Greater London · England
Window & door mastic in Clerkenwell, Greater London
Window mastic for Clerkenwell, by sealant specialists with 20+ years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Black, perished sealant on frames
- Draughty joints inside around the window
- Mastic that has split away from the wall
When something else is needed
New sealant cannot fix everything, and we will tell you before work begins. It will not solve:
- A door that needs adjusting, rehanging or new seals
- Faulty window hardware
- Misting between the panes of a double-glazed unit (that needs a new unit)
Not sure which it is? You can phone 0345 464 0079 or email us and we will tell you honestly before booking.
Joints and surfaces we work on
- Timber windows & doors
- uPVC windows
- Window sills
- Aluminium frames
- Composite doors
- Patio & French doors
Window mastic in Clerkenwell, done properly
Colour matters on a frame. White, brown, anthracite grey, black and clear sealants are all available, so the bead blends with the window rather than framing it. We work on uPVC windows, composite doors and patio & French doors, and people most often call us about gaps left after new windows were fitted and damp patches on the reveal after heavy rain.
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.
Each job carries a 12-month guarantee, whatever its size.
- Location
- Clerkenwell (N1, EC1V, WC1X)
- Region
- Greater London
- Guarantee
- One year on every job
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
How it works
You don’t need to clear the whole room or building, just the space around the work. We protect the rest, and the work takes a morning for a couple of windows and a door for a typical job. In Clerkenwell, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- We check each frame and agree which ones need doing.
- Next the failed sealant is cut away and the joint cleaned.
- Where gaps are deep, backing rod goes in first.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- We clear up and check every joint is fully closed.
Before we arrive
- Mention if the joints have been sealed before
- Try not to wet indoor joints just before the visit
- Let us know if you’ve seen damp or leaks
Get a quote
It all starts with a short chat. Describe the problem, the location and the size of the job, and we will talk you through what we’d do. Whenever you are ready, ring 0345 464 0079 or send us an email.
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Can I do it myself?
If you’ve already had a go yourself, that’s fine. We cut it out and start again.
Sealing over old silicone is the commonest DIY error. New silicone won’t bond to old, so it peels away and traps moisture behind it. All the old material has to come out first.
Keeping the joints in good condition
After the cure time, these simple habits help:
- Keep solvents and bleach off the sealant
- Keep paint off silicone joints
- Check the mastic once a year
- Avoid blasting the frames with a pressure washer
Check the drainage slots in the frames aren’t blocked, 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. If you notice one, it’s time to get the joint looked at.
Questions from Clerkenwell
I let a flat near Farringdon station. Can you help?
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 give you a clear quote.
Is parking a problem for a job in Clerkenwell?
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.
Are you ARBOMaster approved?
Yes. We’re an ARBOMaster approved applicator, which is run for the Arbo sealant brand.
How do I get a quote for window mastic in Clerkenwell?
Every job is different, so each one gets its own quote. For a quick quote, call 0345 464 0079 or email us and tell us what needs doing and where.
Will there be a smell?
Some sealants have a smell while they cure, which fades as it sets. Ventilation helps.
Can you do the inside joint as well?
Yes, we do both. Inside, the joint between frame and plaster is sealed neatly.
Can you reach windows above the ground floor?
Yes, where it’s safe. For high or awkward windows, we will tell you what access is needed.
Is the new sealant paintable?
Most silicone can’t be painted. Let us know beforehand, and we’ll use a paintable product where it suits.
Nearby places to Clerkenwell
What else we do in Clerkenwell
Frames and glazing around Clerkenwell
In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking. With historic houses such as Dr Johnson's House (about 0.8 miles south) nearby, there’s older building stock in the area around Clerkenwell 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.
If you look after a building such as St Peter and St Paul RC Primary School, the mastic around its windows and doors needs looking after like any other building’s. Homes close to St James's Church include some older properties, and the joint between an old wall and a newer frame is generally the first place rain gets in.
Clerkenwell is about 2 miles north of London, in Greater London. Wherever you are in the N1 postcode area, we cover window mastic for homes and businesses. 764 places in Greater London are on our list, large and small.
All of N1, EC1V and WC1X is within our area for window mastic, from the main roads to the quietest streets. That includes homes and businesses on Long Lane, City Road and Noel Road. Being close to the A1 and A5201, Clerkenwell is simple for us to get to for window mastic. Nearby, we also carry out window mastic in Farringdon (1 mile south), Angel (1 mile north), Smithfield (1 mile south), Holborn (1 mile south-west) and St Pancras (1 mile west). We also work in nearby towns such as Kensington (5 miles south-west), Walthamstow (5 miles north-east), Hampstead (4 miles north-west), Ruislip (14 miles west), Brompton (3 miles south-west) and Stockwell (4 miles south).
Local landmarks in Clerkenwell
In Clerkenwell, that means homes and buildings near Barts Health Archives, The Sekforde pub and Elizabeth Garrett Anderson School, among other places. Also close by are Tech City College (under half a mile north-east) and King Square Gardens (less than half a mile north-east). Clerkenwell has its own railway station: Farringdon station. Other landmarks nearby include Brunswick Centre (0.9 miles west) and Montfichet's Tower (0.9 miles south). Green spaces nearby include St. James's Park Lake and Ludgate Hill.
Work for landlords, hotels and businesses
A neglected joint can let water reach the structure, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance that we can handle for you.
Failed sealant is one of the commonest items on a check-out report, and it’s easy to sort out between tenants. We can quote for more than one property at once.
Signs you need window mastic in Clerkenwell
Sun, frost and rain wear sealant out. UV light hardens the outside of the bead, until it loses its stretch and starts to crack.
It’s worth asking for a quote if you see:
- Old mastic that has gone black or come away
- Rushed sealant from a window installation
- Rain getting in at the frame or under the sill
- Cracked sealant at the sill ends
As a London address, Clerkenwell can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
What to look for in a quote
- How much experience the applicator has
- What guarantee comes with the work
- Which sealant they’ll use, and why
- How the joint is cleaned and prepared
What happens if it’s left?
If you’re painting or rendering, reseal at the same time. A clean new bead makes new paint or render look finished. In a flat in Clerkenwell, failed sealant seldom stays inside your own four walls: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
A few things move the cost up or down: how much old sealant there is and how stubborn it is, any mould to treat, and whether the work is at height. Your quote takes all of that into account.
Why us?
- Rated 4.9 stars on Google
- Neat joints and a tidy finish
- Experience in homes, commercial sites and hotels
- White, clear, grey or another colour, product permitting
See our cost guide or our reviews.