Greater London · England
External Mastic in North Finchley
Our applicators work in North Finchley on sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly.
- Weeds or debris growing in open joints
- Damp patches traced to an open external joint
- Movement joints filled with mortar instead of sealant
External mastic in North Finchley, done properly
Ground-floor and low-level joints are straightforward to reach. Where joints are higher up, tell us about the building when you get in touch and we will confirm what access is needed. We work on concrete & block, joints between brick and frames and façade panels, and common reasons people get in touch are hard, crazed mastic that has stopped moving and cracked joints where brick meets render or frames.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. For a home in North Finchley, tell us how high the joints are and how to reach the back of the building.
There’s a 12-month guarantee on every job, large or small.
- Place
- North Finchley (N12, N20, N11)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear price before any work starts
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Aftercare tips
So the new joints stay in good condition:
- Avoid pressure-washing directly into sealant joints
- Ask before painting over external sealant
- Check external joints each spring
- Have failed joints looked at early
Make sure anyone working on the wall later knows where the movement joints are. They must stay as flexible joints, never rendered or pointed over.
Water getting behind cladding or render can go unnoticed for a long time. By the time there’s a damp patch, the damage can be well established so early resealing is worth it.
External mastic in North Finchley: local notes
London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking.
Managing a site like Sacks Morasha Jewish Primary School? Then larger buildings have long runs of movement joint that eventually need resealing. As a London address, North Finchley can be tricky for parking: let us know about parking bays, permits or a driveway.
North Finchley is about 1 mile north of Finchley, in Greater London. If you need external mastic in North Finchley, please phone 0345 464 0079 or send us an email for a quick quote. We are based in Crawley and cover Greater London. North Finchley is one of 764 towns and villages in Greater London we cover for external mastic. There’s also a page for London, about 9 miles away.
Here we cover the N12, N20 and N11 postcode area for external mastic. If you need external mastic at a property on High Road, Lodge Lane and Percy Road or a nearby road, we can help. Being close to the A1000, North Finchley is simple for us to get to. Other places close to North Finchley include Woodside Park (1 mile west), Oakleigh Park (1 mile north), Whetstone (1 mile north), Friern Barnet (1 mile east) and Finchley (1 mile south). Further out, we also cover London (9 miles south-east), City of Westminster (7 miles south), Marylebone (7 miles south), Kensington (8 miles south), St Pancras (7 miles south) and Shoreditch (8 miles south-east).
Local landmarks in North Finchley
Around North Finchley, our work takes us to homes and buildings near Friary Park, Woodhouse College and The Bohemia pub and the streets around them. Nearby too are Francis Skaryna Belarusian Library and Museum (0.5 miles west) and St Michael's Catholic Grammar School (less than half a mile south-west). The closest station to North Finchley is New Southgate station, about 1.4 miles east. Nearby you’ll also find Finchley Memorial Hospital (0.8 miles south) and Francis Skaryna Belarusian Library and Museum (0.5 miles west). Not far away are Darland's Lake and Glebelands Local Nature Reserve.
Why act early in North Finchley
Done well, a resealed joint is a neat, straight line that suits the wall. A rushed bead with no backing looks untidy and doesn’t last, so it pays to do it properly once. In a London flat, a failed joint rarely stays your problem alone: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
No two jobs are quite the same, so we quote each one individually. Size, access and the product the joint needs all play a part.
Why choose Mr Mastic in North Finchley
- 180+ five-star Google reviews
- Sanitary silicone with an anti-fungal additive in wet areas
- We leave the area clean and tidy
- We are fully insured
Take a look at how sealant jobs are priced and customer reviews.
Also near North Finchley
Also in North Finchley
Signs you need external mastic in North Finchley
If plants are growing out of a joint, the sealant has normally failed or was never there. Roots and dirt hold water against the wall.
Look out for these signs:
- Sealant that has lost its bond to the brick or render
- Cracked joints where brick meets render or frames
- Brick movement joints where the sealant has split
- Old sealant gone brittle and cracked
If you live in an older home near St. Barnabas Church, the joints between older walls, newer extensions and the roofline need a sealant that can move.
Questions to ask before booking
- The length of the guarantee
- When the joint can take water or movement
- Whether VAT is included
- Whether they seal over old material or remove it
Should I try it myself first?
If you’ve already had a go yourself, that is fine. We cut it out and start again.
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it doesn’t work out, we can still put it right.
Your questions about external mastic in North Finchley
Is parking an issue for external mastic in North Finchley?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly.
Is North Finchley in your area for external mastic?
Yes, North Finchley is within the area we cover. We work across London and the South East. Just ring 0345 464 0079 or send us an email with a few details of the job, and we will give you a clear price.
Do the sealants smell?
That depends on the sealant. Some products have a noticeable smell, others very little.
Do you do commercial work?
Yes. Commercial and hotel work is a large part of what we do. We can talk about working times when we quote.
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.
Can I add another job to the visit?
Yes, we can. More than one area can go on one quote.
Will the new joint stand out?
There’s a good range of exterior colours, including greys, browns, whites and stone tones. We choose the closest to your brick or render.
I rent my home. Can I book you?
We can work for tenants, landlords or agents. Just make sure your landlord agrees.
What the job involves on each surface
Render joints
Water behind render can lead to blown patches. Resealing the joints early keeps water out.
Joints between dissimilar materials
Wherever two materials meet, they move differently. A flexible sealant bridges the two so neither cracks the other.
When something else is needed
We’d rather tell you now than do work that will not last, so these are the limits:
- Structural movement, which needs a surveyor or engineer
- Walls that need new movement joints cut into them
- Render that’s blown, hollow or coming away
Not sure which it is? You can ring 0345 464 0079 or send us an email and we’ll tell you honestly.
Joints and surfaces we work on
- Brickwork movement joints
- Concrete & block
- Render & cladding joints
- Façade panels
- Joints between brick and frames
- Copings & trims
What we do, step by step
We work through the job in order: protection first, then preparation, sealing and a tidy-up. For most jobs that takes anything from a few hours to several days, depending on the building, and the area is left clean. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- Backing rod goes in so the sealant can stretch between the two faces.
- 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 if you’ve seen damp or leaks
- Where the joints are inside, avoid wetting them before we arrive
- Mention if the joints have been sealed before
How to get a quote
To get a quote, ring 0345 464 0079 or email us with the location and a short description of the problem. You’ll have a clear quote before any work starts.