Greater London · England
Window & door mastic in Greenhill, Greater London
Window mastic for Greenhill and the surrounding area: the right sealant, proper preparation and a neat finish. Call for a quick quote.
- Mastic that has split away from the wall
- Sealant in the wrong colour for the frame
- Cold air getting in at the frame edge
Window mastic in Greenhill, done properly
Most frames have an outside joint and an inside one. The external joint is the weather seal; the internal joint closes the gap to the plaster and stops draughts. We seal one or both, depending on what’s needed. We work on timber windows & doors, patio & French doors and aluminium frames, and people most often call us about mastic that has split away from the wall and cracked internal joints between frame and plaster.
From mansion-block windows to modern glazing in new flats, London has every kind of frame. Over the years, the sealant around them shrinks, cracks and pulls away, letting in draughts and water.
We guarantee the work for a year. If there’s a problem with our work within the year, let us know and we’ll sort it.
- Where
- Greenhill (HA1, HA3, HA2)
- Region
- Greater London
- Guarantee
- One year on every job
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Window mastic in Greenhill: local notes
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. In a converted house or block, who looks after the windows depends on the lease, so check that before you book.
For landlords with property near Harrow-on-the-Hill station, renewing tired window mastic between tenants heads off draught and damp complaints. Greenhill is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Greenhill is about 1 mile north-east of Harrow, in Greater London. We carry out window mastic for homes and businesses in Greenhill and nearby, as part of our work across Greater London. Greenhill is one of 764 towns and villages in Greater London we cover for window mastic. You can also see our page for London, about 12 miles away.
Jobs for window mastic in HA1, HA3 and HA2 works the same way as everywhere else we cover. We cover properties on Lyon Road, Hill Road and Byron Road and the roads around them. Neighbouring places we cover for window mastic include Wealdstone (1 mile north), Northwick Park (1 mile south-east), Harrow (1 mile south-west), Kenton (1 mile east) and Roxeth (1 mile south-west). We also work in nearby towns such as London (12 miles south-east), City of Westminster (9 miles south-east), Marylebone (9 miles south-east), Kensington (8 miles south-east), St Pancras (10 miles south-east) and Shoreditch (12 miles east).
What’s near Greenhill
Locally, jobs take us to homes and businesses close to Royal Oak pub, Northwick Park and Harrow High School. Greenhill has its own railway station: Harrow-on-the-Hill station. Other landmarks nearby include St. Anns (within half a mile south-west) and Hilfield Castle (4.8 miles north). Open spaces near Greenhill include Masons Field and Northala Fields.
Leave it or put it right?
Running fresh sealant over the old joint is tempting, but new sealant cannot bond to old, crumbling mastic. It peels before long, and water still gets in behind. Proper resealing starts with removing the old joint. Converted houses in London often have a bathroom above someone else’s living room, and a slow leak from a failed seal can end up in the flat below. Putting it right early is much less trouble for homes in Greenhill.
The cost depends on how much there is to do, how much old material has to come out and access to the work. We give a clear quote before we start, so you know where you stand.
Why book with us
- We never seal over old sealant
- White, clear, grey or another colour, product permitting
- Fully insured
- Quality sealants from Arbo and Everbuild
Read our cost guide or our reviews.
Keeping the joints in good condition
Once the sealant has cured, a few habits help it last:
- Avoid blasting the frames with a pressure washer
- Use gentle cleaners on frames and sealant
- Don’t use solvent cleaners on the joint
- Ventilate rooms so frames don’t stay wet inside
Check the drainage slots in the frames are not blocked, so rain drains out rather than building up at the sealant.
A small gap around a frame only grows. As the old mastic shrinks further, more air gets through, and heat escapes around the frame. Resealing closes it.
How the visit works
When we arrive, we look over the joints with you first, so there are no surprises. We protect the surfaces around the joints before work begins. Most jobs take a morning for a couple of windows and a door. For a job in Greenhill, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- We check how each frame can be reached safely.
- Old, cracked mastic is removed completely, along with any loose debris.
- Frame and wall are cleaned and must be dry before sealing.
- Deep voids are backed, then the sealant is gunned in.
- The joint is shaped to shed water and the area tidied.
How to prepare
- Tell us about any water getting in
- Keep children and pets away from the work area
- Where the joints are inside, avoid wetting them before we arrive
Getting a quote
Getting a quote is simple: let us know the job and the location, and roughly how big it is. A few pictures by email make the job easier to understand, and we’ll take it from there.
Read more
Do you need window mastic in Greenhill?
A lot of older mastic was never designed to stay flexible. Once it’s rigid, every bit of frame movement pulls at it, and a gap opens along one edge.
Look out for any of the following:
- Gaps between the frame and the inside reveal
- Rushed sealant from a window installation
- Draughts coming in around windows and doors
- Leaking joints at the ends of sills
If you look after a building such as Saint Jerome Church of England Bilingual School, larger buildings have plenty of frames, and the mastic around each one ages.
Before you book anyone
- How long to leave it before use
- Whether you can choose the colour
- How much experience the applicator has
- How the joint is cleaned and prepared
What affects the cost of window mastic
The price is agreed before any work begins. It’s based on:
- The product the joint needs
- Whether old sealant or filler has to be cut out
- How easy the joints are to reach
- Mould in or behind the old joints
A few things move the cost up or down: the old material and how easily it comes out, whether mould needs treating, and whether we need extra access for height. Your quote takes all of that into account.
What we need to know
Photos by email are helpful but not essential. Please mention:
- The type of property
- Roughly how big the job is
- Access, such as stairs, a lift or height
- The problem you’ve noticed
Quotes start with a quick conversation. Describe the problem, the location and the size of the job. When it suits you, phone 0345 464 0079 or email us.
Questions from Greenhill
Do you work for landlords with property near Harrow-on-the-Hill station?
Yes. We work for landlords and agents as well as householders, and several properties can be quoted together. You can call 0345 464 0079 or drop us an email with the details for a clear quote.
Is parking a problem for a job in Greenhill?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly.
Can you seal the gap between the frame and the plaster indoors?
Yes. Plenty of draughts come through the inside joint as well as the outside, so it can be worth sealing both.
Can I do it myself?
You can, for simple jobs. The key is preparation: remove all the old material and work on a clean, dry joint. If it does not work out, we can redo it.
How do I get a quote for window mastic in Greenhill?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. You will get a clear quote before any work starts.
Are you fully insured?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
Do I have to be there?
For indoor joints, yes, someone needs to let us in. After that, you can carry on with your day.
How long will my window job take?
That depends on the number of frames, how they’re reached and the state of the old mastic. You will know the timing when we quote.
Different surfaces, different methods
Patio & French doors
Patio and French doors have the longest joints on most houses. Most leaks start at the bottom corners, so we pay close attention there.
Aluminium frames
Bi-fold and sliding aluminium doors have long frame joints, and the threshold joint takes a lot of water. Each is cleaned, backed where deep and resealed.
Nearby places to Greenhill
More services for Greenhill
Landlords, agents and businesses in Greenhill
Hotels need rooms back in use, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
We work for landlords and letting agents as well as homeowners. Resealing between tenancies is a simple way to keep a property in good order.