Greater London · England
Window Mastic in Westminster
Mastic around window and door frames, sills and patio doors in Westminster, with a 12-month guarantee on every job. Ask us for a quote.
- Untidy mastic left by window fitters
- White mastic on grey or black frames
- Old mastic that has gone black or come away
Looking after it afterwards
Once the sealant has cured, a few habits help it last:
- Look round the frames every year or so
- Clean frames with a soft cloth and soapy water
- Clear any debris from frame drain holes
- Avoid blasting the frames with a pressure washer
Wipe the frames with soapy water when you clean the windows, and keep solvents and harsh chemicals off the joint.
Draughts get worse, not better. As the old mastic shrinks further, more air gets through, and heat escapes around the frame. Resealing closes it.
Window mastic for homes and businesses in Westminster
Homes in Westminster have every kind of window: from uPVC casements to timber and aluminium, along with patio doors, French doors and sills. The sealant is chosen to suit the frame material and the wall. We work on patio & French doors, uPVC windows and composite doors, and the jobs we see most are untidy mastic left by window fitters and mastic that has split away from the wall.
London has a lot of flats and conversions, where windows are often on upper floors. Who looks after the outside of the frames can depend on the lease, so check that first.
There’s a 12-month guarantee on every job.
- Place
- Westminster (SW1P, W1J, SW1V)
- Wider area
- Greater London
- Cover
- A year, on every job
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Signs you need window mastic in Westminster
Water runs down the glass onto the sill, so the sill ends and the joint below the frame are common leak points. Failed sealant there lets rain into the wall or behind the frame.
Signs it’s time to call us include:
- A bead that doesn’t match the frame
- Hard, cracked sealant around windows
- Rushed sealant from a window installation
- Leaking joints at the ends of sills
Letting a property close to London Victoria station? Then renewing tired window mastic between tenants heads off draught and damp complaints.
Before booking anyone
- Is VAT in the price?
- How long to leave it before use
- How the colour is chosen
- What guarantee comes with the work
What we do, step by step
On the day, there’s very little for you to do. Point us to the joints and we’ll get on with it. The job generally takes anything from an hour or two to a full day, depending on how many frames there are. In Westminster, as in most of London, parking needs a little planning. A visitor permit or a nearby bay makes the visit run more smoothly.
- We check how each frame can be reached safely.
- All the failed sealant is cut away, along with any loose debris.
- 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.
Preparing for the visit
- Mention any tricky access
- Mention if the joints have been sealed before
- Tell us if parking is tricky
How to get a quote
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is.
Related advice
Other services in Westminster
What we cannot put right
Sealant is not the answer to every problem, and we’d rather say so up front. Sealant won’t put right:
- A frame that has rotted at the joint
- Broken hinges, locks or handles
- Condensation trapped between the panes
If in doubt, call 0345 464 0079 or drop us an email and we will say what we think before you book.
Where we work in Westminster
- Window sills
- Aluminium frames
- Patio & French doors
- Timber windows & doors
- Composite doors
- uPVC windows
Why deal with it now?
Failed mastic is not a reason to replace sound windows. If the frames and glass are in good order, resealing the joints is often all that’s needed. Problems with the glass or gaskets are for a window company, and we will say so. In a London flat, a failed joint rarely stays your problem alone: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
A failed joint rarely gets cheaper to fix by waiting, as water and mould keep getting in. If you are unsure, call 0345 464 0079 or send us an email and we’ll give you an honest view and a quote.
Why Westminster customers choose us
- ARBOMaster approved applicator
- Colour agreed with you before any work starts
- Anti-fungal sanitary silicone in wet areas
- Tidy, careful work
What affects the cost of window mastic
Every job gets its own quote. This is what makes a difference:
- How easy the joints are to reach
- The number of rooms or windows
- The product the joint needs
- The size of the job
Doing several joints on one visit normally makes better use of the time than several visits, so tell us about everything that needs sealing. We’ll give you a clear quote for the lot.
What we need to know
Before you ask for a quote, have a think about:
- Whether it has been sealed before
- Where the job is, and your postcode
- Roughly how big the job is
- The type of property
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 send us an email.
Common questions in Westminster
Is Westminster in your area for window mastic?
Yes. We work across London and the South East, and Westminster is part of that. You can phone 0345 464 0079 or email us and let us know what needs doing.
Is parking an issue for window mastic in Westminster?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot, so mention what’s available when you book.
Can you seal over the old sealant?
No, because it fails. We remove every bit of old sealant first, so the new joint bonds to clean surfaces.
Can you do several jobs on one visit?
Of course. Combining jobs makes good use of the visit.
Will it make a mess?
We keep the work tidy. We protect what’s around the joints.
I rent my home. Can I book you?
Of course. Check with your landlord; we can send the quote to them too.
Is there any odour?
That depends on the sealant. Some products have a noticeable smell, others very little.
Can you do the inside joint as well?
Yes. Indoors, we seal between the frame and the plaster or reveal, using a paintable sealant if you want to decorate.
Can I do it myself?
If you’ve already had a go yourself, that’s fine. We remove it and do the joint properly.
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, and the work is guaranteed for a year.
Frames and glazing around Westminster
With historic houses such as Clarence House (about 0.4 miles north-west) nearby, there’s older building stock in the area around Westminster 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. London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you look after a building such as Harris Westminster Sixth Form, its window and door frames need their mastic kept sound, just like a home’s. Westminster is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Westminster is about 1 mile south-east of City of Westminster, in Greater London. Jobs in Westminster get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. Our Greater London coverage runs to 764 places, Westminster among them.
All of SW1P, W1J and SW1V is covered for window mastic. Streets in the area include Eaton Lane, Wilton Road and Castle Lane, and we cover them all. Westminster is on the A4 and A202, so it’s easy for us to get to with everything needed for window mastic. Other places close to Westminster include Millbank (1 mile north), Victoria (1 mile south-west), Pimlico (1 mile south), Vauxhall (1 mile south-east) and Lambeth (1 mile south-east). We also work in nearby towns such as Kensington (3 miles west), Shoreditch (3 miles north-east), Walthamstow (8 miles north-east), Hoxton (3 miles north-east), Whitechapel (3 miles north-east) and Hampstead (4 miles north-west).
Landmarks near Westminster
Locally, jobs take us to homes and businesses close to St Matthew's School, St James's Park and Blewcoat School and the streets around them. Other local landmarks include London Library (0.6 miles north) and Grafton Arms (under half a mile south). The closest station to Westminster is London Victoria station, about 0.6 miles south-west. A little further out are Westminster Hospital (within half a mile east) and The Crime Museum (less than half a mile south). Not far away are Barnsbury Wood and St. James's Park Lake.