Portsmouth · England
New-build mastic & snagging in Southsea, Portsmouth
New-build sealant joints in Southsea need attention? We cut out the old, prepare the joints and apply the right sealant.
- Gaps opening as the house dries out and settles
- Sealant work across a run of new homes
- Kitchen sealant that has pulled off the wall
New build mastic in Southsea, done properly
Building dust is behind a lot of failed new-build sealant. We clean every joint thoroughly and prime where the surface and product need it, so the new bead bonds properly rather than sitting on a layer of grit. If you have beads laid onto grit and dust from the build and untidy sealant flagged on a snagging list, we can put it right, whatever the surface.
In a town like Southsea, skirting and floor joints open up as homes settle and floors move with the seasons. A flexible sealant, rather than rigid filler, keeps those joints closed.
All of our work is guaranteed for twelve months, and the guarantee is the same wherever you are.
- Place
- Southsea (PO5, PO4, PO1)
- Region
- Portsmouth
- Guarantee
- A year, on every job
- Quotes
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
DIY versus a professional finish
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it peels away and traps moisture behind it. All the old material has to come out first.
Also near Southsea
More services for Southsea
Honest limits
Sealant isn’t the answer to every problem, and we’ll tell you before we start. Sealant won’t put right:
- Structural cracks in walls or ceilings
- Leaking fittings rather than failed sealant
- Cracked trays, tiles or worktops
If in doubt, call 0345 464 0079 or send us an email and we’ll say what we think.
Joints and surfaces we work on
- Skirting & floors
- Show homes
- Bathrooms & en suites
- Plot handovers
- Kitchens
- Windows & doors
Common problems we fix in Southsea
Baths and trays settle under load once the home is lived in. A bath sealed empty drops slightly when filled, straining the joint and can tear.
Common reasons people contact us include:
- Frame joints opening as the plaster dries
- Shower seals failing in the first year or two
- Gaps behind new kitchen upstands
- Plot mastic for developers ahead of handover
If you’ve bought a new home near Fratton station, the sealant around baths, showers and frames is worth checking in the first year or two.
What to look for in a quote
- Who turns up on the day
- What the quote includes, VAT included or not
- Whether they seal over old material or remove it
- What guarantee comes with the work
New homes and floors in Southsea
Southsea is close to the coast. New homes near the sea put their outside mastic to work from day one, so any gaps are best picked up early. 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.
In and around Southsea, as anywhere, good new build mastic starts with a clean, dry, properly prepared joint.
Southsea is about 2 miles south of Portsmouth, in Portsmouth. Southsea gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a 12-month guarantee. Southsea is one of 19 towns and villages in Portsmouth where we work for new build mastic.
We work across the PO5, PO4 and PO1 postcode area for new build mastic. New build mastic is available to properties on Bath Road, Liss Road and Beach Road. We also 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
Locally, jobs take us to homes and businesses close to 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. Nearby you’ll also find St. Mary's Hospital (1 mile north) and Southsea Castle (1 mile south-west). Green spaces nearby include Milton Locks.
What we do, step by step
On the day, there’s very little for you to do. Show us the job and we’ll take it from there. The work itself takes a few hours for most snagging lists, longer for a run of plots, including the tidy-up. Parking in a town like Southsea is normally straightforward, but tell us if there’s a driveway or any restrictions, and let us know if the work is upstairs, in a flat or up high outside.
- We go through the snagging list or plot schedule and agree the joints to do.
- We cut out every bit of the failed or messy sealant.
- We clean off dust from the build and prime the surfaces where the product needs it.
- We apply a sealant that suits each joint and tool it to a neat finish.
- Finally, each room is checked and you are given the cure time.
Before we arrive
- For indoor joints, keep the area dry beforehand if you can
- Mention any leaks or damp you’ve noticed
- Tell us if parking is tricky
Getting a quote
The more we know about the job, the more useful the quote. Tell us where the job is, what’s wrong and how much there is, and email photos if that’s easy.
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Common questions in Southsea
Is new build mastic in Southsea guaranteed?
All our work, in Southsea and everywhere else, comes with a 12-month guarantee. We’re fully insured, and an ARBOMaster approved applicator.
Do you cover Southsea for new build mastic?
Yes, Southsea is within the area we cover. Our work covers London and the South East. Just ring 0345 464 0079 or send us an email with a few details of the job, and we will give you a clear quote.
Can I send you my snagging list?
Yes. Photos of each sealant item help us quote. If something is not sealant, we will say so.
Is it worth trying it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
Where is Mr Mastic based?
Our base is in Crawley, West Sussex, and we cover South East England, London and all of Scotland.
How long before the joint can be used?
It depends on the product and the temperature. Before we leave, we will tell you the cure time.
Can tenants book the work?
We’re happy to deal with the tenant, landlord or agent. Get your landlord’s agreement first.
Do you work for hotels and businesses?
Yes. We work in offices, washrooms, hotels and other commercial premises, as well as homes. We can talk about working times when we quote.
Landlords, agents and businesses in Southsea
Hotels need rooms back in use, so we plan the work room by room. We’ve worked in hotels as well as homes and businesses.
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.
Keeping the joints in good condition
To keep the joints looking good and working properly:
- Don’t wait for the house to settle if water is getting through
- Avoid scourers and strong chemicals on sealant
- Avoid running a DIY bead over the old one
- Photograph failed sealant before it’s redone
Wipe the sealant with warm soapy water. Avoid abrasive pads and strong solvents, which can damage the surface.
Do not let the snagging period run out with sealant problems unreported. After that, putting it right may fall to you so report it promptly.
How we quote for new build mastic
You will get a clear quote before work begins. It’s based on:
- How easy the joints are to reach
- The number and length of the joints
- The old material and how stubborn it is
- The number of rooms or windows
Rather than a set price list, we price the job in front of us: the amount of work, the old material and the access. You’ll know the price before we begin.
What to tell us for a quote
Photos help, but a description is a good start. Try to tell us:
- If it’s domestic, commercial or a hotel
- Access, such as stairs, a lift or height
- How many joints, rooms or windows are involved
- What the problem is, such as mould, gaps, leaks or cracking
Want a quote for new build mastic? Please call 0345 464 0079 or drop us an email with a few details. We’ll explain what we’d do and give you a clear price before we start.