Greater London · England
Window Mastic in City of Westminster
Mastic around window and door frames, sills and patio doors in City of Westminster, with a 12-month guarantee on every job. Call for a quick quote.
- Rushed sealant from a window installation
- Gaps between the frame and the inside reveal
- Old mastic that has gone black or come away
What happens if it’s left?
Choosing the product is half the job. Interior caulk and bathroom silicone aren’t made for exterior frame joints. An exterior, low-modulus sealant stays flexible in sun and frost. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Dealing with it early is far simpler.
Homes and businesses are quoted the same way: how much there is to do, how we reach it and what it needs, along with when we can work on site. Call for a quick quote and we will explain what it covers.
Why book with us
- Fully insured
- Rated 4.9 stars on Google
- Every job guaranteed for a year
- Sealant colour chosen to suit
See our cost guide and customer reviews.
Window mastic for homes and businesses in City of Westminster
Over two decades of sealing frames has taught us which products suit which walls. We’re ARBOMaster approved and fully insured, and we give a 12-month guarantee on the work. Typical jobs include draughty joints inside around the window and water coming in at the bottom corners of a door, on window sills, timber windows & doors and uPVC windows.
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, which is when draughts and damp patches appear in homes in City of Westminster.
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.
- Place
- City of Westminster (W2, NW8, W9, SW1V)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Do you need window mastic in City of Westminster?
Mastic ages in the weather. UV light hardens the outside of the bead, and over the years it loses its give, cracks and comes away.
The problems people generally mention when they call include:
- Old mastic that has gone black or come away
- Gaps where the sill meets the wall
- Cracked internal joints between frame and plaster
- Cracked or shrunken mastic around the frame
For landlords with property near Bond Street station, sound mastic around windows and doors keeps out the draughts and damp that tenants notice first.
Before booking anyone
- Whether all the old sealant comes out first
- What insurance they hold
- How long to leave it before use
- Whether you can choose the colour
Windows and doors in City of Westminster
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. With historic houses such as Handel Hendrix House (about 0.3 miles east) nearby, there’s older building stock in the area around City of Westminster as well as newer homes. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
For site and facilities teams at buildings such as St Vincent's Catholic Primary School, the mastic around its windows and doors needs looking after like any other building’s. Homes close to St Mark's include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
City of Westminster is about 3 miles west of London, in Greater London. Homes, rented property, offices and hotels in City of Westminster can book us for window mastic. Every job comes with our 12-month guarantee. Our Greater London coverage runs to 764 places, City of Westminster among them.
Every address in W2, NW8, W9 and SW1V is covered for window mastic. Streets in the area include Portman Square, Grosvenor Square and Cavendish Square, all of which we cover. With the A4 and A5 close by, City of Westminster is simple for us to get to for window mastic. Nearby, we also carry out window mastic in Marylebone (1 mile north-east), Mayfair (1 mile south-east), Tyburn (1 mile west), Burlington Estate (1 mile south-east) and Connaught Village (1 mile west). Within a short drive, we also cover London (3 miles south-east), Shoreditch (3 miles east), Walthamstow (7 miles north-east), Hoxton (3 miles north-east), Whitechapel (4 miles east) and Hampstead (3 miles north-west). City of Westminster is among the bigger towns we cover in Greater London.
What’s near City of Westminster
Around City of Westminster, our work takes us to homes and buildings near LITE Regal International School, Royal Society of Medicine Library and Devonshire Arms and the streets around them. You will also find The St Marylebone CofE School (0.5 miles north) and Hyde Park (0.6 miles south-west). There’s a railway station in City of Westminster itself: Bond Street station. Well-known places in the area include Dunhill Museum & Archive (under half a mile north) and Kingly Court (0.6 miles east). Open spaces near City of Westminster include Serpentine and Primrose Hill.
What we do, step by step
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 a morning for a couple of windows and a door from start to finish. In a London area like City of Westminster, 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.
- We check how each frame can be reached safely.
- All the failed sealant is cut away.
- 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.
Getting ready for the visit
- Plan for the work area to be out of bounds to pets and children
- Clear the area around the work
- Mention any sign-in or site rules at work premises
How to get a quote
To get a quote, ring 0345 464 0079 or drop us an email with the location and a short description of the problem. You’ll have a clear quote before we start.
Read more
Should I try it myself first?
The difference is mostly in the preparation and the product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
If you are set on DIY, put the effort into preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it doesn’t work out, we can still put it right.
How to look after the new joints
Good habits help new joints last longer. A few tips:
- Wipe condensation off the frames
- Avoid harsh chemicals near the mastic
- Clear any debris from frame drain holes
- Look round the frames every year or so
Have a look at the joints once a year, ideally after winter. Cracks and lifting edges are easy to spot early, and if anything looks wrong, just call 0345 464 0079 or send us an email.
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. Any of these is worth a call.
Common questions in City of Westminster
Is parking a problem for a job in City of Westminster?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. The visit is then planned around what’s available.
Do you work for landlords with property near Bond Street station?
Yes, rental work is part of what we do. Just call 0345 464 0079 or send us an email and tell us about the property, and we’ll send you a clear quote.
How do I get a quote for window mastic in City of Westminster?
Size, access and the old material all affect the cost. Ask us for a quote.
Will resealing my frames help with draughts?
If the draught is coming in around the frame, yes. If it’s through the window’s own seals or a hinge, that’s a different fix, and we’ll say so.
Can new window sealant be painted?
Not normally, if it’s silicone. We choose the product with your decorating in mind, so mention it when you book.
Do you have sealant for grey or black windows?
Yes. Grey and black frames get grey or black sealant, and wood-effect frames generally suit brown.
Can you do several jobs on one visit?
Yes, we can. More than one area can be quoted together.
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.
Landlords, agents and businesses in City of Westminster
For anyone letting property in or around City of Westminster, several properties can go on one quote. Just tell us the addresses and what each one needs, and photos by email help.
Failed sealant is one of the commonest items on a check-out report. Several properties can be quoted together.
Honest limits
Before you book, it’s worth knowing the limits too:
- A failed sealed unit that has misted up
- Draughts through the window seals rather than the frame
- Soft or decayed wood in the frame
Not sure which it is? You can phone 0345 464 0079 or email us and we will tell you honestly.
Surfaces we seal
- Composite doors
- Timber windows & doors
- Patio & French doors
- Aluminium frames
- Window sills
- uPVC windows