Greater London · England
External Mastic in East Barnet
External mastic for East Barnet and the surrounding area: the right sealant, proper preparation and a neat finish. Call for a quick quote.
- Old sealant gone brittle and cracked
- Brick movement joints where the sealant has split
- Joints pointed up with cement by mistake
External mastic for homes and businesses in East Barnet
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. If you have moss and dirt in joints with no sealant left and panel joints letting water in, we can help, whatever the surface.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. For a home in East Barnet, tell us how high the joints are and how to reach the back of the building.
All our work is covered by our one-year guarantee.
- Location
- East Barnet (N20, EN4, N14)
- Wider area
- Greater London
- Guarantee
- One year on every job
- Quotes
- A clear price before we start
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
What we do, step by step
When we get to you, we compare the joints with what we discussed. If anything is different, we explain it before carrying on. Most jobs then take a few hours for a handful of joints, longer for a whole elevation. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. If the building has a concierge, managing agent or access rules, tell us when you book.
- We start by walking round the building and agreeing the joints and the access.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- Backing rod sized to the joint goes in to set the depth.
- We apply the sealant, tool it and check the whole run.
Before we arrive
- Tell us about any water getting in
- For indoor joints, keep the area dry beforehand if you can
- Tell us about any previous sealing or DIY attempts
Getting a quote
If you’re in East Barnet and need external mastic, ring 0345 464 0079 or send us an email. A short description of the job and where it is helps us quote, and we’ll agree the price before any work begins.
Advice
Towns and villages near East Barnet
More services for East Barnet
Keeping the joints in good condition
Joint life depends on how it’s used and looked after. Here’s what we suggest:
- Keep movement joints as flexible joints, not mortar
- Have failed joints looked at early
- Keep high-pressure jets off the joints
- Fix overflowing gutters above sealed joints
Follow the cure time we give you before the joint is knocked or disturbed. The surface skins over quickly, but full cure takes longer.
Leaks behind façade panels and render often go unseen. When it finally shows inside, the joint may have been open for years.
Walls and rooflines in East Barnet
In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking. Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Schools such as Church Hill School are buildings too, and movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. If you let a flat or house near Oakleigh Park station, outside joints that have cracked can let damp into a rental, so check them between lets.
East Barnet is about 1 mile north-east of Whetstone, in Greater London. We carry out external mastic for homeowners, landlords and businesses in East Barnet and the surrounding area, as part of our work across Greater London. 764 places in Greater London are on our list, from the larger towns to small villages. Our London page covers work nearby.
Here we cover the N20, EN4 and N14 postcode area for external mastic. External mastic is available to properties on Dene Road, Pine Road and Capel Road and the roads around them. We also cover the places around East Barnet: Osidge (1 mile east), Brunswick Park (1 mile south-east), New Barnet (1 mile north-west), Whetstone (1 mile south-west) and Oakleigh Park (1 mile south-west). Within a short drive, we also cover London (10 miles south), City of Westminster (8 miles south), Marylebone (8 miles south), Kensington (10 miles south), St Pancras (8 miles south) and Shoreditch (8 miles south-east).
What’s near East Barnet
In East Barnet, that means homes and buildings near Oak Hill Park, Salcombe School and East Barnet School and the streets around them. You’ll also find The Cavalier pub (within half a mile south) and Francis Skaryna Belarusian Library and Museum (1.8 miles south-west). East Barnet’s nearest station is Oakleigh Park station, about 0.5 miles north-west of the centre. Well-known places in the area include Grand Arcade (1.7 miles south-west) and Finchley Memorial Hospital (2.2 miles south-west). Not far away are Oakleigh Park Rail Cutting and Darland's Lake.
Should I try it myself first?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.
If you do try it yourself, take your time over the 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.
What the job involves on each surface
Render joints
Render is weaker at the surface than brick, so a low-modulus sealant is kinder to the joint edges. We prime where the product needs it.
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.
What we are called out for in East Barnet
Sometimes a movement joint was filled with mortar or a rigid filler by mistake. The joint can’t move, so the wall cracks somewhere else instead.
If you can see any of these, it’s time to have the joints looked at:
- Movement joints with cracked, split or missing sealant
- Failed sealant between panels on a façade
- Cracked joints where brick meets render or frames
- Sealant that has lost its bond to the brick or render
As a London address, East Barnet can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
What your quote should include
- Who does the work, and how experienced they are
- Is VAT in the price?
- Are they insured?
- What product goes in the joint
What affects the cost of external mastic
For a quick quote, just ask. What matters most is:
- The type of sealant required
- How many areas need sealing
- The amount of work
- The old material and how stubborn it is
Commercial jobs are quoted on the same basis as homes: how much there is to do, how we reach it and what it needs. Call for a quick quote and we’ll go through it with you.
What to tell us for a quote
What to tell us when you ask for a quote:
- The rough size of the job
- A few photos by email, if you can
- Access, such as stairs, a lift or height
- The problem you’ve noticed
For a quick quote, get us on the phone, or email us if that’s easier. Tell us about the joints that need doing and we’ll talk you through the work and give you a clear price.
For landlords and businesses
We also work for property managers and facilities teams in East Barnet and across Greater London. Several sites can be quoted together, and we’re fully insured.
From a single let to a portfolio, the work is the same standard: the old material taken out, careful preparation and a 12-month guarantee.
Your questions about external mastic in East Barnet
Is East Barnet in your area for external mastic?
Yes, East Barnet is within the area we cover. Our work covers London and the South East. Just ring 0345 464 0079 or drop us an email with a few details of the job.
Is parking an issue for external mastic in East Barnet?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot, so mention what’s available when you book.
Is it worth trying it myself?
Sometimes. Preparation is everything: all the old sealant out, and a clean, dry joint. We can always put it right if it fails.
Do you seal joints where cladding meets other materials?
Yes. Where different materials meet is one of the most common joints we seal. We use a flexible sealant suited to both surfaces, primed where needed.
What should I tell you?
Only a few details: the address or postcode, what’s wrong and any access issues. After that, simply ring 0345 464 0079 or drop us an email.
I’m a tenant. Can you help?
Yes, though it’s best to check with your landlord first. Many landlords are glad to have it sorted.
Can you reach joints on upper floors?
It depends on the building. Tell us the height, the number of joints and what’s below them.
Is it OK to seal over old sealant?
No. Fresh sealant doesn’t stick to old sealant, and anything trapped underneath, including mould and water, stays there. We remove it all first.