Renfrewshire · Scotland
Johnstone Sand Mastic
Sand mastic across Johnstone and nearby, with old sealant always removed completely.
- Old cement repairs round a window that have failed
- Mastic that needs renewing before redecorating
- A silicone bead on a sash window that spoils the look
Signs you need sand mastic in Johnstone
Paint, silicone or cement used over old mastic causes problems. They don’t suit the joint and we normally remove them.
These are the problems we are asked about most:
- Draughts and rain around sash boxes
- Open joints round the window box
- Gaps round a timber door in stone or brick
- Crumbling sand mastic round a window
In the older streets around St John's Episcopal Chruch, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
What your quote should include
- What happens if they find a problem under the old sealant
- Which sealant they’ll use, and why
- The length of the guarantee
- When the joint can take water or movement
Sand mastic for homes and businesses in Johnstone
For a listed home or one in a conservation area, ask your local planning authority if consent is needed before window work. Like-for-like sand mastic is often the preferred finish. If you are dealing with old cement repairs round a window that have failed and a silicone bead on a sash window that spoils the look, we can put it right, whatever the surface.
Scottish towns like Johnstone tend to mix older stone-built streets, harled houses and newer estates, and windows range from older sash and case to modern uPVC. The sealant has to suit both the frame and the wall it sits in.
A one-year guarantee comes as standard.
- Where
- Johnstone (PA5, PA10)
- Wider area
- Renfrewshire
- Guarantee
- 12 months on all our work
- Quotes
- A clear price before we start
- info@mrmastic.co.uk
- Last updated
- 26 October 2026
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Keep sills and gutters clear so water drains away
- Renew mastic before redecorating the windows
- Find out about consent before window work on a listed home
- Avoid patching sand mastic with silicone
Leave the new mastic alone while it firms up. It skins over quickly but needs longer to fully harden.
Good mastic helps keep the frame dry. Once it fails, water can sit against the timber and timber that stays wet can rot.
Also near Johnstone
Other services in Johnstone
When something else is needed
A few problems are outside what sealant work can do:
- Cracked or broken glass
- Sashes that rattle, stick or will not open
- Decisions on consent for listed homes
If in doubt, send an email to info@mrmastic.co.uk and we’ll say what we think before you book.
Where we work in Johnstone
- Brick reveals
- Stone surrounds
- Timber door frames
- Tenement windows
- Sash and case windows
- Period & listed homes
Should I try it myself first?
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
How we quote for sand mastic
We do not publish a price list, because jobs vary so much. The quote depends on:
- The number and length of the joints
- The type of sealant required
- Whether old sealant or filler has to be cut out
- Whether the work is at height
A failed joint rarely gets cheaper to fix by waiting, because water and mould keep working on it. If you are unsure, email us at info@mrmastic.co.uk and we’ll give you an honest view and a quote.
What to tell us for a quote
You do not need to know the technical terms. It helps if you can tell us:
- How many joints, rooms or windows are involved
- Any previous sealing or DIY work
- How we’d reach the joints
- What the problem is, such as mould, gaps, leaks or cracking
If you are in Johnstone and need sand mastic, drop us a line at info@mrmastic.co.uk. A short description of the job and where it is helps us quote, and you will get a clear quote before work begins.
Work for landlords, hotels and businesses
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.
If you manage several properties in or around Johnstone, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs.
What we do, step by step
Our applicators work methodically: protect, prepare, seal, tidy. Typically it takes anything from a few hours to a full day, depending on how many windows, and the area is left clean. Parking around Johnstone is rarely difficult, though older streets in the centre can be tight. For flats, mention the shared stair or door entry system.
- First, we look at the surrounds with you and agree what needs doing.
- Old, loose mastic is raked out and the joint cleaned.
- Deep voids are packed so the mastic is the right thickness.
- We mix the sand mastic and apply it by hand, shaping it to the joint.
- We dress the surface so it sits neatly against the masonry.
How to prepare
- Mention any tricky access
- Keep children and pets away from the work area
- Mention any parking rules near the property
Getting a quote
We quote each job on its own. Just drop us a line at info@mrmastic.co.uk with the details.
Read more
Johnstone homes and the weather
Many older homes in Scotland have sash and case windows, and the joint between the box frame and the stone or render is traditionally pointed with sand mastic. The west of Scotland is wetter than the east, which means the mastic around older windows and doors has to cope with a lot of rain.
For landlords with property near Johnstone station, any sash windows need sound mastic to keep draughts and rain out. For site and facilities teams at buildings such as Linwood High School, larger buildings have plenty of frames, and the mastic around each one ages.
Johnstone is about 3 miles west of Paisley, in Renfrewshire. Whether you are in the middle of Johnstone or further out, we cover sand mastic for every kind of property, from flats and houses to offices and hotels. We cover 21 towns and villages across Renfrewshire. Our Glasgow page covers work nearby (10 miles or so).
Every address in PA5 and PA10 is covered for sand mastic, from the main roads to the quietest streets. Whether your property is on Houstoun Square, High Street and Armour Square or a nearby road, our applicators can take on the job. Johnstone sits on or near the A737 and B787, so getting to you is simple. Other places close to Johnstone include Kilbarchan (1 mile west), Brookfield (1 mile north), Linwood (2 miles north-east), Howwood (2 miles south-west) and Craigends (2 miles north). Larger places within reach include Paisley (3 miles east), Renfrew (6 miles north-east), Erskine (5 miles north-east), Bishopton (5 miles north), Glenburn (3 miles east) and Charleston (4 miles east).
Landmarks near Johnstone
Locally, jobs take us to homes and businesses close to Gleniffer Braes and 63 High Street pub. For rail, the closest station is Johnstone station, roughly 0.7 miles north-east of the centre. Well-known places in the area include Johnstone Community Museum (0.7 miles north) and Merchiston Hospital (1.1 miles north). For a walk, there’s Walls Loch and Walls Hill.
FAQs for Johnstone
I let a flat near Johnstone station. Can you help?
Yes, landlords and agents are among the people we work for. You can send an email to info@mrmastic.co.uk with the details for a clear quote.
Is sand mastic in Johnstone guaranteed?
All our work, in Johnstone and everywhere else, comes with a 12-month guarantee. We are also fully insured and ARBOMaster approved.
How long does sand mastic take?
It depends on the size of the job, but as a guide it takes anything from a few hours to a full day, depending on how many windows. We’ll give you a better idea when we quote.
Should I use sand mastic or silicone?
It depends on the window. Period windows in stone or brick normally suit sand mastic, while modern frames normally get a flexible sealant.
Are you an approved applicator?
Yes. We’re approved under the ARBOMaster scheme, the approved applicator scheme for Arbo sealants.
Is it possible to take out silicone and use sand mastic instead?
Yes, we do this often. The old silicone has to come out completely so the mastic beds in well.
What is sand mastic?
It’s a mix of sand and a linseed-oil-based binder. It’s applied by hand and shaped to suit the surround.
Is it OK to seal over old sealant?
No, and we never do. It can look neat for a few weeks, but the new bead soon lifts. Removing the old sealant completely is the only lasting way.