Greater London · England
Erith External Mastic
Professional external mastic in and around Erith, with old sealant always removed completely.
- Hard, crazed mastic that has stopped moving
- Joints with sealant missing in places
- Water getting into walls through failed joints
External mastic in Erith, done properly
External mastic is a job where short cuts show quickly. Overfilled joints, missing backing rod and sealant laid over old sealant rarely last long. We strip the joint back and start again. We’re often asked to deal with joints where the bead has come unstuck and joints with sealant missing in places, across concrete & block, joints between brick and frames and render & cladding joints.
Outside work in London starts with access: side passages, upper floors and where to park. In Erith, joints up high may need ladders or other access, which is worth talking through when you book.
Whatever the size of the job, you get the same one-year guarantee.
- Place
- Erith (DA8, DA17, DA7)
- Region
- Greater London
- Guarantee
- One year on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
What affects the quote in Erith
The price is agreed before any work begins. It takes into account:
- The number of rooms or windows
- Any working-time requirements on site
- How much old sealant there is and how hard it is to remove
- Whether the work is at height
Commercial jobs are quoted on the same basis as homes: how much there is to do, how we reach it and what it needs, along with when we can work on site. Call for a quick quote and we will explain what it covers.
What we need to know
What to tell us when you ask for a quote:
- Whether it has been sealed before
- Whether it’s a home or a business
- Where the job is, and your postcode
- Roughly how big the job is
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To arrange one, phone 0345 464 0079 or email us.
Outside joints around Erith
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. 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 brick and stone need a sealant that suits them, at the right joint depth.
Erith is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. If you let a flat or house near Erith station, outside joints that have cracked can let damp into a rental, so check them between lets. If you look after a building such as Christ Church (Erith) CofE Primary School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Erith is about 3 miles north-west of Dartford, in Greater London. If you need external mastic in Erith, it’s easy to get a quote: please phone 0345 464 0079 or drop us an email. We’re based in Crawley and cover Greater London. Across Greater London, we cover 764 places, Erith among them. London is on our list too, around 11 miles away.
Work in DA8, DA17 and DA7 works the same way as everywhere else we cover. Whether your property is on Church Road, Town Square and Erith High Street or a nearby road, we can help. If you’re just outside Erith, we cover 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). Larger places within reach include 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).
What’s near Erith
We work in homes and buildings around Trinity School, The Cross Keys pub and Erith School. There’s a railway station in Erith itself: Erith station. Other landmarks nearby include Erith Museum (under half a mile east) and Erith and District Hospital (less than half a mile south-west). The countryside around Erith includes Crossness Nature Reserve.
Why it’s worth doing now in Erith
Resealing a run of joints in one go is normally better than patching one at a time. Joints of the same age tend to fail together. In a flat in Erith, failed sealant seldom stays inside your own four walls: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
Leaving a failed joint generally makes the job bigger, not smaller, as water and mould keep getting in. If you are not sure whether it needs doing, call 0345 464 0079 or send us an email and we’ll give you an honest view and a quote.
What you get with us
- Sanitary silicone with an anti-fungal additive in wet areas
- Homes, businesses and hotels
- A sealant colour to suit the surroundings
- We agree the colour with you first
See what affects the cost and customer reviews.
Questions from Erith
Is Erith in your area for external mastic?
Yes. We work across London and the South East, and Erith is part of that. You can ring 0345 464 0079 or send us an email and let us know what needs doing.
I let a flat near Erith station. Can you help?
Yes. We work for letting agents and landlords as well as householders. You can call 0345 464 0079 or send us an email with the details for a clear quote.
Do you work at height?
That depends on how high the joints are and the ground below. Ground-floor joints are simple; for higher work, tell us about the building and we’ll confirm what’s needed.
Will it make a mess?
Tidy work is part of the job. Nearby surfaces are protected, and the area is left clean when we finish.
What colours does the sealant come in?
The sealant colour is picked to suit the wall so the joint blends in. Exterior sealants come in a good range of colours.
Can you do several jobs on one visit?
Yes. Tell us about everything you’d like done and you will get one quote.
What’s an expansion joint in brickwork?
Brickwork, render and cladding all move a little, and planned joints take up that movement. The gap is sealed with a flexible sealant over backing rod.
Can you seal over the old sealant?
No. New silicone will not bond to old silicone, and it traps any mould or water underneath. It all has to come out first.
For landlords and businesses
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements.
Whether it’s one flat or a portfolio, the work is the same standard: old sealant fully removed, joints prepared properly and a one-year guarantee.
How to look after the new joints
Good habits help new joints last longer. A few tips:
- Wash walls gently around the sealant
- Have failed joints looked at early
- Look over the joints every year, ideally after winter
- Ask before painting over external sealant
Avoid pressure-washing straight into the joints. A strong jet can damage the edges of the bead and let water in behind.
Small splits are the time to act. Then it’s a straightforward cut-out and reseal before water has had years to get in.
Places near Erith
Also in Erith
Different surfaces, different methods
Render joints
Water behind render can lead to blown patches. A sound joint keeps the render dry behind and helps it last.
Concrete and blockwork
Big joints in concrete need careful depth control. We size the backing rod to the gap.
What happens on the day
Before we leave, we go over the finished joints with you. The visit itself generally takes a few hours for a handful of joints, longer for a whole elevation, depending on the size of the job. 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 start by walking round the building and agreeing the joints and the access.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
Getting ready for the visit
- Keep children and pets away from the work area
- Mention if the joints have been sealed before
- Mention any parking rules near the property
Getting a quote
To get a quote, call 0345 464 0079 or drop us an email and tell us where the job is and what the problem looks like. You’ll have a clear quote before any work starts.
Related advice
DIY versus a professional finish
If you do try it yourself, take your time over the preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it doesn’t work out, we can still put it right.
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.