Kent · England
Sand mastic for sash & case windows in Cotman's Ash, Kent
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for householders, landlords and businesses in Cotman's Ash. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Wind and rain getting in round a sash window
- Window mastic to renew ahead of painting
- Old cement repairs round a window that have failed
What sand mastic looks like in Cotman's Ash
The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. With historic houses such as Lullingstone Castle (about 3.4 miles north-west) nearby, there’s older building stock in the area around Cotman's Ash as well as newer homes. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window.
Managing a site like Kemsing Primary School? Then the mastic around its windows and doors needs looking after like any other building’s. In the older streets around Church of Saint Mary the Virgin, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Cotman's Ash is about 3 miles north-east of Sevenoaks, in Kent. We provide sand mastic to homes and businesses in Cotman's Ash and nearby, as part of our work across Kent. Our area takes in 922 places across Kent, from the larger towns to small villages. London is on our list too, around 19 miles away.
Work in TN15 works the same way as everywhere else we cover. Nearby, we also carry out sand mastic in Woodlands (1 mile north-east), Heaverham (1 mile south-east), Knatts Valley (1 mile north), Romney Street (1 mile north-west) and Kemsing (1 mile south-west). We also work in nearby towns such as Maidstone (13 miles east), Dartford (9 miles north), Sevenoaks (3 miles south-west), Royal Tunbridge Wells (13 miles south), Gravesend (10 miles north-east) and Tonbridge (8 miles south).
What’s near Cotman's Ash
Locally, jobs take us to homes and businesses close to The Rising Sun pub and Kemsing Down and the streets around them. Cotman's Ash’s nearest station is Kemsing station, roughly 1.4 miles south. A little further out are Kemsing Castle Bank (0.9 miles south-west) and Sevenoaks Hospital (2.8 miles south-west). Not far away are Dryhill Nature Reserve.
Sand mastic in Cotman's Ash, done properly
On many period windows, sand mastic looks right and suits the building. Newer frames normally get a flexible sealant instead and we’ll explain which is best for yours. We work on timber door frames, tenement windows and sash and case windows, and people most often call us about mastic round period door frames that has failed and silicone on a period window that looks wrong.
Somewhere as small as Cotman's Ash, older homes often have timber frames set in stone or brickwork. Not every older frame suits a modern silicone bead, and sometimes a traditional sand mastic is the better choice.
Each job carries a 12-month guarantee, whatever its size.
- Location
- Cotman's Ash (TN15)
- Wider area
- Kent
- Guarantee
- One year on every job
- Price
- A clear price before work begins
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
When to call us in Cotman's Ash
Shallow joints are a common cause. Mastic that is too thin cracks and drops out, which is why we pack deep voids first and get the depth right.
The most common problems we see are:
- Mastic that needs renewing before redecorating
- Patchy fillers round a sash window
- Draughts and rain around sash boxes
- Mastic worn away on windows facing the weather
Rented homes near Kemsing station change hands often, and any sash windows need sound mastic to keep draughts and rain out.
What to look for in a quote
- Who turns up on the day
- Whether you can choose the colour
- What insurance they hold
- Which sealant they’ll use, and why
Places near Cotman's Ash
Other services in Cotman's Ash
Should I try it myself first?
Sealing over old silicone is the commonest DIY error. Silicone does not stick to old silicone, so it lifts and traps water and mould underneath. Everything old must be removed first.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
FAQs for Cotman's Ash
Is Cotman's Ash within the area you cover?
Yes, we do. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Can you help a landlord with a rental near Kemsing station?
Yes. We work for letting agents and landlords as well as householders, and several properties can go on one quote. You can phone 0345 464 0079 or email us with the details for a clear quote.
What should I tell you?
Only a few details: where it is, what you’ve noticed and how we reach it. After that, simply ring 0345 464 0079 or drop us an email.
What’s sand mastic made of?
It’s sand mixed with a linseed-oil-based binder, used between timber frames and stone or brick.
Do you have insurance?
Yes. We’re fully insured, and we can confirm the details when we quote.
What guarantee comes with the work?
There’s a 12-month guarantee on every job.
Will you leave a mess?
No. We protect the surfaces around the joints, and we tidy up before we go.
Is it worth trying it myself?
Sometimes. 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.
How it works
We work through the job in order: protection first, then preparation, sealing and a tidy-up. Typically it takes anything from a few hours to a full day, depending on how many windows, and the area is left clean. Somewhere like Cotman's Ash needs a little journey planning: tell us about narrow lanes, gates, long drives and where we can park. We bring what the job needs, so it can be finished in one trip where possible.
- We check each window surround and the condition of the joint.
- The joint is raked out and cleaned.
- We fill deep gaps so the new mastic is not too thick.
- New sand mastic is applied and shaped by hand.
- We finish the mastic to a tidy line.
Before we arrive
- For business premises, tell us about site rules or sign-in
- Plan for the work area to be out of bounds to pets and children
- Tell us if parking is tricky
Getting a quote
Asking for a quote is easy: let us know the job and the location, and roughly how big it is. A few photos by email make the job easier to understand.
Advice
For landlords and businesses
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance.
In hotels, rooms out of use cost money, so the work can be planned room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Honest limits
We will always be straight with you, so here’s what sealant cannot fix:
- Whether work needs listed building consent
- Crumbling stone or brickwork round the window
- Timber that has rotted
If in doubt, ring 0345 464 0079 or send us an email and we will say what we think.
Surfaces we seal
- Stone surrounds
- Sash and case windows
- Timber door frames
- Period & listed homes
- Tenement windows
- Brick reveals
Quotes for sand mastic in Cotman's Ash
There’s no set price list. What we look at:
- Mould in or behind the old joints
- Access and height
- The size of the job
- Working hours on commercial sites
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.
What we need to know
The more you tell us, the more accurate the quote. When you get in contact, it helps to mention:
- Whether it has been sealed before
- A few pictures by email, if you can
- The address or postcode of the job
- Whether it’s a home or a business
We do not publish a price list. Instead, we give you a clear quote for your job. To arrange one, phone 0345 464 0079 or email us.
Why deal with it now?
An open joint round the frame lets weather in. Left, water can reach the timber and the wall so renewing it early protects the window. Older cottages and farmhouses around Cotman's Ash can have timber floors and frames, where water from a failed joint can cause rot if it’s left.
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all make a difference.
Why Cotman's Ash clients choose us
- Old sealant always removed completely
- We are fully insured
- Trusted Arbo and Everbuild sealants
- We leave the area clean and tidy
Read how sealant jobs are priced and customer reviews.