Hampshire · England
External Mastic in South Wonston
External mastic for South Wonston, by sealant specialists with 20+ years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Rain getting behind render or cladding at a joint
- Sealant that has lost its bond to the brick or render
- Movement joints filled with mortar instead of sealant
External mastic for homes and businesses in South Wonston
A movement joint is a deliberate break that lets a wall expand and contract. The sealant in it has to stretch and squeeze for years, so once it splits or hardens, the joint stops working and water gets in. We work on copings & trims, concrete & block and joints between brick and frames, and the jobs we see most are failed sealant between panels on a façade and hard, crazed mastic that has stopped moving.
Somewhere as small as South Wonston, homes and farm buildings often face open ground, so walls and rooflines take the full force of wind and rain. Joints on those walls need a sealant that moves with the building and stays in place.
A 12-month guarantee comes with the work, just as it does everywhere we cover.
- Location
- South Wonston (SO21)
- Region
- Hampshire
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Aftercare tips
So the new joints stay in good condition:
- Never let anyone fill a movement joint with mortar
- Tell anyone working on the walls about the movement joints
- Get split or bare joints resealed while the damage is small
- Check the sealant is paintable before painting near it
Don’t let soil, plants or ivy build up against the new joints. Anything that holds water against the joint wears it out sooner.
Leaks behind façade panels and render often go unseen. When it finally shows inside, the joint may have been open for years, so it’s worth resealing at the first signs.
Surface by surface
Copings and trims
Coping and trim joints face rain and sun head on. Each is resealed with a weatherproof, flexible sealant.
Brickwork movement joints
Clay brickwork grows slightly over its life and moves with the weather. The movement joint takes that up, so the sealant in it must stay soft and stretchy.
Outside joints around South Wonston
London and the South East are among the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
For site and facilities teams at buildings such as South Wonston Primary School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. For an older house near a landmark such as St Margaret's, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
South Wonston is about 4 miles north of Winchester, in Hampshire. Jobs in South Wonston get the same care as everywhere else we work: old sealant removed completely, careful preparation and a 12-month guarantee. Our area takes in 683 places across Hampshire, from the larger towns to small villages. Southampton is on our list too, around 14 miles away.
Here we cover the SO21 postcode area for external mastic. Whether your property is on Norris Gardens, Wrights Way and Lovell Close or a nearby road, our applicators can take on the job. If you’re just outside South Wonston, we cover Worthy Down (1 mile south), Springvale (2 miles south-east), Sutton Scotney (2 miles north), Stoke Charity (2 miles north-east) and Hunton (3 miles north). Within a short drive, we also cover Basingstoke (14 miles north-east), Winchester (4 miles south), Eastleigh (11 miles south), Andover (9 miles north-west), Chandler's Ford (10 miles south) and Alton (15 miles east).
What’s near South Wonston
The closest station to South Wonston is Winchester station, roughly 3.7 miles south. Well-known places in the area include Royal Hampshire County Hospital (4 miles south) and Winchester Castle (4.1 miles south). For a walk, there’s Winnall Moors.
Do you need external mastic in South Wonston?
Many joints fail because they were sealed too deep or with nothing behind them. If the sealant sticks to the back as well as the sides, it cannot stretch and rips as the joint opens.
It’s worth asking for a quote if you see:
- Weathered mastic that no longer stretches
- Joints where the bead has come unstuck
- Leaking joints around cladding and façade panels
- Rigid filler in a joint that should flex
Rented homes near Winchester station change hands often, and outside joints that have cracked can let damp into a rental, so check them between lets.
Before you book anyone
- The length of the guarantee
- Is the old sealant removed completely?
- What product goes in the joint
- Whether VAT is included
Also near South Wonston
More services for South Wonston
DIY sealant or a professional job?
Some sealant jobs are within reach of a careful DIYer, 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.
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it peels away and traps moisture behind it. All the old material has to come out first.
South Wonston questions
Do you cover South Wonston for external mastic?
Yes. Our work covers London and the South East, and South Wonston is part of that. Just call 0345 464 0079 or send us an email with a few details of the job.
Do you work for landlords with property near Winchester station?
Yes, rental work is part of what we do. You can phone 0345 464 0079 or send us an email with the address and a few details, and we’ll give you a fixed price before we start.
How long does external mastic last?
That depends on the wall, the weather and the movement. Look for splits, hardening or edges coming away and have them redone then.
What do you need from me for a quote?
The location, the problem and the rough size of the job. Photos by email help too.
Can you seal joints between render and window frames?
Yes. Different materials move at different rates, so the joint between them must be flexible. The sealant is matched to both sides.
Will you leave a mess?
No. We work neatly, protect the area around the joints and tidy up afterwards.
How long before the joint can be used?
Different products cure at different speeds, so please follow the time we give you when we finish.
What do you put in the joint?
Products from Arbo and Everbuild, among others, picked for each joint. We’ll tell you what we are using and why.
For landlords and businesses
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.
We also work for businesses, from offices to washrooms and kitchens. For commercial premises, we can talk through working times when we quote.
What sealant work can’t fix
We’ll always be straight with you, so here’s what new sealant won’t do:
- Structural movement, which needs a surveyor or engineer
- Cracked brickwork or render that needs a builder or plasterer
- Loose or hollow render, which needs re-rendering
If you’re not sure, just phone 0345 464 0079 or send us an email and we’ll give you a straight answer.
What we seal
- Joints between brick and frames
- Façade panels
- Concrete & block
- Brickwork movement joints
- Copings & trims
- Render & cladding joints
What we do, step by step
At the end, we look at the finished work together and explain the cure time. The visit itself generally takes anything from a few hours to several days, depending on the building, depending on the size of the job. In a small place like South Wonston, access is generally the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
How to prepare
- Mention any tricky access
- Mention any parking rules near the property
- Mention any sign-in or site rules at work premises
Getting a quote
We quote each job on its own, so the first step is telling us about yours. Just phone 0345 464 0079 or send us an email with the details, and pictures are welcome.