Greater London · England
Brondesbury Window Mastic
Mastic around window and door frames, sills and patio doors for homeowners, landlords and businesses in Brondesbury. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Draughts coming in around windows and doors
- Cracked or shrunken mastic around the frame
- Water coming in at the bottom corners of a door
What happens if it’s left?
Running fresh sealant over the old joint is tempting, but new sealant can’t bond to old, crumbling mastic. It soon lifts and the leak carries on behind it. The old mastic has to come out. In a flat in Brondesbury, failed sealant seldom stays inside your own four walls: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
The cost reflects the work involved, not guesswork. That is why we ask a few questions first and agree the price before starting.
Why us?
- 12-month guarantee on every job
- We never seal over old sealant
- Neat joints and a tidy finish
- You choose the colour before work begins
Take a look at how sealant jobs are priced and what customers say.
Window mastic in Brondesbury, done properly
Every window and door frame has a gap around it, and mastic is what closes it. When it cracks, hardens or pulls away, draughts and rain get in. The old mastic is removed and the joint resealed with a flexible exterior sealant. We work on window sills, timber windows & doors and uPVC windows, and common reasons people get in touch are cold air getting in at the frame edge and sealant in the wrong colour for the frame.
From mansion-block windows to modern glazing in new flats, London has every kind of frame. Over the years, the sealant around them shrinks, cracks and pulls away, letting in draughts and water.
There’s a 12-month guarantee on every job.
- Location
- Brondesbury (NW6, NW2, NW10)
- Wider area
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- A clear price before work begins
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
What affects the cost of window mastic
Some jobs are bigger than they look, and some smaller. The main factors:
- Working hours on commercial sites
- Whether there’s mould to deal with
- The size of the job
- The product the joint needs
Some things make a job bigger or smaller: the old material and how easily it comes out, any mould to treat, and whether we need extra access for height. We take all of that into account in your quote.
What we need to know
The more you tell us, the more accurate the quote. When you ask for a quote, tell us:
- Whether it’s a home or a business
- Access, such as stairs, a lift or height
- A few pictures by email, if you can
- How many joints, rooms or windows are involved
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we will talk you through what we’d do. When it suits you, phone 0345 464 0079 or drop us an email.
Brondesbury questions
Is parking a problem for a job in Brondesbury?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. The visit is then planned around what’s available.
I let a flat near Brondesbury station. Can you help?
Yes, landlords and agents are among the people we work for, and several properties can go on one quote. You can call 0345 464 0079 or send us an email with the details for a clear quote.
Can resealing stop a draught around my window?
If the draught is coming in around the frame, yes. If it’s coming through the window seals, we will tell you.
Where is Mr Mastic based?
Our base is Crawley, with over 20 years’ experience. Our area covers South East England, London and Scotland.
Do I need to be at home?
That depends on where the joints are. For work indoors, someone needs to let us in, and for outside work we will agree access with you when we book.
Are you an approved applicator?
Yes. ARBOMaster is the approved applicator scheme for Arbo sealants, and we are part of it.
Do you remove the old sealant?
Yes. We cut out all the old sealant and clean the joint.
Do you work in Brondesbury?
Yes. We are based in Crawley and work across South East England, London and Scotland, Brondesbury included.
The process
Every visit runs the same way: we check the joints, mask and protect the surrounding surfaces, do the work and clear up. Most jobs take anything from an hour or two to a full day, depending on how many frames there are. For a job in Brondesbury, parking and access are the things to plan: let us know about parking, the floor we will be working on and any lift or shared entrance.
- Each frame is looked over and we agree which ones need resealing.
- The old mastic is cut out and scraped back to clean surfaces.
- Where the gap is deep, backing rod goes in first.
- A flexible exterior sealant is applied in a colour to suit the frame.
- We tool each bead neatly and check every joint is closed.
Getting ready for the visit
- Tell us about access, such as stairs, a lift or high-level joints
- Mention any sign-in or site rules at work premises
- Move anything stored near the joints
Ask for a quote
Call for a quick quote, or send an email if you’d rather. Tell us about the joints that need doing and we will explain what’s involved before giving you a price.
Related advice
DIY versus a professional finish
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.
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.
Keeping the joints in good condition
So the new joints stay in good condition:
- Don’t paint over the silicone
- Keep paint and stain on wooden frames in good order
- Clear any debris from frame drain holes
- Do not aim a pressure washer at the joints
Clean the frames with mild soapy water, and avoid solvent cleaners on the sealant.
Water trapped behind a failed joint can start rot in timber frames and sills. Rotten timber needs a joiner, not a sealant, so it pays to reseal before that happens.
Landlords, agents and businesses in Brondesbury
We also work for property managers and facilities teams in Brondesbury and across Greater London. We can quote a run of properties together.
We also work for businesses, from offices to washrooms and kitchens. On commercial sites, working times can be discussed when we quote.
Also near Brondesbury
Also in Brondesbury
What window mastic looks like in Brondesbury
In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking. With historic houses such as Fenton House (about 1.5 miles north-east) nearby, there’s older building stock in the area around Brondesbury as well as newer homes. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window.
Letting a property close to Brondesbury station? Then sound mastic around windows and doors keeps out the draughts and damp that tenants notice first. As a London address, Brondesbury can be tricky for parking: let us know about parking bays, permits or a driveway. In the older streets around Christ Church, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Brondesbury is about 1 mile north of Kilburn, in Greater London. Brondesbury gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a one-year guarantee. Brondesbury is one of 764 towns and villages in Greater London where we work. You can also see our page for London, about 6 miles away.
Postcode districts we cover here for window mastic: NW6, NW2 and NW10. Streets in the area include Dyne Road, Mill Lane and The Avenue. With the A4003 close by, Brondesbury is easy for our applicators to reach for window mastic. Nearby, we also carry out window mastic in Kilburn (1 mile south), Cricklewood (1 mile north-west), Queen's Park (1 mile south), Kensal Rise (1 mile south-west) and Willesden Green (1 mile west). Larger places within reach include London (6 miles south-east), City of Westminster (3 miles south-east), Marylebone (3 miles south-east), Kensington (3 miles south), St Pancras (4 miles east) and Shoreditch (6 miles east).
Near you in Brondesbury
Around Brondesbury, our work takes us to homes and buildings near Black Lion pub, Kilburn Grange Park and Brondesbury College. Brondesbury has its own railway station: Brondesbury station. Nearby you’ll also find New End Hospital (1.5 miles north-east) and Brent Museum and Archives (1 mile west). Green spaces nearby include Primrose Hill and Westbere Copse.
Different surfaces, different methods
Window sills
Every drop off the glass ends up on the sill, so the sill ends and the joint under the frame are vital. Each is cleaned out and resealed.
Patio & French doors
Heavy door frames can move more than windows. A flexible sealant copes with that, where a rigid one would crack.