Portsmouth · England
Southsea External Mastic
Specialist external mastic for Southsea: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Sealant pulling away from one side of the joint
- Movement joints filled with mortar instead of sealant
- Weeds or debris growing in open joints
What we do, step by step
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 work takes anything from a few hours to several days, depending on the building in most cases. A visit in Southsea needs access to the work and a place to park close by. For outside work, let us know about side access, gates and any upper-floor joints.
- 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.
- We fit closed-cell backing rod to control the depth.
- The exterior sealant is applied, tooled and checked along its length.
Preparing for the visit
- For business premises, tell us about site rules or sign-in
- Let us know about stairs, lifts or work at height
- Plan for the work area to be out of bounds to pets and children
Ask for a quote
Want a quote for external mastic? Please ring 0345 464 0079 or email us with a few details. We’ll explain what we’d do and send you a clear quote before work begins.
Advice
About our external mastic in Southsea
Joints in render and cladding are easy to overlook until a damp patch appears. We look over the joints, agree the ones to renew and reseal with a flexible, weatherproof product. If you have water getting into walls through failed joints and weeds or debris growing in open joints, we can help, on copings & trims, brickwork movement joints and façade panels alike.
Plenty of homes in a town like Southsea have been extended, and the line where an extension meets the original house is a common leak point. Sealing it properly means the right joint depth and a flexible sealant, not a quick bead.
Every job comes with a one-year guarantee.
- Where
- Southsea (PO5, PO4, PO1)
- Region
- Portsmouth
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What we cannot put right
Before you book, it’s worth knowing the limits:
- Loose or hollow render, which needs re-rendering
- Adding movement joints to masonry that has none
- Cracked brickwork or render that needs a builder or plasterer
Not sure which it is? You can phone 0345 464 0079 or email us and we will tell you honestly before booking.
What we seal
- Façade panels
- Copings & trims
- Joints between brick and frames
- Render & cladding joints
- Brickwork movement joints
- Concrete & block
Places near Southsea
Other services in Southsea
How to look after the new joints
Looking after new joints is easy, and it makes a real difference:
- Act on the first splits you see
- Keep high-pressure jets off the joints
- Ask before painting over external sealant
- Fix overflowing gutters above sealed joints
Look over the joints once a year, ideally after winter. Watch for splits, edges coming away or growth in the joint.
An open movement joint lets rain into the wall every time it pours. Over time it can mean damp inside, stained render or frost-damaged brick.
What happens if it’s left?
Low-modulus sealants stretch easily, so they put less strain on the joint edges. That matters on brick, render and concrete, which can be weaker at the face. A stiffer product can damage the joint edge as it fails. Draughts from a gap round a frame, damp under a sill or water behind a bath panel all start small, and early is when they’re cheapest and quickest to sort.
The cost reflects the work involved, not guesswork. That’s why we ask a few questions first and agree the price before starting.
Why Southsea clients choose us
- ARBOMaster approved applicator
- 20+ years of sealant experience
- Homes, businesses and hotels
- Every job guaranteed for a year
Read what affects the cost and what customers say.
What external mastic looks like in Southsea
Southsea is within about 1 mile 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.
Letting a property close to Fratton station? Then outside joints that have cracked can let damp into a rental, so check them between lets. If you live in an older home near St Margaret of Scotland, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Southsea is about 2 miles south of Portsmouth, in Portsmouth. Whether you are in the middle of Southsea or further out, external mastic is available for homes and businesses alike, from flats and houses to offices and hotels. 19 places in Portsmouth are on our list, large and small.
Here we cover the PO5, PO4 and PO1 postcode area for external mastic. We cover properties on Bath Road, Liss Road and Beach Road. If you are just outside Southsea, we cover Milton (1 mile north-east), Fratton (1 mile north), Kingston (1 mile north), Landport (1 mile north-west) and Baffins (2 miles north). Larger places within reach include Hilsea (3 miles north), Wymering (4 miles north), Paulsgrove (5 miles north), Cosham (4 miles north), Drayton (4 miles north) and Farlington (5 miles north).
What’s near Southsea
In Southsea, that means homes and buildings near The Festing pub, St Edmund's Catholic School and Mayville High School, among other places. The closest station to Southsea is Fratton station, about 0.8 miles north of the centre. Other landmarks nearby include St. Mary's Hospital (1 mile north) and Southsea Castle (1 mile south-west). For a walk, there’s Milton Locks.
Quotes for external mastic in Southsea
The price is agreed before any work begins. It takes into account:
- The size of the job
- How much old sealant there is and how hard it is to remove
- Which sealant suits the joint
- When we can work, for business premises
Doing several joints on one visit is usually more efficient than separate visits, so it’s worth mentioning everything you’d like done. You’ll get one clear quote for the whole job.
What to tell us for a quote
To help us quote quickly, please include:
- Roughly how big the job is
- How we’d reach the joints
- The address or postcode of the job
- Pictures of the joints, sent by email
There’s no standard price list. Instead, your job gets its own clear quote. To arrange one, phone 0345 464 0079 or email us.
For landlords and businesses
Whether it’s one flat or a portfolio, the work is the same standard: the old material taken out, careful preparation and a 12-month guarantee.
For anyone letting property in or around Southsea, several properties can be quoted together. Send us the addresses and the work at each.
Do you need external mastic in Southsea?
Weeds, moss and debris in a joint are a sign the sealant has gone. Dirt and roots then trap moisture in the joint and make things worse.
Most people get in touch after spotting something like this:
- Water getting into walls through failed joints
- Moss and dirt in joints with no sealant left
- Joints where the bead has come unstuck
- Failed seals between different materials
If you look after a building such as Craneswater Junior School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
What to look for in a quote
- Whether the sealant suits the joint
- How hidden problems are handled
- Which colour the sealant will be
- What preparation is included
Your questions about external mastic in Southsea
Does living near the coast affect external mastic in Southsea?
Coastal homes put outside sealant through more weather than inland ones, so the choice of sealant and the preparation matter even more. Walls facing the sea are normally the first to need attention.
Do you work for landlords with property near Fratton station?
Yes, rental work is part of what we do. Just call 0345 464 0079 or email us and tell us about the property, and we will send you a clear quote.
Are you insured?
Yes. We’re fully insured for every job we do.
When will the joints need doing again?
There’s no fixed answer: sunny, exposed elevations and busy joints wear faster. Check them each year and reseal when they split or harden. Our work comes with a 12-month guarantee.
Do I have to be there?
For indoor joints, yes, someone needs to let us in. Once we have agreed the job, you do not need to watch us work.
Is the work guaranteed?
Yes, for a year. If anything is not right with the work within the year, let us know and we will sort it.
Which products do you use?
We choose the sealant for the joint, not the other way round. Where it moves, gets wet or faces the weather makes a difference, and we will explain our choice.
Will you leave a mess?
Not at all. We work neatly, protect the area around the joints and tidy up afterwards.