Greater London · England
Crossness Sand Mastic
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for homes and businesses in Crossness and across Greater London. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Patchy fillers round a sash window
- Crumbling sand mastic round a window
- Draughts and rain around sash boxes
Sand mastic in Crossness
Fresh sand mastic forms a skin quite soon, but it takes longer to harden fully. Traditionally, sand mastic is left unpainted and we will advise if you are redecorating. We work on sash and case windows, brick reveals and tenement windows, and common reasons people get in touch are draughts and rain around sash boxes and gaps round a timber door in stone or brick.
London’s Victorian and Edwardian terraces were built with timber sash windows, and many still have them or their replacements. Either way, the mastic between frame and brickwork is what stops draughts and rain getting in.
We guarantee the work for a year. If there’s a problem with our work within the year, let us know and we will sort it.
- Where
- Crossness (SE2, SE28, DA18)
- Region
- Greater London
- Guarantee
- One year on every job
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Aftercare tips
Looking after new joints is easy, and it makes a real difference:
- Sort the mastic before the decorators arrive
- Get any rot dealt with first
- Do not run silicone over sand mastic
- Clear gutters so water doesn’t pour onto the windows
Leave the new mastic unpainted, which is the traditional advice. If you are redecorating, ask us first.
An open joint round the box lets weather through. Left, the gap tends to get bigger as more mastic falls out.
Places near Crossness
What else we do in Crossness
Windows and doors in Crossness
With historic houses such as Rainham Hall (about 2.8 miles north-east) nearby, there’s older building stock in the area around Crossness as well as newer homes. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window. Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
If you live in an older home near Church of the Cross, 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 St John Fisher Catholic Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
Crossness is about 2 miles north-west of Erith, in Greater London. We provide sand mastic to homes and businesses in Crossness. Crossness is one of 764 places in Greater London where we work. We also work in London, about 10 miles from Crossness.
Every address in SE2, SE28 and DA18 is covered for sand mastic, from the main roads to the quietest streets. Whether your property is on Kale Road, Haldane Road and Seacourt Road or a nearby road, our applicators can take on the job. You’ll find Crossness on the A2016, so it’s easy for us to get to. Neighbouring places we cover for sand mastic include Thamesmead (1 mile north-west), Dagenham Dock (1 mile north), Barking Riverside (2 miles north-west), Hornchurch Marshes (2 miles north-east) and Dagenham Green (2 miles north). We also work in nearby towns such as London (10 miles west), City of Westminster (12 miles west), Marylebone (12 miles west), Kensington (14 miles west), St Pancras (11 miles west) and Shoreditch (9 miles west).
Near you in Crossness
Locally, jobs take us to homes and businesses close to Lesnes Abbey Woods, Harris Garrard Academy and Belvedere Working Mens Club pub, among other places. The nearest railway station is Abbey Wood station, about 0.8 miles south-west. Well-known places in the area include Erith and District Hospital (2.1 miles south-east) and Gallions Reach Shopping Park (2.4 miles west). Green spaces nearby include Crossness Nature Reserve.
Signs you need sand mastic in Crossness
Previous repairs in cement or silicone often trap water or crack away. They do not suit the joint and we normally remove them.
These are the problems we are asked about most:
- Mastic worn away on windows facing the weather
- Patchy fillers round a sash window
- A silicone bead on a sash window that spoils the look
- Window mastic to renew ahead of painting
Rented homes near Abbey Wood station change hands often, and older sash windows in a rental need their mastic kept sound to keep the weather out.
Questions to ask before you book
- What happens if they find a problem under the old sealant
- How long the guarantee is
- Whether they’re fully insured
- Whether all the old sealant comes out first
What happens on the day
Good joint work is mostly preparation, so that’s where we spend the time. Every joint is cleaned and dried before new material goes in. All told, the work takes a few hours per window, depending on the condition of the joints. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. If the building has a concierge, managing agent or access rules, tell us 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.
- We apply the mastic by hand and shape it.
- We dress the finish so it sits neatly against the masonry.
Before we arrive
- Tell us if parking is tricky
- Where the joints are inside, avoid wetting them before we arrive
- For business premises, tell us about site rules or sign-in
Ask for a quote
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is, and email photos if that is easy.
Read more
What affects the quote in Crossness
Your quote is based on your job. We take into account:
- Whether there’s mould to deal with
- How easy the joints are to reach
- How many areas need sealing
- The type of sealant required
The cost reflects the work involved, not a rough estimate. That is why we ask a few questions first and agree the price before starting.
Asking for a quote
What to tell us when you ask for a quote:
- How many joints, rooms or windows are involved
- Pictures of the joints, sent by email
- Any access issues, like height or stairs
- If someone has resealed it before
Need a quote? Please call 0345 464 0079 or send us an email with a few details. We’ll explain what we’d do and send you a clear quote before work begins.
Work for landlords, hotels and businesses
Housing providers, facilities teams and property managers book us too in Crossness and across Greater London. We can quote a run of properties together.
Letting agents often deal with us directly. Tell us the address, the job and how access works and we’ll quote.
What happens if it’s left?
Filling over old, loose mastic doesn’t last. Raking out and preparing the joint gives it a sound base so the new work lasts. Damp from a failed joint spreads quietly in older London brickwork and timber, and by the time it shows on a wall or ceiling in Crossness, the repair is bigger than the sealant job would have been.
Instead of a standard rate, we price the job in front of us: the amount of work, the old material and the access. The price is agreed before we begin.
Why book with us
- We never seal over old sealant
- Full insurance on every job
- Homes, businesses and hotels
- Neat joints and a tidy finish
See our cost guide and our reviews.
How the job changes by surface
Timber door frames
A neat sand mastic joint round a front door suits a period home.
Sash and case windows
The mastic round a sash window is on show so we finish it carefully.
Common questions in Crossness
Can you do sand mastic in Crossness?
Yes, Crossness is within the area we cover. Our work covers London and the South East. Just ring 0345 464 0079 or drop us an email with a few details of the job.
I let a flat near Abbey Wood station. Can you help?
Yes, we work for landlords and 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.
Should I check with the council before work on a listed or conservation-area home?
Yes, it’s worth checking. Your local planning authority can say if consent is needed for listed or conservation-area properties.
Can I do it myself?
You can, for simple jobs. Preparation is everything: all the old sealant out, and a clean, dry joint. We can always put it right if it fails.
Will the old sealant be removed?
Always. Sealing over old sealant is the main reason resealing fails early, so we never do it.
Is the work guaranteed?
Our 12-month guarantee applies on every job.
What do you put in the joint?
Quality sealants from brands including Arbo and Everbuild, picked for each joint. We explain the product when we quote.
What information do you need?
Tell us what needs doing and where. If we need more, we’ll ask.