Greater London · England
Kingsbury External Mastic
Our applicators work in Kingsbury on sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly and every job guaranteed for a year.
- Damp patches traced to an open external joint
- Cracked joints where brick meets render or frames
- Weathered mastic that no longer stretches
External mastic in Kingsbury, done properly
A movement joint is a deliberate break that lets a wall expand and contract. The sealant in it has to stretch and squeeze for years, so once it splits or hardens, the joint stops working and water gets in. If you have rain getting behind render or cladding at a joint and failed sealant between panels on a façade, we can put it right, on render & cladding joints, joints between brick and frames and concrete & block alike.
Modern London flats rely on sealed movement joints and cladding joints. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall, and both kinds of building are found across London.
Each job carries a 12-month guarantee, large or small.
- Location
- Kingsbury (NW9, HA3, HA9)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- A clear price before we start
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Do you need external mastic in Kingsbury?
If plants are growing out of a joint, the sealant has generally failed or was never there. Dirt and roots then trap moisture in the joint.
Any of these means the joints need attention:
- Cracked joints where brick meets render or frames
- Rigid filler in a joint that should flex
- Moss and dirt in joints with no sealant left
- Joints where the bead has come unstuck
For site and facilities teams at buildings such as Kingsbury Green Primary School, larger buildings have long runs of movement joint that eventually need resealing.
Comparing quotes
- Who does the work, and how experienced they are
- When the joint can take water or movement
- Is the old sealant removed completely?
- The length of the guarantee
How it works
We bring everything the job needs with us, so you don’t need to buy or prepare anything. After a quick look at the joints together, we protect the area and start. Most jobs take a few hours to a few days, depending on the length of joint and the access. In a London area like Kingsbury, the main things to plan are parking and access: let us know about parking, the floor we’ll be working on and any lift or shared entrance.
- 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.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
How to prepare
- Keep pets and children clear of the area while we work
- Tell us about access, such as stairs, a lift or high-level joints
- Mention any parking rules near the property
Getting a quote
Getting a quote is simple: tell us what needs doing and where and its rough size. A few pictures by email make the job easier to understand.
Read more
What the job involves on each surface
Concrete and blockwork
Big joints in concrete need careful depth control. Backing rod sized to the joint sets it so the sealant isn’t too deep.
Render joints
The face of render can be soft, so a sealant that stretches easily protects the edges. We prime where the product needs it.
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Looking after it afterwards
No joint lasts for ever, but care makes a real difference. A few tips:
- Wash walls gently around the sealant
- Keep movement joints as flexible joints, not mortar
- Check external joints each spring
- Leave the joints unpainted unless we have said otherwise
Look over the joints once a year, ideally after winter. Splits, gaps at the edges or plants in the joint are early warning signs.
Gaps, plants or missing sealant in a joint are worth getting looked at. Early work is quicker and leaves a better finish.
When it is not the sealant
It helps to know what we can’t do too:
- Render that is blown, hollow or coming away
- Adding movement joints to masonry that has none
- Cracking across the wall rather than at a joint
If in doubt, phone 0345 464 0079 or drop us an email and we will say what we think before you book.
Surfaces we seal
- Render & cladding joints
- Copings & trims
- Concrete & block
- Brickwork movement joints
- Joints between brick and frames
- Façade panels
DIY sealant or a professional job?
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
What affects the quote in Kingsbury
Some jobs are bigger than they look, and some smaller. What affects the quote:
- Which sealant suits the joint
- Whether there’s mould to deal with
- The number and length of the joints
- Whether the work is at height
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all play a part.
Helping us quote
Photos help, but a description is a good start. Try to tell us:
- The problem you’ve noticed
- Where the property is
- Any previous sealing or DIY work
- Roughly how big the job is
For a quote, phone 0345 464 0079 or email us and tell us where the job is and what the problem looks like. You will have a clear quote before we start.
Kingsbury buildings and the weather
With historic houses such as Headstone Manor (about 3.5 miles west) nearby, there’s older building stock in the area around Kingsbury as well as newer homes. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material. Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Homes close to Church of the Holy Innocents include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep. As a London address, Kingsbury can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Kingsbury is about 2 miles north-east of Wembley, in Greater London. Jobs in Kingsbury get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Our area takes in 764 places across Greater London. You can also see our page for London, about 10 miles away.
All of NW9, HA3 and HA9 is within our area for external mastic. Whether your property is on Bacon Lane, Slough Lane and Minterne Road or a nearby road, our applicators can take on the job. Kingsbury sits on or near the A4006, so getting to you is simple. We also cover Queensbury (1 mile north-west), West Hendon (1 mile east), The Hyde (1 mile east), Preston (1 mile south-west) and Colindale (1 mile north-east). Larger places within reach include London (10 miles south-east), City of Westminster (7 miles south-east), Marylebone (7 miles south-east), Kensington (6 miles south-east), St Pancras (8 miles south-east) and Shoreditch (9 miles south-east).
Around Kingsbury
In Kingsbury, that means homes and buildings near JFS, Woodfield School and J.J. Moon's pub and the streets around them. Kingsbury’s nearest station is Hendon station, about 1.5 miles east. Other landmarks nearby include Church Farmhouse Museum (2.1 miles east) and London Designer Outlet (1.9 miles south). The countryside around Kingsbury includes Castlebar Hill and Darland's Lake.
Kingsbury questions
Can parking be tricky for a visit in Kingsbury?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
Can you do external mastic in Kingsbury?
Yes, Kingsbury is within the area we cover. Our work covers London and the South East. You can call 0345 464 0079 or email us and tell us what needs doing.
Will you leave a mess?
No. The area is protected while we work and cleaned up afterwards.
Are you ARBOMaster approved?
Yes. We are an ARBOMaster approved applicator.
What does external mastic cost?
Size, access and the old material all affect the cost. Call for a quick quote and we’ll talk you through it.
Can tenants book the work?
Yes, but check with your landlord or agent first. Landlords are often happy for the work to be arranged.
Is it OK to seal over old sealant?
No, because it fails. The old sealant always comes out first, so the new joint bonds to clean surfaces.
Do you use backing rod?
Closed-cell backing rod sets the depth of the sealant and stops it sticking to the back of the joint. That way it bonds to the two sides only and can stretch.