Greater London · England
Window Mastic in Friern Barnet
Window mastic across Friern Barnet and nearby, with every bit of old sealant taken out first.
- White mastic on grey or black frames
- Rain getting in at the frame or under the sill
- Cracked sealant at the sill ends
About our window mastic in Friern Barnet
Some gaps around frames are far deeper than they look. Filling it with sealant alone leaves a joint that cannot move properly, so deep gaps get backing rod first. That way the new bead bonds to the frame and the wall only. Typical jobs include cracked internal joints between frame and plaster and untidy mastic left by window fitters, on patio & French doors, timber windows & doors and composite doors.
London has a lot of flats and conversions, where windows are often on upper floors. Who looks after the outside of the frames can depend on the lease, so check that first.
The work is covered for a year after we finish. If anything is not right with it, call 0345 464 0079 or send us an email.
- Where
- Friern Barnet (N11, N12, N10, N20)
- Region
- Greater London
- Guarantee
- One year on every job
- Quote
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What sealant work can’t fix
We will not take on work that won’t last, so these are the limits:
- A failed sealed unit that has misted up
- Damp problems in the wall away from the window
- Rotten timber, which needs a joiner first
If in doubt, phone 0345 464 0079 or drop us an email and we’ll say what we think before you book.
Surfaces we seal
- Patio & French doors
- Aluminium frames
- uPVC windows
- Window sills
- Timber windows & doors
- Composite doors
Looking after it afterwards
Looking after new joints is easy:
- Keep paint off silicone joints
- Keep solvents and bleach off the sealant
- Keep drainage slots and sill grooves clear
- Ventilate rooms so frames do not stay wet inside
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. If you notice one, it’s time to get the joint looked at.
What we’re called out for in Friern Barnet
Every frame moves through the day. Sun on a frame makes it expand, and it contracts again overnight, while the brick or render around it hardly moves. A sealant that can’t keep up eventually tears.
Look out for these signs:
- Hard, cracked sealant around windows
- Untidy mastic left by window fitters
- A bead that doesn’t match the frame
- Draughty joints inside around the window
As a London address, Friern Barnet can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Before booking anyone
- Whether VAT is included
- What insurance they hold
- How the surfaces are prepared before sealing
- Is the old sealant removed completely?
How the visit works
There is not much for you to do on the day. Point us to the joints and we’ll get on with it. The work itself takes most of a day for a typical house, less for a few frames from start to finish. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- First, we confirm safe access to each frame.
- Old, cracked mastic is removed completely, along with any loose debris.
- Frame and wall are cleaned and must be dry before sealing, and primed where the sealant calls for it.
- 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
- On commercial sites, let us know about site rules
- Clear items away from the joints we are working on
- Let us know about parking restrictions
Get a quote
For a quote, ring 0345 464 0079 or email us and tell us where the job is and what the problem looks like. We’ll give you a clear quote before any work starts.
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How the job changes by surface
Composite doors
A composite door normally sits in a plastic outer frame, and the joint around it is sealed like a window. The bead is colour-matched to the frame.
uPVC windows
Plastic frames move a lot between a hot afternoon and a cold night, so the joint needs a low-modulus sealant that stays flexible. White is the usual colour, with brown, anthracite grey and black for coloured frames.
Work for landlords, hotels and businesses
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements.
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Window mastic in Friern Barnet: local notes
In a converted house or block, who looks after the windows depends on the lease, so it’s worth checking before booking. The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Letting a property close to New Southgate station? Then cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets. Schools such as Holly Park Primary School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s.
Friern Barnet is about 2 miles north-east of Finchley, in Greater London. From the centre of Friern Barnet to the outskirts, window mastic is available for homes and businesses alike. Across Greater London, we cover 764 places, Friern Barnet among them. You can also see our page for London, roughly 8 miles from Friern Barnet.
Here we cover the N11, N12, N10 and N20 postcode area for window mastic. Local streets include Martock Gardens, Shapwick Close and Radstock Close. Main roads around Friern Barnet include the A406 and B550, so getting to you is simple. We also cover the places around Friern Barnet: New Southgate (1 mile east), Brunswick Park (1 mile north), North Finchley (1 mile west), Arnos Grove (1 mile east) and Whetstone (1 mile north-west). Within a short drive, we also cover London (8 miles south), City of Westminster (7 miles south), Marylebone (7 miles south), Kensington (8 miles south), St Pancras (6 miles south) and Shoreditch (7 miles south-east).
Around Friern Barnet
We work in homes and buildings around Francis Skaryna Belarusian Library and Museum, Friary Park and Friern Barnet School. Friern Barnet has its own railway station: New Southgate station. Well-known places in the area include Francis Skaryna Belarusian Library and Museum (1.4 miles west) and Grand Arcade (1 mile west). The countryside around Friern Barnet includes Highgate Hill and Darland's Lake.
Quotes for window mastic in Friern Barnet
Some jobs are bigger than they look, and some smaller. The main factors:
- Access and height
- How much there is to do
- When we can work, for business premises
- Whether old sealant or filler has to be cut out
A failed joint rarely gets cheaper to fix by waiting. If you’re unsure, call 0345 464 0079 or email us for an honest opinion and a quote.
What to tell us for a quote
Before you ask for a quote, have a think about:
- Any access issues, like height or stairs
- How many joints, rooms or windows are involved
- Where the job is, and your postcode
- If someone has resealed it before
Need a quote? Please ring 0345 464 0079 or send us an email with a few details. You’ll know what we plan to do, and what it will cost, before any work begins.
Towns and villages near Friern Barnet
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Common questions in Friern Barnet
Do you cover Friern Barnet for window mastic?
Yes. Our work covers London and the South East, and Friern Barnet is part of that. Just phone 0345 464 0079 or drop us an email with a few details of the job.
Can parking be tricky for a visit in Friern Barnet?
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.
Do I need to be at home?
If the work is inside, we need someone to let us in. After that, you can carry on with your day.
Can you do the inside joint as well?
Yes. Indoors, we seal between the frame and the plaster or reveal.
Can you quote for more than one area?
Yes, we can. Several rooms, windows or areas can go on one quote.
What sealant do you use?
Each joint gets the product that suits it. Where it moves, gets wet or faces the weather makes a difference, and we’ll tell you what we’re using.
Will it make a mess?
Very little: the area around the joints is protected first, and we tidy up before we go.
What should I tell you?
Tell us what needs doing and where, with pictures by email if possible. If we need more, we’ll ask.