beckenham Junction station. A little further out are Greenwich Castle (5 miles north) and The Glades (1.9 miles east). For a walk, there’s Summer Hill and Dacres Wood.
When something else is needed
Some problems need a builder, plumber or other trade rather than us:
- Cracked or broken glass
- Rotten sashes, sills or window boxes (a joiner’s job)
- Sashes that need overhauling
Not sure which it is? You can call 0345 464 0079 or drop us an email and we will tell you honestly.
Joints and surfaces we work on
- Sash and case windows
- Brick reveals
- Stone surrounds
- Tenement windows
- Period & listed homes
- Timber door frames