Greater London · England
Window Mastic in Downe
Mastic around window and door frames, sills and patio doors for Downe, backed by a 12-month guarantee. Call for a quick quote.
- Gaps left after new windows were fitted
- Cracked or shrunken mastic around the frame
- Mastic that’s falling out in pieces
What affects the cost of window mastic
We do not publish a price list, because jobs vary so much. What we look at:
- How many areas need sealing
- Working hours on commercial sites
- Any mould that needs treating
- How much old sealant there is and how hard it is to remove
What it costs depends on the size of the job, how much old material has to come out and access to the work. You’ll have a clear quote before any work starts.
Helping us quote
What to tell us when you ask for a quote:
- Access, such as stairs, a lift or height
- If someone has resealed it before
- Where the job is, and your postcode
- The problem you’ve noticed
We quote each job on its own, so the first step is telling us about yours. Just call 0345 464 0079 or send us an email with the details, and pictures are welcome.
Window mastic in Downe
From a single sill to a whole house of windows, you’ll get a clear quote before work begins. Just phone 0345 464 0079 or send us an email and tell us how many frames there are and how they’re reached. If you are dealing with a bead that doesn’t match the frame and black, perished sealant on frames, we can put it right.
From mansion-block windows to modern glazing in new flats, London has every kind of frame. The mastic around them dries out and cracks with age, letting in draughts and water.
Your job is guaranteed for a year, as with all our work.
- Where
- Downe (BR6)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Why deal with it now?
Redecorating is a good moment to renew the mastic. A clean new bead makes new paint or render look finished. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in Downe, the repair is bigger than a sealant job.
Some things make a job bigger or smaller: the old material and how easily it comes out, whether mould needs treating, and whether we need extra access for height. We take all of that into account in your quote.
Why us?
- Approved under the ARBOMaster scheme
- Tidy, careful work
- You choose the colour before work begins
- A sealant colour to suit the surroundings
Take a look at how sealant jobs are priced or our reviews.
How the visit works
On the day, there’s very little for you to do. Show us the job and we will take it from there. The job generally takes 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 Downe. A visitor permit or a nearby bay makes the visit run more smoothly.
- First we look at every frame and agree the list.
- Next the failed sealant is cut away and the joint cleaned.
- 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.
Before we arrive
- Where the joints are inside, avoid wetting them before we arrive
- Clear items away from the joints we are working on
- Tell us about any water getting in
Get a quote
For a quick quote, get us on the phone, or email us if that’s easier. Tell us about the joints that need doing and we will talk you through the work.
Advice
Downe homes and the weather
With historic houses such as Down House (about 0.6 miles south) nearby, there’s older building stock in the area around Downe as well as newer homes. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window. The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
As a London address, Downe can be tricky for parking: tell us about permits, visitor bays or off-street space when you book. If you live in an older home near St Mary's Church, frames set in older brick or stone need a sealant that suits the wall as well as the frame. If you look after a building such as Downe Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
Downe is about 4 miles south-west of Orpington, in Greater London. Our applicators cover window mastic for householders, landlords and businesses in Downe and nearby, as part of our work across Greater London. 764 places in Greater London are on our list. We also work in London, about 13 miles from Downe.
Here we cover the BR6 postcode area for window mastic. Local streets include High Street, North End Lane and Belle Vue Road, and we cover them all. We also cover the places around Downe: Farthing Street (1 mile north-west), Hazelwood (1 mile east), Luxted (1 mile south), Leaves Green (1 mile west) and Single Street (2 miles south). We also work in nearby towns such as London (13 miles north-west), City of Westminster (15 miles north-west), Marylebone (15 miles north-west), St Pancras (15 miles north-west), Shoreditch (14 miles north-west) and Hoxton (15 miles north-west).
What’s near Downe
We work in homes and buildings around The Queens Head pub, Charles Darwin School and South Park. Downe’s nearest station is Chelsfield station, about 2.6 miles north-east. Nearby you’ll also find Crofton Roman Villa (2.7 miles north-east) and Princess Royal University Hospital (1.8 miles north). Not far away are Downe Bank Nature Reserve and Betsom's Hill.
DIY versus a professional finish
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and the joint depth matters as much as the finish.
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. All the old material has to come out first.
FAQs for Downe
Do you work for landlords with property near Chelsfield station?
Yes, rental work is part of what we do. You can call 0345 464 0079 or drop us an email with the address and a few details, and we will give you a fixed price before any work starts.
Can parking be tricky for a visit in Downe?
Parking in Downe, as in most of London, takes a little planning: a visitor permit or a bay close to the door helps a lot.
Can you work on commercial sites?
Yes. Hotels, offices and other businesses use us.
How long should I leave it?
Many sealants skin over quickly but take longer to cure fully. We will give you the cure time for the product we used before we leave.
What do you put in the joint?
Each joint gets the product that suits it. Movement, water and weather all affect the choice, and we’ll explain our choice.
Do I need to be at home?
If the work is inside, we need someone to let us in. Once we’ve agreed the job, you do not need to watch us work.
Do you seal inside as well as outside?
Yes, we do both. Indoors, we seal between the frame and the plaster or reveal.
Can I do it myself?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
What the job involves on each 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.
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.
What we cannot put right
A few problems are outside what sealant work can do:
- Damp coming through the wall itself rather than the frame joint
- Rotten timber, which needs a joiner first
- Misting between the panes of a double-glazed unit (that needs a new unit)
If in doubt, call 0345 464 0079 or email us and we’ll say what we think.
Surfaces we seal
- uPVC windows
- Patio & French doors
- Composite doors
- Window sills
- Timber windows & doors
- Aluminium frames
For landlords and businesses
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements and we’ll quote.
Whether it’s one flat or a portfolio, the work is the same standard: the old material taken out, careful preparation and a 12-month guarantee.