Kent · England
Key's Green Sand Mastic
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for Key's Green, backed by a one-year guarantee. Ask us for a quote.
- Window mastic to renew ahead of painting
- Mastic round period door frames that has failed
- Open joints round the window box
Sand mastic in Key's Green, done properly
For a listed home or one in a conservation area, ask your local planning authority whether consent is needed for work to windows. Sand mastic is often favoured as a like-for-like material. If you have mastic that needs renewing before redecorating and crumbling sand mastic round a window, we can help.
Mastic can only go onto a dry, clean joint, so window work in Key's Green is booked around the forecast. Let us know about access to all the frames, upstairs ones included.
We stand behind the work with a one-year guarantee, so you’re covered after we’ve gone.
- Place
- Key's Green (TN12)
- Wider area
- Kent
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Key's Green homes and the weather
London and the South East are among the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Historic houses like Scotney Castle (about 3.6 miles south-east) are a reminder that the area around Key's Green 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’s traditional sand mastic.
If you let a flat or house near Frant station, any sash windows need sound mastic to keep draughts and rain out.
Key's Green is about 4 miles east of Royal Tunbridge Wells, in Kent. We provide sand mastic to homeowners, landlords and businesses in Key's Green, as part of our work across Kent. Our Kent coverage runs to 922 places, Key's Green among them. There’s also a page for Crawley, about 24 miles away.
Every address in TN12 is covered for sand mastic. That includes homes and businesses on Cryals Road and Beech Lane and the roads around them. Neighbouring places we cover for sand mastic include Lamberhurst Quarter (1 mile south), Petteridge (1 mile north-east), Pembury (2 miles north-west), Matfield (2 miles north-east) and Brenchley (2 miles north-east). Larger places within reach include Maidstone (12 miles north-east), Sevenoaks (13 miles north-west), Royal Tunbridge Wells (4 miles west), Tonbridge (6 miles north-west), Kings Hill (10 miles north) and Foley Park (13 miles north-east).
Near you in Key's Green
Around Key's Green, our work takes us to homes and buildings near Brenchley Wood and The Blue Boys Inn. The nearest railway station is Frant station, roughly 3.5 miles south-west of the centre. Other landmarks nearby include Pembury Hospital (2.4 miles north-west) and Old Scotney Castle (3.7 miles south-east). Not far away are Bewl Water and Tudeley Woods RSPB reserve.
Signs you need sand mastic in Key's Green
Previous repairs in cement or silicone often trap water or crack away. They do not move with the timber, and they generally need raking out.
People generally contact us after spotting one of these:
- Modern sealant on a period surround
- Mastic dropping out of the joint
- Mastic worn away on windows facing the weather
- Tired mastic found when preparing windows for paint
For an older house near a landmark such as Chapel Of Ease Of St Luke, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Before booking anyone
- How the surfaces are prepared before sealing
- Whether all the old sealant comes out first
- What happens if they find a problem under the old sealant
- What the cure time is
Common questions in Key's Green
I let a flat near Frant station. Can you help?
Yes. We work for landlords and letting agents as well as householders. You can ring 0345 464 0079 or send us an email with the details for a clear quote.
Is Key's Green within the area you cover?
Yes, Key's Green is covered. We work across London and the South East, and smaller places are part of that. Longer journeys are simply planned in advance.
Do you offer different sealant colours?
Yes. White, clear and grey are common, and other colours are available for many products, and we’ll agree it with you first.
What is sand mastic?
It’s a mix of sand and a linseed-oil-based binder. It’s built up in the joint by hand and finished to sit neatly against the masonry.
Is it possible to take out silicone and use sand mastic instead?
Usually, yes. With the silicone removed and the joint cleaned, sand mastic is applied by hand.
Do the sealants smell?
There can be a smell while the sealant cures, which fades as it sets. Opening a window helps.
Where do you work from?
Mr Mastic is based in Crawley. Our applicators cover Key's Green, along with the rest of our area.
Do you remove the old sealant?
Always. Sealing over old sealant is the main reason resealing fails early, so we never do it.
What we cannot put right
Some problems need a builder, plumber or other trade rather than us:
- Broken panes
- Sash cords, weights and draught-proofing of the sashes
- Whether work needs listed building consent
Not sure which it is? You can phone 0345 464 0079 or email us and we will tell you honestly.
Surfaces we seal
- Sash and case windows
- Tenement windows
- Stone surrounds
- Period & listed homes
- Timber door frames
- Brick reveals
Why deal with it now?
Not every draught comes from the sashes themselves. Gaps between the frame and the wall can be just as bad, and renewing the mastic closes them. Around Key's Green, older homes often have timber in their floors and frames, where water from a failed joint can cause rot if it’s left.
Combining jobs into one visit is usually more efficient than separate visits. You will get one clear quote for the whole job.
Why Key's Green customers choose us
- A 12-month guarantee on all work
- Anti-fungal sanitary silicone in wet areas
- More than 20 years in sealant work
- Rated 4.9 stars on Google
See our cost guide and our reviews.
Places near Key's Green
Also in Key's Green
Different surfaces, different methods
Brick reveals
Sand mastic is also used where timber frames meet brick. It gives a traditional finish.
Sash and case windows
On a sash window, the mastic joint shows on the outside, so a neat, even finish matters.
Landlord and commercial work in Key's Green
In hotels, rooms out of use cost money, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
Housing providers, facilities teams and property managers book us too. We can quote a run of properties together, and we’re fully insured for the work.
What we do, step by step
When we arrive, we start by going over the job with you, so you know exactly what we’re doing. Surfaces next to the work are protected before we start. Most jobs take anything from a few hours to a full day, depending on how many windows. In a small place like Key's Green, access is usually the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First, we look at the surrounds with you and agree what needs doing.
- The loose and crumbling mastic is raked out and the joint cleaned.
- Deep voids are packed so the mastic is the right thickness.
- Sand mastic is mixed and applied by hand, then shaped to the joint.
- The finish is dressed so it sits neatly against the stone or brick.
Preparing for the visit
- On commercial sites, let us know about site rules
- Tell us about any water getting in
- Tell us if parking is tricky
Get a quote
Asking for a quote is easy: let us know what needs doing and where. A few photos by email make the job easier to understand, and we’ll come back to you with a quote.
Advice
Aftercare tips
Aftercare is simple, and it makes a real difference:
- Keep modern sealant off the mastic
- Inspect the joints round the windows every year or so
- Get any rot dealt with first
- Make sure water runs off the sill
Leave the new mastic alone while it firms up. It skins over quickly but needs longer to fully harden.
Sound mastic protects the frame. Once it fails, water can sit against the timber, which can lead to rot.