West Sussex · England
Sand Mastic in Keymer
Specialist sand mastic for Keymer: careful preparation, the right product and tidy work. Call for a quick quote.
- Cement or filler used on old window joints that has cracked
- Mastic dropping out of the joint
- Window mastic to renew ahead of painting
How we handle sand mastic in Keymer
Traditional burnt sand mastic blends with stone and brick surrounds. It’s a good fit for period properties where a modern sealant bead would stand out. If you are dealing with mastic round period door frames that has failed and weathered mastic on the most exposed windows, we can help, on tenement windows, period & listed homes and brick reveals alike.
Around Keymer, conservatories, garden rooms and patio doors are often part of the house. Those joints need the same attention as the main windows.
There’s a 12-month guarantee on every job.
- Location
- Keymer (BN6)
- Region
- West Sussex
- Guarantee
- One year on every job
- Quote
- A clear quote up front
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
What happens on the day
We work through the job in order: protection first, then preparation, sealing and a tidy-up. For most jobs that takes a few hours for a single window, longer for several. A visit to Keymer is planned like any other: the time, the access and where to park are agreed in advance. If the work is outside, the weather plays a part, as sealant needs a dry surface.
- First we agree which joints need doing.
- Old mastic and any loose material are raked out.
- We pack any deep voids first.
- We apply the mastic by hand and shape it.
- The surface is finished to suit the stone or brick.
Before we arrive
- Tell us about any previous sealing or DIY attempts
- Where the joints are inside, avoid wetting them before we arrive
- Let us know about stairs, lifts or work at height
Get a quote
The more we know about the job, the more useful the quote. Tell us where the job is, what’s wrong and how much there is, and add photos by email if you can.
Read more
What sand mastic looks like in Keymer
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.
In the older streets around St Cosmas and St Damian Church, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall. If you let a flat or house near Hassocks station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
Keymer is about 2 miles south of Burgess Hill, in West Sussex. Our applicators cover sand mastic for homes and businesses in Keymer and nearby. 371 places in West Sussex are on our list, large and small. Our Brighton page covers work nearby.
All of BN6 is within our area for sand mastic. That includes homes and businesses on Flowers Close, The Quadrant and Kymer Gardens and the roads around them. We also cover the places around Keymer: Hassocks (1 mile west), Ditchling (1 mile east), Clayton (1 mile south-west), Hurst Wickham (1 mile north-west) and Westmeston (2 miles south-east). Within a short drive, we also cover Crawley (13 miles north), Horsham (13 miles north-west), Worthing (14 miles south-west), Haywards Heath (5 miles north), East Grinstead (15 miles north) and Shoreham-by-Sea (8 miles south-west).
Landmarks near Keymer
We work in homes and buildings around The Greyhound Public House and Downlands Community School. The closest station to Keymer is Hassocks station, roughly 0.5 miles west. Other landmarks nearby include The Dene Hospital (3.2 miles north-west) and Clayton Castle (1.2 miles south-west). The countryside around Keymer includes Ditchling Beacon and Bedelands Farm Nature Reserve.
Towns and villages near Keymer
Other services in Keymer
Signs you need sand mastic in Keymer
Paint, silicone or cement used over old mastic causes problems. They don’t move with the timber and we normally remove them.
People normally contact us after spotting something like this:
- Weathered mastic on the most exposed windows
- Cement or filler used on old window joints that has cracked
- Mastic that needs renewing before redecorating
- Gaps round a timber door in stone or brick
Managing a site like The Windmills Junior School? Then the mastic around its windows and doors needs looking after like any other building’s.
Comparing quotes
- How the joint is cleaned and prepared
- Whether you can choose the colour
- Who does the work, and how experienced they are
- How long the guarantee is
Should I try it myself first?
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Aftercare tips
Simple care keeps the joints in good condition. Our advice:
- Sort the mastic before the decorators arrive
- Go gently near the mastic when preparing windows
- Make sure water runs off the sill
- Have rotten timber repaired before new mastic goes in
Leave the new mastic unpainted, which is the traditional advice. If you’re redecorating, ask us first.
Renewing mastic before redecorating saves doing it twice. Painting over failed mastic hides the problem for a while.
What affects the cost of sand mastic
Some jobs are bigger than they look, and some smaller. The main factors:
- The size of the job
- Whether old sealant or filler has to be cut out
- Working hours on commercial sites
- How many rooms, windows or areas are involved
What you pay reflects the work, not guesswork. That’s why we ask a few questions first and give you a clear quote before any work starts.
Asking for a quote
To help us quote quickly, let us know:
- The problem you’ve noticed
- If it’s domestic, commercial or a hotel
- Where the property is
- Photos by email, if that’s easy
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is. Whenever you are ready, ring 0345 464 0079 or drop us an email.
What sealant work cannot fix
To be straight with you, there are a few things sealant will not fix:
- Sash cords, weights and draught-proofing of the sashes
- Damaged stone surrounds
- Broken panes
If you are not sure, just ring 0345 464 0079 or send us an email and we’ll give you a straight answer before you book.
Surfaces we seal
- Timber door frames
- Period & listed homes
- Stone surrounds
- Sash and case windows
- Tenement windows
- Brick reveals
Landlord and commercial work in Keymer
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. Several properties can go on one quote.
We also work for businesses, from offices to washrooms and kitchens. On commercial sites, working times can be discussed when we quote.
Keymer questions
Can you help a landlord with a rental near Hassocks station?
Yes, we work for landlords and agents. Just phone 0345 464 0079 or email us and tell us about the property, and we’ll send you a clear quote.
Can you do sand mastic in Keymer?
Yes, Keymer is within the area we cover. Our work covers London and the South East. You can call 0345 464 0079 or email us and tell us what needs doing, and we will give you a clear quote.
Where are you based?
We are based in Crawley, and we work across South East England, London and Scotland.
How do I get a quote for sand mastic in Keymer?
Size, access and the old material all affect the cost. Call for a quick quote.
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 they decide.
Will it make a mess?
Not at all. The area is protected while we work and cleaned up afterwards.
How long does the job take?
Most jobs take a few hours per window, depending on the condition of the joints, including preparation and clearing up. Your quote will say how long we expect yours to take.
Do you guarantee sand mastic work?
Our 12-month guarantee applies on every job.