Greater London · England
Sand Mastic in New Barnet
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homeowners, landlords and businesses in New Barnet. Fully insured, ARBOMaster approved and guaranteed for a year.
- Wind and rain getting in round a sash window
- Crumbling sand mastic round a window
- Patchy fillers round a sash window
For landlords and businesses
Whether it’s one flat or a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a 12-month guarantee.
Mouldy or split sealant often shows up at the end of a tenancy. We can quote for more than one property at once.
Sand mastic in New Barnet, done properly
We renew sand mastic around sash windows and doors in stone and brick. The old mastic is raked out, and new mastic is applied and shaped by hand. We work on tenement windows, period & listed homes and stone surrounds, and the jobs we see most are mastic round period door frames that has failed and failed mastic on an exposed elevation.
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, which is when draughts and damp patches appear in homes in New Barnet.
You are covered for a year from the day we finish. If there’s a problem with it, please call 0345 464 0079 or send us an email.
- Location
- New Barnet (EN5, EN4, N20)
- Region
- Greater London
- Cover
- A year, on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
What sealant work can’t fix
Sealant is not the answer to every problem, and we’ll tell you before work begins. It will not solve:
- Decisions on consent for listed homes
- Putty and glazing repairs
- Decayed frames that need repair
Not sure which it is? You can phone 0345 464 0079 or email us and we will tell you honestly before you book.
Where we work in New Barnet
- Brick reveals
- Timber door frames
- Tenement windows
- Sash and case windows
- Stone surrounds
- Period & listed homes
DIY sealant or a professional job?
If you are set on DIY, put the effort into preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it does not work out, we can still put it right.
If you’ve already had a go yourself, that is fine. We remove it and do the joint properly, so just mention it when you contact us.
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Don’t paint over the new mastic
- Renew mastic before redecorating the windows
- Go gently near the mastic when preparing windows
- Ask the planning authority about consent for listed or conservation-area homes
Keep paint scrapers and sanders off the mastic when redecorating. It can be damaged by heavy scraping.
Sound mastic protects the frame. Failed mastic lets water reach the timber and timber that stays wet can rot.
Towns and villages near New Barnet
Also in New Barnet
Surface by surface
Period and listed homes
A traditional finish suits a period property, and sand mastic is one of them.
Stone surrounds
We take care not to mark the stone when the old mastic comes out.
What we do, step by step
On the day, there’s very little for you to do. Point us to the joints and we’ll get on with it. The job generally takes a few hours per window, depending on the condition of the joints, including the tidy-up. For a job in New Barnet, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- We look at the surrounds with you and agree the joints to renew.
- Old mastic and any loose material are raked out.
- Deep gaps are packed so the mastic sits at the right depth.
- The sand mastic is mixed and pressed into the joint by hand.
- The surface is finished to suit the stone or brick.
Preparing for the visit
- Tell us if parking is tricky
- Clear the area around the work
- Mention if the joints have been sealed before
How to get a quote
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To get started, ring 0345 464 0079 or send us an email.
Related advice
Sand mastic in New Barnet: local notes
Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking.
Rented homes near New Barnet station change hands often, and any sash windows need sound mastic to keep draughts and rain out. Schools such as St Mary's CofE Primary School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s.
New Barnet is about 1 mile east of Barnet, in Greater London. New Barnet gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a 12-month guarantee. Our Greater London coverage runs to 764 places, New Barnet among them. There’s also a page for London, about 11 miles away.
Every address in EN5, EN4 and N20 is within our area for sand mastic. We cover properties on York Road, Park Road and Henry Road. Neighbouring places we cover for sand mastic include Barnet (1 mile west), Cockfosters (1 mile north-east), East Barnet (1 mile south-east), Underhill (1 mile west) and Whetstone (1 mile south). We also work in nearby towns such as London (11 miles south), City of Westminster (9 miles south), Marylebone (9 miles south), Kensington (10 miles south), St Pancras (8 miles south) and Shoreditch (9 miles south-east).
Near you in New Barnet
In New Barnet, that means homes and buildings near Trent School Cockfosters, East Barnet School and The Alexandra pub, among other places. New Barnet has its own railway station: New Barnet station. Nearby you’ll also find Spires Shopping Centre (1.6 miles north-west) and Francis Skaryna Belarusian Library and Museum (2 miles south). The countryside around New Barnet includes Greenhill Gardens and Darland's Lake.
When to call us in New Barnet
Shallow joints are a common cause. A thin layer doesn’t hold well, which is why we pack deep voids first and get the depth right.
Common reasons people contact us are:
- Wind and rain getting in round a sash window
- Failed mastic on an exposed elevation
- A silicone bead on a sash window that spoils the look
- Open joints round the window box
Homes close to Holy Trinity Lyonsdown include some older properties, and the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Questions to ask before you book
- How hidden problems are handled
- Whether they’re fully insured
- Who does the work, and how experienced they are
- What guarantee comes with the work
Your questions about sand mastic in New Barnet
Is New Barnet in your area for sand mastic?
Yes, New Barnet is within the area we cover. We work across London and the South East. You can ring 0345 464 0079 or send us an email and let us know what needs doing, and we’ll give you a clear price.
I let a flat near New Barnet station. Can you help?
Yes, we work for landlords and letting agents. You can ring 0345 464 0079 or drop us an email with the address and a few details, and we’ll give you a fixed price before any work starts.
When will the new mastic be hard?
It forms a skin fairly soon and it hardens fully over a longer time. Timing depends on the weather and the joint.
Where are you based?
Our base is Crawley. We work across South East England, London and Scotland.
Do I need to be at home?
Access is agreed with you when the job is booked. Indoors, that usually means someone at home.
Do you guarantee sand mastic work?
Our 12-month guarantee covers every job.
Can I choose the sealant colour?
We help you choose a colour that suits, from white and clear to greys and other shades. The product needed can limit the range.
What should I tell you?
A short description and the location. We’ll ask anything else we need to know.