Greater London · England
Window Mastic in Fortis Green
Window mastic in Fortis Green from a team with over 20 years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Water coming in at the bottom corners of a door
- Mastic that has split away from the wall
- Rushed sealant from a window installation
FAQs for Fortis Green
Is Fortis Green in your area for window mastic?
Yes. Our work covers London and the South East, and Fortis Green is part of that. Just call 0345 464 0079 or drop us an email with a few details of the job.
Can you help a landlord with a rental near Alexandra Palace station?
Yes, landlords and agents are among the people we work for, and several properties can be quoted together. You can phone 0345 464 0079 or email us with the details for a clear quote.
Should I try DIY first?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
Can you seal the gap between the frame and the plaster indoors?
Yes, we do both. Indoors, we seal between the frame and the plaster or reveal, using a paintable sealant if you want to decorate.
Can you quote for more than one area?
Yes, we can. Several rooms, windows or areas can go on one quote.
Is it messy?
Not at all. We work neatly, protect the area around the joints and tidy up afterwards.
What information do you need?
Only a few details: the address or postcode, what’s wrong and any access issues. After that, simply ring 0345 464 0079 or drop us an email.
Can new window sealant be painted?
It depends on the sealant. Silicone is not paintable, but some hybrid sealants are. Tell us if you’re decorating and we’ll choose accordingly.
How we handle window mastic in Fortis Green
A window frame and the wall around it expand and shrink at different rates. Heat and cold make frames grow and shrink against brick or render that hardly moves. That’s why the joint needs a flexible, low-modulus sealant rather than something rigid. We work on patio & French doors, timber windows & doors and aluminium frames, and people most often call us about hard, cracked sealant around windows and gaps between the frame and the inside reveal.
London’s Victorian and Edwardian terraces were built with timber sash windows, and many still have them or their replacements. Either way, the mastic between frame and brickwork is what stops draughts and rain getting in.
You get a 12-month guarantee, the same in Fortis Green as everywhere else we work.
- Where
- Fortis Green (N10, N2, N6)
- Region
- Greater London
- Guarantee
- One year on every job
- Quote
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Also near Fortis Green
What else we do in Fortis Green
What window mastic looks like in Fortis Green
In London conversions and blocks, the lease decides who is responsible for the frames, so check that before booking. Historic houses like Heath Hall (about 1.4 miles south-west) are a reminder that the area around Fortis Green has older buildings as well as new. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic.
For an older house near a landmark such as United Reformed Church, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint. Managing a site like Fortismere School? Then the mastic around its windows and doors needs looking after like any other building’s. For landlords with property near Alexandra Palace station, renewing tired window mastic between tenants heads off draught and damp complaints.
Fortis Green is about 1 mile south-east of Finchley, in Greater London. We provide window mastic to householders, landlords and businesses in Fortis Green, as part of our work across Greater London. Fortis Green is one of 764 towns and villages in Greater London we cover for window mastic. We also work in London, about 7 miles from Fortis Green.
Jobs for window mastic in N10, N2 and N6 works the same way as everywhere else we cover. We cover properties on Hill Road, Durham Road and Steeds Road and the roads around them. You will find Fortis Green on the A504, so it’s easy for us to get to. If you’re just outside Fortis Green, we cover Muswell Hill (1 mile east), East Finchley (1 mile west), Highgate (1 mile south), Crouch End (1 mile south-east) and Hampstead Garden Suburb (2 miles south-west). Larger places within reach include London (7 miles south), City of Westminster (5 miles south), Marylebone (5 miles south), Kensington (7 miles south), St Pancras (5 miles south) and Shoreditch (6 miles south-east).
Local landmarks in Fortis Green
Locally, jobs take us to homes and businesses close to Tollington School, Cherry Tree Wood and The Clissold Arms, among other places. The closest station to Fortis Green is Alexandra Palace station, about 1.4 miles east. Nearby you’ll also find Kenwood House (1.6 miles south-west) and Grand Arcade (1.8 miles north-west). Green spaces nearby include Highgate Hill and Glebelands Local Nature Reserve.
Why it’s worth doing now in Fortis Green
Failed mastic isn’t a reason to replace sound windows. Where the frames are sound, new mastic usually deals with draughts and leaks at the edges. If we find failed glass units or worn seals, we’ll tell you. In London conversions, one flat’s bathroom is often above another flat’s ceiling, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Dealing with it early is far simpler.
Rather than a set price list, we price the job in front of us: the amount of work, the old material and the access. The price is agreed before we begin.
Why us?
- More than 20 years in sealant work
- Sanitary silicone with an anti-fungal additive in wet areas
- Colour agreed with you before any work starts
- Rated 4.9 stars on Google
Take a look at our cost guide and customer reviews.
Should I try it myself first?
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
If you’ve already had a go yourself, that’s fine. We remove it and do the joint properly, so just mention it when you contact us.
What we can’t put right
In fairness, there are a few things sealant won’t fix:
- 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 you’re not sure, just phone 0345 464 0079 or email us and we’ll give you a straight answer.
Surfaces we seal
- Window sills
- Timber windows & doors
- Composite doors
- Patio & French doors
- uPVC windows
- Aluminium frames
How the visit works
Most of a good job is in the preparation, and we don’t rush it. Every joint is cleaned and dried before new material goes in. All told, the work takes a few hours for a few frames, or a day or more for a whole house. In Fortis Green, flats, stairs and shared entrances are part of the routine. Mention any building rules, key holders or managing agents when you book.
- We start by checking each window and door with you.
- We remove the old mastic and clean the frame and the wall.
- We fit backing rod in deep gaps so the sealant is the right depth.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- We clear up and check every joint is fully closed.
How to prepare
- Let us know about earlier repairs to the joints
- Let us know about stairs, lifts or work at height
- Try not to wet indoor joints just before the visit
Get a quote
To get a quote, ring 0345 464 0079 or email us with the location and a short description of the problem. We will give you a clear quote before any work starts.
Read more
Surface 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.
Timber windows & doors
Wood swells when it’s wet and shrinks when it dries, so a flexible sealant is essential. We seal onto sound, dry paintwork or timber.
How to look after the new joints
How long the joints last depends on use and care. Here’s what we suggest:
- Look round the frames every year or so
- Keep paint and stain on wooden frames in good order
- Avoid blasting the frames with a pressure washer
- Keep paint off silicone joints
Keep the new mastic undisturbed while it cures, following the cure time we give you. Don’t point a pressure washer at the joints.
Leaks normally show up in wet, windy weather, but resealing works best in dry conditions. Sorting cracked mastic early means the joint is sound before the bad weather.
Quotes for window mastic in Fortis Green
We do not publish a price list, because no two jobs are the same. The quote depends on:
- Mould in or behind the old joints
- The size of the job
- The number of rooms or windows
- The product the joint needs
A few things move the cost up or down: how much old sealant there is and how stubborn it is, any mould to treat, and whether we need extra access for height. Your quote takes all of that into account.
What we need to know
To help us quote quickly, please include:
- Any access issues, like height or stairs
- The address or postcode of the job
- Pictures of the joints, sent by email
- Whether it’s a home or a business
The more we know about the job, the more useful the quote. Let us know the location, the problem and roughly how many joints.