Na h-Eileanan Siar · Scotland
Knock Sand Mastic
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homes and businesses in Knock and across Na h-Eileanan Siar. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- A silicone bead on a sash window that spoils the look
- Crumbling sand mastic round a window
- Cracked mastic round a front door frame
Sand mastic in Knock: local notes
Knock is close to 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. Island jobs need planning around ferries and the weather, so the more notice, the better.
Around Knock, as everywhere, sand mastic is only as good as the preparation behind it. For jobs in and around Knock, choosing the right material for each joint is as important as a tidy finish.
Knock (Gaelic: An Cnoc) is in Na h-Eileanan Siar. Anywhere in HS2, we can carry out sand mastic at your property. Across Na h-Eileanan Siar, we cover 87 places, and Knock is one of them.
We cover every part of the HS2 postcode area for sand mastic and the streets around it. We cover properties on Seaview and A' Chnuic and the roads around them. Main roads around Knock include the A866, so getting to you is simple. Nearby, we also carry out sand mastic in Na h-Eileanan an Iar (1 mile west), Aiginis (1 mile west), Lower Bayble (1 mile east), Garrabost (2 miles north-east) and Pabail Uarach (2 miles east). Island and remote addresses take a little more planning, so please mention your location when you email us at info@mrmastic.co.uk.
Near you in Knock
A little further out are Western Isles Hospital (4.5 miles west).
Sand mastic in Knock, done properly
We work across Knock renewing sand mastic on sash windows and doors. Every joint is cleaned out and filled by hand for a neat, traditional finish. If you have cracked mastic round a front door frame and mastic worn away on windows facing the weather, we can help.
Many older Scottish homes still have timber windows set into stone walls. The sealant has to suit the stone, which rules out acetoxy silicones that can mark or attack it.
We guarantee the work for a year. If there’s a problem with our work within the year, let us know and we’ll sort it.
- Location
- Knock (HS2)
- Region
- Na h-Eileanan Siar
- Cover
- A year, on every job
- Price
- Quoted before any work starts
- info@mrmastic.co.uk
- Last updated
- 26 October 2026
How the job changes by surface
Stone surrounds
Sand mastic sits naturally against stone. The finish blends with the masonry.
Brick reveals
Gaps between frame and brick let in rain and draughts. New mastic seals the gap.
For landlords and businesses
If you manage several properties in or around Knock, jobs at different addresses can go on one quote. Just tell us the addresses and what each one needs, and photos by email help.
Hotels need rooms back in use, so the work can be planned room by room. Hotel work is part of what we do, alongside homes and businesses.
Why act early in Knock
Not every draught comes from the sashes themselves. Gaps between the frame and the wall can be just as bad, and renewing the mastic closes them. Exposed walls in smaller Scottish places take a lot of wind and rain, and once water gets behind a failed joint, damp in stone or harled walls is slow to dry out.
A few things move the cost up or down: how much old sealant there is and how stubborn it is, any mould to treat, and whether we need extra access for height. We take all of that into account in your quote.
Why Knock customers choose us
- Arbo and Everbuild products
- We leave the area clean and tidy
- Experience in homes, commercial sites and hotels
- Fully insured
What happens on the day
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 anything from a few hours to a full day, depending on how many windows from start to finish. In smaller Scottish places, parking is usually less of an issue than access and distance. Tell us how to find the property and how to reach the work.
- We check each window surround and the condition of the joint.
- The joint is raked out and cleaned.
- We fill deep gaps so the new mastic is not too thick.
- New sand mastic is applied and shaped by hand.
- We finish the mastic to a tidy line.
Getting ready for the visit
- For business premises, tell us about site rules or sign-in
- Let us know about earlier repairs to the joints
- Tell us about any water getting in
Ask for a quote
We quote each job on its own, so start by telling us what you need. Simply send an email to info@mrmastic.co.uk and describe the job.
Read more
Aftercare tips
So the new joints stay in good condition:
- Get any rot dealt with first
- Find out about consent before window work on a listed home
- Keep sills and gutters clear so water drains away
- Check the mastic when you check the paintwork
Avoid painting over the new mastic, as traditional guidance advises. If you’re redecorating, ask us first.
Crumbling mastic lets rain into the joint. It can soak into the frame and the surrounding masonry, so renewing it early is worth it.
Questions from Knock
Do you cover smaller places like Knock?
Yes, Knock is covered. Our work covers the whole of Scotland, islands included, from towns to the smallest places. The journey is planned ahead, so it helps to know about access.
Can you do sand mastic in Knock?
Yes, Knock is within the area we cover. Our work covers the whole of Scotland. Just drop us a line at info@mrmastic.co.uk with a few details of the job.
What do you need from me for a quote?
A short description and the location, with photos by email if possible. If we need more, we will ask.
Can you seal over the old sealant?
No. New silicone will not bond to old silicone, and it traps any mould or water underneath. We remove it all first.
Do I need permission for sand mastic on a listed building?
Speak to your local planning authority before work starts. Sand mastic is often favoured as like for like but the decision is theirs.
What is sand mastic?
It’s a mix of sand and a linseed-oil-based binder. It’s applied by hand and finished to sit neatly against the masonry.
Should I use sand mastic or silicone?
That depends on your windows. On many period windows, sand mastic looks right and suits the building, while modern frames normally get a flexible sealant.
What does sand mastic cost?
Every job is different, so each one gets its own quote. For a quick quote, email us at info@mrmastic.co.uk and tell us what needs doing and where.
What else we do in Knock
Should I try it myself first?
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
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.
What sealant work cannot fix
In fairness, some problems need a different trade:
- Decisions on consent for listed homes
- Sashes that need overhauling
- Cracked or broken glass
If you are not sure, just email us at info@mrmastic.co.uk and we will give you a straight answer before booking.
What we seal
- Brick reveals
- Period & listed homes
- Timber door frames
- Stone surrounds
- Tenement windows
- Sash and case windows