West Sussex · England
Horsted Keynes External Mastic
External mastic for Horsted Keynes and the surrounding area: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Rigid filler in a joint that should flex
- Cracked joints where brick meets render or frames
- Leaking joints around cladding and façade panels
External mastic for homes and businesses in Horsted Keynes
Many failed façade joints only get noticed once there’s a stain or a damp patch inside. We look over the joints, agree the ones to renew and reseal with a flexible, weatherproof product in a matching colour. We’re often asked to deal with old sealant gone brittle and cracked and rigid filler in a joint that should flex, across concrete & block, joints between brick and frames and brickwork movement joints.
Somewhere as small as Horsted Keynes, homes and farm buildings often face open ground, where walls and rooflines take the weather head on. Gutter joints and wall joints there need a sealant that can flex and stay put.
You are covered for a year from the day we finish. If there’s a problem with it, please ring 0345 464 0079 or drop us an email.
- Where
- Horsted Keynes (RH17)
- Wider area
- West Sussex
- Guarantee
- One year on every job
- Price
- A clear price before work begins
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Outside joints around Horsted Keynes
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. Historic houses like Priest House (about 3 miles north-west) are a reminder that the area around Horsted Keynes has older buildings as well as new. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth.
Homes close to St Giles' Church include some older properties, and the joints between older walls, newer extensions and the roofline need a sealant that can move. For site and facilities teams at buildings such as St Giles CofE Primary School, larger buildings have long runs of movement joint that eventually need resealing.
Horsted Keynes is about 4 miles north-east of Haywards Heath, in West Sussex. From the centre of Horsted Keynes to the outskirts, external mastic is available for homes and businesses alike, from flats and houses to offices and hotels. Across West Sussex, we cover 371 places, and Horsted Keynes is one of them. Crawley is on our list too, around 9 miles away.
Postcode districts we cover here for external mastic: RH17. We cover properties on Station Road, Rixons Orchard and Leighton Road. If you are just outside Horsted Keynes, we cover Danehill (1 mile east), Birchgrove (2 miles north-east), Highbrook (2 miles north-west), Chelwood Common (2 miles east) and Furner's Green (2 miles south-east). Further out, we also cover Crawley (9 miles north-west), Horsham (13 miles west), Haywards Heath (4 miles south-west), Burgess Hill (7 miles south-west), East Grinstead (6 miles north) and Broadfield (9 miles north-west).
Local landmarks in Horsted Keynes
Around Horsted Keynes, our work takes us to homes and buildings near The Green Man pub. For rail, the closest station is Haywards Heath station, roughly 4 miles south-west. Other landmarks nearby include Waterbury Castle (within half a mile north-west) and Princess Royal Hospital (4.1 miles south-west). Not far away are Blunts Wood and Paiges Meadow.
Also near Horsted Keynes
What else we do in Horsted Keynes
Should I try it myself first?
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and does not move well, and the joint depth matters as much as the finish.
If you’ve already had a go yourself, that is fine. We remove it and do the joint properly, so just mention it when you contact us.
Why deal with it now?
Running new sealant over the old bead rarely lasts. New sealant does not bond well to old, weathered sealant, so we always take the old sealant out. Older cottages and farmhouses around Horsted Keynes can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
What you pay reflects the work, not guesswork. That’s why we ask about the job first and send you a clear quote before any work starts.
Why Horsted Keynes clients choose us
- Every job guaranteed for a year
- 4.9 on Google from 180+ five-star reviews
- Anti-fungal silicone where joints get wet
- 20+ years of sealant experience
What happens on the day
When we arrive, we start by going over the job with you. We protect the surfaces around the joints before any work starts. Most jobs take anything from a few hours to several days, depending on the building. For a village or hamlet like Horsted Keynes, the journey is planned in advance: tell us about narrow lanes, gates, long drives and where we can park. Everything for the job comes with us, so a second trip is avoided where possible.
- We start by walking round the building and agreeing the joints and the access.
- We cut out the old mastic and rake out anything in the joint.
- Joint faces are cleaned back and primed if the sealant needs it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
Before we arrive
- Tell us about access, such as stairs, a lift or high-level joints
- Keep children and pets away from the work area
- Tell us about any previous sealing or DIY attempts
Get a quote
For external mastic in Horsted Keynes, call 0345 464 0079 or drop us an email. A short description of the job and where it is helps us quote, and you’ll get a clear quote before any work starts.
Advice
Surface by surface
Copings and trims
Copings expand and contract through the day, so the joints need a sealant that stays flexible.
Joints between dissimilar materials
Where a frame or panel meets masonry, water often finds a way in. The old joint is removed and a sealant that bonds to both sides goes in.
Horsted Keynes questions
Do you work for landlords with property near Haywards Heath station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or drop us an email and tell us about the property, and we’ll give you a clear quote.
Is Horsted Keynes within the area you cover?
Yes, smaller places are covered as well as towns. We work across London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
Do you guarantee your work?
Yes: twelve months. If anything is not right with the work within the year, let us know and we’ll sort it.
What is a movement joint?
Walls move with heat, cold and moisture, and planned joints take up that movement. It’s closed with backing rod and a flexible sealant.
When is the sealant fully cured?
That depends on the sealant used, so follow the cure time we give you.
Can I do it myself?
You can, for simple jobs. Preparation is everything: all the old sealant out, and a clean, dry joint. If it does not work out, we can redo it.
Are you fully insured?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
Do you use backing rod?
Closed-cell backing rod sets the depth of the sealant and stops it sticking to the back of the joint. That way it bonds to the two sides only and can stretch.
When it isn’t the sealant
Before you book, it’s worth knowing the limits too:
- Render that is blown, hollow or coming away
- Adding movement joints to masonry that has none
- Rising or penetrating damp from elsewhere in the wall
Not sure which it is? You can ring 0345 464 0079 or send us an email and we’ll tell you honestly.
Joints and surfaces we work on
- Concrete & block
- Joints between brick and frames
- Brickwork movement joints
- Copings & trims
- Façade panels
- Render & cladding joints
What we are called out for in Horsted Keynes
Poor preparation causes many early failures: dusty or wet faces, no primer where one was needed, or old sealant left in. The sealant never bonds properly.
Any of these means the joints need attention:
- Old sealant gone brittle and cracked
- Rain getting behind render or cladding at a joint
- Brick movement joints where the sealant has split
- Joints where the bead has come unstuck
For landlords with property near Haywards Heath station, split movement joints are easy to miss on a rental until damp shows inside.
What your quote should include
- What happens if the job turns out different
- What insurance they hold
- How much experience the applicator has
- How the joint is cleaned and prepared
Keeping the joints in good condition
Aftercare is simple, and it makes a real difference:
- Keep movement joints as flexible joints, not mortar
- Ask before painting over external sealant
- Deal with leaking gutters that soak the joints below
- Walk round the building once a year and look at the joints
Make sure anyone working on the wall later knows where the movement joints are. They must stay as flexible joints, never rendered or pointed over.
Once a joint cannot move, the wall finds another way, usually as cracking in the brickwork or render nearby. Catch it early and you reduce the risk.