Kent · England
Sand mastic for sash & case windows in Round Street, Kent
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homes and businesses in Round Street and across Kent. Fully insured, ARBOMaster approved and guaranteed for a year.
- Gaps where the frame meets the masonry
- Cement or filler used on old window joints that has cracked
- Cracked mastic round a front door frame
Sand mastic in Round Street, done properly
If your home is listed or in a conservation area, check with your local planning authority whether consent is needed for work to windows. Like-for-like sand mastic is often the preferred finish. We work on brick reveals, stone surrounds and tenement windows, and the jobs we see most are draughts and rain around sash boxes and cement or filler used on old window joints that has cracked.
Outdoor sealant needs dry, clean surfaces, so work on frames around Round Street is planned for dry weather. Tell us about access to every side of the house, including upper-floor windows.
We guarantee the work for a year. If something is not right with it in that time, tell us and we’ll put it right.
- Place
- Round Street (DA13)
- Wider area
- Kent
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
DIY versus a professional finish
Sealing over old silicone is the commonest DIY error. New silicone will not bond to old, so it lifts and traps water and mould underneath. All the old material has to come out first.
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
Honest limits
Sealant isn’t the answer to every problem, and we’d rather say so up front. It won’t solve:
- Sash cords, weights and draught-proofing of the sashes
- Damaged stone surrounds
- Cracked or broken glass
If you are not sure, just phone 0345 464 0079 or send us an email and we’ll give you a straight answer before you book.
Joints and surfaces we work on
- Timber door frames
- Period & listed homes
- Brick reveals
- Sash and case windows
- Stone surrounds
- Tenement windows
Why it’s worth doing now in Round Street
Before painting the windows, it pays to renew the mastic. Painting over failed mastic does not seal it, and the new mastic is traditionally left unpainted. Older cottages and farmhouses around Round Street can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
Doing several joints on one visit generally makes better use of the time than several visits. We’ll send you a clear quote for the lot.
Why Round Street customers choose us
- Homes, businesses and hotels
- Approved under the ARBOMaster scheme
- More than 20 years in sealant work
- Every job guaranteed for a year
Read our cost guide and what customers say.
How we quote for sand mastic
The quote reflects the job in front of us. We take into account:
- How many rooms, windows or areas are involved
- Whether the work is at height
- When we can work, for business premises
- Any mould that needs treating
There are no prices on our website, because each job is priced on what it involves. For a quick quote, please ring 0345 464 0079 or drop us an email and we’ll talk you through it.
Helping us quote
Before you ask for a quote, have a think about:
- Whether it has been sealed before
- Where the property is
- The rough size of the job
- What’s wrong with the joints now
Getting a quote is simple: let us know the job and the location. Photos by email help us understand the job.
Questions from Round Street
Is Round Street in your area for sand mastic?
Yes. We work across London and the South East, and Round Street is part of that. You can call 0345 464 0079 or email us and tell us what needs doing.
Can you help a landlord with a rental near Sole Street station?
Yes, rental work is part of what we do. You can ring 0345 464 0079 or send us an email with the address and a few details, and we will give you a fixed price before we start.
Can I choose the sealant colour?
In most cases you can choose. We will explain which colours are available.
What should I tell you?
A short description and the location, with photos by email if possible. If we need more, we will ask.
Can you replace silicone on a period window with sand mastic?
Yes. The silicone is cut out and the joint cleaned before the sand mastic goes in.
Is it worth trying it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. Most DIY failures come from sealing over old material, wet joints or too much sealant.
Are you insured?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
What exactly is sand mastic?
It’s a mix of sand and a linseed-oil-based binder. It’s applied by hand and finished to sit neatly against the masonry.
What happens on the day
Good joint work is mostly preparation, and we do not rush it. Every joint is cleaned and dried before new material goes in. In total, it generally takes a few hours for a single window, longer for several. Somewhere as small as Round Street, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We check the window surrounds and agree which joints need renewing.
- We rake out the old mastic and clean the joint.
- We pack any deep gaps so the mastic sits at the right depth.
- 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.
Getting ready for the visit
- Keep pets and children clear of the area while we work
- Tell us about any previous sealing or DIY attempts
- Clear items away from the joints we’re working on
How to get a quote
For sand mastic in Round Street, phone 0345 464 0079 or email us. Tell us what the problem is and where, and we will agree the price before any work begins.
Advice
When to call us in Round Street
Scraping and sanding before painting can loosen old mastic. It’s often found when windows are being prepared for paint.
Signs it’s time to call us include:
- Mastic dropping out of the joint
- Tired mastic found when preparing windows for paint
- Old cement repairs round a window that have failed
- Cracked mastic round a front door frame
Managing a site like Cobham Primary School? Then larger buildings have plenty of frames, and the mastic around each one ages.
Before you book anyone
- Whether VAT is included
- Whether they’re fully insured
- How the joint is cleaned and prepared
- Who turns up on the day
Landlords, agents and businesses in Round Street
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements.
Landlords and agents in Round Street can book us as well as homeowners. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
What sand mastic looks like in Round Street
Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. With historic houses such as Cobham College (about 0.9 miles east) nearby, there’s older building stock in the area around Round Street as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
For landlords with property near Sole Street station, older sash windows in a rental need their mastic kept sound to keep the weather out. For an older house near a landmark such as St Mary's Room, the joint between an old wall and a newer frame is usually the first place rain gets in.
Round Street is about 3 miles south of Gravesend, in Kent. Homes, rented property, offices and hotels in Round Street can book us for sand mastic. The work is guaranteed for a year. Our Kent coverage runs to 922 places, Round Street among them. We also work in London, around 22 miles away.
Work in DA13 is quoted and booked the same way as anywhere else. Neighbouring places we cover for sand mastic include Sole Street (1 mile south), Gold Street (1 mile south-east), Nash Street (1 mile west), Meopham (1 mile south-west) and Henley Street (1 mile south-east). We also work in nearby towns such as Maidstone (11 miles south-east), Dartford (8 miles north-west), Sevenoaks (11 miles south-west), Gravesend (3 miles north), Tonbridge (14 miles south) and Northfleet (3 miles north-west).
What’s near Round Street
Around Round Street, our work takes us to homes and buildings near The Railway Inn, Jeskyns and Meopham School and the streets around them. For rail, the closest station is Sole Street station, roughly 0.6 miles south. Well-known places in the area include Gravesham Museum (3.5 miles north) and Gravesham Community Hospital (3.6 miles north). Open spaces near Round Street include Gad's Hill and Ranscombe Farm.