Surrey · England
External & façade joints in Coldharbour, Surrey
Specialist external mastic for Coldharbour: the right sealant, proper preparation and a neat finish. Call for a quick quote.
- Weathered mastic that no longer stretches
- Rain getting behind render or cladding at a joint
- Movement joints filled with mortar instead of sealant
About our external mastic in Coldharbour
External mastic is a job where short cuts show quickly. Overfilled joints, missing backing rod and sealant laid over old sealant all tend to fail early. We take the old material out and do it properly. Typical jobs include weeds or debris growing in open joints and rain getting behind render or cladding at a joint, across render & cladding joints, joints between brick and frames and brickwork movement joints.
Outside joints can only be sealed when they’re dry, so work in Coldharbour is booked around the forecast. Let us know about access to every wall, plus any garages or outbuildings.
You are covered for a year from the day we finish. If anything is not right with it, ring 0345 464 0079 or send us an email.
- Location
- Coldharbour (RH5)
- Wider area
- Surrey
- Cover
- One year on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Your questions about external mastic in Coldharbour
Is Coldharbour in your area for external mastic?
Yes. We work across London and the South East, and Coldharbour is part of that. Just ring 0345 464 0079 or send us an email with a few details of the job, and we’ll give you a clear quote.
I let a flat near Holmwood station. Can you help?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or email us and tell us about the property, and we will give you a clear price.
Are you ARBOMaster approved?
Yes. ARBOMaster is the approved applicator scheme for Arbo sealants, and we’re part of it.
Can I add another job to the visit?
Of course. Doing several areas at once is usually more efficient.
How long will you be here?
Typically it takes a few hours for a handful of joints, longer for a whole elevation. Bigger jobs take longer.
Do you have insurance?
Yes. We are fully insured.
How long does external mastic last?
There’s no fixed answer: joints on exposed walls or with a lot of movement age sooner. Check them each year and reseal when they split or harden. Every job carries our 12-month guarantee.
Where is Mr Mastic based?
Our base is Crawley. Our area covers South East England, London and Scotland.
What sealant work can’t fix
Before booking, it’s worth knowing the limits:
- Subsidence or other structural problems
- Cracking across the wall rather than at a joint
- Adding movement joints to masonry that has none
Not sure which it is? You can phone 0345 464 0079 or send us an email and we’ll tell you honestly before booking.
Surfaces we seal
- Concrete & block
- Brickwork movement joints
- Joints between brick and frames
- Façade panels
- Copings & trims
- Render & cladding joints
How to look after the new joints
So the new joints stay in good condition:
- Avoid pressure-washing directly into sealant joints
- Ask before painting over external sealant
- Tell anyone working on the walls about the movement joints
- Walk round the building once a year and look at the joints
Follow the cure time we give you before the joint is knocked or disturbed. The surface skins over quickly, but full cure takes longer.
Once a joint cannot move, the wall finds another way, often as cracks near the joint. Catch it early and you reduce the risk.
How the visit works
At the end, we look at the finished work together. The visit itself usually takes anything from a few hours to several days, depending on the building, depending on how much there is to do. In a small place like Coldharbour, access is generally the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First we look over the joints with you, agree which to renew and talk through access.
- Old sealant and any debris are cut and raked out.
- Both sides are cleaned back to sound material and primed if needed.
- 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.
How to prepare
- Tell us about any previous sealing or DIY attempts
- Let us know about stairs, lifts or work at height
- Where the joints are inside, avoid wetting them before we arrive
How to get a quote
The more we know about the job, the more useful the quote. Tell us where the job is, what’s wrong and how much there is, and email photos if that is easy.
Related advice
Landlords, agents and businesses in Coldharbour
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. Hotel work is part of what we do, alongside homes and businesses.
Coldharbour buildings and the weather
The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Letting a property close to Holmwood station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Coldharbour is about 4 miles south of Dorking, in Surrey. Coldharbour gets the same service as everywhere we cover: the old material taken out, joints prepared properly and a 12-month guarantee. Coldharbour is one of 395 towns and villages in Surrey we cover for external mastic. For nearby work, see our Crawley page, about 9 miles away.
Our applicators cover all of RH5 for external mastic. Neighbouring places we cover for external mastic include Abinger Bottom (2 miles north-west), South Holmwood (2 miles north-east), Holmwood Corner (2 miles east), Friday Street (2 miles north-west) and Beare Green (2 miles east). Larger places within reach include Guildford (10 miles north-west), Woking (13 miles north-west), Epsom (11 miles north), Horley (8 miles east), Redhill (9 miles north-east) and Ewell (13 miles north).
Local landmarks in Coldharbour
In Coldharbour, that means homes and buildings near Wotton and Abinger Commons and Plough Inn, among other places. Coldharbour’s nearest station is Holmwood station, roughly 1.6 miles east. A little further out are Mesolithic Museum (2.6 miles north-west) and Abinger Castle (2.6 miles north-west). For a walk, there’s Vann Lake and Leith Hill.
Why it’s worth doing now in Coldharbour
An open joint keeps letting water into the wall with every downpour. In cold weather, frost can damage wet brick and render, so the problem grows beyond the joint itself. In a small place like Coldharbour, homes can be exposed to wind and rain, which finds any gap, and older walls, once damp, take a long time to dry.
The cost depends on the size of the job, how much old material has to come out and access to the work. You’ll have a clear quote before any work starts.
Why Coldharbour clients choose us
- Approved under the ARBOMaster scheme
- A choice of colours where the product allows
- Anti-fungal silicone where joints get wet
- We’re fully insured
Take a look at what affects the cost and what customers say.
When to call us in Coldharbour
If plants are growing out of a joint, the sealant has usually failed or was never there. Dirt and roots then trap moisture in the joint and make things worse.
Common reasons people contact us include:
- Gaps where render, brick and frames meet
- Joints with sealant missing in places
- Rigid filler in a joint that should flex
- Failed sealant between panels on a façade
In the older streets around Christ Church, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Before you book anyone
- How the surfaces are prepared before sealing
- When the joint can take water or movement
- What happens if the job turns out different
- Is VAT in the price?
Surface by 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.
Cladding and façade panels
Panel systems often rely on sealant between and around the panels. Each joint gets a sealant that suits the panel and its movement.