Greater London · England
New Southgate External Mastic
External mastic for New Southgate, by sealant specialists with 20+ years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Weeds or debris growing in open joints
- Old sealant gone brittle and cracked
- Joints pointed up with cement by mistake
How we handle external mastic in New Southgate
Many failed façade joints only get noticed once there’s a stain or a damp patch inside. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a colour to suit. We are often asked to deal with damp patches traced to an open external joint and joints pointed up with cement by mistake, across brickwork movement joints, render & cladding joints and concrete & block.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. In New Southgate, joints up high may need ladders or other access, which is worth talking through when you book.
You get a one-year guarantee, the same in New Southgate as everywhere else we work.
- Location
- New Southgate (N11, N10, N14)
- Wider area
- Greater London
- Cover
- A year, on every job
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Do you need external mastic in New Southgate?
A lot of failed joints come down to preparation: joint faces that were dusty or damp, unprimed where they needed it, or still carrying old sealant. The sealant never bonds properly.
Look out for these signs:
- Brick movement joints where the sealant has split
- Rigid filler in a joint that should flex
- Panel joints letting water in
- Joints where the bead has come unstuck
New Southgate is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
What your quote should include
- When the joint can take water or movement
- Who does the work, and how experienced they are
- Whether they seal over old material or remove it
- Which colour the sealant will be
Also near New Southgate
What else we do in New Southgate
Aftercare tips
To keep the joints looking good and working properly:
- Tell anyone working on the walls about the movement joints
- Leave the joints unpainted unless we have said otherwise
- Keep soil, plants and ivy away from the joints
- Keep movement joints as flexible joints, not mortar
Only paint over the joint if we have confirmed the sealant can take paint. Many exterior sealants aren’t designed to be painted.
Act while the splits are small. At that stage it’s a simple cut out and reseal before water has had years to get in.
How it works
Once we’re on site, 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 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 New Southgate. A visitor permit or a nearby bay makes the visit run more smoothly.
- We start by checking each joint, agreeing the ones to redo and how we’ll reach them.
- The old mastic and anything lodged in the joint is removed.
- Both sides are cleaned back to sound material and primed if needed.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
Preparing for the visit
- For indoor joints, keep the area dry beforehand if you can
- Let us know about parking restrictions
- Plan for the work area to be out of bounds to pets and children
Getting a quote
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is, and we will explain how we’d tackle it. Whenever you are ready, ring 0345 464 0079 or send us an email.
Related advice
New Southgate buildings and the weather
Historic houses like Heath Hall (about 2.9 miles south-west) are a reminder that the area around New Southgate has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material. In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts.
For an older house near a landmark such as St Paul's Church, old and new materials meet at the roofline and walls, which is where sealant earns its keep. Schools such as St Paul's CofE Primary School N11 are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
New Southgate is about 2 miles north-east of Finchley, in Greater London. Wherever you are in the N11 postcode area, we can carry out external mastic at your property. We cover 764 towns and villages across Greater London. There’s also a page for London, about 8 miles away.
Postcode districts we cover here for external mastic: N11, N10 and N14. Whether your property is on High Road, Orion Road and Atlas Road or a nearby road, we can help. New Southgate sits on or near the A1003 and A1110, which makes travel easy. We also cover Friern Barnet (1 mile west), Arnos Grove (1 mile east), Bounds Green (1 mile south-east), Brunswick Park (1 mile north) and Southgate (1 mile north). Within a short drive, we also cover London (8 miles south), City of Westminster (7 miles south), Marylebone (7 miles south), Kensington (8 miles south), St Pancras (6 miles south) and Shoreditch (7 miles south-east).
Landmarks near New Southgate
Around New Southgate, our work takes us to homes and buildings near Friern Barnet School, Ming-Ai and The Ranelagh pub and the streets around them. You’ll also find O. R. Tambo Recreation Ground (0.9 miles south-east) and Francis Skaryna Belarusian Library and Museum (1.8 miles west). New Southgate has its own railway station: New Southgate station. Well-known places in the area include Grand Arcade (1.5 miles west) and Broomfield House Museum (1.1 miles east). The countryside around New Southgate includes Barfield Allotments Nature Park and Highgate Hill.
Honest limits
To be straight with you, some problems need a different trade:
- Damp that isn’t coming from the joint
- 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 before booking.
What we seal
- Copings & trims
- Façade panels
- Render & cladding joints
- Concrete & block
- Joints between brick and frames
- Brickwork movement joints
What the job involves on each surface
Cladding and façade panels
If the façade has a specified sealant, that’s what we use, or one the system allows. Tell us what the building has when you get in touch.
Concrete and blockwork
Concrete faces can be dusty and porous, so cleaning and priming matter. We prime where the sealant needs it before the bead.
New Southgate: your questions answered
Can parking be tricky for a visit in New Southgate?
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.
Do you work for landlords with property near New Southgate station?
Yes. We work for landlords and letting agents as well as homeowners, and several properties can be quoted together. You can ring 0345 464 0079 or email us with the details for a clear quote.
Do you work at height?
That depends on the building and the joints. Where joints can be reached safely, we will do them. Give us some details and we’ll confirm the access.
Should I try DIY first?
You can, for simple jobs. Preparation is everything: all the old sealant out, and a clean, dry joint. If it doesn’t work out, we can redo it.
What should I tell you?
Tell us what needs doing and where, with pictures by email if possible. We’ll ask anything else we need to know.
Does someone need to be in?
That depends on where the joints are. Inside work needs someone to give us access, and for outside work we will agree access with you when we book.
Do you come to New Southgate?
Yes. We’re based in Crawley and work across South East England, London and Scotland, and that includes New Southgate.
When will the joints need doing again?
That varies with the weather the wall faces, how much it moves and the sealant used. Sealant is a maintenance item, so check the joints once a year and renew it when it starts to fail.
Can I do it myself?
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and does not move well, and the joint depth matters as much as the finish.
For landlords and businesses
For anyone letting property in or around New Southgate, jobs at different addresses can be quoted together. Send us the addresses and the work at each, and pictures by email help.
We work for letting agents and landlords as well as homeowners. Sealant work between tenants keeps a property looking cared for.