Greater London · England
Window & door mastic in Kings Cross, Greater London
Problem with your window and door frames in Kings Cross? We cut out the old, prepare the joints and apply the right sealant, and the work is guaranteed for a year.
- Gaps left after new windows were fitted
- Sealant in the wrong colour for the frame
- Rain getting in at the frame or under the sill
How we handle window mastic in Kings Cross
Mr Mastic’s applicators have more than 20 years’ experience with window and door sealants. We’re fully insured ARBOMaster approved applicators, and we give a one-year guarantee on the work. We work on window sills, patio & French doors and aluminium frames, and people most often call us about leaking joints at the ends of sills and cracked or shrunken mastic around the frame.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. The mastic around them dries out and cracks with age, which is when draughts and damp patches appear in homes in Kings Cross.
The work is covered for a year after we finish. If there’s a problem with it, please phone 0345 464 0079 or send us an email.
- Place
- Kings Cross (NW1W, NW1, N1)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Looking after it afterwards
How long the joints last depends on use and care. We suggest:
- Avoid blasting the frames with a pressure washer
- Paint up to the joint, not over it
- Keep timber frames painted
- Wipe condensation off the frames
Keep sill grooves and drainage slots clear, so rain drains out rather than building up at the sealant.
Look out for the warning signs: split or missing mastic, gaps, damp patches inside or black mould on the reveal. Any of these is worth a call.
DIY versus a professional 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.
If you do try it yourself, take your time over the preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it does not work out, we can still put it right.
For landlords and businesses
Landlords and letting agents in Kings Cross can book us as well as householders. Resealing between tenancies keeps a property looking cared for before the next move-in.
Failed sealant is one of the commonest items on a check-out report, and it’s quick to put right between tenancies. Several properties can be quoted together.
How it works
Before we leave, we go over the finished joints with you and explain the cure time. The work normally takes a few hours for a few frames, or a day or more for a whole house, depending on the size of the job. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- We check each frame and agree which ones need doing.
- We remove the old mastic and clean the frame and the wall.
- Where gaps are deep, backing rod goes in first.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- Finally we tidy up and check each joint.
Getting ready for the visit
- Let us know about parking restrictions
- On commercial sites, let us know about site rules
- Plan for the work area to be out of bounds to pets and children
How to get a quote
For a quote, call 0345 464 0079 or send us an email and tell us where the job is and what the problem looks like. We’ll send you a clear quote before any work starts.
Advice
Places near Kings Cross
More services for Kings Cross
What affects the cost of window mastic
Jobs vary more than people expect. What affects the quote:
- The number and length of the joints
- Whether old sealant or filler has to be cut out
- How many rooms, windows or areas are involved
- When we can work, for business premises
What you pay reflects the work, not guesswork. That’s why we ask about the job first and send you a clear quote before we start.
Helping us quote
Before you ask for a quote, have a think about:
- The address or postcode of the job
- Any previous sealing or DIY work
- If it’s domestic, commercial or a hotel
- What’s wrong with the joints now
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and add photos by email if you can.
FAQs for Kings Cross
Is parking an issue for window mastic in Kings Cross?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Can you do window mastic in Kings Cross?
Yes, Kings Cross is within the area we cover. We work across London and the South East. Just call 0345 464 0079 or email us with a few details of the job.
I rent my home. Can I book you?
We’re happy to deal with the tenant, landlord or agent. Just make sure your landlord agrees.
Is it messy?
We keep the work tidy. We protect what’s around the joints, and the area is left clean when we finish.
Will resealing my frames help with draughts?
Often, yes. The gap between frame and wall is a common source of draughts, and sealing the inside and outside joints closes that path.
Do you hold any approvals?
Yes. We’re approved under the ARBOMaster scheme.
Do you guarantee window mastic?
Yes. Our 12-month guarantee covers every job, inside or out.
When is the sealant fully cured?
It depends on the product and the conditions. Before we leave, we’ll tell you the cure time.
When it is not the sealant
In fairness, some problems need a different trade:
- A door that needs adjusting, rehanging or new seals
- Damp problems in the wall away from the window
- A failed sealed unit that has misted up
If you are not sure, just phone 0345 464 0079 or drop us an email and we’ll give you a straight answer before booking.
Surfaces we seal
- Aluminium frames
- Window sills
- Timber windows & doors
- Composite doors
- Patio & French doors
- uPVC windows
Windows and doors in Kings Cross
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. In a converted house or block, who looks after the windows depends on the lease, so it’s worth checking before booking.
In the older streets around Holy Cross Church, the joint between an old wall and a newer frame is generally the first place rain gets in. For site and facilities teams at buildings such as Argyle Primary School, larger buildings have plenty of frames, and the mastic around each one ages. Kings Cross is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Kings Cross is about 1 mile north-west of St Pancras, in Greater London. Homes, rented property, offices and hotels in Kings Cross can book us for window mastic. The work is guaranteed for a year. Our Greater London coverage runs to 764 places, Kings Cross among them.
Every address in NW1W, NW1 and N1 is covered for window mastic. Window mastic is available to properties on Euston Road, Duke's Road and Phoenix Road and the roads around them. Main roads around Kings Cross include the A501 and A4200, so getting to you is simple. We also cover Somers Town (1 mile west), St Pancras (1 mile south-east), Euston (1 mile south-west), Bloomsbury (1 mile south) and Agar Town (1 mile north-west). Further out, we also cover Kensington (4 miles south-west), Walthamstow (6 miles north-east), Whitechapel (3 miles east), Hampstead (3 miles north-west), Ruislip (13 miles west) and Brompton (3 miles south-west).
Local landmarks in Kings Cross
In Kings Cross, that means homes and buildings near The Fellow pub, Lewis Cubitt Park and Pilsudski Institute of London and the streets around them. You’ll also find Regent High School (0.5 miles north-west) and The Poor School (within half a mile east). Kings Cross has its own railway station: London Kings Cross station. Nearby you will also find Sartorial Contemporary Art (less than half a mile south-east) and Brunswick Centre (within half a mile south). Green spaces nearby include St. James's Park Lake and Ludgate Hill.
Surface by surface
Patio & French doors
Patio and French doors have the longest joints on most houses. The threshold and the bottom corners take the most water, so they get particular care.
Window sills
Masonry sills can have joints where water gets in, including the one between the sill and the frame above. Those are sealed with a product suited to stone or concrete.