Greater London · England
Underhill Glazing Silicone
Glazing joints in Underhill need attention? We cut out the old, prepare the joints and apply the right sealant.
- Failed sealant around rooflight glass
- Water running down inside the glass
- Leaks from the base of a shower screen
Glazing silicone in Underhill
Our work covers conservatory joints, rooflights and glass panels, as well as frameless shower screens and glass balustrade bases. Each joint is cut out, cleaned and resealed. We work on rooflights, glass balustrade bases and glass-to-glass joints, and common reasons people get in touch are leaking glazing joints on a rooflight and glass-to-glass joints that have split.
London has a lot of flats and conversions, where windows are often on upper floors. In a converted house or block, the lease usually says who is responsible for the windows, so it’s worth checking before booking, and access in Underhill is something to talk through when you book.
We stand behind the work with a 12-month guarantee, so you are not left on your own once the job is done.
- Place
- Underhill (EN5, N20)
- Region
- Greater London
- Cover
- One year on every job
- Quote
- A clear price before work begins
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
What affects the cost of glazing silicone
The quote reflects the job in front of us. We look at:
- Access and height
- The type of sealant required
- When we can work, for business premises
- Any mould that needs treating
Doing several joints on one visit is usually more efficient than separate visits, so it’s worth mentioning everything you’d like done. You’ll get one clear quote for the whole job.
What we need to know
You do not need to know the technical terms. Just tell us:
- Whether it has been sealed before
- The problem you’ve noticed
- The type of property
- Photos by email, if that’s easy
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To arrange one, phone 0345 464 0079 or drop us an email.
Leave it or put it right?
Topping up old silicone can look like a fix, but silicone doesn’t stick to silicone, and the leak generally returns. A proper reseal is the lasting answer. In a London flat, a failed joint rarely stays your problem alone: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
The cost depends on the amount of work, how hard the old material is to remove and how easy the joints are to reach. You’ll have a clear quote before any work starts, so you know where you stand.
Why us?
- Old sealant always removed completely
- Approved under the ARBOMaster scheme
- Homes, businesses and hotels
- Rated 4.9 stars on Google
See our cost guide or customer reviews.
Keeping the joints in good condition
No joint lasts for ever, but care makes a real difference. A few tips:
- Keep air moving in the conservatory
- Inspect the sealant on glazing annually
- Use a gentle glass cleaner and a soft cloth
- Wipe the screen down after showering
Avoid scraping near the new silicone when you clean. Stick to a soft cloth.
Do not leave lifting or mouldy silicone on glazing. Peeling silicone lets water in behind and the leak gets worse.
Honest limits
Sealant is not the answer to every problem, and we’d rather say so up front. It will not solve:
- Frames that have decayed or split
- Structural problems with a conservatory roof
- Glass that needs replacing
If you are not sure, just call 0345 464 0079 or drop us an email and we will give you a straight answer.
Surfaces we seal
- Rooflights
- Shower screens
- Glass-to-frame joints
- Glass balustrade bases
- Conservatory frames
- Glass-to-glass joints
Do you need glazing silicone in Underhill?
New silicone over old silicone will not bond. Many failed joints we see have been topped up rather than cut out leaving a path for water.
Most people get in touch after spotting something like this:
- Failed sealant around rooflight glass
- Glazing silicone that has cracked or come away
- Drips on the inside of a conservatory window
- Black or yellowed silicone on glass joints
Schools such as St Catherine's RC School are buildings too, and its window and door frames need their mastic kept sound, just like a home’s.
What your quote should include
- Is VAT in the price?
- Whether they’re fully insured
- How hidden problems are handled
- How the surfaces are prepared before sealing
Underhill homes and the weather
Historic houses like Wyllyotts Manor (about 3.4 miles north) are a reminder that the area around Underhill has older buildings as well as new. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. 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.
For an older house near a landmark such as St John the Baptist Church, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall. As a London address, Underhill can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Underhill is about 1 mile west of Barnet, in Greater London. Across the EN5 area, we cover glazing silicone for homes and businesses. Our Greater London coverage runs to 764 places, and Underhill is one of them. We also work in London, around 11 miles away.
Jobs for glazing silicone in EN5 and N20 works the same way as everywhere else we cover. We cover properties on Park Road, May's Lane and Manor Road and the roads around them. Neighbouring places we cover for glazing silicone include Barnet (1 mile east), New Barnet (1 mile east), Monken Hadley (1 mile north), Hadley Wood (1 mile north-east) and Cockfosters (2 miles east). Larger places within reach include London (11 miles south-east), City of Westminster (9 miles south), Marylebone (9 miles south), Kensington (10 miles south), St Pancras (9 miles south) and Shoreditch (10 miles south-east).
Landmarks near Underhill
Around Underhill, our work takes us to homes and buildings near Susi Earnshaw Theatre School, Highlands Gardens and The Red Lion pub and the streets around them. For rail, the closest station is New Barnet station, roughly 1 mile east. A little further out are Francis Skaryna Belarusian Library and Museum (2.2 miles south) and Barnet General Hospital (0.9 miles west). The countryside around Underhill includes Greenhill Gardens and Darland's Lake.
DIY sealant or a professional job?
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
Sealing over old silicone is the commonest DIY error. New silicone won’t bond to old, so it lifts and traps water and mould underneath. All the old material has to come out first.
Nearby places to Underhill
Also in Underhill
The process
On the day, we start by going over the job with you, so there are no surprises. Surfaces next to the work are protected before any work starts. Most jobs take a few hours, depending on how many joints need doing. For a job in Underhill, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- We start by finding the leak and making sure sealant is the cause.
- Old silicone is cut away from the glass and frame without scratching either.
- Surfaces are cleaned with a solvent suited to glass and the frame.
- We apply a neutral-cure glazing silicone and tool it smooth.
- The finished joints are checked and, where it’s safe, tested with water.
Getting ready for the visit
- Plan for the work area to be out of bounds to pets and children
- Tell us about any previous sealing or DIY attempts
- Clear items away from the joints we’re working on
Getting a quote
Getting a quote is simple: let us know the job and the location, and roughly how big it is. Photos by email help us understand the job, and we’ll take it from there.
Advice
Your questions about glazing silicone in Underhill
I let a flat near New Barnet station. Can you help?
Yes, landlords and agents are among the people we work for. You can ring 0345 464 0079 or email us with the details for a clear quote.
Do you cover Underhill for glazing silicone?
Yes, Underhill is within the area we cover. Our work covers London and the South East. You can call 0345 464 0079 or drop us an email and tell us what needs doing, and we’ll give you a clear quote.
What information do you need?
Only a few details: the address or postcode, what’s wrong and any access issues. After that, simply phone 0345 464 0079 or email us.
Do you have insurance?
Yes. We are fully insured.
What does glazing silicone cost?
We do not publish prices, because the cost depends on the job: how much there is, what’s there now, how we reach it and what it needs. We agree the price before any work begins.
Where do you work from?
Mr Mastic is based in Crawley. Our applicators cover Underhill, along with the rest of our area.
Do you reseal glass shower screens?
Yes. We remove the old sealant and reseal the wall and tray joints.
Is there any odour?
It depends on the product. Some products have a noticeable smell, others very little, and any smell fades as they cure.