Greater London · England
London Window Mastic
Mastic around window and door frames, sills and patio doors for homeowners, landlords and businesses in London. Fully insured, ARBOMaster approved and guaranteed for a year.
- Draughty joints inside around the window
- Cracked sealant at the sill ends
- Water coming in at the bottom corners of a door
About our window mastic in London
Homes in London have every kind of window: from uPVC casements to timber and aluminium, plus patio doors, French doors and sills. The sealant is chosen to suit the frame material and the wall. If you are dealing with draughts coming in around windows and doors and cracked internal joints between frame and plaster, we can help, whatever the surface.
Beyond its homes, London has shopfronts, offices and flats with plenty of frames and glazing, often on upper floors. Failed joints up there let in water that can go unnoticed for a while.
There’s a 12-month guarantee on every job, whatever its size.
- Location
- London (CR0, E14, CR4, SW11)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Leave it or put it right?
Getting a straight, even bead on an outside frame takes practice, especially upstairs. A professional job is cut out properly, backed where needed and finished neatly, using a product chosen for the frame and wall. For landlords in London, failed sealant soon turns into tenant complaints about mould, damp or draughts. Sorting it between tenancies is easier than dealing with it mid-let.
Homes and businesses are quoted the same way: how much there is to do, how we reach it and what it needs. Call for a quick quote and we’ll go through it with you.
Why choose Mr Mastic in London
- One-year guarantee on every job
- Domestic, commercial and hotel work
- Arbo and Everbuild products
- Rated 4.9 stars on Google
Take a look at how sealant jobs are priced and customer reviews.
How the job changes by surface
Patio & French doors
The joints around patio doors run a long way, top, sides and threshold. The threshold and the bottom corners take the most water, so they get particular care.
Timber windows & doors
Where timber has rotted at the joint, it needs repairing first. If we find rot, we will tell you before going ahead, as a joiner will need to deal with it.
London: your questions answered
Do you work for landlords with property near Elephant & Castle station?
Yes, we work for letting agents and landlords. You can phone 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before any work starts.
Is there a guarantee on window mastic in London?
Every job comes with our one-year guarantee, wherever it is. We are also fully insured and ARBOMaster approved.
How do I get a quote for window mastic in London?
Every job is different, so each one gets its own quote. For a quick quote, ring 0345 464 0079 or drop us an email with a short description of the job.
Where is Mr Mastic based?
Our base is Crawley, with over 20 years’ experience. We work across South East England, London and Scotland.
Do you work in London?
Yes. We’re based in Crawley and work across South East England, London and Scotland, and that includes London.
Can I add another job to the visit?
Of course. Doing several areas at once is generally more efficient.
Do you have insurance?
Yes. We are fully insured, and we can confirm the details when we quote.
What information do you need?
Let us know what needs doing and where, with photos by email if possible. If we need more, we will ask.
Window mastic in London: local notes
With historic houses such as Mansion House (about 1 mile north) nearby, there’s older building stock in the area around London as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic. Rainfall in the South East is lower than in much of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Managing a site like Charles Dickens Primary School? Then larger buildings have plenty of frames, and the mastic around each one ages. In the older streets around St George the Martyr, frames set in older brick or stone need a sealant that suits the wall as well as the frame. For landlords with property near Elephant & Castle station, renewing tired window mastic between tenants heads off draught and damp complaints.
London is in Greater London. Jobs in London get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. Across Greater London, we cover 764 places, and London is one of them.
Every address in CR0, E14, CR4 and SW11 is within our area for window mastic. You will find streets such as Walcot Square, Surrey Square and Sutherland Square, and we cover them all. Being close to the A2 and A10, London is easy for our applicators to reach for window mastic. Other places close to London include Walworth (1 mile south), Bermondsey (1 mile east), Camberwell (2 miles south), South Bermondsey (2 miles south-east) and Surrey Canal (2 miles south-east). We also work in nearby towns such as City of Westminster (3 miles west), Marylebone (3 miles north-west), Kensington (5 miles west), Walthamstow (7 miles north-east), Hampstead (5 miles north-west) and Ruislip (14 miles west). As one of the bigger places in Greater London, London has homes, rented property and businesses of every kind.
Near you in London
We work in homes and buildings around Newington Gardens, Trinity Arms Public House and London School of Musical Theatre. Also close by are St Mary-at-Hill (0.9 miles north-east), Ark Globe Academy (less than half a mile south) and The BFI Reuben Library (1 mile north-west). London has its own railway station: Elephant & Castle station. A little further out are Surrey Dispensary (within half a mile south-east) and Baynard's Castle (0.9 miles north). For a walk, there’s Bellenden Road Nature Garden and St. James's Park Lake.
What we cannot put right
In fairness, there are a few things sealant won’t fix:
- Broken hinges, locks or handles
- Worn gaskets, brush seals or a door that has dropped
- A failed sealed unit that has misted up
If in doubt, ring 0345 464 0079 or email us and we’ll say what we think.
Surfaces we seal
- Window sills
- Timber windows & doors
- uPVC windows
- Aluminium frames
- Patio & French doors
- Composite doors
How it 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. In total, it normally takes a morning for a couple of windows and a door. Where a business in London needs to stay open, out-of-hours working can be arranged, and homes are booked within our usual hours, Monday to Saturday.
- First, we confirm safe access to each frame.
- All the failed sealant is cut away.
- The surfaces are cleaned and left dry, 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.
Before we arrive
- Mention any sign-in or site rules at work premises
- Move anything stored near the joints
- For indoor joints, keep the area dry beforehand if you can
How to get a quote
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is. Whenever you’re ready, call 0345 464 0079 or send us an email.
Read more
Towns and villages near London
Also in London
Looking after it afterwards
Joint life depends on how it’s used and looked after. Here’s what we suggest:
- Repaint timber before it’s bare
- Use gentle cleaners on frames and sealant
- Don’t paint over the silicone
- Keep jet washers away from the mastic
Timber frames need their paint kept up, because bare, wet timber moves more and pulls at the joint. Keep paint off the silicone itself.
A small gap around a frame only grows. As the old mastic shrinks further, more air gets through, and heat escapes around the frame. A new joint closes it up.
What affects the cost of window mastic
There’s no set price list, because no two jobs are the same. What we look at:
- Whether the work is at height
- Any mould that needs treating
- Any working-time requirements on site
- Whether old sealant or filler has to be cut out
Doing several joints on one visit is usually more efficient than separate visits. You’ll get one clear quote for the whole job.
What we need to know
The more you tell us, the more accurate the quote. When you get in contact, it helps to mention:
- What the problem is, such as mould, gaps, leaks or cracking
- The address or postcode of the job
- Whether it has been sealed before
- The type of property
Want a quote for window mastic? Please call 0345 464 0079 or send us an email with a few details. We will explain what we’d do and send you a clear quote before work begins.
Should I try it myself first?
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it doesn’t work out, we can still put it right.