Portsmouth · England
Sand mastic for sash & case windows in Portsea, Portsmouth
Sand mastic across Portsea and nearby, with every bit of old sealant taken out first and a one-year guarantee.
- Window mastic to renew ahead of painting
- Old sand mastic that has cracked, crumbled or fallen out
- Draughts and rain around sash boxes
When it is not the sealant
We’d rather tell you now than do work that will not last, so here’s what sealant can’t put right:
- Planning or listed building consent (your local planning authority decides)
- Sashes that rattle, stick or will not open
- Damaged stone surrounds
If in doubt, ring 0345 464 0079 or send us an email and we’ll say what we think.
Joints and surfaces we work on
- Timber door frames
- Sash and case windows
- Brick reveals
- Stone surrounds
- Tenement windows
- Period & listed homes
Sand mastic for homes and businesses in Portsea
Sand mastic is the traditional way to point the gap between a timber window frame and the stone or brick around it. It’s made from sand and a linseed-oil-based binder, applied by hand. On older homes, it suits the building far better than silicone. We work on sash and case windows, period & listed homes and stone surrounds, and the jobs we see most are patchy fillers round a sash window and draughty sash windows at the surround.
In smaller places like Portsea, homes range from older cottages to newer houses, with windows to match: timber, uPVC and aluminium. The right sealant depends on the frame and on what it sits in.
The work is covered for a year after we finish. If anything isn’t right with it, ring 0345 464 0079 or email us.
- Where
- Portsea (PO1, PO12, PO5)
- Region
- Portsmouth
- Guarantee
- A year, on every job
- Quote
- Quoted before any work starts
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Common problems we fix in Portsea
Water gets into small cracks in the mastic and loosens it further. Exposed elevations normally fail first.
Keep an eye out for these signs:
- Old cement repairs round a window that have failed
- Weathered mastic on the most exposed windows
- Window mastic to renew ahead of painting
- Old sand mastic that has cracked, crumbled or fallen out
If you look after a building such as Portsmouth Grammar School, larger buildings have plenty of frames, and the mastic around each one ages.
Before booking anyone
- What happens if they find a problem under the old sealant
- Whether you can choose the colour
- What guarantee comes with the work
- Who turns up on the day
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is.
A careful DIYer can reseal a simple joint, 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.
Windows and doors in Portsea
Portsea is within about 1 mile of the coast, and homes near the sea take more wind-driven rain, with salt in the air closer to the shore. Both are hard on the mastic around older windows and doors, which can dry out and crack sooner where a building faces the weather. The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
If you live in an older home near St Ann's Church, the joint between an old wall and a newer frame is normally the first place rain gets in. For landlords with property near Portsmouth Harbour station, any sash windows need sound mastic to keep draughts and rain out.
Portsea is about 1 mile south-west of Portsmouth, in Portsmouth. Every kind of property in Portsea can book us for sand mastic. The work is guaranteed for a year. Our Portsmouth coverage runs to 19 places, and Portsea is one of them.
Jobs for sand mastic in PO1, PO12 and PO5 works the same way as everywhere else we cover. That includes homes and businesses on Main Road, Park Road and Scott Road and the roads around them. Other places close to Portsea include Portsmouth Point (1 mile south), Clayhall (2 miles south-west), Haslar (2 miles south-west), Alverstoke (2 miles south-west) and Privett (2 miles west). Larger places within reach include Hilsea (3 miles north-east), Wymering (4 miles north-east), Paulsgrove (4 miles north), Cosham (3 miles north-east), Drayton (4 miles north-east) and Farlington (5 miles north-east).
Local landmarks in Portsea
In Portsea, that means homes and buildings near The Ship & Castle pub, St Jude's CofE Primary School and Charter Academy, among other places. Portsea has its own railway station: Portsmouth Harbour station. Well-known places in the area include Royal Portsmouth Hospital (0.8 miles east) and Genesis Expo Creationist Museum (under half a mile south). The countryside around Portsea includes Milton Locks and Portsdown Hill.
Aftercare tips
Good habits help new joints last longer. A few tips:
- Ask us before painting near the mastic
- Ask the planning authority about consent for listed or conservation-area homes
- Take care around the mastic when scraping paint
- Do not run silicone over sand mastic
Keep gutters and sills clear so water runs away from the surround. Water sitting against the mastic shortens its life.
Sound mastic protects the frame. Once it fails, water can sit against the timber and timber that stays wet can rot.
Also near Portsea
Also in Portsea
What we do, step by step
Before we leave, we go over the finished joints with you and explain the cure time. The work normally takes a few hours per window, depending on the condition of the joints, depending on the size of the job. Parking around Portsea is usually easier than in a town centre, but mention any lanes, gates or long drives. If the job is outside, tell us about side access and how high the joints are.
- First, we look at the surrounds with you and agree what needs doing.
- We rake out the old mastic and clean the joint.
- Large voids are packed out first, so the mastic isn’t too thick.
- We mix the sand mastic and apply it by hand, shaping it to the joint.
- The mastic is finished to sit tidily against the stone or brick.
Before we arrive
- Clear items away from the joints we’re working on
- Try not to wet indoor joints just before the visit
- Keep pets and children clear of the area while we work
How to get a quote
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is.
Advice
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.
Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Portsea questions
Do you work for landlords with property near Portsmouth Harbour station?
Yes, we work for landlords and letting agents. You can phone 0345 464 0079 or drop us an email with the address and a few details, and we’ll give you a fixed price before work begins.
Is Portsea within the area you cover?
Yes, Portsea is covered. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Will there be a smell?
There can be a smell while the sealant cures, which fades as it sets. Ventilation helps.
Can old silicone round a sash window be swapped for sand mastic?
Often, yes. With the silicone removed and the joint cleaned we point it with sand mastic.
Are you an approved applicator?
Yes. Mr Mastic is an ARBOMaster approved applicator and we’re fully insured too.
What sealant do you use?
It depends on the joint: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. Brands we use include Arbo and Everbuild.
Where do you work from?
We are based in Crawley, and we cover South East England, London and all of Scotland.
What’s sand mastic made of?
It’s a mix of sand and a linseed-oil-based binder. It’s applied by hand and shaped to suit the surround.
Leave it or put it right?
Draughts round a sash window are not always the sashes. Gaps between the frame and the wall can be just as bad and new mastic seals them. Homes in smaller places like Portsea can face more weather, and failed outside joints let damp into walls. Indoors, a failed seal lets water into floors and panels as it would anywhere.
Some things make a job bigger or smaller: how much old sealant there is and how stubborn it is, whether mould needs treating, and whether we need extra access for height. We take all of that into account in your quote.
Why us?
- Over 20 years’ experience
- Anti-fungal sanitary silicone in wet areas
- We leave the area clean and tidy
- 180+ five-star Google reviews
See what affects the cost or our reviews.