West Sussex · England
Sharpthorne Window Mastic
Professional window mastic in and around Sharpthorne, with every bit of old sealant taken out first and a 12-month guarantee.
- Rain getting in at the frame or under the sill
- Cracked internal joints between frame and plaster
- White mastic on grey or black frames
About our window mastic in Sharpthorne
Behind a thin line of old mastic there’s sometimes a deep void. Filling it with sealant alone leaves a joint that can’t move properly, so we fit backing rod to set the right depth. That way the new bead bonds to the frame and the wall only. We work on uPVC windows, composite doors and aluminium frames, and common reasons people get in touch are cold air getting in at the frame edge and draughty joints inside around the window.
Homes in small places like Sharpthorne 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.
You get a 12-month guarantee, the same in Sharpthorne as everywhere else we work.
- Place
- Sharpthorne (RH19)
- Region
- West Sussex
- Guarantee
- A year, on every job
- Price
- A clear price before work begins
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What we do, step by step
A visit follows a simple pattern: we check the joints, protect the area around them, carry out the job and clear up. Most jobs take anything from an hour or two to a full day, depending on how many frames there are. Somewhere as small as Sharpthorne, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- First, we go round the frames with you and agree the list.
- The old mastic is cut out and scraped back to clean surfaces.
- Where the gap is deep, backing rod goes in first.
- The new sealant goes on in white, brown, anthracite grey, black or clear to suit.
- Every joint is tooled smooth and checked before we leave.
Before we arrive
- Tell us about access, such as stairs, a lift or high-level joints
- Where the joints are inside, avoid wetting them before we arrive
- Clear items away from the joints we’re working on
Get a quote
Every job is quoted individually, so start by telling us what you need. Just call 0345 464 0079 or email us with the details, and photos are welcome.
Advice
Keeping the joints in good condition
Simple care keeps the joints in good condition. Our advice:
- Clear any debris from frame drain holes
- Avoid harsh chemicals near the mastic
- Do not aim a pressure washer at the joints
- Clean frames with a soft cloth and soapy water
Check the drainage slots in the frames are not blocked, so water can run away instead of sitting against the joint.
A failed joint lets water into the wall a little at a time. You might not see it until plaster blows or a damp patch appears inside. Early resealing stops it reaching that point.
How the job changes by surface
Patio & French doors
Patio and French doors have the longest joints on most houses. Most leaks start at the bottom corners, so we pay close attention there.
uPVC windows
Plastic frames move a lot between a hot afternoon and a cold night, so we use a flexible, low-modulus sealant. We match white, brown, anthracite grey and black frames.
Nearby places to Sharpthorne
Also in Sharpthorne
DIY versus a professional finish
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and does not move well, and getting the depth right matters as much as the look.
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
Why it’s worth doing now in Sharpthorne
The work is quick compared with the damage it prevents: it takes a few hours for a handful of frames, longer for a whole house. Wait for damp to appear and there may be plaster and decorating to sort out too. Around Sharpthorne, older homes often have timber in their floors and frames, where water from a failed joint can cause rot if it’s left.
Rather than a set price list, we look at what your job involves: the amount of work, the old material and the access. You’ll know the price before we begin.
Why choose Mr Mastic in Sharpthorne
- We leave the area clean and tidy
- Sanitary silicone with an anti-fungal additive in wet areas
- 20+ years of sealant experience
- We’re fully insured
Take a look at our cost guide and our reviews.
Questions from Sharpthorne
Do you cover Sharpthorne for window mastic?
Yes, Sharpthorne is within the area we cover. We work across London and the South East. Just phone 0345 464 0079 or email us with a few details of the job, and we will give you a clear price.
Do you cover smaller places like Sharpthorne?
Yes, Sharpthorne is covered. Our work covers London and the South East, from towns to the smallest places. The journey is planned ahead, so it helps to know about access.
Will the old sealant be removed?
Yes. Sealing over the old bead is the commonest cause of early failure, so we never do it.
Is it worth trying it myself?
You can, for simple jobs. Preparation is everything: all the old sealant out, and a clean, dry joint. We can always put it right if it fails.
Where are you based?
We are based in Crawley, West Sussex, and we cover South East England, London and all of Scotland.
Does someone need to be in?
That depends on where the joints are. For work indoors, someone needs to let us in.
Does the work come with a guarantee?
Yes, with our one-year guarantee. Keeping drainage clear and checking the joints yearly helps them last.
Can you seal over the old sealant?
No, it will not last. It can look neat for a few weeks, but the new bead soon lifts. Removing the old sealant completely is the only lasting way.
Signs you need window mastic in Sharpthorne
Joints that are too thin or too deep fail early. A skim of sealant over a wide gap soon tears, while a joint packed solid cannot stretch. That is what backing rod is for.
The most common problems we see are:
- Whistling draughts around closed windows
- Rushed sealant from a window installation
- Leaking joints at the ends of sills
- Cracked or shrunken mastic around the frame
For an older house near a landmark such as St Margaret's Church, the joint between an old wall and a newer frame is usually the first place rain gets in.
What your quote should include
- Who turns up on the day
- How long the guarantee is
- Are they insured?
- How the surfaces are prepared before sealing
Sharpthorne homes and the weather
With historic houses such as Priest House (about 0.5 miles west) nearby, there’s older building stock in the area around Sharpthorne as well as newer homes. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Schools such as West Hoathly CofE Primary School are buildings too, and larger buildings have plenty of frames, and the mastic around each one ages. Letting a property close to East Grinstead station? Then cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Sharpthorne is about 4 miles south of East Grinstead, in West Sussex. Jobs in Sharpthorne get the same care as everywhere else we work: old sealant removed completely, careful preparation and a 12-month guarantee. 371 places in West Sussex are on our list, from the larger towns to small villages. Our Crawley page covers work nearby (7 miles or so).
All of RH19 is covered for window mastic, from the main roads to the quietest streets. Streets in the area include Station Road, Marlpit Road and Bayhams Field, all of which we cover. Neighbouring places we cover for window mastic include West Hoathly (1 mile west), Highbrook (2 miles south), Selsfield Common (2 miles north-west), Little London (2 miles south-west) and Birchgrove (3 miles south-east). Larger places within reach include Crawley (7 miles west), Horsham (12 miles west), Haywards Heath (6 miles south-west), Burgess Hill (9 miles south-west), East Grinstead (4 miles north) and Broadfield (7 miles west).
What’s near Sharpthorne
We work in homes and buildings around The Fox pub and the streets around them. For rail, the closest station is East Grinstead station, about 3.6 miles north of the centre. Nearby you will also find Waterbury Castle (2.6 miles south) and East Grinstead Museum (3.7 miles north-east). For a walk, there’s Hedgecourt Lake.
For landlords and businesses
Mouldy or split sealant often shows up at the end of a tenancy, and it’s quick to put right between tenancies. We can quote for more than one property at once.
Water getting past a failed joint can damage the building, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance that we can handle for you.