Greater London · England
External & façade joints in Greenhill, Greater London
External mastic in Greenhill from a team with over 20 years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Weathered mastic that no longer stretches
- Rain getting behind render or cladding at a joint
- Failed seals between different materials
DIY sealant or a professional job?
If you’re set on DIY, put the effort into 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.
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
External mastic in Greenhill, done properly
External mastic is a job where short cuts show quickly. Overfilled joints, missing backing rod and sealant laid over old sealant rarely last long. We take the old material out and do it properly. If you are dealing with brick movement joints where the sealant has split and rain getting behind render or cladding at a joint, we can help.
Newer London blocks are built with movement joints in brick and render, and with cladding joints sealed with mastic. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall.
Our work is backed for twelve months, and the guarantee is the same wherever you are.
- Place
- Greenhill (NW3, NW6)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Quote
- A clear price before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Landlords, agents and businesses in Greenhill
Whether it’s one flat or a portfolio, the work is the same standard: the old material taken out, careful preparation and a 12-month guarantee.
In hotels, rooms out of use cost money, so the work can be planned room by room around your bookings where we can. We’ve worked in hotels as well as homes and businesses.
Common problems we fix in Greenhill
Buildings move more than people expect. Brickwork grows a little over the years, blockwork and concrete shrink, and all of it moves with heat and moisture. The sealant in the movement joints takes that strain.
Look out for any of the following:
- Cracked joints where brick meets render or frames
- Sealant pulling away from one side of the joint
- Damp patches traced to an open external joint
- Rigid filler in a joint that should flex
In the older streets around Rosslyn Hill Unitarian Chapel, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Questions to ask before booking
- Whether they seal over old material or remove it
- What product goes in the joint
- Whether you can choose the colour
- How hidden problems are handled
Why act early in Greenhill
It often makes sense to reseal all the failing joints on an elevation together. They’ve weathered the same way. In London conversions, one flat’s bathroom is often above another flat’s ceiling, and a slow leak from a failed seal can end up in the flat below. Dealing with it early is far simpler for homes in Greenhill.
Homes and businesses are quoted the same way: the amount of work, the access and the products needed, plus any working-time requirements on site. Call for a quick quote and we will explain what it covers.
Why Greenhill customers choose us
- 180+ five-star Google reviews
- Anti-fungal sanitary silicone in wet areas
- Colour agreed with you before we start
- Fully insured
Take a look at how sealant jobs are priced or what customers say.
Greenhill questions
Can you help a landlord with a rental near Hampstead Heath station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or drop us an email and tell us about the property, and we’ll give you a clear price.
Is parking an issue for external mastic in Greenhill?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. That way the visit can be planned around it.
Can you match the colour of my brickwork?
The aim is a neat, even joint in a colour that suits the wall. Colour is agreed with you before we begin.
Is there a guarantee?
Yes. Every job comes with our one-year guarantee.
Are you fully insured?
Yes. We are fully insured.
What do you need from me for a quote?
Only a few details: the address or postcode, what’s wrong and any access issues. Then ring 0345 464 0079 or send us an email.
Do you remove the old sealant?
Yes. All of the old material is cut out and the joint cleaned before applying anything new.
Why do you put foam in the joint first?
The foam is closed-cell backing rod. It keeps the sealant at the right depth and bonded to the sides only, which would stop it stretching.
What we do, step by step
A visit follows a simple pattern: we check the joints, protect the area around them, do the work and clear up. Most jobs take a few hours for a handful of joints, longer for a whole elevation. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Greenhill. A visitor permit or a nearby bay makes the visit run more smoothly.
- 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.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
Getting ready for the visit
- Mention any sign-in or site rules at work premises
- Tell us about any previous sealing or DIY attempts
- Tell us about any water getting in
Get a quote
Asking for a quote is easy: let us know the job and the location and its rough size. A few photos by email make the job easier to understand.
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Also near Greenhill
Other services in Greenhill
What the job involves on each surface
Render joints
Rendered walls have joints at beads, openings and changes of material. They’re resealed in a sealant that suits the render.
Copings and trims
Copings expand and contract through the day, so a flexible sealant suits them best in all weathers.
Walls and rooflines in Greenhill
Historic houses like 2 Willow Road (about 0.3 miles north-east) are a reminder that the area around Greenhill 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 check who is responsible for the outside before booking.
Greenhill is in London, so parking needs planning: let us know about parking bays, permits or a driveway. Schools such as The Royal School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
Greenhill is about 1 mile north-east of Hampstead, in Greater London. If you need external mastic in Greenhill, it’s easy to get a quote: please ring 0345 464 0079 or email us. We’re based in Crawley and cover Greater London. We cover 764 towns and villages across Greater London.
We work across the NW3 and NW6 postcode area for external mastic. That includes homes and businesses on Back Lane, Well Road and Ornan Road. Neighbouring places we cover for external mastic include Hampstead (1 mile south-west), Vale of Health (1 mile north), West Hampstead (1 mile west), Fortune Green (1 mile west) and Haverstock (1 mile south-east). We also work in nearby towns such as London (5 miles south-east), City of Westminster (3 miles south), Marylebone (3 miles south-east), Kensington (4 miles south), St Pancras (3 miles south-east) and Shoreditch (5 miles south-east).
What’s near Greenhill
Typical jobs here are in homes near Cecil Sharp House, Fitzjohn's Primary School and King William IV Public House. You will also find South Hampstead High School (0.6 miles south) and Hampstead Heath (0.7 miles north-east). There’s a railway station in Greenhill itself: Hampstead Heath station. Nearby you’ll also find New End Hospital (within half a mile north-west) and Montfichet's Tower (4.3 miles south-east). Open spaces near Greenhill include Belsize Wood and Parliament Hill.
How we quote for external mastic
Call for a quick quote. What matters most is:
- When we can work, for business premises
- Whether there’s mould to deal with
- Whether the work is at height
- Whether old sealant or filler has to be cut out
No two jobs are quite the same, so we quote each one individually. Size, access and the product the joint needs all make a difference, and we will explain the quote if you ask.
What we need to know
Photos help, but a description is a good start. Please mention:
- Whether it’s a home or a business
- The address or postcode of the job
- How we’d reach the joints
- Any previous sealing or DIY work
Need a quote? Please phone 0345 464 0079 or send us an email and tell us about the job. We will explain what we’d do and send you a clear quote before work begins.