Greater London · England
Sand Mastic in Seven Sisters
Sand mastic for Seven Sisters and the surrounding area: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Crumbling sand mastic round a window
- Silicone on a period window that looks wrong
- Window mastic to renew ahead of painting
Sand mastic in Seven Sisters
A silicone bead around a sash window can look out of place and is not always the right material. Sand mastic is the traditional choice, and we can replace one with the other. Typical jobs include tired mastic found when preparing windows for paint and crumbling sand mastic round a window, across tenement windows, period & listed homes and timber door frames.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. Over the years, the sealant around them shrinks, cracks and pulls away, letting in draughts and water.
A 12-month guarantee comes as standard, so you are not left on your own once the job is done.
- Location
- Seven Sisters (N15, N17, N16)
- Region
- Greater London
- Cover
- One year on every job
- Quotes
- A clear price before work begins
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
When it is not the sealant
New sealant can’t fix everything, and we will tell you before any work starts. It will not solve:
- Decayed frames that need repair
- Whether work needs listed building consent
- Masonry that needs repairing
If you are not sure, just call 0345 464 0079 or send us an email and we will give you a straight answer before booking.
Surfaces we seal
- Timber door frames
- Period & listed homes
- Sash and case windows
- Brick reveals
- Stone surrounds
- Tenement windows
What affects the cost of sand mastic
The price is agreed before any work begins. It’s based on:
- The number and length of the joints
- Which sealant suits the joint
- Any mould that needs treating
- Whether the work is at height
We do not show prices on the website, because the cost depends so much on the job itself. For a quick quote, please ring 0345 464 0079 or email us.
Helping us quote
A few details help us give you an accurate quote. When you get in contact, it helps to mention:
- Where the job is, and your postcode
- What’s wrong with the joints now
- Roughly how big the job is
- Any previous sealing or DIY work
There’s no standard price list. Instead, we give you a clear price for your job. To get started, call 0345 464 0079 or send us an email.
How to look after the new joints
Looking after new joints is easy:
- Sort the mastic before the decorators arrive
- Ask us before painting near the mastic
- Have rotten timber repaired before new mastic goes in
- Inspect the joints round the windows every year or so
When preparing windows for paint, take care around the mastic. It can be damaged by heavy scraping.
An open joint round the box lets weather through. The longer it’s left, the more the joint opens as more mastic falls out.
Can I do it myself?
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
Seven Sisters questions
Do you work for landlords with property near Seven Sisters station?
Yes. We work for landlords and agents as well as homeowners, and several properties can go on one quote. Just ring 0345 464 0079 or send us an email with the address and what needs doing, and we will give you a clear quote.
Is Seven Sisters in your area for sand mastic?
Yes, Seven Sisters is within the area we cover. Our work covers London and the South East. You can phone 0345 464 0079 or drop us an email and let us know what needs doing.
Can you match the sealant colour?
We’ll suggest a colour to suit the surroundings, from white and clear to greys and other shades. The product needed can limit the range.
Will you leave a mess?
Tidy work is part of the job. Nearby surfaces are protected, and we clear up when we are done.
How long does sand mastic take to go off?
The surface skins quite quickly and it hardens fully over a longer time. Timing depends on the weather and the joint.
Is consent needed for window work on a listed home?
Yes, it’s worth checking. Your local planning authority can say if consent is needed for work on a listed home or in a conservation area.
Where are you based?
We work from Crawley. We cover Seven Sisters and the rest of Greater London, along with the rest of our area.
Is it worth trying it myself?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
Common problems we fix in Seven Sisters
Paint, silicone or cement used over old mastic causes problems. They do not move with the timber, and they generally need raking out.
Any of these means the joints need attention:
- Old cement repairs round a window that have failed
- Gaps where the frame meets the masonry
- Mastic that needs renewing before redecorating
- Cracked mastic round a front door frame
As a London address, Seven Sisters can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Questions to ask before you book
- How the joint is cleaned and prepared
- When the joint can take water or movement
- Whether the sealant suits the joint
- Whether they’re fully insured
Places near Seven Sisters
What else we do in Seven Sisters
Landlords, agents and businesses in Seven Sisters
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements and we’ll quote.
A neglected joint can let water reach the structure, which is a bigger problem in a rented property. Keeping joints in good order is simple maintenance.
The process
We bring everything the job needs with us. After a quick look at the joints together, we protect the area and start. It normally takes anything from a few hours to a full day, depending on how many windows. For a job in Seven Sisters, 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.
- First we agree which joints need doing.
- Old mastic and any loose material are raked out.
- Deep gaps are packed so the mastic sits at the right depth.
- We apply the mastic by hand and shape it.
- The surface is finished to suit the stone or brick.
Getting ready for the visit
- Where the joints are inside, avoid wetting them before we arrive
- Keep children and pets away from the work area
- Let us know about stairs, lifts or work at height
Get a quote
Need a quote? Please call 0345 464 0079 or send us an email and tell us about the job. You’ll know what we plan to do, and what it will cost, before any work begins.
Advice
Seven Sisters homes and the weather
In a converted house or block, who looks after the windows depends on the lease, so check that before you book. Historic houses like Bruce Castle (about 1.2 miles north) are a reminder that the area around Seven Sisters has older buildings as well as new. 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.
Homes close to Church of Holy Trinity include some older properties, and frames set in older brick or stone need a sealant that suits the wall as well as the frame. If you look after a building such as Earlsmead Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
Seven Sisters is about 2 miles west of Walthamstow, in Greater London. Whether you are in the middle of Seven Sisters or further out, we cover sand mastic for every kind of property, from flats and houses to offices and hotels. 764 places in Greater London are on our list, large and small. For nearby work, see our London page (6 miles or so).
Jobs for sand mastic in N15, N17 and N16 is quoted and booked the same way as anywhere else. That includes homes and businesses on Ida Road, Elmar Road and Grove Road. If you are just outside Seven Sisters, we cover South Tottenham (1 mile north), Tottenham Green (1 mile north), St Ann's (1 mile west), Tottenham Hale (1 mile north-east) and West Green (1 mile west). Further out, we also cover London (6 miles south), City of Westminster (6 miles south-west), Marylebone (5 miles south-west), Kensington (8 miles south-west), St Pancras (4 miles south-west) and Shoreditch (4 miles south).
What’s near Seven Sisters
Around Seven Sisters, our work takes us to homes and buildings near No.8 Seven Sisters pub, Ada College and Chestnuts Park. Other local landmarks include Gladesmore Community School (under half a mile east) and Church of St Andrew (0.8 miles south). Seven Sisters has its own railway station: Seven Sisters station. A little further out are Montfichet's Tower (4.9 miles south) and The Mall Wood Green (1.7 miles north-west). For a walk, there’s Highgate Hill and Woodberry Wetlands.