Greater London · England
Window & door mastic in Mitcham, Greater London
Mastic around window and door frames, sills and patio doors in Mitcham, with a 12-month guarantee on every job. Call for a quick quote.
- Cracked sealant at the sill ends
- White mastic on grey or black frames
- Black, perished sealant on frames
What affects the cost of window mastic
Some jobs are bigger than they look, and some smaller. What affects the quote:
- Whether there’s mould to deal with
- Whether old sealant or filler has to be cut out
- The size of the job
- Access and height
No two jobs are quite the same, so each one gets its own quote. Size, access and the product the joint needs all play a part, and we’ll explain the quote if you ask.
What to tell us for a quote
Photos by email are helpful but not essential. Please mention:
- Whether it has been sealed before
- What’s wrong with the joints now
- Where the job is, and your postcode
- The rough size of the job
Getting a quote is simple: tell us what needs doing and where. A few pictures by email make the job easier to understand, and we will take it from there.
Window mastic in Mitcham, done properly
There are two joints on most windows. The external joint is the weather seal; the internal joint closes the gap to the plaster and stops draughts. Either or both can be done. We work on uPVC windows, patio & French doors and aluminium frames, and common reasons people get in touch are mastic that’s falling out in pieces and water coming in at the bottom corners of a door.
Much of London’s older housing was built with timber sash windows, some still in place and some long since replaced. Whatever is in the opening now, the joint between frame and wall is what keeps the weather out.
The work is covered for a year after we finish. If there’s a problem with it, please ring 0345 464 0079 or email us.
- Place
- Mitcham (CR4, SW16, SM4)
- Region
- Greater London
- Cover
- A year, on every job
- Price
- Quoted before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
Leave it or put it right?
A quick bead over the top of old mastic looks like an easy fix, but new sealant cannot bond to old, crumbling mastic. It soon lifts and the leak carries on behind it. The old mastic has to come out. In a London flat, a failed joint rarely stays your problem alone: 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 a rough estimate. That is why we ask about the job first and give you a clear price before we start.
Why Mitcham customers choose us
- Experience in homes, commercial sites and hotels
- Any old sealant cut out fully, not covered over
- We agree the colour with you first
- A choice of colours where the product allows
Honest limits
In fairness, some problems need a different trade:
- Damp problems in the wall away from the window
- Soft or decayed wood in the frame
- A door that needs adjusting, rehanging or new seals
Not sure which it is? You can call 0345 464 0079 or drop us an email and we will tell you honestly before booking.
Joints and surfaces we work on
- Window sills
- Composite doors
- Timber windows & doors
- Aluminium frames
- Patio & French doors
- uPVC windows
What we do, step by step
Our applicators work methodically: protect, prepare, seal, tidy. For most jobs that takes anything from an hour or two to a full day, depending on how many frames there are. For a job in Mitcham, 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.
- First, we confirm safe access to each frame.
- Old, cracked mastic is removed completely.
- 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
- Let us know about earlier repairs to the joints
- Mention any parking rules near the property
- On commercial sites, let us know about site rules
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, ring 0345 464 0079 or send us an email.
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Mitcham: your questions answered
Can you help a landlord with a rental near Mitcham Eastfields station?
Yes, rental work is part of what we do. You can call 0345 464 0079 or send us an email with the address and a few details, and we will give you a fixed price before any work starts.
Is Mitcham in your area for window mastic?
Yes, Mitcham is within the area we cover. We work across London and the South East. You can call 0345 464 0079 or email us and let us know what needs doing, and we will give you a clear quote.
How long will my window job take?
A few frames take a few hours, while a whole house takes longer. You’ll get a timescale with the quote.
Do you work on first-floor windows?
Yes, if safe access is possible. Higher or awkward frames may need extra access, and we’ll confirm what’s needed.
Is it messy?
We keep the work tidy. We protect what’s around the joints, and the area is left clean when we finish.
Where is Mr Mastic based?
We work from Crawley. Our applicators cover Mitcham, along with the rest of our area.
Can new sealant go over the old?
No. New silicone will not bond to old silicone, and it traps any mould or water underneath. It all has to come out first.
Do you work for hotels and businesses?
Yes. We can plan bigger jobs in stages.
Common problems we fix in Mitcham
A lot of older mastic was never designed to stay flexible. Once it has hardened, the frame’s movement tears it from the wall, leaving a hairline gap down one side.
Any of these means the joints need attention:
- Black, perished sealant on frames
- Cold air getting in at the frame edge
- Leaking joints at the ends of sills
- Draughty joints inside around the window
Mitcham is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Questions to ask before you book
- How hidden problems are handled
- Whether they seal over old material or remove it
- Whether the sealant suits the joint
- Who does the work, and how experienced they are
Looking after it afterwards
Good habits help new joints last longer. Our tips:
- Keep jet washers away from the mastic
- Check the mastic once a year
- Use gentle cleaners on frames and sealant
- Keep solvents and bleach off the sealant
On timber frames, keep the paintwork in good order, because bare, wet timber moves more and pulls at the joint. Paint up to the joint, not over the silicone.
Water gets in quietly when mastic fails. You might not see it until plaster blows or a damp patch appears inside. Catching it early keeps the fix to a reseal.
Window mastic in Mitcham: local notes
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. With historic houses such as Southside House (about 3.6 miles west) nearby, there’s older building stock in the area around Mitcham 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.
In the older streets around St. Mark's Church, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint. If you let a flat or house near Mitcham Eastfields station, renewing tired window mastic between tenants heads off draught and damp complaints.
Mitcham is about 2 miles west of Thornton Heath, in Greater London. Our applicators cover window mastic for homeowners, landlords and businesses in Mitcham and the surrounding area. Across Greater London, we cover 764 places, Mitcham among them. There’s also a page for London, roughly 7 miles from Mitcham.
We cover every part of the CR4, SW16 and SM4 postcode area for window mastic. You’ll find streets such as Kings Road, Baker Lane and Manor Road, and we cover them all. If you’re just outside Mitcham, we cover Hackbridge (1 mile north), Eastfields (1 mile north), Colliers Wood (1 mile north-west), Merton Abbey (2 miles north-west) and Furzedown (2 miles north). Further out, we also cover London (7 miles north), City of Westminster (8 miles north), Marylebone (8 miles north), Kensington (7 miles north), St Pancras (9 miles north) and Shoreditch (9 miles north).
Around Mitcham
Locally, jobs take us to homes and businesses close to The Archbishop Lanfranc School, St Mark's Church of England Academy and The White Lion of Mortimer pub, among other places. The closest station to Mitcham is Mitcham Eastfields station, roughly 0.5 miles north. A little further out are Wandle Industrial Museum (0.7 miles west) and Centrale Croydon (2.7 miles south-east). Green spaces nearby include Duppas Hill and Cranmer Green.
Towns and villages near Mitcham
Other services in Mitcham
How the job changes by surface
Window sills
Where a sill meets brick or render, the ends often crack first. We reseal them so rain can’t run into the wall.
Patio & French doors
Not every patio door leak is a mastic problem: blocked drain slots, worn brush seals and threshold details can let water in too. We look for the cause first.