Greater London · England
Sand mastic for sash & case windows in Bentley Heath, Greater London
Sand mastic in Bentley Heath from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Failed mastic on an exposed elevation
- Gaps between timber frames and stone or brick
- Draughty sash windows at the surround
How we handle sand mastic in Bentley Heath
Sand mastic is the traditional way to point the gap between a timber window frame and the stone or brick around it. It’s made from sand and a linseed-oil-based binder and built up by hand. On older homes, it suits the building far better than silicone. We are often asked to deal with cracked mastic round a front door frame and tired mastic found when preparing windows for paint, across tenement windows, brick reveals and stone surrounds.
Many London homes are flats, with windows high above the street. In a converted house or block, the lease generally says who is responsible for the windows, so it’s worth checking before booking, and access in Bentley Heath is something to talk through when you book.
Big or small, you get the same 12-month guarantee.
- Location
- Bentley Heath (EN5)
- Region
- Greater London
- Guarantee
- One year on every job
- Quotes
- A clear price before work begins
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
FAQs for Bentley Heath
Is Bentley Heath in your area for sand mastic?
Yes. Our work covers London and the South East, and Bentley Heath is part of that. Just call 0345 464 0079 or drop us an email with a few details of the job.
Can you help a landlord with a rental near Potters Bar station?
Yes. We work for letting agents and landlords as well as homeowners. Just ring 0345 464 0079 or drop us an email with the address and what needs doing, and we’ll give you a clear quote.
What should I tell you?
Only a few details: where it is, what you’ve noticed and how we reach it. After that, simply phone 0345 464 0079 or send us an email.
What does sand mastic cost?
It depends on the job, so we quote each one individually. To get one, phone 0345 464 0079 or send us an email and tell us what needs doing and where.
Can I paint the new mastic?
Traditional guidance is not to paint over sand mastic. Ask us before you decorate around it and we will talk you through it.
Can you match the sealant colour?
Yes. White, clear and grey are common, and other colours are available for many products, and we agree the colour with you before we start.
Do you work for hotels and businesses?
Yes. Commercial and hotel work is a large part of what we do, as well as homes. We can talk about working times when we quote.
Which products do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. Brands we use include Arbo and Everbuild.
Aftercare tips
How long the joints last depends on use and care. Here’s what we suggest:
- Don’t paint over the new mastic
- Avoid patching sand mastic with silicone
- Get any rot dealt with first
- Take care around the mastic when scraping paint
Keep gutters and sills clear so water runs away from the surround. Water sitting against the mastic shortens its life.
Renewing mastic before redecorating saves doing it twice. Painting over failed mastic hides the problem for a while.
When it is not the sealant
We’d rather tell you now than do work that won’t last, so these are the limits:
- Decayed frames that need repair
- Broken panes
- Crumbling stone or brickwork round the window
Not sure which it is? You can call 0345 464 0079 or email us and we will tell you honestly.
What we seal
- Tenement windows
- Stone surrounds
- Brick reveals
- Timber door frames
- Sash and case windows
- Period & listed homes
How it works
We keep the work tidy and contained to the area we are working on. The job normally takes a few hours for a single window, longer for several. In a London area like Bentley Heath, 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.
- We check each window surround and the condition of the joint.
- 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.
Getting ready for the visit
- Move anything stored near the joints
- Plan for the work area to be out of bounds to pets and children
- Mention any leaks or damp you’ve noticed
How to get a quote
For sand mastic in Bentley Heath, phone 0345 464 0079 or drop us an email. Tell us what the problem is and where, and we’ll agree the price before any work begins.
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Landlords, agents and businesses in Bentley Heath
Housing providers, facilities teams and property managers book us too in Bentley Heath and across Greater London. We can quote a run of properties together, and we’re fully insured for the work.
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements.
Windows and doors in Bentley Heath
With historic houses such as Wyllyotts Manor (about 0.9 miles north) nearby, there’s older building stock in the area around Bentley Heath as well as newer homes. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking.
As a London address, Bentley Heath can be tricky for parking: tell us about permits, visitor bays or off-street space when you book. For site and facilities teams at buildings such as Pope Paul Catholic Primary School, the mastic around its windows and doors needs looking after like any other building’s.
Bentley Heath is about 1 mile south-west of Potters Bar, in Greater London. Bentley Heath gets the same service as everywhere we cover: the old material taken out, joints prepared properly and a 12-month guarantee. Bentley Heath is one of 764 places in Greater London where we work. You can also see our page for London, roughly 13 miles from Bentley Heath.
Work in EN5 is quoted and booked the same way as anywhere else. We also cover the places around Bentley Heath: Potters Bar (1 mile north-east), Monken Hadley (1 mile south), Hadley Wood (2 miles south-east), Underhill (3 miles south) and Northaw Valley (3 miles east). Larger places within reach include London (13 miles south), City of Westminster (12 miles south), Marylebone (12 miles south), Kensington (13 miles south), St Pancras (11 miles south) and Shoreditch (12 miles south-east).
Around Bentley Heath
In Bentley Heath, that means homes and buildings near King George's Fields (Monken Hadley), Dame Alice Owen's School and Duke of York pub. Bentley Heath’s nearest station is Potters Bar station, about 1 mile north of the centre. Nearby you’ll also find Barnet General Hospital (2.4 miles south) and Potters Bar Museum (0.9 miles north). For a walk, there’s Furzefield Wood and Lower Halfpenny and Darland's Lake.
DIY sealant or a professional job?
Sealing over old silicone is the commonest DIY error. Silicone doesn’t stick to old silicone, so it lifts and traps water and mould underneath. All the old material has to come out first.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
Surface by surface
Tenement and terrace windows
Upper-floor windows need access planning. Let us know the floor and we will confirm access.
Brick reveals
Loose mastic comes out and deep gaps are packed before the new mastic goes in.
Signs you need sand mastic in Bentley Heath
Timber frames move with the seasons. The movement cracks the mastic little by little.
If you can see any of these, it’s time to have the joints looked at:
- Tired mastic found when preparing windows for paint
- Old sand mastic that has cracked, crumbled or fallen out
- Failed mastic on an exposed elevation
- Draughts and rain around sash boxes
For an older house near a landmark such as Church of King Charles and the Martyr, the joint between an old wall and a newer frame is generally the first place rain gets in.
Questions to ask before booking
- Is the old sealant removed completely?
- How hidden problems are handled
- Who does the work, and how experienced they are
- Which sealant they’ll use, and why