Greater London · England
Sand mastic for sash & case windows in Cockfosters, Greater London
We cover Cockfosters for traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old sealant removed completely, joints prepared properly and every job guaranteed for a year.
- Mastic round period door frames that has failed
- Old sand mastic that has cracked, crumbled or fallen out
- A silicone bead on a sash window that spoils the look
Surface by surface
Stone surrounds
Old stone surrounds are often uneven, so the gap isn’t the same all the way round. We shape it by hand to follow the stone.
Timber door frames
Sand mastic is used round timber door frames too. The method is the same as for windows.
About our sand mastic in Cockfosters
Across Cockfosters, we renew sand mastic around sash and case windows. Each joint is raked out, prepared and pointed by hand, finished to suit the masonry. If you have mastic that needs renewing before redecorating and silicone on a period window that looks wrong, we can put it right, whatever the surface.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. The mastic around them dries out and cracks with age, which is when draughts and damp patches appear in homes in Cockfosters.
You are covered for a year from the day we finish. If there’s a problem with it, please call 0345 464 0079 or drop us an email.
- Where
- Cockfosters (EN4, N14)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
FAQs for Cockfosters
Do you cover Cockfosters for sand mastic?
Yes. We work across London and the South East, and Cockfosters is part of that. Just call 0345 464 0079 or send us an email with a few details of the job.
I let a flat near New Barnet station. Can you help?
Yes, we work for landlords and letting agents. You can phone 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before we start.
What’s sand mastic made of?
It’s sand mixed with a linseed-oil-based binder for the joint between timber frames and masonry.
Is it messy?
Very little: the area around the joints is protected first, and we tidy up before we go.
Will the old sealant be removed?
Always. Sealing over the old bead is the commonest cause of early failure, and it’s something we never do.
How long does the job take?
It depends on the size of the job, but most jobs take a few hours per window, depending on the condition of the joints. We will tell you when we quote.
Can I choose the sealant colour?
Generally, yes. White, clear and grey are common, and other colours are available, and we agree the colour with you before we start.
Which is right for my windows, sand mastic or modern sealant?
That depends on your windows. Period windows in stone or brick normally suit sand mastic and newer frames generally get a flexible sealant.
Aftercare tips
Joint life depends on how it’s used and looked after. Here’s what we suggest:
- Keep modern sealant off the mastic
- Renew mastic before redecorating the windows
- Avoid heavy scraping on the mastic joint
- Inspect the joints round the windows every year or so
Check the mastic when you check the paintwork. Catching cracks early keeps repairs small.
Sound mastic protects the frame. Once it fails, water can sit against the timber, which can lead to rot.
How the visit works
We bring everything the job needs with us, so you do not need to buy or prepare anything. Once we have agreed what’s being done, we protect the area and start. Most jobs take a few hours per window, depending on the condition of the joints. For a job in Cockfosters, parking and access are the things to plan: let us know about parking, the floor we will be working on and any lift or shared entrance.
- Each surround is checked first.
- The joint is raked out and cleaned.
- We fill deep gaps so the new mastic is not too thick.
- New sand mastic is applied and shaped by hand.
- The finish is dressed neatly.
Preparing for the visit
- Let us know about earlier repairs to the joints
- Clear items away from the joints we are working on
- Tell us if parking is tricky
How to get a quote
Every job is quoted individually. Simply call 0345 464 0079 or send us an email and describe the job.
Advice
For landlords and businesses
Letting agents often deal with us directly. Tell us the address, the job and how access works.
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. Several properties can be quoted together.
Windows and doors in Cockfosters
In London conversions and blocks, the lease decides who is responsible for the frames, so check that before booking. Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you look after a building such as Trent CofE Primary School, the mastic around its windows and doors needs looking after like any other building’s. Rented homes near New Barnet station change hands often, and any sash windows need sound mastic to keep draughts and rain out.
Cockfosters is about 1 mile east of Barnet, in Greater London. For sand mastic in and around Cockfosters, it’s easy to get a quote: please ring 0345 464 0079 or email us. We are based in Crawley and cover Greater London. Cockfosters is one of 764 places in Greater London where we work. There’s also a page for London, roughly 11 miles from Cockfosters.
Our applicators cover all of the EN4 and N14 postcode area for sand mastic. You’ll find streets such as Park Road, Grove Road and Bevan Road, and we cover them all. Being close to the A111, Cockfosters is simple for us to get to for sand mastic. We also cover New Barnet (1 mile south-west), Hadley Wood (1 mile north-west), East Barnet (1 mile south), Oakwood (1 mile south-east) and Osidge (1 mile south-east). We also work in nearby towns such as London (11 miles south), City of Westminster (10 miles south), Marylebone (9 miles south), Kensington (11 miles south), St Pancras (9 miles south) and Shoreditch (9 miles south).
Near you in Cockfosters
In Cockfosters, that means homes and buildings near The Cock Inn, Trent School Cockfosters and Belmont Open Space. The nearest railway station is New Barnet station, about 0.8 miles west of the centre. Other landmarks nearby include Francis Skaryna Belarusian Library and Museum (2.8 miles south-west) and Chase Farm Hospital (2.5 miles north-east). Green spaces nearby include Covert Way and Darland's Lake.
Nearby places to Cockfosters
More services for Cockfosters
What sealant work cannot fix
We’d rather tell you now than do work that won’t last, so these are the limits:
- Planning or listed building consent (your local planning authority decides)
- Cracked or broken glass
- Sash cords, weights and draught-proofing of the sashes
If in doubt, call 0345 464 0079 or drop us an email and we will say what we think.
Joints and surfaces we work on
- Sash and case windows
- Stone surrounds
- Brick reveals
- Tenement windows
- Timber door frames
- Period & listed homes
DIY versus a professional finish
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and does not move well, and getting the depth right matters as much as the look.
A DIY attempt doesn’t rule out a professional job. We cut it out and start again, so tell us about it when you ask for a quote.
When to call us in Cockfosters
Paint, silicone or cement used over old mastic causes problems. They don’t move with the timber and we normally remove them.
Any of these means the joints need attention:
- Window mastic to renew ahead of painting
- Crumbling sand mastic round a window
- A silicone bead on a sash window that spoils the look
- Gaps where the frame meets the masonry
Cockfosters is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
What to look for in a quote
- Whether all the old sealant comes out first
- How long the guarantee is
- Are they insured?
- What preparation is included