West Dunbartonshire · Scotland
Arrochar External Mastic
External mastic across Arrochar and nearby, with every bit of old sealant taken out first and a 12-month guarantee.
- Old sealant gone brittle and cracked
- Brick movement joints where the sealant has split
- Plants rooting in failed movement joints
Aftercare tips
Looking after new joints is easy:
- Fix overflowing gutters above sealed joints
- Avoid pressure-washing directly into sealant joints
- Make sure movement joints are not pointed over
- Have failed joints looked at early
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They should be kept open and resealed, not filled.
A joint that has stopped moving pushes the movement elsewhere, often as cracks near the joint. Resealing it early helps prevent that.
How we handle external mastic in Arrochar
Joints in render and cladding are easy to overlook until a damp patch appears. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a colour to suit. We work on joints between brick and frames, render & cladding joints and concrete & block, and people most often call us about old sealant gone brittle and cracked and failed seals between different materials.
Stone walls need a stone-friendly sealant, as acetoxy products can attack some stone. On newer homes, the movement joints and roofline trims are what need watching.
A 12-month guarantee comes as standard, so you’re not left on your own once the job is done.
- Place
- Arrochar (G83)
- Wider area
- West Dunbartonshire
- Guarantee
- A year, on every job
- Quotes
- A clear price before we start
- info@mrmastic.co.uk
- Updated
- 26 October 2026
What the job involves on each surface
Brickwork movement joints
Brick walls have vertical movement joints to absorb expansion. We reseal them with a low-modulus sealant over backing rod in a colour to suit the brick.
Copings and trims
A failed coping joint lets water into the top of the wall. Sealing them early saves the wall below.
Common problems we fix in Arrochar
Weeds, moss and debris in a joint are a sign the sealant has gone. Roots and dirt hold water against the wall.
Common reasons people contact us include:
- Joints pointed up with cement by mistake
- Hard, crazed mastic that has stopped moving
- Sealant that has lost its bond to the brick or render
- Panel joints letting water in
In the older streets around Arrochar Church, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Comparing quotes
- What happens if the job turns out different
- How long to leave it before use
- Are they insured?
- Whether VAT is included
The process
When we get to you, we compare the joints with what we discussed. If we find something unexpected, we talk it through with you first. After that, the work takes anything from a few hours to several days, depending on the building. Somewhere like Arrochar may be a longer drive, and the journey is planned ahead. Tell us about tracks, gates, a ferry crossing or anything unusual about getting there.
- We start by checking each joint, agreeing the ones to redo and how we’ll reach them.
- Old sealant and any debris are cut and raked out.
- The joint faces are cleaned and primed where the sealant needs it.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
Preparing for the visit
- Tell us about any water getting in
- Move anything stored near the joints
- Tell us if parking is tricky
Get a quote
If you are in Arrochar and need external mastic, send an email to info@mrmastic.co.uk. Tell us what the problem is and where, and we will agree the price before any work begins.
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Places near Arrochar
What else we do in Arrochar
External mastic in Arrochar: local notes
Arrochar is close to the coast, and homes near the sea take more wind-driven rain, with salt in the air closer to the shore. That is hard on movement joints and outside wall joints, especially on the side facing the sea. The west of Scotland is wetter than the east, so there’s plenty of rain for movement joints and outside wall joints to keep out.
Letting a property close to Arrochar & Tarbet station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Arrochar (Gaelic: An t-Àrchar) is about 13 miles north of Helensburgh, in West Dunbartonshire. Whether you are in the middle of Arrochar or further out, external mastic is available for homes and businesses alike, from flats and houses to offices and hotels. Our West Dunbartonshire coverage runs to 31 places, Arrochar among them. There’s also a page for Glasgow, about 30 miles away.
We work across the G83 postcode area for external mastic. External mastic is available to properties on Church Road, Beechwood and Macfarlane Drive. Neighbouring places we cover for external mastic include Succoth (1 mile north), Tarbet (1 mile north-east), An Tairbeart (2 miles north-east), Lochgoilhead (6 miles west) and Ardlui (7 miles north). We also work in nearby towns such as Alexandria (15 miles south-east), Balloch (15 miles south-east) and Jamestown (15 miles south-east).
Near you in Arrochar
The closest station to Arrochar is Arrochar & Tarbet station, about 1 mile north-east. Other landmarks nearby include Inveruglas Isle Castle (3.9 miles north). Not far away are Loch Lomond.
Honest limits
We’ll always be straight with you, so here’s what sealant can’t fix:
- Structural movement, which needs a surveyor or engineer
- Rising or penetrating damp from elsewhere in the wall
- Cracks in the bricks or render themselves, away from the joints
If in doubt, email us at info@mrmastic.co.uk and we will say what we think before you book.
Surfaces we seal
- Brickwork movement joints
- Render & cladding joints
- Concrete & block
- Façade panels
- Joints between brick and frames
- Copings & trims
Should I try it myself first?
A careful DIYer can reseal a simple joint, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
Questions from Arrochar
I let a flat near Arrochar & Tarbet station. Can you help?
Yes, landlords and agents are among the people we work for. Just drop us a line at info@mrmastic.co.uk with the address and what needs doing, and we will give you a clear price.
Does living near the coast affect external mastic in Arrochar?
Coastal weather is harder on outside sealant: there’s more wind-driven rain and, closer to the shore, salt in the air. The right product, a clean joint and the right depth all help it cope.
Can you work on commercial sites?
Yes. We work in offices, washrooms, hotels and other commercial premises, as well as homes. Working times can be discussed when we quote.
Do the sealants smell?
It depends on the product. Some smell for a while, some hardly at all, and any smell fades as they cure.
Is it worth trying it myself?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
Will you leave a mess?
We keep the work tidy. Nearby surfaces are protected.
Can you quote for more than one area?
Yes. More than one area can go on one quote.
Are you fully insured?
Yes. Mr Mastic is fully insured, and we’ve been doing sealant work for more than 20 years.
Why deal with it now?
Done well, a resealed joint is a neat, straight line that suits the wall. A rushed bead with no backing looks untidy and does not last, so it pays to do it properly once. When the nearest tradesperson is a drive away, it’s tempting to leave a small leak, but water through a failed joint keeps working away until it’s fixed.
A failed joint rarely gets cheaper to fix by waiting, because water and mould keep working on it. If you’re unsure, email us at info@mrmastic.co.uk and we will give you an honest view and a quote.
Why book with us
- Full insurance on every job
- White, clear, grey or another colour, product permitting
- Anti-fungal sanitary silicone in wet areas
- Any old sealant cut out fully, not covered over
Read what affects the cost or our reviews.