Greater London · England
External & façade joints in Blackwall, Greater London
Professional external mastic in and around Blackwall, with every bit of old sealant taken out first.
- Rain getting behind render or cladding at a joint
- Movement joints filled with mortar instead of sealant
- Brick movement joints where the sealant has split
What we do, step by step
The work is kept neat and contained to the area we’re working on, so you can get on with your day. Expect the work to take a few hours for a handful of joints, longer for a whole elevation. 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.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
How to prepare
- Let us know about earlier repairs to the joints
- Tell us if parking is tricky
- For business premises, tell us about site rules or sign-in
Getting a quote
For a quote, phone 0345 464 0079 or email us with the location and a short description of the problem. You will have a clear quote before we start.
Advice
External mastic in Blackwall, done properly
Low-level joints can usually be done from the ground. Where joints are higher up, tell us about the building when you get in touch and we’ll confirm what access is needed. If you have failed seals between different materials and old sealant gone brittle and cracked, we can put it right, whatever the surface.
Newer London blocks are built with movement joints in brick and render, and with cladding joints sealed with mastic. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall.
Your job is guaranteed for a year, as with all our work.
- Where
- Blackwall (E14, SE10, E16)
- Region
- Greater London
- Guarantee
- One year on every job
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
How to look after the new joints
Joint life depends on how it’s used and looked after. We suggest:
- Wash walls gently around the sealant
- Check the sealant is paintable before painting near it
- Keep movement joints as flexible joints, not mortar
- Keep soil, plants and ivy away from the joints
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They should be kept open and resealed, not filled.
Leave a failed movement joint and water keeps getting into the wall. That can lead to damp patches, staining and frost damage which cost more to put right than the joint.
Nearby places to Blackwall
More services for Blackwall
When to call us in Blackwall
Sunlight, wet weather and frost wear exterior sealant down. Over the years it hardens, cracks on the surface and loses its give, so the joint eventually tears or comes away from one side.
Most people get in touch after spotting something like this:
- Joints where the bead has come unstuck
- Hard, crazed mastic that has stopped moving
- Moss and dirt in joints with no sealant left
- Water getting into walls through failed joints
In the older streets around All Saints Church, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Comparing quotes
- Who does the work, and how experienced they are
- What insurance they hold
- How the joint is cleaned and prepared
- Whether the sealant suits the joint
Why it’s worth doing now in Blackwall
Resealing a run of joints in one go is usually better than patching one at a time. Joints of the same age tend to fail together. In London conversions, one flat’s bathroom is often above another flat’s ceiling, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble.
A failed joint rarely gets cheaper to fix by waiting, because water and mould keep working on it. If you are unsure, call 0345 464 0079 or email us for an honest opinion and a quote.
Why Blackwall clients choose us
- Old sealant always removed completely
- A 12-month guarantee on all work
- Sanitary silicone with an anti-fungal additive in wet areas
- ARBOMaster approved applicator
Take a look at our cost guide or customer reviews.
What affects the cost of external mastic
Jobs vary more than people expect. The main factors:
- The number and length of the joints
- Access and height
- Whether there’s mould to deal with
- How many rooms, windows or areas are involved
Instead of a standard rate, we price the job in front of us: the amount of work, the old material and the access. You’ll know the price before we begin.
What to tell us for a quote
You do not need to know the technical terms. It helps if you can tell us:
- Whether it’s a home or a business
- The rough size of the job
- Access, such as stairs, a lift or height
- The problem you’ve noticed
We do not publish a price list, as no two jobs are quite the same. Instead, we give you a clear quote for your job. To get started, call 0345 464 0079 or email us.
Different surfaces, different methods
Cladding and façade panels
Metal and composite panels move a lot with temperature, so the joints work hard every day. We choose the product to suit.
Brickwork movement joints
Brick walls have vertical movement joints to absorb expansion. We reseal them with a low-modulus sealant over backing rod in a colour to suit the brick.
Your questions about external mastic in Blackwall
Do you cover Blackwall for external mastic?
Yes. We work across London and the South East, and Blackwall is part of that. You can ring 0345 464 0079 or email us and tell us what needs doing.
Can you help a landlord with a rental near Canary Wharf station?
Yes, we work for landlords and agents. Just ring 0345 464 0079 or email us and tell us about the property, and we will give you a clear price.
Do you hold any approvals?
Yes. We’re approved under the ARBOMaster scheme, the approved applicator scheme for Arbo sealants.
Should I try DIY first?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
How do you reach high-level joints?
Each building is different. Tell us the height, the number of joints and what’s below them, and we will confirm what access is needed.
Can you do several jobs on one visit?
Yes. Just list everything you need.
Can new sealant go over the old?
No. New silicone won’t bond to old silicone, and it traps any mould or water underneath. It all has to come out first.
How much does external mastic cost in Blackwall?
Size, access and the old material all affect the cost. Call for a quick quote and we will talk you through it.
DIY versus a professional finish
If you’ve already had a go yourself, that is fine. We remove it and do the joint properly.
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.
Walls and rooflines in Blackwall
London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking. With historic houses such as Queen's House (about 1.7 miles south) nearby, there’s older building stock in the area around Blackwall as well as newer homes. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth.
Schools such as Woolmore Primary School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing. As a London address, Blackwall can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Blackwall is about 1 mile south-west of Canning Town, in Greater London. For external mastic in and around Blackwall, please phone 0345 464 0079 or email us for a quick quote. We cover Greater London from our Crawley base, Blackwall included. We cover 764 towns and villages across Greater London.
Postcode districts we cover here for external mastic: E14, SE10 and E16. External mastic is available to properties on Nutmeg Lane, Athol Square and Leamouth Road. Being close to the A102 and A1206, Blackwall is easy for our applicators to reach for external mastic. Neighbouring places we cover for external mastic include Coldharbour (1 mile south-west), Leamouth (1 mile north-east), Limmo Peninsula (1 mile north-east), Poplar (1 mile west) and London Docklands (1 mile west). Further out, we also cover London (4 miles west), City of Westminster (6 miles west), Marylebone (6 miles west), Kensington (9 miles west), St Pancras (5 miles west) and Shoreditch (3 miles north-west).
Local landmarks in Blackwall
We work in homes and buildings around The Gun pub, Tower Hamlets College and Bow Creek Ecology Park. The closest station to Blackwall is Canary Wharf station, about 0.6 miles west. Other landmarks nearby include Poplar Hospital (under half a mile north-west) and London Gas Museum (1.1 miles north). Not far away are Lavender Pond and Tower Hill.