Hampshire · England
Keyhaven External Mastic
External mastic in Keyhaven from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Plants rooting in failed movement joints
- Movement joints filled with mortar instead of sealant
- Old sealant gone brittle and cracked
How to look after the new joints
Good habits help new joints last longer. Our tips:
- Act on the first splits you see
- Deal with leaking gutters that soak the joints below
- Leave the joints unpainted unless we’ve said otherwise
- Make sure movement joints are not pointed over
Do not let soil, plants or ivy build up against the new joints. Anything that holds water against the joint wears it out sooner.
If you can see gaps, plants or bare sections in a joint, have it checked. Earlier resealing means a smaller job and a better result.
External mastic for homes and businesses in Keyhaven
For buildings in Keyhaven, we reseal external joints of all kinds, from brick movement joints to cladding panels. The preparation is the same whatever the wall: clean, sound faces and a controlled depth. If you have water getting into walls through failed joints and plants rooting in failed movement joints, we can help, whatever the surface.
External sealant needs dry, clean surfaces, so work around Keyhaven is planned for dry weather. Tell us about access to all sides of the building, including outbuildings and garages.
All our work is covered by our 12-month guarantee.
- Where
- Keyhaven (SO41)
- Region
- Hampshire
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
When to call us in Keyhaven
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.
Keep an eye out for any of the following:
- Cracked joints where brick meets render or frames
- Brick movement joints where the sealant has split
- Weeds or debris growing in open joints
- Panel joints letting water in
In the older streets around Church of All Saints, an extension built onto an older house moves differently, and the joint between them takes the strain.
What your quote should include
- What happens if the job turns out different
- What guarantee comes with the work
- How much experience the applicator has
- Is the old sealant removed completely?
How we quote for external mastic
You will get a clear quote before work begins. It takes into account:
- When we can work, for business premises
- How many rooms, windows or areas are involved
- How much old sealant there is and how hard it is to remove
- Any mould that needs treating
There are no prices on our website, because the cost depends so much on the job itself. Call for a quick quote.
What to tell us for a quote
Photos help, but a description is a good start. Try to tell us:
- The type of property
- A few photos by email, if you can
- How many joints, rooms or windows are involved
- How we’d reach the joints
Getting a quote is simple: tell us what needs doing and where. Photos by email help us understand the job, and we will take it from there.
Work for landlords, hotels and businesses
For anyone letting property in or around Keyhaven, several properties can go on one quote. Send us the addresses and the work at each.
We work for letting agents and landlords as well as homeowners. Resealing between tenancies is a simple way to keep a property in good order before the next move-in.
Common questions in Keyhaven
I let a flat near Lymington Town station. Can you help?
Yes. We work for landlords and letting agents as well as homeowners. Just call 0345 464 0079 or send us an email with the address and what needs doing, and we will give you a clear quote.
Does living near the coast affect external mastic in Keyhaven?
Near the sea, outside joints face more wind, rain and salt than they would inland, so preparation and the right sealant matter all the more. It’s worth checking the walls that face the sea first.
What does external mastic cost?
It depends on the job, so we quote each one individually. To get one, ring 0345 464 0079 or send us an email and tell us what needs doing and where.
Which products do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. We use products from Arbo and Everbuild.
Where do you work from?
Our base is in Crawley, West Sussex, and we work across South East England, London and Scotland.
Do you seal joints where cladding meets other materials?
Yes. We cut out the old sealant, prepare both faces and reseal with a flexible exterior product. The colour is chosen to suit.
Do you guarantee your work?
Yes. Every job comes with a 12-month guarantee.
Should I point up the gap in my brickwork?
No. Mortar locks the joint solid, so the wall cracks somewhere else instead. It needs a flexible sealant over backing rod.
How it works
You do not need to clear the whole room or building before we come, only the area right around the joints. Everything nearby is protected, and the job takes a few hours for a handful of joints, longer for a whole elevation for a typical job. For a village or hamlet like Keyhaven, the journey is planned in advance: let us know about lanes, gates and parking. Everything for the job comes with us, so a second trip is avoided where possible.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
How to prepare
- Plan for the work area to be out of bounds to pets and children
- Try not to wet indoor joints just before the visit
- Mention any sign-in or site rules at work premises
Ask for a quote
Need a quote? Please call 0345 464 0079 or send us an email with a few details. We will explain what we’d do and give you a clear quote before work begins.
Read more
Also near Keyhaven
What else we do in Keyhaven
How the job changes by surface
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. The movement joint takes that up, so its sealant has to stay flexible.
Cladding and façade panels
If the façade has a specified sealant, that’s what we use or an approved alternative. Send us any details you have about the façade.
Outside joints around Keyhaven
Keyhaven is within about 1 mile of the coast, and homes near the sea take more wind-driven rain, with salt in the air closer to the shore. That’s hard on movement joints and outside wall joints, especially on the side facing the sea. 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.
Managing a site like Milford-on-Sea Church of England Primary School? Then its movement joints, gutters and trims need looking after like any other building’s. Rented homes near Lymington Town station change hands often, and split movement joints are easy to miss on a rental until damp shows inside.
Keyhaven is about 3 miles south of Lymington, in Hampshire. Every kind of property in Keyhaven is covered for external mastic, old or new, large or small. Every job comes with our one-year guarantee. Across Hampshire, we cover 683 places, and Keyhaven is one of them. You can also see our page for Southampton, roughly 16 miles from Keyhaven.
Our applicators cover all of SO41 for external mastic. Whether your property is on New Road, Keyhaven Road and Saltgrass Lane or anywhere close by, our applicators can take on the job. We also cover the places around Keyhaven: Milford on Sea (1 mile west), Lymore (1 mile north-west), Lower Pennington (1 mile north-east), Everton (2 miles north-west) and Pennington (2 miles north). Larger places within reach include Totton (14 miles north), Hythe (12 miles north-east), New Milton (4 miles north-west), Ringwood (13 miles north-west), Warsash (15 miles north-east) and Barton on Sea (4 miles west).
Local landmarks in Keyhaven
Typical jobs here are in homes near The Gun Public House and Priestlands School and the streets around them. For rail, the closest station is Lymington Town station, roughly 3 miles north-east. A little further out are St Barbe Museum and Art Gallery (2.8 miles north-east) and Yarmouth Castle (3.3 miles east). The countryside around Keyhaven includes Milford on Sea LNR and Tennyson Down.
Should I try it myself first?
A DIY attempt does not rule out a professional job. We cut it out and start again.
If you’re set on DIY, put the effort into preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it fails, we can still redo it.