Greater London · England
Ashburton External Mastic
Specialist external mastic for Ashburton: careful preparation, the right product and tidy work. Ask us for a quick quote.
- Failed sealant between panels on a façade
- Damp patches traced to an open external joint
- Rigid filler in a joint that should flex
What we can’t put right
Sealant isn’t the answer to every problem, and we will tell you before any work starts. Sealant won’t put right:
- Loose or hollow render, which needs re-rendering
- Subsidence or other structural problems
- Cracking across the wall rather than at a joint
If in doubt, ring 0345 464 0079 or drop us an email and we’ll say what we think.
What we seal
- Joints between brick and frames
- Render & cladding joints
- Copings & trims
- Façade panels
- Brickwork movement joints
- Concrete & block
External mastic for homes and businesses in Ashburton
We cut out failed sealant, set the joint depth with closed-cell backing rod and reseal with a low-modulus exterior sealant. The colour is chosen to suit the brick or render. We work on concrete & block, brickwork movement joints and joints between brick and frames, and the jobs we see most are moss and dirt in joints with no sealant left and weathered mastic that no longer stretches.
London’s terraces and conversions often share walls, gutters and downpipes with their neighbours, so one failed joint can cause damp for more than one household. For a flat in Ashburton, check the lease for who looks after the outside.
The work is covered for a year after we finish. If anything is not right with it, phone 0345 464 0079 or send us an email.
- Where
- Ashburton (CR0, SE25, CR9)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
Also near Ashburton
Also in Ashburton
How we quote for external mastic
The quote reflects the job in front of us. We take into account:
- The product the joint needs
- Working hours on commercial sites
- The number and length of the joints
- How many areas need sealing
Leaving a failed joint generally makes the job bigger, not smaller, as water and mould keep getting in. If you are unsure, phone 0345 464 0079 or email us for an honest opinion and a quote.
What to tell us for a quote
What to tell us when you ask for a quote:
- Any previous sealing or DIY work
- Roughly how big the job is
- If it’s domestic, commercial or a hotel
- Pictures of the joints, sent by email
If you’re in Ashburton and need external mastic, ring 0345 464 0079 or email us. A short description of the job and where it is helps us quote, and you will get a clear quote before we start.
Ashburton: your questions answered
Do you cover Ashburton for external mastic?
Yes. Our work covers London and the South East, and Ashburton is part of that. You can phone 0345 464 0079 or send us an email and tell us what needs doing.
Is parking a problem for a job in Ashburton?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. That way the visit can be planned around it.
Can tenants book the work?
We are happy to deal with the tenant, landlord or agent. Get your landlord’s agreement first.
When will the joints need doing again?
There’s no fixed answer: joints on exposed walls or with a lot of movement age sooner. A yearly look will tell you when they need doing. Our work comes with a one-year guarantee.
Can you seal joints between render and window frames?
Yes. Materials like render, brick, metal and uPVC all move differently, so the joint between them must be flexible. The sealant is matched to both sides.
Will it make a mess?
Tidy work is part of the job. We protect what’s around the joints, and the area is left clean when we finish.
Should I point up the gap in my brickwork?
No, not if it’s a movement joint. Filling it with mortar defeats its purpose and can lead to cracking. We will reseal it with a flexible sealant.
Why is there a gap in my brick wall?
A vertical gap in a long brick wall is normally a movement joint. It lets the bricks expand without cracking and needs a flexible seal, not mortar.
What happens on the day
Most of a good job is in the preparation, and we don’t rush it. Joints are cleaned back and dried before anything new goes in. In total, it generally takes a few hours for a handful of joints, longer for a whole elevation. For a job in Ashburton, parking and access are the things to plan: let us know about parking, the floor we will be working on and any lift or shared entrance.
- We look at every joint and agree a colour to suit the wall.
- We take out the old sealant until the faces are sound.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Getting ready for the visit
- Let us know about earlier repairs to the joints
- Move anything stored near the joints
- Mention any sign-in or site rules at work premises
Get a quote
For a quick quote, get us on the phone, or send an email if you’d rather. Describe what needs sealing and we’ll explain what’s involved.
Read more
How the job changes by surface
Concrete and blockwork
Blockwork and concrete shrink over time and move with the seasons. We reseal their joints with backing rod and a flexible product.
Joints between dissimilar materials
Different materials may need different primers. We prepare both faces so the sealant bonds properly.
Ashburton buildings and the weather
With historic houses such as Addington Palace (about 2.4 miles south-east) nearby, there’s older building stock in the area around Ashburton as well as newer homes. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material. London and the South East are among the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Homes close to Church of St Luke include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain. As a London address, Ashburton can be tricky for parking: let us know about parking bays, permits or a driveway. Managing a site like St Thomas Becket Catholic Primary School? Then larger buildings have long runs of movement joint that eventually need resealing.
Ashburton is about 6 miles south of New Cross, in Greater London. Every kind of property in Ashburton can book us for external mastic, old or new, large or small. The work is guaranteed for a year. Across Greater London, we cover 764 places, and Ashburton is one of them. We also work in London, about 8 miles from Ashburton.
Every address in CR0, SE25 and CR9 is covered for external mastic, from the main roads to the quietest streets. Whether your property is on Long Lane, Tudor Road and Coe Avenue or a nearby road, we can help. We also cover the places around Ashburton: Woodside (1 mile north), Addiscombe (1 mile south), Shirley Oaks (1 mile south-east), Monks Orchard (1 mile south-east) and Shirley (1 mile south-east). We also work in nearby towns such as London (8 miles north), City of Westminster (9 miles north-west), Marylebone (10 miles north), Kensington (10 miles north-west), St Pancras (10 miles north) and Shoreditch (10 miles north).
Around Ashburton
Locally, jobs take us to homes and businesses close to Oasis Academy Shirley Park, Ashburton Park and The Beehive pub, among other places. The nearest railway station is Norwood Junction station, about 0.7 miles north-west. Well-known places in the area include National Psychosis Unit (1.7 miles east) and Whitgift Centre (1.6 miles south-west). For a walk, there’s Duppas Hill and Bramley Bank.
Aftercare tips
Good habits help new joints last longer. A few tips:
- Do not let climbing plants root in the sealant
- Walk round the building once a year and look at the joints
- Check the sealant is paintable before painting near it
- Avoid pressure-washing directly into sealant joints
Give the sealant the cure time we tell you before anything rubs against it. Most exterior sealants skin fast but take longer to cure right through.
Small splits are the time to act. At that stage it’s a simple cut out and reseal with no damage behind it to deal with.
Landlords, agents and businesses in Ashburton
Mouldy or split sealant often shows up at the end of a tenancy. Several properties can go on one quote.
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Should I try it myself first?
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
If you’re set on DIY, put the effort into preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it does not work out, we can still put it right.