Scottish Borders · Scotland
Denholm External Mastic
Movement joints in Denholm need attention? We cut out the old, prepare the joints and apply the right sealant, with a 12-month guarantee.
- Damp patches traced to an open external joint
- Joints pointed up with cement by mistake
- Hard, crazed mastic that has stopped moving
How to look after the new joints
After the cure time, these simple habits help:
- Make sure movement joints are not pointed over
- Keep soil, plants and ivy away from the joints
- Get split or bare joints resealed while the damage is small
- Tell anyone working on the walls about the movement joints
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They must stay as flexible joints, never rendered or pointed over.
Once a joint can’t move, the wall finds another way, often as cracks near the joint. Resealing it early helps prevent that.
External mastic in Denholm, done properly
A movement joint is a deliberate break that lets a wall expand and contract. The sealant in it has to stretch and squeeze for years, so once it splits or hardens, the joint stops working and water gets in. If you have sealant pulling away from one side of the joint and old sealant gone brittle and cracked, we can help, whatever the surface.
Stone walls need a stone-friendly sealant, as acetoxy products can attack some stone. Newer houses need their movement joints and roofline trims kept sound.
The work is covered for a year after we finish. If anything isn’t right with it, send an email to info@mrmastic.co.uk.
- Place
- Denholm (TD9)
- Wider area
- Scottish Borders
- Cover
- A year, on every job
- Quotes
- Quoted before any work starts
- info@mrmastic.co.uk
- Updated
- 26 October 2026
Surface by surface
Copings and trims
Copings expand and contract through the day, so the joints need a sealant that stays flexible.
Brickwork movement joints
Vertical joints in long brick walls let the brickwork expand without cracking. We reseal them with a low-modulus sealant over backing rod in a colour to suit the brick.
Also near Denholm
What else we do in Denholm
Do you need external mastic in Denholm?
Sometimes a movement joint was filled with mortar or a rigid filler. The joint cannot move, so the wall cracks somewhere else instead.
Most people get in touch after spotting something like this:
- Cracked joints where brick meets render or frames
- Sealant that has lost its bond to the brick or render
- Old sealant gone brittle and cracked
- Damp patches traced to an open external joint
For site and facilities teams at buildings such as Craigmount School, larger buildings have long runs of movement joint that eventually need resealing.
Questions to ask before you book
- How hidden problems are handled
- When the joint can take water or movement
- What guarantee comes with the work
- What product goes in the joint
Honest limits
New sealant can’t fix everything, and we’d rather say so up front. It will not solve:
- Structural movement, which needs a surveyor or engineer
- Cracking across the wall rather than at a joint
- Rising or penetrating damp from elsewhere in the wall
Not sure which it is? You can send an email to info@mrmastic.co.uk and we will tell you honestly before you book.
Surfaces we seal
- Joints between brick and frames
- Concrete & block
- Copings & trims
- Façade panels
- Brickwork movement joints
- Render & cladding joints
Questions from Denholm
Is Denholm within the area you cover?
Yes, Denholm is covered. Our work covers the whole of Scotland, from towns to the smallest places. The journey is planned ahead, so it helps to know about access.
Is there a guarantee on external mastic in Denholm?
All our work, in Denholm and everywhere else, comes with a 12-month guarantee. We’re also fully insured and ARBOMaster approved.
Can landlords and businesses book you?
Yes. We work in homes, commercial premises and hotels.
Is it OK to seal over old sealant?
No, and we never do. It can look neat for a few weeks, but the new layer lifts away from the old one. The old sealant has to come out completely.
Can you quote for more than one area?
Yes, and it often makes sense. Doing several areas at once is generally more efficient.
Can you match the colour of my brickwork?
There’s a good range of exterior colours, including greys, browns, whites and stone tones. We pick the one that suits your wall best so it doesn’t stand out.
Will the old sealant be removed?
Always. Sealing over old sealant is the main reason resealing fails early, and it’s something we never do.
Can I do it myself?
Some simple jobs can be done by a careful DIYer. Most DIY failures come from sealing over old material, wet joints or too much sealant.
What happens if it’s left?
A low-modulus sealant is chosen because it moves without pulling hard at the edges. That matters on brick, render and concrete, which can be weaker at the face. A stiffer product can damage the joint edge as it fails. In an older home around Denholm, damp from a failed joint can get into timber and plaster.
Every job is a little different, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all make a difference.
What you get with us
- Trusted Arbo and Everbuild sealants
- Sanitary silicone with an anti-fungal additive in wet areas
- Any old sealant cut out fully, not covered over
- ARBOMaster approved applicator
Read what affects the cost or what customers say.
Landlord and commercial work in Denholm
Failed sealant is one of the commonest items on a check-out report, and it’s easy to sort out between tenants. We can quote for more than one property at once.
We also work for property managers and facilities teams. We can quote a run of properties together, and we’re fully insured for the work.
How the visit works
A visit follows a simple pattern: we look at the joints together, protect the area around them, carry out the job and tidy away. It usually takes anything from a few hours to several days, depending on the building. Outside jobs in Denholm need a dry day, because sealant will not bond to a wet joint, so an outdoor job can move if the forecast changes. Work indoors isn’t affected.
- We start by checking each joint, agreeing the ones to redo and how we’ll reach them.
- We cut out the failed sealant and rake out any dirt or growth.
- We clean both faces of the joint and prime them where the product calls for it.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
Getting ready for the visit
- Clear the area around the work
- Keep children and pets away from the work area
- Mention if the joints have been sealed before
Get a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and add photos by email if you can.
Related advice
Outside joints around Denholm
Private landlords in Scotland must meet the Repairing Standard, which includes keeping a home wind and watertight, and failed outside joints work against that. Harled (roughcast) walls are common in Scotland, and joints where harling meets other materials need a sealant that can grip and flex.
Homes close to Minto Parish Church include some older properties, and the joints between older walls, newer extensions and the roofline need a sealant that can move.
Denholm is about 5 miles north-east of Hawick, in the Scottish Borders. Wherever you are in the TD9 postcode area, our applicators can take on external mastic. Denholm is one of 89 towns and villages in the Scottish Borders where we work for external mastic. For nearby work, see our Edinburgh page (39 miles or so).
Our applicators cover all of TD9 for external mastic. External mastic is available to properties on Main Street, Douglas Drive and Murray Place and the roads around them. If you are just outside Denholm, we cover Burnfoot (4 miles south-west), Belses (4 miles north), Bonchester Bridge (4 miles south), Stirches (5 miles west) and Hawick (5 miles south-west). Larger places within reach include Galashiels (12 miles north-west), Kelso (14 miles north-east), Selkirk (9 miles north-west), Jedburgh (5 miles east), Wilton (5 miles south-west) and Melrose (10 miles north).
Landmarks near Denholm
Well-known places in the area include Bedrule Castle (1.8 miles east) and Hawick Community Hospital (5 miles south-west). Not far away are Rubers Law.