Greater London · England
Barnsbury External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Barnsbury and across Greater London. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Gaps where render, brick and frames meet
- Moss and dirt in joints with no sealant left
- Joints where the bead has come unstuck
Barnsbury buildings and the weather
With historic houses such as Dr Johnson's House (about 2.1 miles south) nearby, there’s older building stock in the area around Barnsbury as well as newer homes. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth. London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking.
For landlords with property near Caledonian Road & Barnsbury station, outside joints that have cracked can let damp into a rental, so check them between lets. Homes close to Former Church of St Clement include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant.
Barnsbury is about 1 mile north of St Pancras, in Greater London. For external mastic in and around Barnsbury, please ring 0345 464 0079 or drop us an email for a quick quote. We are based in Crawley and cover Greater London. Barnsbury is one of 764 towns and villages in Greater London we cover for external mastic.
All of N1, N1P and N7 is within our area for external mastic. Streets in the area include Cliff Road, Lough Road and North Road, and we cover them all. Being close to the A5200 and A5203, Barnsbury is simple for us to get to for external mastic. We also cover Lower Holloway (1 mile north), Islington (1 mile south-east), Agar Town (1 mile south-west), Pentonville (1 mile south-east) and Holloway (1 mile north). Within a short drive, we also cover London (3 miles south), City of Westminster (3 miles south-west), Kensington (5 miles south-west), Walthamstow (5 miles north-east), Whitechapel (3 miles south-east) and Hampstead (3 miles west).
Local landmarks in Barnsbury
Around Barnsbury, our work takes us to homes and buildings near Vaughan Williams Memorial Library, St Mary Magdalene Academy and Bingfield Park, among other places. Also close by are Musical Theatre Academy (0.5 miles north-east) and The White Horse Public House (under half a mile north-west). There’s a railway station in Barnsbury itself: Caledonian Road & Barnsbury station. Well-known places in the area include Brunswick Centre (1.4 miles south) and Montfichet's Tower (2.2 miles south). Open spaces near Barnsbury include Dartmouth Park Hill and Barnsbury Wood.
External mastic for homes and businesses in Barnsbury
Failed sealant is cut out, the depth set with closed-cell backing rod, and the joint resealed with a low-modulus sealant made for outside. The colour is chosen to suit the brick or render so the joint doesn’t stand out. Common call-outs are for failed sealant between panels on a façade and joints pointed up with cement by mistake, across copings & trims, brickwork movement joints and render & cladding joints.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. For a home in Barnsbury, tell us how high the joints are and how to reach the back of the building.
All of our work is guaranteed for twelve months, in Barnsbury and everywhere else we cover.
- Place
- Barnsbury (N1, N1P, N7)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What sealant work can’t fix
Honest advice matters more to us than a booking, so here’s what sealant cannot fix:
- Cracking across the wall rather than at a joint
- Rising or penetrating damp from elsewhere in the wall
- Cutting new joints into brickwork, which is building work rather than sealant work
If in doubt, ring 0345 464 0079 or send us an email and we’ll say what we think before booking.
Surfaces we seal
- Render & cladding joints
- Concrete & block
- Joints between brick and frames
- Brickwork movement joints
- Copings & trims
- Façade panels
Common questions in Barnsbury
Do you cover Barnsbury for external mastic?
Yes, Barnsbury is within the area we cover. We work across London and the South East. Just phone 0345 464 0079 or drop us an email with a few details of the job.
Can parking be tricky for a visit in Barnsbury?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
I’m a tenant. Can you help?
Yes, but check with your landlord or agent first. Landlords are often happy for the work to be arranged.
Does someone need to be in?
For indoor joints, yes, someone needs to let us in. After that, you can carry on with your day.
Can new sealant go over the old?
No, and we never do. It may look fine at first, but the new layer lifts away from the old one. The old sealant has to come out completely.
How do you reach high-level joints?
That depends on how high the joints are and the ground below. Ground-floor joints are simple; for higher work, tell us about the building and we’ll confirm what’s needed.
What information do you need?
A short description and the location, with photos by email if possible. If we need more, we’ll ask.
Will you leave a mess?
Not at all. We work neatly, protect the area around the joints and tidy up afterwards.
Why act early in Barnsbury
Water gets in through a failed movement joint and can run behind render or cladding. Dealing with it early keeps the repair to the joint, instead of the wall and finishes around it. In older London homes, water behind a failed joint soaks into brick and timber without much sign, and by the time it shows on a wall or ceiling in Barnsbury, the repair is bigger than the sealant job would have been.
Leaving a failed joint usually makes the job bigger, not smaller, as water and mould keep getting in. If you are not sure whether it needs doing, call 0345 464 0079 or send us an email and we will give you an honest view and a quote.
Why us?
- Approved under the ARBOMaster scheme
- Domestic, commercial and hotel work
- We never seal over old sealant
- We agree the colour with you first
Take a look at what affects the cost and our reviews.
How it works
Good joint work is mostly preparation, so that’s where we spend the time. Every joint is cleaned and dried before new material goes in. In total, it usually takes a few hours for a handful of joints, longer for a whole elevation. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Barnsbury. A visitor permit or a nearby bay makes the visit run more smoothly.
- We look at every joint and agree a colour to suit the wall.
- We take out the old sealant until the faces are sound.
- Backing rod goes in so the sealant can stretch between the two faces.
- We prime the faces where required.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- Try not to wet indoor joints just before the visit
- Let us know about parking restrictions
- Clear items away from the joints we’re working on
Get a quote
Want a quote for external mastic? Please ring 0345 464 0079 or drop us an email with a few details. We’ll explain what we’d do and give you a clear quote before work begins.
Related advice
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
If you’re set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it fails, we can still redo it.
Aftercare tips
Good habits help new joints last longer. A few tips:
- Point out the joints to other trades
- Keep water from gutters off the wall
- Check the sealant is paintable before painting near it
- Check external joints each spring
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. Then it’s a straightforward cut-out and reseal with no damage behind it to deal with.
When to call us in Barnsbury
Sunlight, wet weather and frost wear exterior sealant down. Over the years it hardens, cracks on the surface and loses its give, so the next time the wall moves, it splits or pulls away.
These are the problems we are asked about most:
- Cracked joints where brick meets render or frames
- Leaking joints around cladding and façade panels
- Rain getting behind render or cladding at a joint
- Weeds or debris growing in open joints
Barnsbury is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
What your quote should include
- When the joint can take water or movement
- Whether they’re fully insured
- What product goes in the joint
- What happens if they find a problem under the old sealant
Work for landlords, hotels and businesses
We work for letting agents and landlords as well as homeowners. Resealing between tenancies is a simple way to keep a property in good order before the next move-in.
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance that we can handle for you.