Hampshire · England
Sandy Down External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Sandy Down and across Hampshire. Fully insured, ARBOMaster approved and guaranteed for a year.
- Brick movement joints where the sealant has split
- Water getting into walls through failed joints
- Sealant pulling away from one side of the joint
How the visit works
We work through the job in order: protect, prepare, seal, tidy. For most jobs that takes anything from a few hours to several days, depending on the building and we leave things clean and tidy. For a village or hamlet like Sandy Down, 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.
- First we look over the joints with you, agree which to renew and talk through access.
- Old sealant and any debris are cut and raked out.
- We clean both faces of the joint and prime them where the product calls for it.
- Backing rod goes in next, setting the depth and keeping the sealant off the back of the joint.
- We gun in a flexible exterior sealant in a colour that suits the wall and tool it neatly.
How to prepare
- Mention if the joints have been sealed before
- Mention any sign-in or site rules at work premises
- Try not to wet indoor joints just before the visit
Getting a quote
Every job is quoted individually. Simply ring 0345 464 0079 or drop us an email and describe the job, and photos are welcome.
Advice
About our external mastic in Sandy Down
Joints in render and cladding are easy to overlook until a damp patch appears. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a matching colour. If you are dealing with cracked joints where brick meets render or frames and rain getting behind render or cladding at a joint, we can put it right, whatever the surface.
Older homes in small places like Sandy Down may be stone, brick or timber-framed, often with later extensions. Where one material meets another is where water usually gets in, and they need the right sealant at the right depth.
The work is guaranteed for twelve months. If something isn’t right with it in that time, tell us and we will put it right.
- Place
- Sandy Down (SO41)
- Wider area
- Hampshire
- Guarantee
- A year, on every job
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
Signs you need external mastic in Sandy Down
Poor preparation causes many early failures: dusty or wet faces, no primer where one was needed, or old sealant left in. The new sealant then lets go long before it should.
These are the problems we’re asked about most:
- Leaking joints around cladding and façade panels
- Brick movement joints where the sealant has split
- Joints where the bead has come unstuck
- Cracked joints where brick meets render or frames
For an older house near a landmark such as Church of St John, an extension built onto an older house moves differently, and the joint between them takes the strain.
Questions to ask before booking
- What preparation is included
- Is the old sealant removed completely?
- Whether they’re fully insured
- What happens if they find a problem under the old sealant
When it is not the sealant
Honest advice matters more to us than a booking, so here’s what new sealant won’t do:
- Rising or penetrating damp from elsewhere in the wall
- Subsidence or other structural problems
- Cracks in the bricks or render themselves, away from the joints
Not sure which it is? You can phone 0345 464 0079 or drop us an email and we’ll tell you honestly.
What we seal
- Render & cladding joints
- Concrete & block
- Joints between brick and frames
- Copings & trims
- Façade panels
- Brickwork movement joints
How to look after the new joints
No joint lasts for ever, but care makes a real difference. Our tips:
- Walk round the building once a year and look at the joints
- Act on the first splits you see
- Clear growth from the base of walls and joints
- Never let anyone fill a movement joint with mortar
Only paint over the joint if we’ve confirmed the sealant can take paint. Many exterior sealants are not designed to be painted and spoil the finish.
Water getting behind cladding or render can go unnoticed for a long time. By the time there’s a damp patch, the damage can be well established, so it’s worth resealing at the first signs.
DIY versus a professional finish
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
A careful DIYer can reseal a simple joint, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Your questions about external mastic in Sandy Down
Do you cover smaller places like Sandy Down?
Yes. Sandy Down is within the area we cover, which takes in towns, villages and rural addresses. We work across London and the South East. Just mention lanes, gates or anything else about the route when you book.
I let a flat near Brockenhurst station. Can you help?
Yes, rental work is part of what we do. Just ring 0345 464 0079 or send us an email and tell us about the property, and we’ll give you a clear price.
Where is Mr Mastic based?
Mr Mastic is based in Crawley. Our applicators cover Sandy Down, along with the rest of our area.
How long does external mastic take?
Typically it takes a few hours for a handful of joints, longer for a whole elevation. Bigger jobs take longer.
Do you have insurance?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
How long before the joint can be used?
Most sealants are touch-dry well before they’re fully cured. We’ll give you the cure time for the product we used before we leave.
What should I tell you?
Tell us what needs doing and where, with photos by email if possible. If we need more, we’ll ask.
What’s an expansion joint in brickwork?
Brickwork, render and cladding all move a little, so long walls have planned gaps to take that movement. The gap is sealed with a flexible sealant over backing rod.
For landlords and businesses
Housing providers, facilities teams and property managers book us too. Several sites can be quoted together.
For anyone letting property in or around Sandy Down, several properties can be quoted together. Send us the addresses and the work at each.
Different surfaces, different methods
Render joints
Cracks along render joints let water in behind the coat. A sound joint keeps the render dry behind and protects the render itself.
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. Their movement joints are sealed over backing rod with a flexible sealant.
Walls and rooflines in Sandy Down
Sandy Down is within about 3 miles 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.
If you let a flat or house near Brockenhurst station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Sandy Down is about 3 miles north of Lymington, in Hampshire. Homes, rented property, offices and hotels in Sandy Down can book us for external mastic. Every job comes with our 12-month guarantee. We cover 683 towns and villages across Hampshire, from the larger towns to small villages. You can also see our page for Southampton, about 11 miles away.
Jobs for external mastic in SO41 works the same way as everywhere else we cover. Local streets include Sandy Down, Lower Sandy Down and Hurstly Lane, all of which we cover. If you are just outside Sandy Down, we cover Battramsley (1 mile south), Boldre (1 mile south-east), Mount Pleasant (1 mile south-west), Pilley (1 mile south-east) and Warborne (2 miles south-east). We also work in nearby towns such as Eastleigh (15 miles north-east), Totton (9 miles north), Chandler's Ford (15 miles north-east), Hedge End (14 miles north-east), Lymington (3 miles south) and Romsey (14 miles north).
Landmarks near Sandy Down
We work in homes and buildings around The Hobler Public House and the streets around them. The closest station to Sandy Down is Brockenhurst station, roughly 1.6 miles north of the centre. Well-known places in the area include Lymington New Forest Hospital (1.9 miles south) and St Barbe Museum and Art Gallery (2.6 miles south). For a walk, there’s Boldre Foreshore.