West Sussex · England
South Mundham External Mastic
External mastic for South Mundham and the surrounding area: careful preparation, the right product and tidy work. Ask us for a quick quote.
- Plants rooting in failed movement joints
- Sealant that has lost its bond to the brick or render
- Old sealant gone brittle and cracked
Outside joints around South Mundham
South Mundham is within about 2 miles of the coast, where wind-driven rain is a fact of life and, nearer the shore, so is salt air. That is 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, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
In the older streets around The Parish Church of St Stephen, older walls, gutters and the joints where extensions meet them need a flexible sealant. For landlords with property near Chichester station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
South Mundham is about 3 miles south of Chichester, in West Sussex. Anywhere in PO20, we cover external mastic for homes and businesses. South Mundham is one of 371 towns and villages in West Sussex we cover for external mastic. For nearby work, see our Portsmouth page, about 14 miles away.
Work in PO20 works the same way as everywhere else we cover. We cover properties on Manor Lane and Honer Lane. If you’re just outside South Mundham, we cover Fisher (1 mile west), Street End (2 miles south-west), Sidlesham Common (2 miles west), Nyetimber (2 miles south-east) and Sidlesham (2 miles south-west). Further out, we also cover Bognor Regis (3 miles east), Chichester (3 miles north), Selsey (5 miles south), Littlehampton (10 miles east), Emsworth (9 miles north-west) and Rustington (11 miles east).
Around South Mundham
Typical jobs here are in homes near Chichester High School For Girls and Avisford. The closest station to South Mundham is Chichester station, about 2.5 miles north-west. Other landmarks nearby include Chichester Castle (3 miles north) and Chichester Cathedral Treasury (2.7 miles north-west).
External mastic in South Mundham
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 colour to suit. If you have water getting into walls through failed joints and moss and dirt in joints with no sealant left, we can put it right.
Somewhere as small as South Mundham, homes and farm buildings often face open ground, where walls and rooflines take the weather head on. Joints on those walls need a sealant that moves with the building and stays in place.
You’re covered for a year from the day we finish. If anything isn’t right with it, ring 0345 464 0079 or drop us an email.
- Location
- South Mundham (PO20)
- Region
- West Sussex
- Guarantee
- A year, on every job
- Quote
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Towns and villages near South Mundham
More services for South Mundham
Questions from South Mundham
Do you cover smaller places like South Mundham?
Yes, smaller places are covered as well as towns. We work across London and the South East. Just mention lanes, gates or anything else about the route when you book.
Does the coastal weather in South Mundham affect outside sealant?
Coastal weather is harder on outside sealant: there’s more wind-driven rain and, closer to the shore, salt in the air. The right product, a clean joint and the right depth all help it cope.
Will the old sealant be removed?
Yes. Sealing over the old bead is the commonest cause of early failure, and it’s something we never do.
Are you fully insured?
Yes. Full insurance covers our work, and we can confirm the details when we quote.
Will it make a mess?
Very little: the area around the joints is protected first, and we tidy up before we go.
Can you seal joints between render and window frames?
Yes. The old joint is removed, both surfaces cleaned and primed where needed, and a flexible sealant applied. The colour is chosen to suit.
What is a movement joint?
It’s a deliberate gap that lets the wall expand and contract without cracking. It should be filled with flexible sealant, never mortar.
Do the sealants smell?
There can be a smell while the sealant cures. Ventilation helps.
What happens on the day
There’s no need to move everything out before we come, just the space around the work. We protect the rest, and the work takes a few hours to a few days, depending on the length of joint and the access for a typical job. Somewhere as small as South Mundham, 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.
- The old mastic and anything lodged in the joint is removed.
- 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.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
How to prepare
- Where the joints are inside, avoid wetting them before we arrive
- Move anything stored near the joints
- Let us know if you’ve seen damp or leaks
Getting a quote
Every job is quoted individually. Just ring 0345 464 0079 or drop us an email with the details.
Read more
Looking after it afterwards
Aftercare is simple, and it makes a real difference:
- Wash walls gently around the sealant
- Keep movement joints as flexible joints, not mortar
- Tell anyone working on the walls about the movement joints
- Ask before painting over external sealant
Keep the joints clear of soil, plants and climbing growth. Anything that holds water against the joint wears it out sooner.
A joint that has stopped moving pushes the movement elsewhere, often as cracks near the joint. Catch it early and you reduce the risk.
DIY sealant or a professional job?
A DIY attempt doesn’t rule out a professional job. We cut it out and start again.
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.
Why act early in South Mundham
Low-modulus sealants stretch easily, so they put less strain on the joint edges. That protects surfaces like brick, render and concrete. Too stiff a sealant can pull at the edges and break them. Around South Mundham, older homes often have timber in their floors and frames, and water through a failed joint can rot timber if it’s left.
Instead of a standard rate, we look at what your job involves: the amount of work, the old material and the access. You will know the price before we begin.
Why book with us
- 20+ years of sealant experience
- 180+ five-star Google reviews
- A 12-month guarantee on all work
- We agree the colour with you first
Read what affects the cost or customer reviews.
Do you need external mastic in South Mundham?
Sometimes a movement joint was filled with mortar or a rigid filler by mistake. With the joint locked solid, the movement turns into cracks elsewhere in the wall.
People normally contact us when they notice one of these:
- Joints with sealant missing in places
- Plants rooting in failed movement joints
- Cracked joints where brick meets render or frames
- Hard, crazed mastic that has stopped moving
If you look after a building such as North Mundham Primary School, larger buildings have long runs of movement joint that eventually need resealing.
Questions to ask before you book
- When the joint can take water or movement
- Whether all the old sealant comes out first
- Which sealant they’ll use, and why
- How the colour is chosen
Honest limits
We’ll always be straight with you, so here’s what sealant can’t fix:
- Subsidence or other structural problems
- Cracked brickwork or render that needs a builder or plasterer
- Loose or hollow render, which needs re-rendering
Not sure which it is? You can phone 0345 464 0079 or drop us an email and we’ll tell you honestly before booking.
Joints and surfaces we work on
- Façade panels
- Concrete & block
- Joints between brick and frames
- Copings & trims
- Brickwork movement joints
- Render & cladding joints
How the job changes by surface
Copings and trims
Metal and stone copings both move with temperature, so a flexible sealant suits them best.
Cladding and façade panels
Cladding and façade panels are usually separated by sealed joints. We reseal them with a sealant suited to the panel material.