Greater London · England
Sand mastic for sash & case windows in Erith, Greater London
Sand mastic for Erith and the surrounding area: careful preparation, the right product and tidy work. Ask us for a quick quote.
- Weathered mastic on the most exposed windows
- Old sand mastic that has cracked, crumbled or fallen out
- Tired mastic found when preparing windows for paint
About our sand mastic in Erith
Sand mastic has long been used to fill the joint between timber frames and masonry. It’s a mix of sand and a linseed-oil-based binder, applied by hand. On period homes, it looks right where silicone wouldn’t. We work on brick reveals, sash and case windows and period & listed homes, and the jobs we see most are crumbling sand mastic round a window and cement or filler used on old window joints that has cracked.
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, which is when draughts and damp patches appear in homes in Erith.
You’re covered for a year from the day we finish. If anything isn’t right with it, ring 0345 464 0079 or send us an email.
- Location
- Erith (DA8, DA17, DA7)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Quote
- Quoted before any work starts
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
What affects the cost of sand mastic
Every job gets its own quote. These are the things that affect it:
- The size of the job
- The type of sealant required
- The number of rooms or windows
- Access and height
Leaving a failed joint normally makes the job bigger, not smaller. If you’re unsure, call 0345 464 0079 or email us for an honest opinion and a quote.
What to tell us for a quote
There’s no need for technical detail. Just tell us:
- If it’s domestic, commercial or a hotel
- Any previous sealing or DIY work
- What the problem is, such as mould, gaps, leaks or cracking
- Where the property is
For a quick quote, get us on the phone, or email us if that’s easier. Describe what needs sealing and we’ll talk you through the work.
Honest limits
In fairness, there are a few things sealant will not fix:
- Planning or listed building consent (your local planning authority decides)
- Crumbling stone or brickwork round the window
- Decayed frames that need repair
If in doubt, ring 0345 464 0079 or send us an email and we’ll say what we think.
Where we work in Erith
- Timber door frames
- Period & listed homes
- Tenement windows
- Sash and case windows
- Brick reveals
- Stone surrounds
Why deal with it now?
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. In older London homes, water behind a failed joint soaks into brick and timber without much sign, and by the time it shows on a wall or ceiling in Erith, the repair is bigger than the sealant job would have been.
We do not show prices on the website, because each job is priced on what it involves. Call for a quick quote and we will talk you through it.
Why us?
- Tidy, careful work
- More than 20 years in sealant work
- Full insurance on every job
- Old sealant always removed completely
Do you need sand mastic in Erith?
Previous repairs in cement or silicone often trap water or crack away. They do not suit the joint, and they generally need raking out.
These are the problems we’re asked about most:
- Old cement repairs round a window that have failed
- Mastic round period door frames that has failed
- Draughty sash windows at the surround
- A silicone bead on a sash window that spoils the look
If you look after a building such as Christ Church (Erith) CofE Primary School, its window and door frames need their mastic kept sound, just like a home’s.
Before booking anyone
- How much experience the applicator has
- Is the old sealant removed completely?
- What insurance they hold
- Whether you can choose the colour
Erith homes and the weather
In London conversions and blocks, the lease decides who is responsible for the frames, so check that before booking. Historic houses like Hall Place and Gardens (about 2.3 miles south) are a reminder that the area around Erith has older buildings as well as new. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window.
Erith is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. In the older streets around Christ Church, the joint between an old wall and a newer frame is usually the first place rain gets in.
Erith is about 3 miles north-west of Dartford, in Greater London. If you need sand mastic in Erith, please call 0345 464 0079 or drop us an email for a quick quote. We cover Greater London from our Crawley base. Erith is one of 764 places in Greater London we cover for sand mastic. London is on our list too, around 11 miles away.
Here we cover the DA8, DA17 and DA7 postcode area for sand mastic. Streets in the area include Church Road, Town Square and Erith High Street, all of which we cover. Other places close to Erith include Northumberland Heath (1 mile south), Bexley Riverside (1 mile south), Belvedere (1 mile north-west), Lessness Heath (1 mile north-west) and Barnehurst (1 mile south). Within a short drive, we also cover London (11 miles west), City of Westminster (14 miles west), Marylebone (14 miles west), St Pancras (13 miles west), Shoreditch (11 miles west) and Walthamstow (11 miles north-west).
Landmarks near Erith
In Erith, that means homes and buildings near Trinity School, The Cross Keys pub and Erith School, among other places. Erith has its own railway station: Erith station. Other landmarks nearby include Erith Museum (less than half a mile east) and Erith and District Hospital (less than half a mile south-west). Green spaces nearby include Crossness Nature Reserve.
How the job changes by surface
Period and listed homes
Many older homes were built with sand mastic round the windows. If your home is listed, ask your local planning authority about consent.
Sash and case windows
Most of our sand mastic work is on sash windows. We renew the mastic round each box.
What we do, step by step
On the day, we start by going over the job with you, so you know exactly what we are doing. We protect the surfaces around the joints before we start. Most jobs take a few hours per window, depending on the condition of the joints. In Erith, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- We check the window surrounds and agree which joints need renewing.
- We rake out the old mastic and clean the joint.
- Deep voids are packed so the mastic is the right thickness.
- The mastic is mixed, pressed into the joint by hand and shaped.
- The finish is dressed so it sits neatly against the stone or brick.
How to prepare
- Clear the area around the work
- Let us know about stairs, lifts or work at height
- Tell us if parking is tricky
Get 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 add pictures by email if you can.
Advice
How to look after the new joints
So the new joints stay in good condition:
- Inspect the joints round the windows every year or so
- Ask the planning authority about consent for listed or conservation-area homes
- Get any rot dealt with first
- Sort the mastic before the decorators arrive
Make sure water drains away from the window surround. Water sitting against the mastic shortens its life.
It’s best to renew mastic before painting the windows. Painting over failed mastic hides the problem for a while.
Nearby places to Erith
Also in Erith
Erith: your questions answered
Can parking be tricky for a visit in Erith?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. That way the visit can be planned around it.
Can you help a landlord with a rental near Erith station?
Yes, we work for landlords and agents. Just ring 0345 464 0079 or send us an email and tell us about the property, and we will give you a clear price.
Can old silicone round a sash window be swapped for sand mastic?
Usually, yes. Once the silicone is out and the joint prepared, sand mastic is applied by hand.
Is sand mastic better than silicone for my windows?
For period timber windows in stone or brick, sand mastic is often the better fit. On modern frames, we’d normally use a flexible sealant.
Can you work on commercial sites?
Yes. Hotels, offices and other businesses use us and we’re fully insured.
What’s sand mastic made of?
Sand plus a binder based on linseed oil. It’s built up in the joint by hand and shaped to suit the surround.
Do the sealants smell?
Some sealants have a smell while they cure, which fades as it sets. Opening a window helps.
Where are you based?
We’re based in Crawley, West Sussex, and we cover South East England, London and all of Scotland.