Greater London · England
Window & door mastic in Thornton Heath, Greater London
Specialist window mastic for Thornton Heath: the right sealant, proper preparation and a neat finish. Call for a quick quote.
- Whistling draughts around closed windows
- Damp patches on the reveal after heavy rain
- White mastic on grey or black frames
Window mastic in Thornton Heath
From a single sill to a whole house of windows, you will get a clear quote before work begins. Just call 0345 464 0079 or drop us an email and tell us how many frames there are and how they’re reached. Typical jobs include old mastic that has gone black or come away and draughts coming in around windows and doors, across aluminium frames, window sills and patio & French doors.
London has a lot of flats and conversions, where windows are often on upper floors. In a converted house or block, the lease usually says who is responsible for the windows, so it’s worth checking before booking.
There’s a 12-month guarantee on every job, whatever its size.
- Place
- Thornton Heath (CR7, SW16, SE25)
- Region
- Greater London
- Cover
- One year on every job
- Quotes
- A clear quote up front
- Call
- 0345 464 0079
- Updated
- 26 October 2026
What sealant work cannot fix
New sealant can’t fix everything, and we’ll tell you before any work starts. It won’t solve:
- Condensation trapped between the panes
- Penetrating damp from a failed cavity tray or render
- 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.
Joints and surfaces we work on
- Patio & French doors
- Timber windows & doors
- Aluminium frames
- Window sills
- Composite doors
- uPVC windows
What we’re called out for in Thornton Heath
Water runs down the glass onto the sill, so the sill ends and the joint below the frame are common leak points. When that sealant fails, water gets into the wall or under the frame.
Keep an eye out for these signs:
- Sealant in the wrong colour for the frame
- Gaps left after new windows were fitted
- Cracked internal joints between frame and plaster
- Draughts coming in around windows and doors
Thornton Heath is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
What your quote should include
- Is VAT in the price?
- What insurance they hold
- Who does the work, and how experienced they are
- What happens if the job turns out different
What happens on the day
Every visit runs the same way: we look at the joints together, mask and protect the surrounding surfaces, do the work and clear up. Most jobs take a few hours for a handful of frames, longer for a whole house. In a London area like Thornton Heath, the main things to plan are parking and access: let us know about parking, the floor we will be working on and any lift or shared entrance.
- Each frame is looked over and we agree which ones need resealing.
- The old mastic is cut out and scraped back to clean surfaces.
- Where the gap is deep, backing rod goes in first.
- A flexible exterior sealant is applied in a colour to suit the frame.
- We tool each bead neatly and check every joint is closed.
Preparing for the visit
- Let us know about earlier repairs to the joints
- Mention any parking rules near the property
- Try not to wet indoor joints just before the visit
Getting a quote
The more we know about the job, the more useful the quote. Tell us where the job is, what’s wrong and how much there is.
Related advice
Thornton Heath: your questions answered
Is parking an issue for window mastic in Thornton Heath?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. That way the visit can be planned around it.
Do you work for landlords with property near Thornton Heath station?
Yes, landlords and agents are among the people we work for, and several properties can go on one quote. Just ring 0345 464 0079 or email us with the address and what needs doing, and we’ll give you a clear quote.
Can I paint over the new sealant?
Not if it’s silicone. Tell us your decorating plans and we’ll pick a sealant to suit.
Can new sealant go over the old?
No. Fresh sealant doesn’t stick to old sealant, and anything trapped underneath, including mould and water, stays there. It all has to come out first.
What do you put in the joint?
Each joint gets the product that suits it. Where it moves, gets wet or faces the weather makes a difference, and we will explain our choice.
What should I tell you?
Only a few details: where it is, what you’ve noticed and how we reach it. After that, simply ring 0345 464 0079 or drop us an email.
Where do you work from?
We are based in Crawley, and we cover South East England, London and all of Scotland.
Do you hold any approvals?
Yes. We’re approved under the ARBOMaster scheme.
DIY versus a professional finish
A careful DIYer can reseal a simple joint, like a short, easy-to-reach 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’s fine. We cut it out and start again, so tell us about it when you ask for a quote.
What affects the cost of window mastic
For a quick quote, just ask. The main things that affect it are:
- Whether the work is at height
- When we can work, for business premises
- Whether old sealant or filler has to be cut out
- Any mould that needs treating
Rather than a set price list, we price the job in front of us: how many joints, what’s in them now and how we reach them. The price is agreed before we begin.
Helping us quote
The more you tell us, the more accurate the quote. When you ask for a quote, tell us:
- Any access issues, like height or stairs
- The rough size of the job
- The address or postcode of the job
- A few pictures by email, if you can
We quote each job on its own, so start by telling us what you need. Just call 0345 464 0079 or email us with the details, and pictures are welcome.
Surface by surface
Timber windows & doors
Wood swells when it’s wet and shrinks when it dries, so the joint must stay flexible. The paint or stain needs to be sound where the sealant meets it.
Aluminium frames
Large aluminium doors have long joints down each side and across the head, and the bottom joint sees the most water. We prepare and reseal every joint, backing the deep ones.
Keeping the joints in good condition
Aftercare is simple:
- Make sure the drainage slots are not blocked
- Keep timber frames painted
- Wipe condensation off the frames
- Keep jet washers away from the mastic
Keep the new mastic undisturbed while it cures, for as long as we advise. Keep jet washers away from the frames.
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.
Windows and doors in Thornton Heath
The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Historic houses like Kingswood House (about 2.4 miles north-east) are a reminder that the area around Thornton Heath 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.
If you live in an older home near Church of St Stephen, the joint between an old wall and a newer frame is normally the first place rain gets in. Schools such as Winterbourne Junior Girls' School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s.
Thornton Heath is about 7 miles south of London, in Greater London. Thornton Heath 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, from the larger towns to small villages. You can also see our page for London, about 7 miles away.
Work in CR7, SW16 and SE25 works the same way as everywhere else we cover. If you need window mastic at a property on Ena Road, Elm Road and Mayo Road or a nearby road, our applicators can take on the job. Thornton Heath sits on or near the A23 and A212, so getting to you is simple. Nearby, we also carry out window mastic in Norbury (1 mile north), Pollards Hill (1 mile north), Mitcham (2 miles west), Hackbridge (2 miles west) and Eastfields (2 miles west). Within a short drive, we also cover London (7 miles north), City of Westminster (8 miles north), Marylebone (8 miles north), Kensington (8 miles north-west), St Pancras (9 miles north) and Shoreditch (9 miles north).
Landmarks near Thornton Heath
In Thornton Heath, that means homes and buildings near The Archbishop Lanfranc School, Prince George pub and Grangewood Park, among other places. There’s a railway station in Thornton Heath itself: Thornton Heath station. Other landmarks nearby include Centrale Croydon (1.7 miles south) and Croydon University Hospital (0.7 miles south). Not far away are Biggin Wood and Duppas Hill.