Greater London · England
Friern Barnet Sand Mastic
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homeowners, landlords and businesses in Friern Barnet. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Weathered mastic on the most exposed windows
- Open joints round the window box
- Draughts and rain around sash boxes
Different surfaces, different methods
Sash and case windows
Sash windows are where we do most sand mastic work. Each joint round the box is raked out and renewed.
Period and listed homes
On a listed home or in a conservation area, the right material matters. Sand mastic is often the preferred finish.
Sand mastic in Friern Barnet, done properly
Sand mastic suits most period window surrounds. Newer frames generally get a flexible sealant instead, and we’ll talk through which suits your home. If you’re dealing with silicone on a period window that looks wrong and gaps where the frame meets the masonry, we can help, on sash and case windows, tenement windows and stone surrounds alike.
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.
Your job is guaranteed for a year, as with all our work.
- Place
- Friern Barnet (N11, N12, N10, N20)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
DIY sealant or a professional job?
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Frames and glazing around Friern Barnet
Rainfall in the South East is lower than in much 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 check that before you book.
Friern Barnet is in London, so parking needs planning: let us know about parking bays, permits or a driveway. Schools such as Holly Park Primary School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s.
Friern Barnet is about 2 miles north-east of Finchley, in Greater London. If you need sand mastic in Friern Barnet, please phone 0345 464 0079 or email us for a quick quote. We are based in Crawley and cover Greater London. Our area takes in 764 places across Greater London. There’s also a page for London, about 8 miles away.
Every address in N11, N12, N10 and N20 is covered for sand mastic, from the main roads to the quietest streets. Streets in the area include Martock Gardens, Shapwick Close and Radstock Close. Being close to the A406 and B550, Friern Barnet is simple for us to get to. Other places close to Friern Barnet include New Southgate (1 mile east), Brunswick Park (1 mile north), North Finchley (1 mile west), Arnos Grove (1 mile east) and Whetstone (1 mile north-west). Further out, we also cover London (8 miles south), City of Westminster (7 miles south), Marylebone (7 miles south), Kensington (8 miles south), St Pancras (6 miles south) and Shoreditch (7 miles south-east).
Landmarks near Friern Barnet
Typical jobs here are in homes near Francis Skaryna Belarusian Library and Museum, Friary Park and Friern Barnet School, among other places. Friern Barnet has its own railway station: New Southgate station. A little further out are Francis Skaryna Belarusian Library and Museum (1.4 miles west) and Grand Arcade (1 mile west). Open spaces near Friern Barnet include Highgate Hill and Darland's Lake.
Signs you need sand mastic in Friern Barnet
Timber frames move with the seasons. That movement opens up the mastic joint over time.
People usually contact us after spotting something like this:
- Old cement repairs round a window that have failed
- Draughty sash windows at the surround
- Mastic dropping out of the joint
- Window mastic to renew ahead of painting
If you let a flat or house near New Southgate station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
Questions to ask before booking
- The length of the guarantee
- How long to leave it before use
- What happens if they find a problem under the old sealant
- What insurance they hold
Why it’s worth doing now in Friern Barnet
An open joint round the frame lets weather in. Left, water can reach the timber and the wall, so dealing with it now protects both. In a flat in Friern Barnet, 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: the old material and how easily it comes out, whether mould needs treating, and whether the work is at height. We take all of that into account in your quote.
Why choose Mr Mastic in Friern Barnet
- Trusted Arbo and Everbuild sealants
- Full insurance on every job
- We leave the area clean and tidy
- Experience in homes, commercial sites and hotels
See what affects the cost and what customers say.
Places near Friern Barnet
Other services in Friern Barnet
What affects the cost of sand mastic
Jobs vary more than people expect. The main factors:
- Access and height
- The product the joint needs
- The number and length of the joints
- Any mould that needs treating
The cost depends on the amount of work, how hard the old material is to remove and access to the work. You’ll have a clear quote before any work starts.
What we need to know
To make quoting easier, let us know:
- Roughly how big the job is
- Any previous sealing or DIY work
- Access, such as stairs, a lift or height
- Where the property is
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and email photos if that is easy.
Your questions about sand mastic in Friern Barnet
Do you work for landlords with property near New Southgate station?
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 will give you a clear quote.
Can parking be tricky for a visit in Friern Barnet?
Parking in Friern Barnet, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Do you work for hotels and businesses?
Yes, regularly. Larger jobs can be planned room by room or area by area to suit the site.
Which is right for my windows, sand mastic or modern sealant?
We’ll help you decide. Sand mastic suits many period homes, and modern sealants suit newer frames.
What does sand mastic cost?
Size, access and the old material all affect the cost. Ask us for a quote and we will talk you through it.
Should I check with the council before work on a listed or conservation-area home?
Speak to your local planning authority before work starts. Sand mastic is often favoured as like for like but the decision is theirs.
Can you replace silicone on a period window with sand mastic?
Yes. We remove the silicone and clean the joint, then point it with sand mastic.
Do you come to Friern Barnet?
Yes. We’re based in Crawley and work across South East England, London and Scotland.
What happens on the day
Our applicators work methodically: protect, prepare, seal, tidy. For most jobs that takes anything from a few hours to a full day, depending on how many windows and we leave things clean and tidy. In a London area like Friern Barnet, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- Each surround is checked first.
- We rake out the old mastic and clean the joint.
- We fill deep gaps so the new mastic isn’t too thick.
- We point the joint with sand mastic by hand.
- We finish the mastic to a tidy line.
Before we arrive
- Mention any tricky access
- Clear the area around the work
- Mention any leaks or damp you’ve noticed
Ask for a quote
Asking for a quote is easy: let us know what needs doing and where, and roughly how big it is. Photos by email help us understand the job, and we will take it from there.
Read more
What sealant work cannot fix
Honest advice matters more to us than a booking, so here’s what new sealant will not do:
- Masonry that needs repairing
- Sashes that need overhauling
- Timber that has rotted
If in doubt, phone 0345 464 0079 or send us an email and we’ll say what we think.
Joints and surfaces we work on
- Sash and case windows
- Tenement windows
- Brick reveals
- Stone surrounds
- Period & listed homes
- Timber door frames