Greater London · England
Window & door mastic in Coldharbour, Greater London
Problem with your window and door frames in Coldharbour? We cut out the old, prepare the joints and apply the right sealant.
- Draughty joints inside around the window
- Untidy mastic left by window fitters
- Cracked or shrunken mastic around the frame
About our window mastic in Coldharbour
A cold draught around a closed window often comes from the frame edge. A new joint stops the air getting through and quietens the whistle on windy days. Where the air is getting in through the window itself, we will say so. We work on patio & French doors, aluminium frames and composite doors, and the jobs we see most are mastic that’s falling out in pieces and cracked sealant at the sill ends.
Many London homes are flats, with windows high above the street. In a converted house or block, the lease normally says who is responsible for the windows, so it’s worth checking before booking.
We guarantee the work for a year. If something is not right with it in that time, tell us and we’ll put it right.
- Where
- Coldharbour (SE9, BR7)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- A clear price before any work starts
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Landlords, agents and businesses in Coldharbour
Letting agents often deal with us directly. Tell us the address, the job and how access works and we will give you a quote.
Landlords and agents in Coldharbour can book us as well as homeowners. Resealing between tenancies is a simple way to keep a property in good order before the next move-in.
Coldharbour: your questions answered
Do you work for landlords with property near Mottingham station?
Yes, we work for landlords and letting agents. Just phone 0345 464 0079 or send us an email and tell us about the property, and we will give you a clear price.
Can parking be tricky for a visit in Coldharbour?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. That way the visit can be planned around it.
What does window mastic cost?
Size, access and the old material all affect the cost. Call for a quick quote and we’ll talk you through it.
Where are you based?
Our base is Crawley. Our area covers South East England, London and Scotland.
Will you leave a mess?
Tidy work is part of the job. We protect what’s around the joints, and we clear up when we’re done.
What sealant do you use?
Products from Arbo and Everbuild, among others, chosen to suit the joint. We explain the product when we quote.
Are you fully insured?
Yes. We are fully insured, and we can confirm the details when we quote.
Are you ARBOMaster approved?
Yes. Mr Mastic is an ARBOMaster approved applicator.
What sealant work cannot fix
It helps to know what we cannot do:
- Faulty window hardware
- A failed sealed unit that has misted up
- Soft or decayed wood in the frame
Not sure which it is? You can call 0345 464 0079 or email us and we’ll tell you honestly before booking.
Joints and surfaces we work on
- uPVC windows
- Window sills
- Composite doors
- Timber windows & doors
- Patio & French doors
- Aluminium frames
The process
On the day, we start by going over the job with you, so you know exactly what we’re doing. Surfaces next to the work are protected before we start. Most jobs take most of a day for a typical house, less for a few frames. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Coldharbour. It helps if you can point us to a visitor permit or a bay close to the door.
- First, we confirm safe access to each frame.
- All the failed sealant is cut away.
- The surfaces are cleaned and left dry.
- 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
- Keep pets and children clear of the area while we work
- Let us know if you’ve seen damp or leaks
- Mention any parking rules near the property
Get a quote
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To get started, ring 0345 464 0079 or email us.
Related advice
Quotes for window mastic in Coldharbour
Every job gets its own quote. These are the things that affect it:
- Which sealant suits the joint
- The amount of work
- When we can work, for business premises
- Whether the work is at height
A few things move the cost up or down: the old material and how easily it comes out, whether mould needs treating, and whether the work is at height. We take all of that into account in your quote.
Asking for a quote
Photos by email are helpful but not essential. Try to tell us:
- Photos by email, if that’s easy
- Access, such as stairs, a lift or height
- Whether it’s a home or a business
- What’s wrong with the joints now
Asking for a quote is easy: let us know what needs doing and where and its rough size. Photos by email help us understand the job, and we’ll come back to you with a quote.
Aftercare tips
Good habits help new joints last longer. Our tips:
- Clean frames with a soft cloth and soapy water
- Check the mastic once a year
- Repaint timber before it’s bare
- Make sure the drainage slots aren’t blocked
Check the drainage slots in the frames aren’t blocked, so rain drains out rather than building up at the sealant.
Water trapped behind a failed joint can start rot in timber frames and sills. Once wood has rotted, it needs repair before it can be sealed, so early resealing is worth it.
Frames and glazing around Coldharbour
With historic houses such as Eltham Palace (about 1.1 miles north) nearby, there’s older building stock in the area around Coldharbour 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. Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Managing a site like Mottingham Primary School? Then its window and door frames need their mastic kept sound, just like a home’s. If you live in an older home near St Alban, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall. Coldharbour is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Coldharbour is about 4 miles north-west of Orpington, in Greater London. From the centre of Coldharbour to the outskirts, we cover window mastic for every kind of property. Coldharbour is one of 764 towns and villages in Greater London where we work for window mastic. London is on our list too, about 8 miles from Coldharbour.
Our applicators cover all of SE9 and BR7 for window mastic and the streets around it. Whether your property is on Green Lane, Horley Road and Dorset Road or a nearby road, we can help. We also cover the places around Coldharbour: Mottingham (1 mile west), Chinbrook (1 mile west), New Eltham (1 mile north-east), Eltham (1 mile north) and Middle Park (1 mile north-west). We also work in nearby towns such as London (8 miles north-west), City of Westminster (11 miles north-west), Marylebone (10 miles north-west), Kensington (12 miles north-west), St Pancras (10 miles north-west) and Shoreditch (9 miles north-west).
Around Coldharbour
We work in homes and buildings around Elmstead Wood and St Thomas More Catholic Comprehensive School, among other places. The nearest railway station is Mottingham station, about 0.6 miles north. Nearby you will also find The Glades (2.4 miles south-west) and Metropolitan Police Museum (2.2 miles east). Green spaces nearby include The Tarn and Summer Hill.
Why deal with it now?
Running fresh sealant over the old joint is tempting, but new sealant cannot bond to old, crumbling mastic. It soon lifts and the leak carries on behind it. Proper resealing starts with removing the old joint. In a flat in Coldharbour, failed sealant seldom stays inside your own four walls: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
Doing several joints on one visit generally makes better use of the time than several visits, so tell us about everything that needs sealing. You will get one clear quote for the whole job.
Why book with us
- We agree the colour with you first
- We never seal over old sealant
- We’re fully insured
- Domestic, commercial and hotel work
Read how sealant jobs are priced and our reviews.
DIY sealant or a professional job?
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 does not work out, we can still put it right.
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.