Greater London · England
Sand Mastic in Westerham
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homes and businesses in Westerham and across Greater London. Fully insured, ARBOMaster approved and guaranteed for a year.
- Old cement repairs round a window that have failed
- Mastic worn away on windows facing the weather
- Mastic round period door frames that has failed
Sand mastic in Westerham, done properly
Sand mastic skins over fairly quickly, but it takes longer to harden fully. Traditionally, sand mastic is left unpainted and we will advise if you’re redecorating. We work on stone surrounds, timber door frames and sash and case windows, and people most often call us about window mastic to renew ahead of painting and mastic worn away on windows facing the weather.
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.
Whatever the size of the job, it’s backed by our 12-month guarantee.
- Where
- Westerham (TN16)
- Region
- Greater London
- Cover
- One year on every job
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
How to look after the new joints
Looking after new joints is easy:
- Renew mastic before redecorating the windows
- Do not paint over the new mastic
- Go gently near the mastic when preparing windows
- Ask a joiner to look at soft timber first
Keep gutters and sills clear so water runs away from the surround. Constant wetting wears the mastic faster.
Fine cracks show the mastic is starting to fail. Renewing it then is simpler than waiting until it falls out.
Surface by surface
Tenement and terrace windows
Tenements and terraces often have many sash windows with ageing mastic. We work on single windows or whole elevations.
Stone surrounds
We take care not to mark the stone when the old mastic comes out.
What happens on the day
Every visit runs the same way: we check the joints, protect the area around them, carry out the job and tidy away. It usually takes a few hours per window, depending on the condition of the joints. In Westerham, flats, stairs and shared entrances are part of the routine. Mention any building rules, key holders or managing agents when you book.
- First, we look at the surrounds with you and agree what needs doing.
- We rake out the old mastic and clean the joint.
- Large voids are packed out first, so the mastic is not too thick.
- The mastic is mixed, pressed into the joint by hand and shaped.
- We dress the surface so it sits neatly against the masonry.
Before we arrive
- Mention if the joints have been sealed before
- Tell us about access, such as stairs, a lift or high-level joints
- Plan for the work area to be out of bounds to pets and children
Get a quote
If you’re in Westerham and need sand mastic, call 0345 464 0079 or send us an email. A short description of the job and where it is helps us quote, and we will agree the price before any work begins.
Related advice
Why act early in Westerham
Replacing sash windows is a big decision for a period home, 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 Westerham, the repair is bigger than a sealant job.
What it costs depends on the size of the job, how hard the old material is to remove and access to the work. You will have a clear quote before any work starts.
Why Westerham customers choose us
- We leave the area clean and tidy
- One-year guarantee on every job
- Experience in homes, commercial sites and hotels
- Approved under the ARBOMaster scheme
Take a look at our cost guide or what customers say.
Also near Westerham
Other services in Westerham
Windows and doors in Westerham
In a converted house or block, who looks after the windows depends on the lease, so check that before booking. Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Letting a property close to Hurst Green station? Then any sash windows need sound mastic to keep draughts and rain out. As a London address, Westerham can be tricky for parking: let us know about parking bays, permits or a driveway.
Westerham is about 5 miles west of Sevenoaks, in Greater London. Wherever you are in the TN16 postcode area, we can carry out sand mastic at your property. Our Greater London coverage runs to 764 places, Westerham among them. We also work in Crawley, around 16 miles away.
Jobs for sand mastic in TN16 works the same way as everywhere else we cover. If you need sand mastic at a property on Market Square, London Road and High Street or anywhere close by, our applicators can take on the job. With the A25 and B2024 close by, Westerham is simple for us to get to. We also cover the places around Westerham: Force Green (1 mile north), Moorhouse Bank (1 mile south-west), Goodley Stock (2 miles south), The Chart (2 miles south-west) and South Street (2 miles north-west). Within a short drive, we also cover Orpington (8 miles north), New Cross (15 miles north), Thornton Heath (12 miles north-west), Croydon (10 miles north-west), East Dulwich (15 miles north-west) and Plumstead (15 miles north).
Local landmarks in Westerham
Around Westerham, our work takes us to homes and buildings near The Olde House At Home Public House, among other places. For rail, the closest station is Hurst Green station, roughly 3.4 miles south-west of the centre. Other landmarks nearby include Tandridge Priory (2.2 miles south-west). For a walk, there’s Betsom's Hill and Dryhill Nature Reserve.
Westerham: your questions answered
Do you cover Westerham for sand mastic?
Yes, Westerham is within the area we cover. Our work covers London and the South East. You can phone 0345 464 0079 or drop us an email and let us know what needs doing.
I let a flat near Hurst Green station. Can you help?
Yes, we work for letting agents and landlords. Just call 0345 464 0079 or send us an email and tell us about the property, and we will give you a clear price.
Can I choose the sealant colour?
Usually, yes. White, clear and grey are common, and other colours are available, and we agree the colour with you before any work starts.
Do I have to be there?
It depends on the job. Inside work needs someone to give us access, while outside work can sometimes be arranged differently.
Can you quote for more than one area?
Yes, we can. More than one area can go on one quote.
Where do you work from?
We work from Crawley. We cover Westerham and the rest of Greater London, along with the rest of our area.
Is there any odour?
Sometimes, a little. Any smell clears as the sealant cures.
Is it worth trying it myself?
You can, for simple jobs. The key is preparation: remove all the old material and work on a clean, dry joint. We can always put it right if it fails.
What we are called out for in Westerham
Shallow joints are a common cause. A thin layer doesn’t hold well so we make sure the new mastic is the right thickness.
If you can see any of these, it’s time to have the joints looked at:
- Draughty sash windows at the surround
- Gaps where the frame meets the masonry
- Gaps round a timber door in stone or brick
- Crumbling sand mastic round a window
Homes close to Church of St Mary the Virgin include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Before booking anyone
- Whether they seal over old material or remove it
- What the cure time is
- Which sealant they’ll use, and why
- What preparation is included
When it is not the sealant
New sealant cannot fix everything, and we’d rather say so up front. It will not solve:
- Broken panes
- Masonry that needs repairing
- Rotten sashes, sills or window boxes (a joiner’s job)
If you are not sure, just ring 0345 464 0079 or drop us an email and we will give you a straight answer before booking.
Surfaces we seal
- Brick reveals
- Sash and case windows
- Period & listed homes
- Tenement windows
- Timber door frames
- Stone surrounds
Landlords, agents and businesses in Westerham
From a single let to a portfolio, the work is the same standard: the old material taken out, careful preparation and a 12-month guarantee.
Housing providers, facilities teams and property managers book us too in Westerham and across Greater London. We can quote a run of properties together, and we’re fully insured for the work.