Hampshire · England
Mastic man in Gosport
Resealing and coastal mastic work across the Gosport peninsula, from Alverstoke and Lee-on-the-Solent to converted naval buildings and harbour flats.
- Anti-fungal silicone as standard
- 20+ years in the trade
- Guaranteed for a year
Sealant jobs we do in Gosport
The Gosport peninsula has about 17 miles of waterfront on Portsmouth Harbour and the Solent, and that shapes almost every outside sealant job here. Salt air, wind and rain test window and door mastic hard, while flats and converted naval buildings bring their own indoor challenges. Mr Mastic covers Gosport from our base in Crawley, including Alverstoke, Lee-on-the-Solent, Rowner, Bridgemary, Elson, Hardway, Forton and the town centre.
We reseal baths, showers, basins and kitchens, replace failed window and door mastic, and seal external joints exposed to the weather. Every old bead is removed in full, the surface cleaned and dried, and the new sealant chosen for its position. For seafront homes, our window and door mastic service uses flexible, weatherproof products made to cope.
Naval buildings, tower blocks and seaside suburbs
Gosport’s naval history is written into its housing. Several former military sites have become homes: the New Barracks, which closed in 1991, Royal Clarence Yard, the old victualling yard that closed in 1992 and now has housing around Royal Clarence Marina, and Royal Hospital Haslar, converted between 2018 and 2020 into retirement flats. Haslar was built of brick, and its eighteenth-century quadrangle blocks are Grade II* listed. In historic buildings like these, new bathrooms sit inside thick old walls, and sealant has to suit both the fittings and the fabric.
The town centre is marked by Seaward Tower and Harbour Tower, built in 1963. In blocks like these, a failed shower seal on one floor can mark the ceiling of the flat below, so sound sealant matters to neighbours too.
Out in the suburbs, Alverstoke and Lee-on-the-Solent sit close to the shore, while Rowner, where most of the former naval married quarters estate has been demolished, Bridgemary and Elson have their own mix of homes, many now with uPVC windows and refitted bathrooms.
Salt, wind and flats with neighbours below
Homes along Stokes Bay, the harbour front and Lee-on-the-Solent take the full force of wind and salt spray. External mastic on exposed faces dries, cracks and lets wind-driven rain behind frames much sooner than inland. We cut out the old joint, clean back to sound brick or render, and use a durable weatherproof sealant set to the right depth with backing rod.
In tower blocks, converted naval buildings and flats near the marinas, access needs planning. Let us know about lifts, parking and the managing agent when you book. Inside, we reseal with anti-fungal silicone, because damp coastal air gives mould every chance. A quick squeegee and an open window after showering help the new bead stay clean for longer.
Marinas, colleges, the navy and landlords
Gosport has three marinas, at Gosport, Haslar and Royal Clarence, each with shower blocks and facilities that need regular resealing. HMS Sultan is the Royal Navy’s largest training establishment, and the town also has St Vincent College in part of the old Forton Barracks and CEMAST at the former Daedalus site in Lee-on-the-Solent. Colleges and training sites have washrooms best resealed outside term time.
Landlords are a big part of our work here too. We reseal between tenancies, and our guide for landlords explains how to keep on top of it.
How it works
- Tell us about the job. A quick call or email with what needs sealing and where. Photos help us quote accurately.
- Get a clear quote. We give you a clear price before any work starts, and agree a date with you.
- Preparation first. Old sealant out completely, surfaces cleaned, mould treated and the joint left dry.
- Seal and finish. The right sealant for each joint is applied and tooled to a neat, even finish.
- Cure and guarantee. We tell you when it can be used, and every job has our one-year guarantee.
Our services in Gosport
- Bathroom & kitchen resealing: Bathroom and kitchen joints taken back to a clean, dry surface and finished with fresh anti-fungal silicone that won’t lift.
- Window & door mastic: Cracked or shrunken mastic around window and door frames, sills and patio doors replaced with a weatherproof sealant.
- Commercial & hotel sealant: Sealant programmes for offices, hotels, care settings and schools, with early or late working where it helps.
- Remedial sealant & repairs: Messy, layered or wrong-product sealant cut out and replaced with the right sealant, laid the right way.
- Fire-rated sealant: Fire-rated sealant for service penetrations and frame gaps where it has been specified, applied to the tested details.
- External & façade joints: Outside movement joints given new backing rod and a flexible, weatherproof sealant in a colour to match the wall.
- New-build mastic & snagging: Failed builder sealant in new homes put right, and plot mastic for developers.
- Floor & skirting joints: Movement joints in tiled and concrete floors, and skirting gaps, sealed so they stay tidy and keep dirt out.
- Regrouting: Crumbling grout in showers and wet areas raked out and refilled, so water stays out of the wall behind.
- Glazing & conservatory sealant: Glass-to-frame joints on conservatories, rooflights and shower screens cut out and resealed.
- Gutter, fascia & soffit sealing: Gutter unions, outlets and fascia joints that leak in heavy rain cleaned and resealed.
- Sand mastic for sash & case windows: Traditional burnt sand mastic renewed around sash and case windows and doors in stone and brick.
Why choose Mr Mastic in Gosport
From Crawley we reach Gosport along the coast, and we bring coastal know-how with us. That means 20+ years’ experience, full insurance and ARBOMaster approved applicator status, plus Arbo and Everbuild sealants suited to salt and wind. Our 2,847+ projects have earned 180+ five-star Google reviews and a 4.9-star average. You always get a clear quote before we start, and a one-year guarantee on every job.
Getting around Gosport
From the centre, the nearest railway station is Portsmouth Harbour station. Well-known places nearby include Tricorn Centre (2.7 miles east), Search (1.3 miles south-east) and Portchester Castle (2.8 miles north-east). Closer in, we work on homes, rented flats and businesses near Brockhurst Primary School, Brune Park Community School, St Vincent College and St Faith's Church. Green spaces within reach include West of the River Alver and Portsdown Hill.
What customers say
Rated 4.9 on Google from 180+ five-star reviews. Read the reviews on Google.
“1950s terrace on Crossways — bath had black mould coming back constantly. Mr Mastic stripped it all back and did it properly. Bathroom looks brand new.”
“New build in Forge Wood — shower seal had failed after 16 months. Mr Mastic came out quickly, removed everything and did it properly. Perfect finish and no more leaks.”
“Harper Drive in Maidenbower — kitchen worktop had been leaking behind for a while. Came out the next day, sorted it properly. Really tidy job.”
Where we work in Gosport
Choose your part of town for local details, or call 07833 053749 or email us and tell us your postcode.
Other towns around Gosport
Questions from Gosport
Do you cover all of Gosport?
Yes. We cover the town centre, Alverstoke, Lee-on-the-Solent, Rowner, Bridgemary, Elson, Hardway, Forton and the streets around Stokes Bay and the harbour.
Why does the window mastic on my seafront home keep failing?
Salt spray, sun and wind dry out and stress external sealant. We cut out the old joint and use a flexible, weatherproof sealant with backing rod where needed.
I live in a converted building at Royal Clarence Yard or Haslar. Can you reseal my bathroom?
Yes. We can liaise with the managing agent on access and choose a sealant that suits the fittings and the surrounding walls.
Water is coming through my ceiling from the flat above. Could it be sealant?
Often it’s a failed bath or shower seal upstairs. We can reseal the upstairs bathroom, though a leaking pipe needs a plumber first.
Do you reseal marina shower blocks?
Yes. We use anti-fungal sanitary silicone and can work at quieter times so facilities stay open.
Do you work for Gosport landlords?
Yes. We reseal between tenancies and can quote for several properties at once.
Can you work in a college during the holidays?
Yes. Out-of-term working gives the sealant time to cure, and out-of-hours working can be arranged too.
Can you reseal around a wet room floor in a retirement flat?
Yes. We remove the old sealant, check the joints around the floor and walls and reseal with anti-fungal silicone, keeping the visit tidy and short.