Hampshire · England
External Mastic in Alverstoke
Our applicators work in Alverstoke on sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly.
- Weathered mastic that no longer stretches
- Movement joints with cracked, split or missing sealant
- Plants rooting in failed movement joints
External mastic in Alverstoke, done properly
Ground-floor and low-level joints are straightforward to reach. Where joints are higher up, tell us about the building when you get in touch and we will confirm what’s needed to reach them safely. We work on joints between brick and frames, copings & trims and façade panels, and people most often call us about sealant pulling away from one side of the joint and leaking joints around cladding and façade panels.
Somewhere as small as Alverstoke, homes and farm buildings often face open ground, so walls and rooflines take the full force of wind and rain. Gutter joints and wall joints there need a sealant that can flex and stay put.
Whatever the size of the job, you get the same one-year guarantee.
- Place
- Alverstoke (PO12)
- Region
- Hampshire
- Guarantee
- One year on every job
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
What external mastic looks like in Alverstoke
Alverstoke is close to the coast, where wind-driven rain is a fact of life and, nearer the shore, so is salt air. Both are hard on movement joints and outside wall joints, which can dry out and crack sooner where a building faces the weather. The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
For an older house near a landmark such as The Little Church, old and new materials meet at the roofline and walls, which is where sealant earns its keep. For landlords with property near Portsmouth Harbour station, split movement joints are easy to miss on a rental until damp shows inside.
Alverstoke is about 2 miles south of Gosport, in Hampshire. Whether you are in the middle of Alverstoke or further out, we cover external mastic for every kind of property, from flats and houses to offices and hotels. Across Hampshire, we cover 683 places, Alverstoke among them.
We work across PO12 for external mastic and the streets around it. External mastic is available to properties on The Lane, Fort Road and Church Road. Neighbouring places we cover for external mastic include Clayhall (1 mile east), Haslar (1 mile east), Privett (1 mile north-west), Portsmouth Point (2 miles north-east) and Portsea (2 miles north-east). We also work in nearby towns such as Havant (9 miles north-east), Fareham (5 miles north), Horndean (11 miles north-east), Hedge End (12 miles north-west), Waterlooville (9 miles north-east) and Purbrook (8 miles north-east).
Around Alverstoke
Locally, jobs take us to homes and businesses close to Bay House School and Village Home pub and the streets around them. Alverstoke’s nearest station is Portsmouth Harbour station, about 2.1 miles north-east. Well-known places in the area include Tricorn Centre (3 miles north-east) and Gosport War Memorial Hospital (0.9 miles north). The countryside around Alverstoke includes West of the River Alver.
More services for Alverstoke
When something else is needed
Some problems need a builder, plumber or other trade rather than us:
- Damp that is not coming from the joint
- Movement that’s more than a sealant joint can take
- Walls that need new movement joints cut into them
Not sure which it is? You can call 0345 464 0079 or drop us an email and we’ll tell you honestly.
Where we work in Alverstoke
- Render & cladding joints
- Façade panels
- Brickwork movement joints
- Concrete & block
- Joints between brick and frames
- Copings & trims
DIY versus a professional finish
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
The biggest DIY mistake is sealing over old sealant. Silicone doesn’t stick to old silicone, so it lifts and traps water and mould underneath. Everything old must be removed first.
Looking after it afterwards
Simple care keeps the joints in good condition. We recommend:
- Check external joints each spring
- Ask before painting over external sealant
- Don’t let climbing plants root in the sealant
- Keep movement joints as flexible joints, not mortar
Only paint over the joint if we’ve confirmed the sealant can take paint. Paint can crack on a flexible joint and spoil the finish.
Gaps, plants or missing sealant in a joint are worth getting looked at. Early work is quicker and leaves a better finish.
How it works
Once we’re on site, we check the joints match what you told us. If anything is different, we explain it before carrying on. After that, the work takes a few hours to a few days, depending on the length of joint and the access. Somewhere as small as Alverstoke, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- We inspect the joints and agree which need resealing and how they’ll be reached.
- We cut out the failed sealant and rake out any dirt or growth.
- Both sides are cleaned back to sound material and primed if needed.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
How to prepare
- Clear items away from the joints we’re working on
- Mention any tricky access
- Tell us if parking is tricky
Get a quote
It all starts with a short chat. Describe the problem, the location and the size of the job, and we will explain how we’d tackle it. Whenever you are ready, phone 0345 464 0079 or send us an email.
Related advice
Common questions in Alverstoke
Can you help a landlord with a rental near Portsmouth Harbour station?
Yes, rental work is part of what we do. Just call 0345 464 0079 or send us an email and tell us about the property, and we’ll give you a clear quote.
Is external mastic in a coastal place like Alverstoke any different?
Near the coast, wind-driven rain and, nearer the shore, salt air make outside sealant work harder. Choosing the right sealant for the frame and wall, laid at the right depth, helps it last.
Can you work on commercial sites?
Yes, regularly. We can plan bigger jobs in stages.
Where are you based?
We work from Crawley. Our applicators cover Alverstoke.
Should I try DIY first?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs.
Do you hold any approvals?
Yes. We hold ARBOMaster approved applicator status, and we are fully insured.
Do you work in Alverstoke?
Yes. From our base in Crawley, we cover South East England, London and all of Scotland, and that includes Alverstoke.
Do I have to be there?
It depends on the job. Inside work needs someone to give us access, while outside work can sometimes be arranged differently.
Do you need external mastic in Alverstoke?
UV, rain and frost all age exterior sealant. Over the years it hardens, cracks on the surface and loses its give, so the joint eventually tears or comes away from one side.
It’s worth asking for a quote if you see:
- Old sealant gone brittle and cracked
- Joints pointed up with cement by mistake
- Moss and dirt in joints with no sealant left
- Panel joints letting water in
For site and facilities teams at buildings such as Alverstoke Community Infant School, larger buildings have long runs of movement joint that eventually need resealing.
Questions to ask before you book
- Which colour the sealant will be
- What guarantee comes with the work
- What product goes in the joint
- Is the old sealant removed completely?
What happens if it’s left?
The longer a joint stays open, the more water the wall takes in. Wet masonry is more easily damaged by frost near the open joint, so the problem grows beyond the joint itself. Older cottages and farmhouses around Alverstoke can have timber floors and frames, where water from a failed joint can cause rot if it’s left.
No two jobs are quite the same, so each one gets its own quote. Size, access and the product the joint needs all play a part, and we will explain the quote if you ask.
What you get with us
- We never seal over old sealant
- One-year guarantee on every job
- Over 20 years’ experience
- 180+ five-star Google reviews
See our cost guide and customer reviews.
How we quote for external mastic
The price is agreed before any work begins. It takes into account:
- How many areas need sealing
- The type of sealant required
- The size of the job
- Mould in or behind the old joints
Leaving a failed joint usually makes the job bigger, not smaller. If you’re unsure, phone 0345 464 0079 or email us and we will give you an honest view and a quote.
What to tell us for a quote
You don’t need to know the technical terms. It helps if you can tell us:
- Where the property is
- Photos by email, if that is easy
- Whether it’s a home or a business
- Any access issues, like height or stairs
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To get started, phone 0345 464 0079 or drop us an email.