Greater London · England
Brockley External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for Brockley, backed by a 12-month guarantee. Ask us for a quote.
- Moss and dirt in joints with no sealant left
- Failed sealant between panels on a façade
- Joints pointed up with cement by mistake
About our external mastic in Brockley
A movement joint is a deliberate break that lets a wall expand and contract. Its sealant has to flex with the building, season after season, and when it fails, the wall takes the strain and water finds a way in. We work on brickwork movement joints, render & cladding joints and concrete & block, and common reasons people get in touch are rigid filler in a joint that should flex and moss and dirt in joints with no sealant left.
Modern London flats rely on sealed movement joints and cladding joints. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall.
We guarantee the work for a year. If there’s a problem with our work within the year, let us know and we’ll sort it.
- Place
- Brockley (SE4, SE23, SE6)
- Wider area
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- A clear price before we start
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
How the visit works
Good joint work is mostly preparation, and we do not rush it. Joints are cleaned back and dried before anything new goes in. In total, it usually takes anything from a few hours to several days, depending on the building. In a London area like Brockley, the main things to plan are parking and access: let us know about parking, the floor we will be working on and any lift or shared entrance.
- We inspect the joints and agree which need resealing and how they’ll be reached.
- Old sealant and any debris are cut and raked out.
- We clean both faces of the joint and prime them where the product calls for it.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- We gun in a flexible exterior sealant in a colour that suits the wall and tool it neatly.
Preparing for the visit
- Let us know if you’ve seen damp or leaks
- Mention any sign-in or site rules at work premises
- Tell us about any previous sealing or DIY attempts
Getting a quote
Want a quote for external mastic? Please ring 0345 464 0079 or send us an email and tell us about the job. We’ll explain what we’d do and give you a clear price before work begins.
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Questions from Brockley
Do you work for landlords with property near Crofton Park station?
Yes, rental work is part of what we do. You can call 0345 464 0079 or email us with the address and a few details, and we’ll give you a fixed price before work begins.
Can parking be tricky for a visit in Brockley?
Parking in Brockley, as in most of London, takes a little planning: a visitor permit or a bay close to the door helps a lot.
Should I try DIY first?
Some simple jobs can be done by a careful DIYer. Most DIY failures come from sealing over old material, wet joints or too much sealant.
Is there any odour?
It depends on the product. Some smell for a while, some hardly at all, and any smell fades as they cure.
How long will you be here?
Typically it takes a few hours for a handful of joints, longer for a whole elevation. Larger jobs naturally take longer, and we will tell you how long to expect.
Can new sealant go over the old?
No, because it fails. We remove every bit of old sealant first.
Why do you put foam in the joint first?
We fit closed-cell backing rod wherever the joint depth needs controlling. It sets the sealant depth and prevents three-sided bonding.
How often do external joints need resealing?
There’s no fixed answer: sunny, exposed elevations and busy joints wear faster. Check them each year and reseal when they split or harden. Our work comes with a one-year guarantee.
Common problems we fix in Brockley
The wrong product in a moving joint is a classic cause. A high-modulus or general-purpose sealant can be too rigid for a busy joint, so it pulls away from the edges.
Most people get in touch when they notice one of these:
- Plants rooting in failed movement joints
- Cracked joints where brick meets render or frames
- Weathered mastic that no longer stretches
- Joints where the bead has come unstuck
Rented homes near Crofton Park station change hands often, and split movement joints are easy to miss on a rental until damp shows inside.
What your quote should include
- When the joint can take water or movement
- Are they insured?
- How hidden problems are handled
- What guarantee comes with the work
How we quote for external mastic
We do not publish a price list. What we look at:
- How easy the joints are to reach
- The type of sealant required
- The size of the job
- The old material and how stubborn it is
The cost reflects the work involved, not guesswork. That’s why we ask a few questions first.
Helping us quote
To make quoting easier, let us know:
- The problem you’ve noticed
- Pictures of the joints, sent by email
- Where the property is
- The rough size of the job
Every job is quoted individually. Simply ring 0345 464 0079 or email us and describe the job and send pictures if you have them.
Towns and villages near Brockley
More services for Brockley
DIY versus a professional finish
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
If you are 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.
Surface by surface
Render joints
Cracks along render joints let water in behind the coat. Resealing the joints early keeps water out and helps it last.
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. The movement joint takes that up, so the sealant in it must stay soft and stretchy.
Work for landlords, hotels and businesses
For anyone letting property in or around Brockley, several properties can be quoted together. Send us the addresses and the work at each.
Housing providers, facilities teams and property managers book us too. Several sites can go on one quote, and we are fully insured.
What external mastic looks like in Brockley
With historic houses such as Queen's House (about 2.4 miles north-east) nearby, there’s older building stock in the area around Brockley as well as newer homes. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth. London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking.
Managing a site like Beecroft Garden Primary? Then movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. Brockley is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Brockley is about 1 mile south of New Cross, in Greater London. For external mastic in and around Brockley, it’s easy to get a quote: please ring 0345 464 0079 or drop us an email. We cover Greater London from our Crawley base. 764 places in Greater London are on our list.
Postcode districts we cover here for external mastic: SE4, SE23 and SE6. We cover properties on Ivy Road, Nash Road and Lindal Road. Close by, we work in Crofton Park (1 mile south-east), Honor Oak (1 mile west), Ladywell (1 mile east), Forest Hill (1 mile south-west) and Nunhead (1 mile north-west). Further out, we also cover London (4 miles north-west), City of Westminster (7 miles north-west), Marylebone (7 miles north-west), Kensington (8 miles north-west), St Pancras (6 miles north-west) and Shoreditch (5 miles north).
Landmarks near Brockley
Around Brockley, our work takes us to homes and buildings near Blythe Hill Tavern, Allenby Tutorial Trust and Blythe Hill Fields, among other places. There’s a railway station in Brockley itself: Crofton Park station. Other landmarks nearby include Horniman Museum and Gardens (1.4 miles south-west) and University Hospital Lewisham (0.7 miles east). Green spaces nearby include One Tree Hill and Knight's Hill.
How to look after the new joints
Once the sealant has cured, a few habits help it last:
- Fix overflowing gutters above sealed joints
- Ask before painting over external sealant
- Show decorators and builders where the movement joints are
- Make sure movement joints aren’t pointed over
Keep pressure washers away from the sealant. High-pressure water can lift the edges and let water in behind.
Leave a failed movement joint and water keeps getting into the wall. Over time it can mean damp inside, stained render or frost-damaged brick.