Greater London · England
Window & door mastic in Kensal Green, Greater London
Professional window mastic in and around Kensal Green, with every bit of old sealant taken out first.
- Black, perished sealant on frames
- Draughts coming in around windows and doors
- Mastic that has split away from the wall
Window mastic in Kensal Green, done properly
Mr Mastic’s applicators have more than 20 years’ experience with window and door sealants. We’re fully insured ARBOMaster approved applicators, and every job is covered by a 12-month guarantee. We work on timber windows & doors, patio & French doors and composite doors, and people most often call us about rushed sealant from a window installation and rain getting in at the frame or under the sill.
Much of London’s older housing was built with timber sash windows, some still in place and some long since replaced. Whatever is in the opening now, the joint between frame and wall is what keeps the weather out.
Big or small, it’s backed by our one-year guarantee in Kensal Green and across Greater London.
- Place
- Kensal Green (NW10, W10, NW6)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Quotes
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
What happens on the day
When we get to you, we compare the joints with what we discussed. If we find something unexpected, we talk it through with you first. Most jobs then take a few hours for a handful of frames, longer for a whole house. In Kensal Green, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- First, we confirm safe access to each frame.
- Old, cracked mastic is removed completely.
- The surfaces are cleaned and left dry.
- Deep voids are backed, then the sealant is gunned in.
- We tool the joint so water runs off, then clear up.
Preparing for the visit
- Let us know if you’ve seen damp or leaks
- Move anything stored near the joints
- Let us know about stairs, lifts or work at height
Get a quote
Every job is quoted individually, so the first step is telling us about yours. Simply phone 0345 464 0079 or send us an email and describe the job and send photos if you have them.
Related advice
Work for landlords, hotels and businesses
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.
For anyone letting property in or around Kensal Green, several properties can be quoted together. Just tell us the addresses and what each one needs, and pictures by email help.
Common questions in Kensal Green
Is Kensal Green in your area for window mastic?
Yes. We work across London and the South East, and Kensal Green is part of that. Just phone 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 window mastic in Kensal Green?
Parking in Kensal Green, 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.
Will it make a mess?
Tidy work is part of the job. Nearby surfaces are protected.
Can you match the sealant to my frames?
Yes, we choose a colour to suit the frame. Anthracite grey, black, brown and white cover most frames, with clear as an option.
How long will my window job take?
A few frames take a few hours. We confirm the timing with your quote.
Are you insured?
Yes. We are fully insured for domestic and commercial work.
Can tenants book the work?
Of course. Ask your landlord first, and we can send them the quote if that helps.
Do you do commercial work?
Yes. Commercial and hotel work is a large part of what we do. Working times can be discussed when we quote.
Kensal Green homes and the weather
With historic houses such as Kensington Palace (about 2.4 miles south-east) nearby, there’s older building stock in the area around Kensal Green as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. In a converted house or block, who looks after the windows depends on the lease, so it’s worth checking before booking.
For site and facilities teams at buildings such as Princess Frederica CofE Primary School, its window and door frames need their mastic kept sound, just like a home’s. As a London address, Kensal Green can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Kensal Green is about 1 mile south-west of Kilburn, in Greater London. Every kind of property in Kensal Green can book us for window mastic. The work is guaranteed for a year. Kensal Green is one of 764 places in Greater London we cover for window mastic. Our London page covers work nearby, about 6 miles away.
Work in NW10, W10 and NW6 is quoted and booked the same way as anywhere else. Local streets include Waldo Road, Hazel Road and Hiley Road, and we cover them all. Other places close to Kensal Green include Kensal Rise (1 mile east), College Park (1 mile west), North Kensington (1 mile south-east), Willesden Green (1 mile north) and Kensal Town (1 mile south-east). Within a short drive, we also cover London (6 miles east), City of Westminster (3 miles east), Marylebone (3 miles east), St Pancras (5 miles east), Shoreditch (6 miles east) and Walthamstow (9 miles north-east).
Near you in Kensal Green
Around Kensal Green, our work takes us to homes and buildings near Little Wormwood Scrubs, Queens Park Community School and The Masons Arms and the streets around them. There’s a railway station in Kensal Green itself: Kensal Green station. Other landmarks nearby include Westfield London (1.6 miles south) and Princess Louise Hospital (0.7 miles south). Not far away are Greville Place nature reserve and The Long Water.
Common problems we fix in Kensal Green
Water runs down the glass onto the sill, so the sill ends and the joint below the frame are common leak points. Failed sealant there lets rain into the wall or behind the frame.
Keep an eye out for these signs:
- Mastic that has split away from the wall
- Cracked sealant at the sill ends
- Untidy mastic left by window fitters
- Sealant in the wrong colour for the frame
Homes close to St Martin include some older properties, and frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Questions to ask before booking
- What the quote includes, VAT included or not
- Whether all the old sealant comes out first
- How long to leave it before use
- What preparation is included
Also near Kensal Green
Also in Kensal Green
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
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 does not work out, we can still put it right.
How we quote for window mastic
Some jobs are bigger than they look, and some smaller. The main factors:
- Whether old sealant or filler has to be cut out
- How easy the joints are to reach
- Whether there’s mould to deal with
- How many areas need sealing
What it costs depends on how much there is to do, how much old material has to come out and how easy the joints are to reach. You will have a clear quote before any work starts.
What to tell us for a quote
Before you ask for a quote, have a think about:
- Where the job is, and your postcode
- How we’d reach the joints
- A few photos by email, if you can
- What’s wrong with the joints now
For a quote, phone 0345 464 0079 or drop us an email with the location and a short description of the problem. You will have a clear quote before work begins.
Honest limits
Some problems need a builder, plumber or other trade rather than us:
- Condensation trapped between the panes
- Draughts through the window seals rather than the frame
- Faulty window hardware
If you’re not sure, just ring 0345 464 0079 or drop us an email and we’ll give you a straight answer before you book.
What we seal
- Timber windows & doors
- uPVC windows
- Composite doors
- Patio & French doors
- Window sills
- Aluminium frames
Looking after it afterwards
Simple care keeps the joints in good condition. We recommend:
- Make sure the drainage slots are not blocked
- Walk round the house once a year and look at the joints
- Avoid harsh chemicals near the mastic
- Keep jet washers away from the mastic
A yearly look round the frames is enough. Small splits are simple to catch before they leak, and if anything looks wrong, just ring 0345 464 0079 or drop us an email.
Water trapped behind a failed joint can start rot in timber frames and sills. Once wood has rotted, it needs repair before it can be sealed, so early resealing is worth it.