Greater London · England
External & façade joints in St Johns, Greater London
Problem with your movement joints in St Johns? We remove the old material, prepare the joints and seal them properly, with a one-year guarantee.
- Weathered mastic that no longer stretches
- Gaps where render, brick and frames meet
- Brick movement joints where the sealant has split
How we quote for external mastic
Your quote is based on your job. We take into account:
- Whether the work is at height
- How many areas need sealing
- Mould in or behind the old joints
- The product the joint needs
The cost reflects the work involved, not a rough estimate. That is why we ask a few questions first.
What we need to know
Photos by email are helpful but not essential. Please mention:
- The rough size of the job
- The address or postcode of the job
- Pictures of the joints, sent by email
- If someone has resealed it before
Getting a quote is simple: tell us what needs doing and where and its rough size. A few pictures by email make the job easier to understand, and we’ll take it from there.
How we handle external mastic in St Johns
A movement joint is only as good as its depth. Closed-cell backing rod sets the depth and stops the sealant sticking to the back, so it bonds to the two sides only and can stretch. If you’re dealing with sealant pulling away from one side of the joint and plants rooting in failed movement joints, we can put it right.
In London terraces and converted houses, gutters and walls are often shared with the house next door, so one failed joint can cause damp for more than one household. For a flat in St Johns, check the lease for who looks after the outside.
You are covered for a year from the day we finish. If anything isn’t right with it, call 0345 464 0079 or email us.
- Location
- St Johns (SE13, SE10, SE8)
- Region
- Greater London
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
FAQs for St Johns
Do you work for landlords with property near St Johns station?
Yes. We work for landlords and agents as well as homeowners. You can call 0345 464 0079 or drop us an email with the details for a clear quote.
Is parking a problem for a job in St Johns?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. The visit is then planned around what’s available.
How long does external mastic last?
It varies from wall to wall: sunny, exposed elevations and busy joints wear faster. A yearly look will tell you when they need doing. Every job carries our 12-month guarantee.
Why is there a gap in my brick wall?
Most straight vertical gaps in brickwork are movement joints. It gives the wall room to move and needs a flexible seal, not mortar.
Can you work on commercial sites?
Yes. Hotels, offices and other businesses use us and we’re fully insured.
Is it worth trying it myself?
That depends on the joint. Work at height, movement joints, fire-rated gaps and large areas are best left to a professional, while a short indoor joint may be within reach.
Which products do you use?
We choose the sealant for the joint, not the other way round. Movement, water and weather all affect the choice, and we’ll explain our choice.
Is there a guarantee?
Yes, for a year. If there’s a problem with our work in that time, tell us and we’ll put it right.
What we do, step by step
Once we are on site, we check the joints match what you told us. If we find something unexpected, we talk it through with you first. After that, the work takes 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.
- We cut out the old mastic and rake out anything in the joint.
- 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.
Preparing for the visit
- Mention any tricky access
- Try not to wet indoor joints just before the visit
- Tell us about any previous sealing or DIY attempts
How to get a quote
For a quote, phone 0345 464 0079 or send us an email with the location and a short description of the problem. We’ll give you a clear quote before any work starts.
Related advice
Why it’s worth doing now in St Johns
It often makes sense to reseal all the failing joints on an elevation together. They’ve weathered the same way, and access only has to be arranged once. Converted houses in London often have a bathroom above someone else’s living room, 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.
Every job is a little different, so each one gets its own quote. Size, access and the product the joint needs all make a difference.
What you get with us
- Colour agreed with you before we start
- A sealant colour to suit the surroundings
- Neat joints and a tidy finish
- Over 20 years’ experience
Surface by surface
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. That movement goes into the joint, so its sealant has to stay flexible.
Joints between dissimilar materials
Different materials may need different primers. Both surfaces are cleaned and primed as the product requires.
Landlords, agents and businesses in St Johns
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
From a single let to a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a one-year guarantee.
What sealant work cannot fix
Sealant is not the answer to every problem, and we will tell you before we start. Sealant won’t put right:
- Cutting new joints into brickwork, which is building work rather than sealant work
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Structural movement, which needs a surveyor or engineer
If you’re not sure, just ring 0345 464 0079 or email us and we’ll give you a straight answer.
Joints and surfaces we work on
- Copings & trims
- Concrete & block
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
- Façade panels
Other services in St Johns
Can I do it myself?
If you’re set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it does not work out, we can still put it right.
Sealing over old silicone is the commonest DIY error. New silicone will not bond to old, so it lifts and traps water and mould underneath. Everything old must be removed first.
External mastic in St Johns: local notes
Historic houses like Queen's House (about 1.1 miles north-east) are a reminder that the area around St Johns has older buildings as well as new. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth. London and the South East are among the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
As a London address, St Johns can be tricky for parking: let us know about parking bays, permits or a driveway. Letting a property close to St Johns station? Then outside joints that have cracked can let damp into a rental, so check them between lets. Homes close to Church of St John include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant.
St Johns is about 4 miles south-east of London, in Greater London. Wherever you are in the SE13 postcode area, our applicators can take on external mastic. St Johns is one of 764 towns and villages in Greater London we cover for external mastic.
Jobs for external mastic in SE13, SE10 and SE8 works the same way as everywhere else we cover. That includes homes and businesses on Avon Road, Mill Lane and Clare Road and the roads around them. St Johns is on the A2210 and A2211, which makes it straightforward to reach with everything needed for external mastic. Other places close to St Johns include New Cross (1 mile west), Deptford (1 mile north), Lewisham (1 mile south-east), Telegraph Hill (1 mile west) and Ladywell (1 mile south). We also work in nearby towns such as London (4 miles north-west), City of Westminster (6 miles north-west), Marylebone (6 miles north-west), Kensington (8 miles west), St Pancras (6 miles north-west) and Shoreditch (5 miles north-west).
Around St Johns
Around St Johns, our work takes us to homes and buildings near Wickham Arms, Brookmill Park and Addey and Stanhope School, among other places. Nearby too are St. Paul's (0.7 miles north) and Laban Centre (0.8 miles north). There’s a railway station in St Johns itself: St Johns station. A little further out are Fan Museum (0.9 miles north-east) and Lewisham Shopping Centre (0.7 miles south-east). Not far away are Brookmill Road Local Nature Reserve and Tower Hill.