Greater London · England
External & façade joints in Southgate, Greater London
External mastic for Southgate, by sealant specialists with 20+ years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Damp patches traced to an open external joint
- Gaps where render, brick and frames meet
- Sealant pulling away from one side of the joint
External mastic in Southgate, done properly
Short cuts in external joints show up within a season or two. New sealant over old, joints packed with mortar and beads with no backing rarely last long. We strip the joint back and start again. We work on joints between brick and frames, façade panels and copings & trims, and people most often call us about old sealant gone brittle and cracked and panel joints letting water in.
Newer London blocks are built with movement joints in brick and render, and with cladding joints sealed with mastic. Period houses have different weak points, such as gutter joints, trims and the line where an extension meets the old wall, and both kinds of building are found across London.
The work is guaranteed for twelve months. If something is not right with it in that time, tell us and we will put it right.
- Where
- Southgate (N14, N11, N21, N13)
- Region
- Greater London
- Cover
- A year, on every job
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
External mastic in Southgate: local notes
In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking. Rainfall in the South East is lower than in much of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
If you let a flat or house near New Southgate station, outside joints that have cracked can let damp into a rental, so check them between lets. Homes close to Christ Church Southgate Parish Church include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain.
Southgate is about 3 miles south-east of Barnet, in Greater London. For external mastic in and around Southgate, it’s easy to get a quote: please call 0345 464 0079 or drop us an email. We cover Greater London from our Crawley base. Southgate is one of 764 places in Greater London where we work for external mastic. There’s also a page for London, roughly 9 miles from Southgate.
All of N14, N11, N21 and N13 is covered for external mastic. You will find streets such as High Street, Station Road and Blagden's Close, and we cover them all. With the A111 and A1004 close by, Southgate is easy for our applicators to reach for external mastic. Other places close to Southgate include Osidge (1 mile north-west), Brunswick Park (1 mile west), Arnos Grove (1 mile south), New Southgate (1 mile south) and Oakwood (1 mile north). Larger places within reach include London (9 miles south), City of Westminster (8 miles south), Marylebone (8 miles south), Kensington (9 miles south), St Pancras (7 miles south) and Shoreditch (7 miles south).
Near you in Southgate
We work in homes and buildings around The New Crown pub, Grovelands Park and Ashmole Academy and the streets around them. The nearest railway station is New Southgate station, about 1 mile south-west of the centre. Well-known places in the area include Grand Arcade (2.1 miles south-west) and Greentrees Hospital (1.9 miles south-east). Open spaces near Southgate include Highgate Hill and Barfield Allotments Nature Park.
Surface by surface
Concrete and blockwork
Concrete faces can be dusty and porous, so preparation is key. A primer goes on where the product requires one before sealing.
Cladding and façade panels
Panels heat up and cool down quickly, so the joints work hard every day. We choose the product to suit.
Southgate questions
Do you work for landlords with property near New Southgate station?
Yes, we work for letting agents and landlords. You can ring 0345 464 0079 or drop us an email with the address and a few details, and we will give you a fixed price before work begins.
Is Southgate in your area for external mastic?
Yes, Southgate is within the area we cover. We work across London and the South East. Just call 0345 464 0079 or email us with a few details of the job.
Where do you work from?
We’re a Crawley-based firm. Our area covers South East England, London and Scotland.
How long will you be here?
As a guide, most jobs take a few hours for a handful of joints, longer for a whole elevation. Larger jobs naturally take longer, and we will say how long yours will take.
Do you take out the old sealant first?
Yes. We cut out all the old sealant and clean the joint before resealing.
Is the work guaranteed?
Yes. There’s a 12-month guarantee on every job, wherever you are.
Do you seal joints where cladding meets other materials?
Yes. Materials like render, brick, metal and uPVC all move differently, so a flexible sealant is needed where they meet. We choose one that suits both surfaces.
Will it make a mess?
Not at all. We work neatly, protect the area around the joints and tidy up afterwards.
Do you need external mastic in Southgate?
The wrong product in a moving joint is a classic cause. A high-modulus or general-purpose sealant can be too rigid for a busy joint, and it tears off the sides.
The problems people usually mention when they call are:
- Damp patches traced to an open external joint
- Sealant that has lost its bond to the brick or render
- Brick movement joints where the sealant has split
- Failed seals between different materials
Southgate is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
What your quote should include
- Whether they seal over old material or remove it
- Who does the work, and how experienced they are
- Which colour the sealant will be
- What the quote includes, VAT included or not
Keeping the joints in good condition
Once the sealant has cured, a few habits help it last:
- Keep soil, plants and ivy away from the joints
- Walk round the building once a year and look at the joints
- Never let anyone fill a movement joint with mortar
- Tell anyone working on the walls about the movement joints
Only paint over the joint if we’ve confirmed the sealant can take paint. Many exterior sealants aren’t designed to be painted and spoil the finish.
An open movement joint lets rain into the wall every time it pours. Over time it can mean damp inside, stained render or frost-damaged brick, all bigger jobs than a reseal.
Also near Southgate
Other services in Southgate
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly.
For landlords and businesses
Failed sealant is one of the commonest items on a check-out report, and it’s quick to put right between tenancies. Several properties can go on one quote.
For anyone letting property in or around Southgate, jobs at different addresses can go on one quote. Send us the addresses and the work at each.
When something else is needed
Some problems need a builder, plumber or other trade rather than us:
- Cracked brickwork or render that needs a builder or plasterer
- Rising or penetrating damp from elsewhere in the wall
- Loose or hollow render, which needs re-rendering
Not sure which it is? You can phone 0345 464 0079 or drop us an email and we’ll tell you honestly.
Surfaces we seal
- Brickwork movement joints
- Concrete & block
- Façade panels
- Joints between brick and frames
- Copings & trims
- Render & cladding joints
What we do, step by step
A visit follows a simple pattern: we check the joints, mask and protect the surrounding surfaces, do the work and clear up. It usually takes anything from a few hours to several days, depending on the building. In Southgate, as in most of London, parking needs a little planning. 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.
- Primer is applied wherever the sealant needs it.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
Before we arrive
- For indoor joints, keep the area dry beforehand if you can
- Tell us about any previous sealing or DIY attempts
- Clear items away from the joints we are working on
How to get a quote
We do not publish a price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To arrange one, ring 0345 464 0079 or drop us an email.