Kent · England
Cotman's Ash Window Mastic
Window mastic for Cotman's Ash and the surrounding area: careful preparation, the right product and tidy work. Call for a quick quote.
- Whistling draughts around closed windows
- Mastic that’s falling out in pieces
- A bead that does not match the frame
Window mastic for homes and businesses in Cotman's Ash
Mr Mastic’s applicators have more than 20 years’ experience with window and door sealants. We are ARBOMaster approved and fully insured, and every job is covered by a 12-month guarantee. Common call-outs are for old mastic that has gone black or come away and gaps between the frame and the inside reveal, across window sills, uPVC windows and composite doors.
Homes in small places like Cotman's Ash often stand in the open, with little to shelter their windows from wind and rain. Exposed frames and sills lose their mastic sooner than sheltered ones.
Big or small, you get the same one-year guarantee in Cotman's Ash and across Kent.
- Place
- Cotman's Ash (TN15)
- Region
- Kent
- Guarantee
- A year, on every job
- Quote
- A clear price before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
What happens on the day
Our applicators work methodically: protection first, then preparation, sealing and a tidy-up. Typically it takes most of a day for a typical house, less for a few frames and we leave things clean and tidy. In a small place like Cotman's Ash, access is usually the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- We start by checking each window and door with you.
- We remove the old mastic and clean the frame and the wall.
- Where gaps are deep, backing rod goes in first.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- Every joint is checked before we leave.
Before we arrive
- Keep children and pets away from the work area
- Mention any tricky access
- On commercial sites, let us know about site rules
Getting a quote
Getting a quote is simple: let us know what needs doing and where, and roughly how big it is. Photos by email help us understand the job, and we’ll come back to you with a quote.
Read more
Window mastic in Cotman's Ash: local notes
Historic houses like Lullingstone Castle (about 3.4 miles north-west) are a reminder that the area around Cotman's Ash has older buildings as well as new. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window. London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
In the older streets around Church of Saint Mary the Virgin, the joint between an old wall and a newer frame is normally the first place rain gets in. For site and facilities teams at buildings such as Kemsing Primary School, the mastic around its windows and doors needs looking after like any other building’s. Letting a property close to Kemsing station? Then cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Cotman's Ash is about 3 miles north-east of Sevenoaks, in Kent. We carry out window mastic for homeowners, landlords and businesses in Cotman's Ash and nearby. 922 places in Kent are on our list, large and small. Our London page covers work nearby, about 19 miles away.
We cover every part of TN15 for window mastic and the streets around it. We also cover the places around Cotman's Ash: 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).
Local landmarks in Cotman's Ash
Typical jobs here are in homes near The Rising Sun pub and Kemsing Down and the streets around them. The closest station to Cotman's Ash is Kemsing station, about 1.4 miles south. Other landmarks nearby include Kemsing Castle Bank (0.9 miles south-west) and Sevenoaks Hospital (2.8 miles south-west). Green spaces nearby include Dryhill Nature Reserve.
For landlords and businesses
In hotels, rooms out of use cost money, so the work can be planned room by room. Hotel work is part of what we do, alongside homes and businesses.
Whether it’s one flat or a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a one-year guarantee.
When it isn’t the sealant
Honest advice matters more to us than a booking, so here’s what sealant cannot fix:
- Worn gaskets, brush seals or a door that has dropped
- Damp problems in the wall away from the window
- A sash or casement that will not close properly
If in doubt, ring 0345 464 0079 or email us and we’ll say what we think.
Where we work in Cotman's Ash
- Window sills
- Patio & French doors
- Aluminium frames
- uPVC windows
- Timber windows & doors
- Composite doors
Aftercare tips
Aftercare is simple, and it makes a real difference:
- Keep timber frames painted
- Use gentle cleaners on frames and sealant
- Keep solvents and bleach off the sealant
- Paint up to the joint, not over it
Try not to touch the new joint while it cures, for as long as we advise. Keep jet washers away from the frames.
A small gap around a frame only grows. As old mastic keeps shrinking, the gap widens, and a cold room gets colder. A new joint closes it up.
Should I try it myself first?
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it doesn’t work out, we can still put it right.
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
Also near Cotman's Ash
Other services in Cotman's Ash
What happens if it’s left?
Not every sealant suits a window. Interior caulk and bathroom silicone are not made for exterior frame joints. An exterior, low-modulus sealant stays flexible in sun and frost. Around Cotman's Ash, older homes often have timber in their floors and frames, where water from a failed joint can cause rot if it’s left.
Leaving a failed joint generally makes the job bigger, not smaller, because water and mould keep working on it. If you’re unsure, ring 0345 464 0079 or email us for an honest opinion and a quote.
Why us?
- A 12-month guarantee on all work
- A sealant colour to suit the surroundings
- Sanitary silicone with an anti-fungal additive in wet areas
- We agree the colour with you first
Take a look at how sealant jobs are priced or what customers say.
What affects the cost of window mastic
You will get a clear quote before any work starts. It’s based on:
- Mould in or behind the old joints
- The size of the job
- Working hours on commercial sites
- Whether the work is at height
Every job is a little different, so we quote each one individually. Size, access and the product the joint needs all make a difference, and we will explain the quote if you ask.
Helping us quote
When you contact us, it’s useful to know:
- If someone has resealed it before
- The address or postcode of the job
- Pictures of the joints, sent by email
- What’s wrong with the joints now
Every job is quoted individually, so start by telling us what you need. Just call 0345 464 0079 or send us an email with the details and send photos if you have them.
Cotman's Ash: your questions answered
Do you cover Cotman's Ash for window mastic?
Yes, Cotman's Ash is within the area we cover. Our work covers London and the South East. You can ring 0345 464 0079 or email us and tell us what needs doing, and we’ll give you a clear price.
Do you cover smaller places like Cotman's Ash?
Yes, smaller places are covered as well as towns. Our work covers London and the South East. Just mention lanes, gates or anything else about the route when you book.
Can I paint over the new sealant?
Silicone generally will not take paint. If you plan to paint, tell us first and we can use a paintable sealant where it suits the joint.
Do I need to be at home?
That depends on where the joints are. Inside work needs someone to give us access.
Will the old sealant be removed?
Yes. Sealing over old sealant is the main reason resealing fails early, and it’s something we never do.
What do you need from me for a quote?
Where the job is, what the problem is and roughly how big it is. Photos by email help too.
How many windows can you do in a day?
A handful of frames is a short visit, while a whole house takes longer. You will get a timescale with the quote.
What does window mastic cost?
Every job is different, so each one gets its own quote. To get one, ring 0345 464 0079 or drop us an email with a short description of the job.