Greater London · England
Highgate Window Mastic
Specialist window mastic for Highgate: careful preparation, the right product and tidy work. Call for a quick quote.
- Leaking joints at the ends of sills
- Rushed sealant from a window installation
- Black, perished sealant on frames
What we’re called out for in Highgate
Water runs down the glass onto the sill, and the ends of the sill, where it meets the wall, are where it gets in. Failed sealant there lets rain into the wall or behind the frame.
Common reasons people contact us include:
- Mastic that is falling out in pieces
- Gaps between the frame and the inside reveal
- Rushed sealant from a window installation
- Gaps where the sill meets the wall
Schools such as St Michael's Church of England Primary School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s.
What your quote should include
- How long to leave it before use
- Is VAT in the price?
- How the colour is chosen
- Whether they seal over old material or remove it
Window mastic in Highgate, done properly
Mr Mastic’s applicators have more than 20 years’ experience with window and door sealants. We’re fully insured ARBOMaster approved applicators, and every job is covered by a 12-month guarantee. If you have rain getting in at the frame or under the sill and mastic that has split away from the wall, we can help.
London has a lot of flats and conversions, where windows are often on upper floors. In a converted house or block, the lease generally says who is responsible for the windows, so it’s worth checking before booking.
Our work is backed for twelve months.
- Location
- Highgate (N6, N19, NW5)
- Region
- Greater London
- Guarantee
- A year, on every job
- Price
- A clear price before we start
- Call
- 0345 464 0079
- Updated
- 26 October 2026
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.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Different surfaces, different methods
uPVC windows
uPVC expands and contracts noticeably with temperature, so we use a flexible, low-modulus sealant. We match white, brown, anthracite grey and black frames.
Composite doors
Front doors take the weather head on. We pay most attention there.
What we do, step by step
There is not much for you to do on the day. 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, including the tidy-up. In Highgate, as in most of London, parking needs a little planning. A visitor permit or a nearby bay makes the visit run more smoothly.
- Each frame is looked over and we agree which ones need resealing.
- We remove the old mastic and clean the frame edge and wall.
- Deep gaps get closed-cell backing rod to set the depth.
- A flexible exterior sealant is applied in a colour to suit the frame.
- Every joint is tooled smooth and checked before we leave.
How to prepare
- Tell us about any previous sealing or DIY attempts
- Mention any leaks or damp you’ve noticed
- Let us know about parking restrictions
How to get a quote
To get a quote, ring 0345 464 0079 or drop us an email and tell us where the job is and what the problem looks like. We will give you a clear price before any work starts.
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Nearby places to Highgate
Also in Highgate
Highgate homes and the weather
London and the South East are among 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 it’s worth checking before booking.
If you live in an older home near Highgate United Reformed Church, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint. Rented homes near Upper Holloway station change hands often, and sound mastic around windows and doors keeps out the draughts and damp that tenants notice first.
Highgate is about 2 miles north-east of Hampstead, in Greater London. Wherever you are in the N6 postcode area, we cover window mastic for homes and businesses. 764 places in Greater London are on our list, from the larger towns to small villages.
Here we cover the N6, N19 and NW5 postcode area for window mastic. Local streets include Wood Lane, Grange Road and Talbot Road. Other places close to Highgate include Upper Holloway (1 mile south-east), Dartmouth Park (1 mile south), Lissenden Gardens (1 mile south), Crouch End (1 mile north-east) and Tufnell Park (1 mile south-east). We also work in nearby towns such as London (5 miles south-east), City of Westminster (4 miles south), Marylebone (4 miles south), Kensington (6 miles south-west), St Pancras (3 miles south) and Shoreditch (4 miles south-east).
Local landmarks in Highgate
We work in homes and buildings around The Angel Inn, St Aloysius RC College and Whittington Park. The closest station to Highgate is Upper Holloway station, about 0.9 miles south-east of the centre. A little further out are Highgate Private Hospital (0.6 miles north-west) and Montfichet's Tower (4.4 miles south-east). Not far away are Darland's Lake and Parkland Walk.
Looking after it afterwards
Good habits help new joints last longer. A few tips:
- Ventilate rooms so frames do not stay wet inside
- Clear any debris from frame drain holes
- Repaint timber before it’s bare
- Avoid blasting the frames with a pressure washer
On timber frames, keep the paintwork in good order, since wood that gets wet swells and shrinks more. Keep paint off the silicone itself.
Water trapped behind a failed joint can start rot in timber frames and sills. Once wood has rotted, it needs repair before it can be sealed, so it pays to reseal before that happens.
Quotes for window mastic in Highgate
The quote reflects the job in front of us. We look at:
- Whether the work is at height
- The old material and how stubborn it is
- The type of sealant required
- Whether there’s mould to deal with
The cost depends on how much there is to do, how much old material has to come out and access to the work. You’ll have a clear quote before any work starts, so you know where you stand.
What to tell us for a quote
Before you ask for a quote, have a think about:
- If someone has resealed it before
- The rough size of the job
- Photos by email, if that’s easy
- How we’d reach the joints
Call for a quick quote, or send an email if you’d rather. Describe what needs sealing and we’ll talk you through the work.
Your questions about window mastic in Highgate
Do you cover Highgate for window mastic?
Yes. Our work covers London and the South East, and Highgate is part of that. You can ring 0345 464 0079 or email us and let us know what needs doing, and we will give you a clear price.
Can parking be tricky for a visit in Highgate?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
Where is Mr Mastic based?
Our base is in Crawley, and we cover South East England, London and all of Scotland.
How long does it take to reseal the windows on a house?
A handful of frames is a short visit. You will get a timescale with the quote.
Will you leave a mess?
No. We work neatly, protect the area around the joints and tidy up afterwards.
Can tenants book the work?
Of course. Ask your landlord first, and we can send them the quote if that helps.
Will resealing my frames help with draughts?
Yes, if the air is getting in around the frame. If it’s through the window’s own seals or a hinge, that is a different fix, and we will say so.
Are you fully insured?
Yes. We are fully insured for domestic and commercial work.
Leave it or put it right?
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 is needed. If we find failed glass units or worn seals, we’ll tell you. In a flat in Highgate, failed sealant seldom stays inside your own four walls: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
What you pay reflects the work, not a rough estimate. That is why we ask a few questions first and agree the price before starting.
What you get with us
- A choice of colours where the product allows
- Sealant colour chosen to suit
- Trusted Arbo and Everbuild sealants
- Domestic, commercial and hotel work
See our cost guide or our reviews.