West Sussex · England
Sand mastic for sash & case windows in Merston, West Sussex
Professional sand mastic in and around Merston, with every bit of old sealant taken out first and a one-year guarantee.
- Failed mastic on an exposed elevation
- Draughts and rain around sash boxes
- A silicone bead on a sash window that spoils the look
Sand mastic in Merston
If your home is listed or in a conservation area, check with your local planning authority whether consent is needed for work to windows. Sand mastic is often favoured as a like-for-like material. If you are dealing with a silicone bead on a sash window that spoils the look and mastic that needs renewing before redecorating, we can help, on timber door frames, period & listed homes and sash and case windows alike.
In a village or hamlet like Merston, older cottages and farmhouses often have timber windows set in stone or brick. Older buildings like these do not always suit modern silicone, so the sealant has to be chosen to suit the building.
Your job is guaranteed for a year, as with all our work.
- Where
- Merston (PO20)
- Region
- West Sussex
- Cover
- A year, on every job
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Windows and doors in Merston
Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. Historic houses like Goodwood House (about 3.5 miles north) are a reminder that the area around Merston has older buildings as well as new. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic.
For site and facilities teams at buildings such as North Mundham Primary School, larger buildings have plenty of frames, and the mastic around each one ages. If you let a flat or house near Chichester station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
Merston is about 3 miles south-east of Chichester, in West Sussex. Whether you’re in the middle of Merston or further out, we cover sand mastic for every kind of property, from flats and houses to offices and hotels. Across West Sussex, we cover 371 places, Merston among them. There’s also a page for Portsmouth, about 15 miles away.
Postcode districts we cover here for sand mastic: PO20. If you are just outside Merston, we cover Runcton (1 mile south-west), Colworth (1 mile east), Oving (1 mile north), North Mundham (1 mile west) and Lagness (1 mile south). Within a short drive, we also cover Worthing (15 miles east), Bognor Regis (3 miles south-east), Chichester (3 miles north-west), Selsey (6 miles south), Littlehampton (9 miles east) and Emsworth (9 miles west).
Landmarks near Merston
We work in homes and buildings around Chichester High School For Girls, among other places. For rail, the closest station is Chichester station, about 2.3 miles west. Other landmarks nearby include The Chichester City Museum (2.3 miles north-west) and St Richard's Hospital (2.3 miles north-west).
Questions from Merston
Is Merston in your area for sand mastic?
Yes. We work across London and the South East, and Merston is part of that. You can call 0345 464 0079 or drop us an email and let us know what needs doing.
I let a flat near Chichester station. Can you help?
Yes, landlords and agents are among the people we work for. You can phone 0345 464 0079 or drop us an email with the details for a clear quote.
What does sand mastic cost?
It depends on the job, so we quote each one individually. For a quick quote, ring 0345 464 0079 or drop us an email and tell us what needs doing and where.
How long does the job take?
That depends on how much there is to do, but as a guide it takes a few hours for a single window, longer for several. We’ll give you a better idea when we quote.
Can you replace silicone on a period window with sand mastic?
In most cases. The silicone is cut out and the joint cleaned before the sand mastic goes in.
Can I add another job to the visit?
Yes, and it often makes sense. Doing several areas at once is normally more efficient.
Can sand mastic be painted?
It’s traditionally left unpainted, which is what traditional guidance recommends. Talk to us before any painting near it.
What exactly is sand mastic?
Sand plus a binder based on linseed oil. It’s applied by hand and shaped to suit the surround.
Honest limits
Some problems need a builder, plumber or other trade rather than us:
- Broken panes
- Crumbling stone or brickwork round the window
- Whether work needs listed building consent
If you are not sure, just phone 0345 464 0079 or send us an email and we will give you a straight answer before you book.
What we seal
- Sash and case windows
- Stone surrounds
- Brick reveals
- Timber door frames
- Period & listed homes
- Tenement windows
Keeping the joints in good condition
So the new joints stay in good condition:
- Plan mastic work ahead of painting
- Make sure water runs off the sill
- Take care around the mastic when scraping paint
- Find out about consent before window work on a listed home
When preparing windows for paint, take care around the mastic. It can be damaged by heavy scraping.
Crumbling mastic lets rain into the joint. That water can reach the timber frame and the wall, so renewing it early is worth it.
Also near Merston
What else we do in Merston
What happens if it’s left?
New sash windows are a major, costly change, and in listed buildings it may need consent. Where the frames are in good order, new mastic seals the surround. Where a wall is exposed, as many are in small places like Merston, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
A failed joint rarely gets cheaper to fix by waiting, as water and mould keep getting in. If you’re unsure, call 0345 464 0079 or drop us an email and we will give you an honest view and a quote.
Why choose Mr Mastic in Merston
- More than 20 years in sealant work
- Arbo and Everbuild products
- Experience in homes, commercial sites and hotels
- Neat joints and a tidy finish
Surface by surface
Tenement and terrace windows
Rows of sash windows on tenements and terraces often need renewing together. We can do one window or several.
Timber door frames
Period doors in stone or brick openings are often pointed with sand mastic. We renew it the same way as on windows.
How the visit works
You don’t need to clear the whole room or building, just the space around the work. Everything nearby is protected, and the job takes anything from a few hours to a full day, depending on how many windows for a typical job. Somewhere like Merston needs a little journey planning: let us know about lanes, gates and parking. Everything for the job comes with us, so a second trip is avoided where possible.
- We look at the surrounds with you and agree the joints to renew.
- We remove the old, loose mastic.
- We pack any deep voids first.
- We apply the mastic by hand and shape it.
- The surface is finished to suit the stone or brick.
Before we arrive
- Mention if the joints have been sealed before
- Where the joints are inside, avoid wetting them before we arrive
- For business premises, tell us about site rules or sign-in
Get a quote
Call for a quick quote, or send an email if you’d rather. Describe what needs sealing and we’ll talk you through the work and give you a clear quote.
Read more
Can I do it myself?
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is, and the work is guaranteed for a year.
What we are called out for in Merston
Rain on the window surround works into any crack and pushes it out. Windows facing the weather tend to go first.
It’s worth asking for a quote if you see:
- Draughts and rain around sash boxes
- Gaps between timber frames and stone or brick
- Patchy fillers round a sash window
- Crumbling sand mastic round a window
Homes close to Church of St Giles include some older properties, and the joint between an old wall and a newer frame is usually the first place rain gets in.
Comparing quotes
- How long to leave it before use
- What insurance they hold
- Whether you can choose the colour
- What the quote includes, VAT included or not