Greater London · England
Sand Mastic in New Eltham
We cover New Eltham for traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old material cut out, joints cleaned and sealed neatly and a 12-month guarantee.
- Cement or filler used on old window joints that has cracked
- Mastic worn away on windows facing the weather
- Mastic that needs renewing before redecorating
Surface by surface
Stone surrounds
Old stone surrounds are often uneven, so the joint varies in width. We shape it by hand to follow the stone.
Period and listed homes
Sand mastic is the like-for-like choice for many period homes. On listed buildings, check with your planning authority first.
About our sand mastic in New Eltham
Sand mastic suits most period window surrounds. On modern frames we’d normally use a flexible sealant, and we’ll talk through which suits your home. If you’re dealing with patchy fillers round a sash window and cracked mastic round a front door frame, we can put it right, whatever the surface.
From mansion-block windows to modern glazing in new flats, London has every kind of frame. The mastic around them dries out and cracks with age, letting in draughts and water.
Whatever the size of the job, you get the same one-year guarantee.
- Location
- New Eltham (SE9, DA15, BR7)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Honest limits
In fairness, some problems need a different trade:
- Cracked or broken glass
- Crumbling stone or brickwork round the window
- Sash cords, weights and draught-proofing of the sashes
Not sure which it is? You can call 0345 464 0079 or drop us an email and we will tell you honestly.
What we seal
- Period & listed homes
- Brick reveals
- Stone surrounds
- Timber door frames
- Tenement windows
- Sash and case windows
Should I try it myself first?
What a professional job adds is preparation and the right 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.
If you’ve already had a go yourself, that’s fine. We cut it out and start again, so just mention it when you contact us.
Also near New Eltham
Also in New Eltham
Aftercare tips
Aftercare is simple, and it makes a real difference:
- Take care around the mastic when scraping paint
- Get any rot dealt with first
- Leave the new mastic unpainted
- Make sure water runs off the sill
Avoid painting over the new mastic, which is the traditional advice. Ask us before any decorating around it.
Crumbling mastic lets rain into the joint. That water can reach the timber frame and the wall, so renewing it early is worth it.
Windows and doors in New Eltham
In a converted house or block, who looks after the windows depends on the lease, so it’s worth checking before booking. With historic houses such as Eltham Palace (about 1.1 miles north-west) nearby, there’s older building stock in the area around New Eltham as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic.
In the older streets around All Saints Church, frames set in older brick or stone need a sealant that suits the wall as well as the frame. Rented homes near New Eltham station change hands often, and older sash windows in a rental need their mastic kept sound to keep the weather out.
New Eltham is about 1 mile south-east of Eltham, in Greater London. Anywhere in SE9, we can carry out sand mastic at your property. New Eltham is one of 764 towns and villages in Greater London we cover. Our London page covers work nearby (8 miles or so).
We work across SE9, DA15 and BR7 for sand mastic. That includes homes and businesses on Green Lane, Gerda Road and Novar Road. We also cover the places around New Eltham: Eltham (1 mile north-west), Longlands (1 mile south-east), Coldharbour (1 mile south-west), Avery Hill (1 mile north) and Blackfen (1 mile north-east). We also work in nearby towns such as London (8 miles north-west), City of Westminster (11 miles north-west), Marylebone (11 miles north-west), Kensington (13 miles west), St Pancras (10 miles north-west) and Shoreditch (9 miles north-west).
What’s near New Eltham
In New Eltham, that means homes and buildings near Elmstead Wood and St Thomas More Catholic Comprehensive School, among other places. There’s a railway station in New Eltham itself: New Eltham station. Well-known places in the area include Metropolitan Police Museum (1.4 miles east) and Eltham Community Hospital (1.1 miles north-west). Open spaces near New Eltham include Summer Hill and The Tarn.
Why it’s worth doing now in New Eltham
Filling over old, loose mastic does not last. Raking out and preparing the joint gives it a sound base so the new mastic stays put. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in New Eltham, the repair is bigger than a sealant job.
Combining jobs into one visit normally makes better use of the time than several visits, so tell us about everything that needs sealing. You’ll get one clear quote for the whole job.
Why us?
- 20+ years of sealant experience
- Homes, businesses and hotels
- Trusted Arbo and Everbuild sealants
- Full insurance on every job
See what affects the cost and what customers say.
How the visit works
There is not much for you to do on the day. Show us the job and we will take it from there. The work itself takes a few hours per window, depending on the condition of the joints from start to finish. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- We look at the surrounds with you and agree the joints to renew.
- Old mastic and any loose material are raked out.
- We pack any deep voids first.
- The sand mastic is mixed and pressed into the joint by hand.
- The surface is finished to suit the stone or brick.
Getting ready for the visit
- Mention any leaks or damp you’ve noticed
- Mention any parking rules near the property
- Keep children and pets away from the work area
Getting a quote
To get a quote, call 0345 464 0079 or email us and tell us where the job is and what the problem looks like. You will have a clear quote before we start.
Related advice
FAQs for New Eltham
Is New Eltham in your area for sand mastic?
Yes, New Eltham is within the area we cover. We work across London and the South East. Just phone 0345 464 0079 or email us with a few details of the job.
Can you help a landlord with a rental near New Eltham station?
Yes. We work for landlords and agents as well as householders. You can ring 0345 464 0079 or drop us an email with the details for a clear quote.
Are you insured?
Yes. Mr Mastic is fully insured, and we have been doing sealant work for more than 20 years.
What exactly is sand mastic?
Sand mastic is a traditional material for pointing round windows and doors. It’s made with sand and a linseed-oil-based binder.
Is there any odour?
It depends on the product. Some products have a noticeable smell, others very little.
Is the work guaranteed?
There’s a 12-month guarantee on every job.
Do I need permission for sand mastic on a listed building?
Yes, it’s worth checking. Ask your local planning authority whether consent is needed for listed or conservation-area properties.
What does sand mastic cost?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. We agree the price before any work begins.
What we’re called out for in New Eltham
Timber frames move with the seasons. The movement cracks the mastic over time.
Keep an eye out for these signs:
- Modern sealant on a period surround
- Mastic dropping out of the joint
- Mastic round period door frames that has failed
- Old cement repairs round a window that have failed
For site and facilities teams at buildings such as Wyborne Primary School, the mastic around its windows and doors needs looking after like any other building’s.
Before you book anyone
- Whether all the old sealant comes out first
- What guarantee comes with the work
- What preparation is included
- What insurance they hold