Greater London · England
External Mastic in Welling
Specialist external mastic for Welling: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Rigid filler in a joint that should flex
- Panel joints letting water in
- Hard, crazed mastic that has stopped moving
When it is not the sealant
It helps to know what we can’t do too:
- Cracked brickwork or render that needs a builder or plasterer
- Loose or hollow render, which needs re-rendering
- Walls that need new movement joints cut into them
Not sure which it is? You can call 0345 464 0079 or send us an email and we’ll tell you honestly.
Where we work in Welling
- Concrete & block
- Brickwork movement joints
- Joints between brick and frames
- Render & cladding joints
- Copings & trims
- Façade panels
How we handle external mastic in Welling
A movement joint is only as good as its depth. Backing rod controls how deep the sealant goes and keeps it off the back of the joint, so it bonds to the two sides only and can stretch. Common call-outs are for movement joints with cracked, split or missing sealant and failed seals between different materials, on copings & trims, concrete & block and joints between brick and frames.
Modern London flats rely on sealed movement joints and cladding joints. Period houses have different weak points, such as gutter joints, trims and the line where an extension meets the old wall.
Whatever the size of the job, it’s backed by our 12-month guarantee.
- Where
- Welling (DA16, DA15, DA6)
- Wider area
- Greater London
- Guarantee
- One year on every job
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Nearby places to Welling
What else we do in Welling
What affects the cost of external mastic
Your quote is based on your job. We take into account:
- The number of rooms or windows
- The number and length of the joints
- Whether the work is at height
- When we can work, for business premises
Commercial jobs are quoted on the same basis as homes: how much there is to do, how we reach it and what it needs, plus any working-time requirements on site. Call for a quick quote and we will explain what it covers.
What we need to know
To make quoting easier, let us know:
- If it’s domestic, commercial or a hotel
- The rough size of the job
- The problem you’ve noticed
- Pictures of the joints, sent by email
For a quick quote, get us on the phone, or send an email if you’d rather. Describe what needs sealing and we’ll talk you through the work.
What we’re called out for in Welling
Joints sealed without backing rod, or far too deep, rarely last. If the sealant sticks to the back as well as the sides, it can’t stretch and tears as soon as the joint widens.
Most people get in touch after spotting one of these:
- Sealant pulling away from one side of the joint
- Gaps where render, brick and frames meet
- Water getting into walls through failed joints
- Leaking joints around cladding and façade panels
Schools such as Danson Primary School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
Before you book anyone
- What insurance they hold
- What preparation is included
- Whether they seal over old material or remove it
- When the joint can take water or movement
External mastic in Welling: local notes
Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Historic houses like Danson House (about 0.4 miles south-east) are a reminder that the area around Welling has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
Homes close to St John's Church include some older properties, and the joints between older walls, newer extensions and the roofline need a sealant that can move. As a London address, Welling can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Welling is about 9 miles east of London, in Greater London. Across the DA16 area, we can carry out external mastic at your property. 764 places in Greater London are on our list, from the larger towns to small villages. We also work in London, around 9 miles away.
Our applicators cover all of DA16, DA15 and DA6 for external mastic and the streets around it. If you need external mastic at a property on Days Lane, Hook Lane and Lyme Road or a nearby road, our applicators can take on the job. Being close to the A207, Welling is easy for our applicators to reach for external mastic. Neighbouring places we cover for external mastic include Crook Log (1 mile east), Blendon (1 mile south-east), Upton (1 mile east), Bexleyheath (1 mile east) and West Heath (1 mile north-east). Within a short drive, we also cover London (9 miles west), City of Westminster (12 miles west), Marylebone (12 miles west), Kensington (14 miles west), St Pancras (11 miles north-west) and Shoreditch (9 miles north-west).
What’s near Welling
In Welling, that means homes and buildings near Nags Head pub, Danson Park and Bexley Grammar School and the streets around them. For rail, the closest station is Welling station, roughly 0.5 miles north-west of the centre. Other landmarks nearby include Greenwich Castle (5 miles west) and Broadway Shopping Centre (1.6 miles east). Green spaces nearby include The Tarn and Summer Hill.
What the job involves on each surface
Brickwork movement joints
Clay brickwork grows slightly over its life and moves with the weather. That movement goes into the joint, so the sealant in it must stay soft and stretchy.
Joints between dissimilar materials
Each side of the joint may need its own preparation. Both surfaces are cleaned and primed as the product requires.
Can I do it myself?
Sealing over old silicone is the commonest DIY error. New silicone will not bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, and the work is guaranteed for a year.
How the visit works
You do not need to clear the whole room or building, just the space around the work. Everything nearby is protected, and the work takes anything from a few hours to several days, depending on the building for a typical job. In Welling, 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.
- Each joint is checked and the colour of the new sealant agreed.
- Failed sealant is removed back to clean, sound faces.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- We prime the faces where required.
- We gun in low-modulus sealant and tool it neatly.
Preparing for the visit
- Mention if the joints have been sealed before
- Plan for the work area to be out of bounds to pets and children
- Move anything stored near the joints
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 add pictures by email if you can.
Advice
For landlords and businesses
We work for letting agents and landlords as well as homeowners. Resealing between tenancies keeps a property looking cared for.
From a single let to a portfolio, the work is the same standard: the old material taken out, careful preparation and a 12-month guarantee.
Your questions about external mastic in Welling
I let a flat near Welling station. Can you help?
Yes, we work for landlords and letting agents. Just call 0345 464 0079 or email us and tell us about the property, and we’ll give you a clear price.
Do you cover Welling for external mastic?
Yes. We work across London and the South East, and Welling is part of that. You can ring 0345 464 0079 or send us an email and tell us what needs doing, and we’ll give you a clear quote.
Is there a guarantee?
Yes, always. There’s a 12-month guarantee on every job, wherever you are.
Where are you based?
We’re based in Crawley, and we work across South East England, London and Scotland.
What does external mastic cost?
The cost depends on the size of the job, access and how much old sealant has to come out. Call for a quick quote and we’ll talk you through it.
Do you use backing rod?
Backing rod goes into deeper joints as a matter of course. It sets the sealant depth and prevents three-sided bonding so the bead can stretch.
Do you do commercial work?
Yes. Hotels, offices and other businesses use us and we’re fully insured.
Can I do it myself?
Some simple jobs can be done by a careful DIYer. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.