Greater London · England
Colindale External Mastic
We cover Colindale for sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly and a one-year guarantee.
- Old sealant gone brittle and cracked
- Failed seals between different materials
- Joints where the bead has come unstuck
External mastic for homes and businesses in Colindale
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible exterior sealant takes up that movement where a rigid filler would soon crack. We work on concrete & block, copings & trims and façade panels, and people most often call us about joints with sealant missing in places and movement joints filled with mortar instead of sealant.
In London terraces and converted houses, gutters and walls are often shared with the house next door, so a leaking gutter joint or failed wall joint can affect more than one home. For a flat in Colindale, check the lease for who looks after the outside.
Our work is backed for twelve months, in Colindale and everywhere else we cover.
- Where
- Colindale (NW9, NW4, HA8)
- Region
- Greater London
- Cover
- One year on every job
- Quotes
- A clear quote up front
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Different surfaces, different methods
Cladding and façade panels
Metal and composite panels move a lot with temperature, so the joint sealant has to cope with frequent movement. We choose the product to suit.
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. We reseal their joints with backing rod and a flexible product.
What affects the quote in Colindale
We quote each job individually. This is what makes a difference:
- Whether there’s mould to deal with
- The number of rooms or windows
- Whether the work is at height
- The product the joint needs
Leaving a failed joint usually makes the job bigger, not smaller. 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.
What we need to know
What to tell us when you ask for a quote:
- How many joints, rooms or windows are involved
- Where the job is, and your postcode
- Any access issues, like height or stairs
- Whether it has been sealed before
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 will explain what’s involved.
Colindale buildings and the weather
Historic houses like Heath Hall (about 3.5 miles east) are a reminder that the area around Colindale has older buildings as well as new. 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 it’s worth agreeing who is responsible before work starts.
Colindale is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. If you live in an older home near St Matthias the Apostle church, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Colindale is about 1 mile south-east of Burnt Oak, in Greater London. Across the NW9 area, our applicators can take on external mastic. Across Greater London, we cover 764 places, and Colindale is one of them. Our London page covers work nearby.
Here we cover the NW9, NW4 and HA8 postcode area for external mastic. If you need external mastic at a property on Cecil Road, Booth Road and Ajax Avenue or a nearby road, we can help. Colindale sits on or near the A5150. We also cover the places around Colindale: West Hendon (1 mile south), The Hyde (1 mile south), The Burroughs (1 mile east), Hendon (1 mile south-east) and Kingsbury (1 mile south-west). Larger places within reach include London (9 miles south-east), City of Westminster (7 miles south-east), Marylebone (7 miles south-east), Kensington (7 miles south), St Pancras (7 miles south-east) and Shoreditch (9 miles south-east).
Around Colindale
We work in homes and buildings around Sunny Hill Park, Saracens High School and Kisharon College and the streets around them. Colindale’s nearest station is Hendon station, roughly 1 mile south-east. Nearby you will also find Edgware Community Hospital (1.3 miles north-west) and Brent Cross Shopping Centre (1.5 miles south-east). Open spaces near Colindale include Darland's Lake and Parliament Hill.
Also near Colindale
More services for Colindale
Aftercare tips
Good habits help new joints last longer. A few tips:
- Leave the joints unpainted unless we have said otherwise
- Wash walls gently around the sealant
- Make sure movement joints aren’t pointed over
- Keep water from gutters off the wall
Do not let soil, plants or ivy build up against the new joints. Damp material against the sealant shortens its life.
Once a joint can’t move, the wall finds another way, generally as cracking in the brickwork or render nearby. Resealing it early helps prevent that.
When it isn’t the sealant
Before booking, it’s worth knowing the limits:
- Cracked brickwork or render that needs a builder or plasterer
- Failed render or damaged cladding panels
- Cutting new joints into brickwork, which is building work rather than sealant work
If you’re not sure, just ring 0345 464 0079 or email us and we’ll give you a straight answer before booking.
Joints and surfaces we work on
- Brickwork movement joints
- Joints between brick and frames
- Copings & trims
- Concrete & block
- Render & cladding joints
- Façade panels
What we are called out for in Colindale
Poor preparation causes many early failures: dusty or wet faces, no primer where one was needed, or old sealant left in. The new sealant then lets go long before it should.
It’s worth asking for a quote if you see:
- Brick movement joints where the sealant has split
- Movement joints filled with mortar instead of sealant
- Failed seals between different materials
- Sealant that has lost its bond to the brick or render
For landlords with property near Hendon station, split movement joints are easy to miss on a rental until damp shows inside.
Before booking anyone
- Whether they’re fully insured
- Whether all the old sealant comes out first
- How the joint is cleaned and prepared
- Whether the sealant suits the joint
Your questions about external mastic in Colindale
I let a flat near Hendon station. Can you help?
Yes, landlords and agents are among the people we work for. You can call 0345 464 0079 or email us with the details for a clear quote.
Can parking be tricky for a visit in Colindale?
Parking in Colindale, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly.
Is there any odour?
Some sealants have a smell while they cure, but it fades. Opening a window helps.
Does someone need to be in?
We need access to the joints, so we will agree that with you when we book. Indoors, that generally means someone at home.
What does external mastic cost?
Size, access and the old material all affect the cost. Ask us for a quote.
How long does external mastic last?
It varies with how exposed the wall is and how much the joint moves. Look for splits, hardening or edges coming away and have them redone then.
Will you leave a mess?
No. The area is protected while we work and cleaned up afterwards.
Where are you based?
We work from Crawley. Our applicators cover Colindale.
DIY versus a professional finish
Sealing over old silicone is the commonest DIY error. Silicone doesn’t stick to old silicone, so it lifts and traps water and mould underneath. Everything old must be removed first.
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
What happens on the day
Every visit runs the same way: we check the joints, protect the area around them, do the work and clear up. Most jobs take a few hours to a few days, depending on the length of joint and the access. For a job in Colindale, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- First, the joints are inspected and the access agreed.
- We cut out the old mastic and rake out anything in the joint.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- We apply the sealant, tool it and check the whole run.
Preparing for the visit
- Mention any sign-in or site rules at work premises
- Move anything stored near the joints
- Mention if the joints have been sealed before
How to get a quote
If you’re in Colindale and need external mastic, call 0345 464 0079 or email us. Tell us what the problem is and where, and you’ll get a clear quote before work begins.