Greater London · England
Finchley Window Mastic
Mastic around window and door frames, sills and patio doors for homes and businesses in Finchley and across Greater London. Fully insured, ARBOMaster approved and guaranteed for a year.
- Rushed sealant from a window installation
- Mastic that has split away from the wall
- Draughty joints inside around the window
Can I do it myself?
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
If you’ve already had a go yourself, that is fine. We cut it out and start again.
Window mastic in Finchley, done properly
The mastic around a window or door seals the gap between the frame and the wall. Once that seal fails, wind and rain find the gap. Our applicators cut it out and replace it with a flexible, weatherproof sealant. We work on composite doors, window sills and patio & French doors, and common reasons people get in touch are gaps between the frame and the inside reveal and hard, cracked sealant around windows.
From mansion-block windows to modern glazing in new flats, London has every kind of frame. The mastic around them dries out and cracks with age, which is when draughts and damp patches appear in homes in Finchley.
The work is guaranteed for twelve months. If there’s a problem with our work within the year, let us know and we’ll sort it.
- Place
- Finchley (N3, N2, N12, NW11)
- Region
- Greater London
- Cover
- A year, on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
How to look after the new joints
Good habits help new joints last longer. A few tips:
- Keep timber frames painted
- Keep solvents and bleach off the sealant
- Do not paint over the silicone
- Use gentle cleaners on frames and sealant
Keep sill grooves and drainage slots clear, so rain drains out rather than building up at the sealant.
Signs to watch for: cracks in the mastic, gaps you can see light through, damp on the reveal or mould around the inside of the frame. Any of these is worth a call.
Work for landlords, hotels and businesses
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements and we’ll quote.
In hotels, rooms out of use cost money, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
When to call us in Finchley
Older frames were often sealed with products that set hard. Once it has hardened, the frame’s movement tears it from the wall, and a gap opens along one edge.
Signs it’s time to call us include:
- Rain getting in at the frame or under the sill
- Old mastic that has gone black or come away
- Whistling draughts around closed windows
- Draughty joints inside around the window
As a London address, Finchley can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
What to look for in a quote
- Who does the work, and how experienced they are
- Whether all the old sealant comes out first
- What happens if they find a problem under the old sealant
- Is VAT in the price?
Also near Finchley
Also in Finchley
Finchley: your questions answered
Is Finchley in your area for window mastic?
Yes. We work across London and the South East, and Finchley is part of that. Just ring 0345 464 0079 or email us with a few details of the job, and we’ll give you a clear price.
Can parking be tricky for a visit in Finchley?
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.
Is the new sealant paintable?
It depends on the sealant. Some hybrid sealants can be painted; silicone can’t. Tell us if you are decorating and we’ll choose accordingly.
How long before the joint can be used?
Most sealants are touch-dry well before they’re fully cured. We’ll tell you how long to leave the joint before we leave.
Can you do upstairs windows?
Generally, yes. Access is planned before any work starts.
What information do you need?
Just the basics: the address or postcode, what’s wrong and any access issues. After that, simply call 0345 464 0079 or send us an email.
Will it make a mess?
No. We protect the surfaces around the joints, and we clear up the old sealant and our materials before we leave.
Do you work for letting agents?
Yes. We work for householders, landlords, letting agents, businesses and hotels in Finchley.
Window mastic in Finchley: local notes
Historic houses like Heath Hall (about 1.8 miles south) are a reminder that the area around Finchley has older buildings as well as new. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
For site and facilities teams at buildings such as Manorside Primary School, its window and door frames need their mastic kept sound, just like a home’s. Rented homes near New Southgate station change hands often, and renewing tired window mastic between tenants heads off draught and damp complaints.
Finchley is about 6 miles north of City of Westminster, in Greater London. Finchley gets the same service as everywhere we cover: the old material taken out, joints prepared properly and a 12-month guarantee. 764 places in Greater London are on our list, large and small. You can also see our page for London, roughly 8 miles from Finchley.
Work in N3, N2, N12 and NW11 is quoted and booked the same way as anywhere else. Local streets include Station Road, Chaplin Square and Market Place, and we cover them all. Being close to the B1462, Finchley is simple for us to get to. We also cover Church End (1 mile west), Woodside Park (1 mile north), North Finchley (1 mile north), Friern Barnet (2 miles north-east) and Oakleigh Park (2 miles north). We also work in nearby towns such as London (8 miles south-east), City of Westminster (6 miles south), Marylebone (6 miles south), Kensington (7 miles south), St Pancras (6 miles south-east) and Shoreditch (7 miles south-east).
Around Finchley
Typical jobs here are in homes near The Elephant Inn, Bishop Douglass School and Francis Skaryna Belarusian Library and Museum and the streets around them. You’ll also find Victoria Park (less than half a mile north) and Woodhouse College (1 mile north-east). The closest station to Finchley is New Southgate station, roughly 1.9 miles north-east of the centre. Well-known places in the area include Finchley Memorial Hospital (under half a mile north-east) and Grand Arcade (1 mile north). The countryside around Finchley includes Highgate Hill and Lakeside Nature Reserve.
What affects the quote in Finchley
Your quote is based on your job. We look at:
- How easy the joints are to reach
- Any working-time requirements on site
- Whether there’s mould to deal with
- The number of rooms or windows
What it costs depends on how much there is to do, how much old material has to come out and access to the work. We give a clear quote before work begins, so you know where you stand.
Asking for a quote
A few details help us give you an accurate quote. When you ask for a quote, tell us:
- If it’s domestic, commercial or a hotel
- How we’d reach the joints
- The address or postcode of the job
- What’s wrong with the joints now
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To arrange one, phone 0345 464 0079 or email us.
How the job changes by surface
Aluminium frames
Coated aluminium needs a compatible sealant and we avoid acetoxy silicones, which can react with some metals. We use a neutral-cure product.
Patio & French doors
Patio and French doors have the longest joints on most houses. The threshold and the bottom corners take the most water, so they get particular care.
How it works
You don’t need to clear the whole room or building, just the space around the work. We protect the rest, and the job takes a few hours for a few frames, or a day or more for a whole house in most cases. In a London area like Finchley, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- First, we go round the frames with you and agree the list.
- We remove the old mastic and clean the frame edge and wall.
- Where the gap is deep, backing rod goes in first.
- The new sealant goes on in white, brown, anthracite grey, black or clear to suit.
- Every joint is tooled smooth and checked before we leave.
How to prepare
- Move anything stored near the joints
- Plan for the work area to be out of bounds to pets and children
- Let us know if you’ve seen damp or leaks
How to get a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and email photos if that is easy.