Greater London · England
Grahame Park External Mastic
External mastic in Grahame Park from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Panel joints letting water in
- Weathered mastic that no longer stretches
- Brick movement joints where the sealant has split
External mastic in Grahame Park, done properly
Movement joints let brickwork, render and cladding expand and shrink without cracking. Its sealant has to flex with the building, season after season, and when it fails, the wall takes the strain and water finds a way in. We work on brickwork movement joints, render & cladding joints and copings & trims, and people most often call us about joints where the bead has come unstuck and plants rooting in failed movement joints.
Modern London flats rely on sealed movement joints and cladding joints. 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.
All of our work is guaranteed for twelve months, and the guarantee is the same wherever you are.
- Location
- Grahame Park (NW9, NW7, NW4)
- Wider area
- Greater London
- Cover
- One year on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Landlords, agents and businesses in Grahame Park
We also work for property managers and facilities teams in Grahame Park and across Greater London. Several sites can be quoted together.
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Can I do it myself?
A careful DIYer can reseal a simple joint, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
What we do, step by step
When we arrive, we look over the joints with you first. Surfaces next to the work are protected before any work starts. The work normally takes anything from a few hours to several days, depending on the building. 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.
- First we look over the joints with you, agree which to renew and talk through access.
- We cut out the failed sealant and rake out any dirt or growth.
- Both sides are cleaned back to sound material and primed if needed.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
Before we arrive
- Let us know if you’ve seen damp or leaks
- For indoor joints, keep the area dry beforehand if you can
- Keep pets and children clear of the area while we work
Getting a quote
There’s no standard price list. Instead, your job gets its own clear quote. To get started, call 0345 464 0079 or send us an email.
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What we are called out for in Grahame Park
If plants are growing out of a joint, the sealant has usually failed or was never there. Dirt and roots then trap moisture in the joint and speed up the damage.
Signs it’s time to call us include:
- Sealant pulling away from one side of the joint
- Weathered mastic that no longer stretches
- Movement joints filled with mortar instead of sealant
- Rain getting behind render or cladding at a joint
Homes close to St Augustine Grahame Park include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep.
What your quote should include
- How long the guarantee is
- What preparation is included
- What insurance they hold
- Who turns up on the day
External mastic in Grahame Park: local notes
Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking.
Letting a property close to Mill Hill Broadway station? Then outside joints that have cracked can let damp into a rental, so check them between lets. For site and facilities teams at buildings such as St James' Catholic High School, its movement joints, gutters and trims need looking after like any other building’s.
Grahame Park is about 1 mile south-east of Burnt Oak, in Greater London. Jobs in Grahame Park get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. We cover 764 towns and villages across Greater London, from the larger towns to small villages. London is on our list too, around 9 miles away.
We cover every part of NW9, NW7 and NW4 for external mastic and the streets around it. Whether your property is on Hall Lane, Booth Road and Harrier Road or a nearby road, our applicators can take on the job. Grahame Park sits on or near the M1. If you are just outside Grahame Park, we cover Burnt Oak (1 mile north-west), Mill Hill (1 mile north), The Hale (2 miles north-west), Edgware (2 miles north-west) and Little Stanmore (2 miles west). Within a short drive, we also cover 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).
Near you in Grahame Park
Locally, jobs take us to homes and businesses close to Sunny Hill Park, Blessed Dominic Catholic Primary School and The Greyhound pub and the streets around them. Grahame Park’s nearest station is Mill Hill Broadway station, about 0.9 miles north of the centre. Well-known places in the area include Broadwalk Centre (1.7 miles north-west) and Church Farmhouse Museum (0.8 miles south-east). The countryside around Grahame Park includes Copthall South Fields and Parliament Hill.
When it isn’t the sealant
New sealant cannot fix everything, and we’ll tell you before any work starts. It will not solve:
- Cracking across the wall rather than at a joint
- Movement that’s more than a sealant joint can take
- Walls that need new movement joints cut into them
If in doubt, ring 0345 464 0079 or drop us an email and we’ll say what we think.
What we seal
- Copings & trims
- Render & cladding joints
- Façade panels
- Joints between brick and frames
- Brickwork movement joints
- Concrete & block
Grahame Park questions
Do you cover Grahame Park for external mastic?
Yes. We work across London and the South East, and Grahame Park is part of that. Just ring 0345 464 0079 or send us an email with a few details of the job, and we’ll give you a clear quote.
Is parking an issue for external mastic in Grahame Park?
Parking in Grahame Park, as in most of London, takes a little planning: a visitor permit or a bay close to the door helps a lot, so mention what’s available when you book.
How much does external mastic cost in Grahame Park?
It depends on the job, so we quote each one individually. For a quick quote, ring 0345 464 0079 or email us and tell us what needs doing and where.
Do you use backing rod?
Backing rod goes into deeper joints as a matter of course. It sets the sealant depth and prevents three-sided bonding.
What should I tell you?
Just the basics: where it is, what you’ve noticed and how we reach it. Then phone 0345 464 0079 or send us an email.
What colours does the sealant come in?
We choose a sealant colour to suit the brick, stone or render. Exterior sealants come in a good range of colours.
How do you reach high-level joints?
That depends on the building and the joints. We work on joints that can be reached safely. Give us some details and we’ll confirm the access.
Is it messy?
Tidy work is part of the job. Nearby surfaces are protected, and we clear up when we are done.
Also near Grahame Park
Other services in Grahame Park
Looking after it afterwards
So the new joints stay in good condition:
- Wash walls gently around the sealant
- Deal with leaking gutters that soak the joints below
- Act on the first splits you see
- Keep movement joints as flexible joints, not mortar
Don’t let soil, plants or ivy build up against the new joints. Anything that holds water against the joint wears it out sooner.
Act while the splits are small. Then it’s a straightforward cut-out and reseal with no damage behind it to deal with.
What the job involves on each surface
Concrete and blockwork
Concrete faces can be dusty and porous, so preparation is key. We prime where the sealant needs it before sealing.
Cladding and façade panels
Panel systems often rely on sealant between and around the panels. Each joint gets a sealant that suits the panel and its movement.