West Sussex · England
Sand mastic for sash & case windows in Crawley, West Sussex
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homes and businesses in Crawley and across West Sussex. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- A silicone bead on a sash window that spoils the look
- Mastic dropping out of the joint
- Mastic worn away on windows facing the weather
Windows and doors in Crawley
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. Crawley was built as one of England’s post-war new towns. Many homes date from the post-war decades, and many will have had their original windows replaced. That mastic ages as well, and sills and frame heads are where leaks start.
If you look after a building such as Three Bridges Junior School, larger buildings have plenty of frames, and the mastic around each one ages. In the older streets around Friary Church of St Francis and St Anthony, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Crawley is about 27 miles south of London, in West Sussex. Homes, rented property, offices and hotels in Crawley is covered for sand mastic, old or new, large or small. Every job comes with our one-year guarantee. 371 places in West Sussex are on our list.
We cover every part of the RH10, RH11, RH12 and RH6 postcode area for sand mastic. Local streets include Station Road, Queens Square and High Street. You will find Crawley on the A23 and A264, which makes it straightforward to reach. Neighbouring places we cover for sand mastic include Southgate (1 mile south-west), Tilgate (1 mile south-east), West Green (1 mile north), Three Bridges (1 mile east) and Langley Green (1 mile north). Larger places within reach include Horsham (7 miles south-west), Haywards Heath (9 miles south-east), Burgess Hill (11 miles south), East Grinstead (8 miles east), Billingshurst (13 miles south-west) and Roffey (5 miles south-west). As one of the bigger places in West Sussex, Crawley has every kind of property, from flats to offices.
Local landmarks in Crawley
Locally, jobs take us to homes and businesses close to Tilgate Park, St Wilfrid's Catholic School and St Francis of Assisi Catholic Primary School. There’s a railway station in Crawley itself: Crawley station. A little further out are Crawley Hospital (0.5 miles north-west) and County Mall (under half a mile north-east). Not far away are Tilgate Lake.
How we handle sand mastic in Crawley
We work across Crawley renewing sand mastic on sash windows and doors. Every joint is cleaned out and filled by hand for a neat, traditional finish. Typical jobs include gaps where the frame meets the masonry and weathered mastic on the most exposed windows, on sash and case windows, timber door frames and brick reveals.
Beyond its homes, Crawley has shopfronts, offices and flats with plenty of frames and glazing. Failed joints up there let in water that can go unnoticed for a while.
All of our work is guaranteed for twelve months, and the guarantee is the same wherever you are.
- Where
- Crawley (RH10, RH11, RH12, RH6)
- Wider area
- West Sussex
- Cover
- 12 months on all our work
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What happens on the day
All our tools and materials come with us in the van, so you do not need to buy or prepare anything. After a quick look at the joints together, the area is protected and the work begins. It normally takes a few hours per window, depending on the condition of the joints. In Crawley, we work in everything from flats and family homes to offices and hotels. Whichever it is, tell us how to get in, where to park and where the work is.
- Each surround is checked first.
- We rake out the old mastic and clean the joint.
- Large voids are packed out.
- New sand mastic is applied and shaped by hand.
- We finish the mastic to a tidy line.
Before we arrive
- Tell us about access, such as stairs, a lift or high-level joints
- Keep pets and children clear of the area while we work
- Tell us if parking is tricky
Get a quote
Getting a quote is simple: let us know the job and the location. Photos by email help us understand the job, and we’ll come back to you with a quote.
Advice
Surface by surface
Stone surrounds
Old stone surrounds are often uneven, so the gap isn’t the same all the way round. We shape it by hand to follow the stone.
Timber door frames
Sand mastic is used round timber door frames too. We renew it the same way as on windows.
Your questions about sand mastic in Crawley
Is it worth replacing old sealant in an older home in Crawley?
If it hasn’t been replaced for some years, it’s normally worth it. Sealant doesn’t last for ever, and its life depends on use, cleaning and weather.
Can you do sand mastic in Crawley?
Yes, Crawley is within the area we cover. Our work covers London and the South East. You can phone 0345 464 0079 or send us an email and tell us what needs doing, and we’ll send you a clear quote.
What is sand mastic?
It’s a mix of sand and a linseed-oil-based binder. It’s built up in the joint by hand and shaped to suit the surround.
Do you take out the old sealant first?
Yes. All of the old material is cut out and the joint cleaned before resealing.
What information do you need?
Tell us what needs doing and where, plus photos if you have them. We will ask anything else we need to know.
Should I check with the council before work on a listed or conservation-area home?
Your local planning authority is the one to ask. They decide whether consent is needed.
Is the work guaranteed?
Our 12-month guarantee applies on every job.
When will the new mastic be hard?
Not straight away. The skin forms first, and the full set comes later, and we will tell you what to expect.
When to call us in Crawley
Sand mastic slowly weathers. It hardens, cracks and starts to come away from the frame or the masonry.
Any of these means the joints need attention:
- Open joints round the window box
- Silicone on a period window that looks wrong
- Patchy fillers round a sash window
- Mastic dropping out of the joint
Letting a property close to Crawley station? Then cracked sand mastic around sash windows lets in the draughts tenants complain about.
Before booking anyone
- When the joint can take water or movement
- Are they insured?
- How the surfaces are prepared before sealing
- What product goes in the joint
Why deal with it now?
Cement-based fillers and modern sealants do not always suit a period surround. Sand mastic matches what was there and that can be important for listed homes. For businesses in Crawley, a room closed because of a leak or mould costs more than the sealant, so failing joints are best replaced on a planned basis.
What you pay reflects the work, not guesswork. That is why we ask a few questions first and agree the price before starting.
Why us?
- Old sealant always removed completely
- Anti-fungal silicone where joints get wet
- Rated 4.9 stars on Google
- We leave the area clean and tidy
See what affects the cost and our reviews.
How we quote for sand mastic
Call for a quick quote. What matters most is:
- Whether the work is at height
- The type of sealant required
- Whether there’s mould to deal with
- How many areas need sealing
Commercial jobs are quoted on the same basis as homes: the amount of work, how we reach it and what it needs. Call for a quick quote and we’ll go through it with you.
What to tell us for a quote
A few details help us give you an accurate quote. When you ask for a quote, tell us:
- Photos by email, if that’s easy
- How we’d reach the joints
- How many joints, rooms or windows are involved
- What’s wrong with the joints now
To get a quote, ring 0345 464 0079 or send us an email with the location and a short description of the problem. We’ll give you a clear quote before any work starts.
Landlord and commercial work in Crawley
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance that we can handle for you.
Housing providers, facilities teams and property managers book us too in Crawley and across West Sussex. We can quote a run of properties together.
Should I try it myself 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.
Sealing over old silicone is the commonest DIY error. Silicone doesn’t stick to old silicone, so it peels away and traps moisture behind it. Everything old must be removed first.