Medway · England
Capstone Sand Mastic
We cover Capstone for traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old sealant removed completely, joints prepared properly and a 12-month guarantee.
- Draughts and rain around sash boxes
- Mastic that needs renewing before redecorating
- Open joints round the window box
DIY versus a professional finish
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, then guaranteed for a year.
If you do try it yourself, take your time over the preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it fails, we can still redo it.
Sand mastic in Capstone, done properly
Burnt sand mastic is a traditional material blends with stone and brick surrounds. It suits period and listed homes where a modern sealant bead would stand out. Common call-outs are for failed mastic on an exposed elevation and old cement repairs round a window that have failed, across tenement windows, stone surrounds and brick reveals.
Homes in small places like Capstone often stand in the open, with little to shelter their windows from wind and rain. That exposure dries out and cracks the mastic around frames and sills faster.
We stand behind the work with a one-year guarantee, so you are covered after we have gone.
- Location
- Capstone (ME7)
- Region
- Medway
- Guarantee
- One year on every job
- Quotes
- A clear price before any work starts
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
How the visit works
When we arrive, we start by going over the job with you, so there are no surprises. Surfaces next to the work are protected before any work begins. The work generally takes a few hours for a single window, longer for several. In a small place like Capstone, access is normally the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- First, we look at the surrounds with you and agree what needs doing.
- Old, loose mastic is raked out and the joint cleaned.
- Deep voids are packed so the mastic is the right thickness.
- The mastic is mixed, pressed into the joint by hand and shaped.
- The finish is dressed so it sits neatly against the stone or brick.
Preparing for the visit
- Tell us about any previous sealing or DIY attempts
- Mention any parking rules near the property
- Tell us about access, such as stairs, a lift or high-level joints
Get a quote
Getting a quote is simple: let us know the job and the location and its rough size. Photos by email help us understand the job, and we’ll take it from there.
Related advice
Common problems we fix in Capstone
Age is the main cause. Sand mastic is a maintenance item like any pointing, depending on exposure and upkeep.
If you can see any of these, it’s time to have the joints looked at:
- Mastic dropping out of the joint
- Modern sealant on a period surround
- Mastic round period door frames that has failed
- Old cement repairs round a window that have failed
If you let a flat or house near Gillingham (Kent) station, older sash windows in a rental need their mastic kept sound to keep the weather out.
Before you book anyone
- When the joint can take water or movement
- What product goes in the joint
- Whether they seal over old material or remove it
- Whether they’re fully insured
What affects the quote in Capstone
The price is agreed before any work begins. It’s based on:
- Which sealant suits the joint
- Any mould that needs treating
- The size of the job
- How easy the joints are to reach
Doing several joints on one visit generally makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. You will get one clear quote for the whole job.
Helping us quote
What to tell us when you ask for a quote:
- The problem you’ve noticed
- Where the property is
- If it’s domestic, commercial or a hotel
- Any previous sealing or DIY work
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is, and we’ll explain how we’d tackle it. When it suits you, ring 0345 464 0079 or drop us an email.
Other services in Capstone
Your questions about sand mastic in Capstone
Can you help a landlord with a rental near Gillingham (Kent) station?
Yes, landlords and agents are among the people we work for, and several properties can go on one quote. You can call 0345 464 0079 or email us with the details for a clear quote.
Will you come out to Capstone?
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.
Is consent needed for window work on a listed home?
Speak to your local planning authority before work starts. Sand mastic is often favoured as like for like but the decision is theirs.
Which is right for my windows, sand mastic or modern sealant?
Sand mastic normally suits period timber windows best. On modern frames, we’d normally use a flexible sealant.
Is it worth trying it myself?
Some simple jobs can be done by a careful DIYer. Most DIY failures come from sealing over old material, wet joints or too much sealant.
Are you an approved applicator?
Yes. We are an ARBOMaster approved applicator.
Can you replace silicone on a period window with sand mastic?
In most cases. We remove the silicone and clean the joint, then point it with sand mastic.
Can I paint the new mastic?
Traditional guidance is not to paint over sand mastic. Ask us before you decorate around it and we will talk you through it.
Surface by surface
Stone surrounds
Stone openings are rarely perfectly straight, so the gap is not the same all the way round. We shape it by hand to follow the stone.
Timber door frames
A neat sand mastic joint round a front door suits a period home.
Frames and glazing around Capstone
Capstone is within about 3 miles of the coast, where wind-driven rain is a fact of life and, nearer the shore, so is salt air. That’s hard on the mastic around older windows and doors, especially on the side facing the sea. 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.
For an older house near a landmark such as All Saints Church, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint. For site and facilities teams at buildings such as Hempstead Infant School, its window and door frames need their mastic kept sound, just like a home’s.
Capstone is about 1 mile south-west of Gillingham, in Medway. If you need sand mastic in Capstone, please call 0345 464 0079 or send us an email for a quick quote. We are based in Crawley and cover Medway, Capstone included. Our area takes in 68 places across Medway. Our Chelmsford page covers work nearby.
We cover every part of the ME7 postcode area for sand mastic and the streets around it. We also cover the places around Capstone: Darland (1 mile north), Hale (1 mile north-west), Hempstead (1 mile south-east), Gillingham (1 mile north-east) and Chatham (1 mile west). Within a short drive, we also cover Rochester (4 miles north-west), Strood (4 miles north-west), Hoo St Werburgh (5 miles north), Rochester Riverside (3 miles north-west), Peters Village (4 miles west) and Brompton (3 miles north-west).
Local landmarks in Capstone
Around Capstone, our work takes us to homes and buildings near Chatham Grammar School for Girls, The Star pub and The Robert Napier School and the streets around them. For rail, the closest station is Gillingham (Kent) station, roughly 2 miles north. Well-known places in the area include Medway Maritime Hospital (1.7 miles north-west) and Pentagon Shopping Centre (2.3 miles north-west). Not far away are Burham Down and Blue Bell Hill.
What we can’t put right
We will not take on work that will not last, so these are the limits:
- Sash cords, weights and draught-proofing of the sashes
- Rotten sashes, sills or window boxes (a joiner’s job)
- Masonry that needs repairing
If you’re not sure, just call 0345 464 0079 or email us and we will give you a straight answer before booking.
Surfaces we seal
- Timber door frames
- Sash and case windows
- Tenement windows
- Brick reveals
- Period & listed homes
- Stone surrounds
Landlords, agents and businesses in Capstone
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements.
In hotels, rooms out of use cost money, so we plan the work room by room. We’ve worked in hotels as well as homes and businesses.