Greater London · England
New Cross External Mastic
Professional external mastic in and around New Cross, with every bit of old sealant taken out first and a 12-month guarantee.
- Cracked joints where brick meets render or frames
- Joints pointed up with cement by mistake
- Weeds or debris growing in open joints
How we handle external mastic in New Cross
External mastic is a job where short cuts show quickly. Overfilled joints, missing backing rod and sealant laid over old sealant all tend to fail early. We strip the joint back and start again. If you are dealing with weeds or debris growing in open joints and joints pointed up with cement by mistake, we can put it right, on façade panels, render & cladding joints and copings & trims alike.
London’s terraces and conversions often share walls, gutters and downpipes with their neighbours, so one failed joint can cause damp for more than one household. In a converted house in New Cross, it’s worth checking who is responsible for the outside before booking.
We guarantee the work for a year. If something is not right with it in that time, tell us and we’ll put it right.
- Location
- New Cross (SE8, SE14, SE4)
- Region
- Greater London
- Guarantee
- A year, on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Surface by surface
Cladding and façade panels
Metal and composite panels move a lot with temperature, so the joint sealant has to cope with frequent movement. The sealant is chosen with that in mind.
Render joints
Cracks along render joints let water in behind the coat. Resealing the joints early keeps water out and protects the render itself.
Other services in New Cross
DIY versus a professional finish
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
What we can’t put right
A few problems are outside what sealant work can do:
- Cracking across the wall rather than at a joint
- Subsidence or other structural problems
- Damp that isn’t coming from the joint
If you are not sure, just ring 0345 464 0079 or email us and we’ll give you a straight answer before you book.
Joints and surfaces we work on
- Concrete & block
- Brickwork movement joints
- Joints between brick and frames
- Copings & trims
- Façade panels
- Render & cladding joints
Do you need external mastic in New Cross?
Sometimes a movement joint was filled with mortar or a rigid filler. With the joint locked solid, the movement turns into cracks elsewhere in the wall.
Most people get in touch after spotting something like this:
- Old sealant gone brittle and cracked
- Movement joints with cracked, split or missing sealant
- Leaking joints around cladding and façade panels
- Joints where the bead has come unstuck
New Cross is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Before you book anyone
- Who does the work, and how experienced they are
- Which sealant they’ll use, and why
- Which colour the sealant will be
- What preparation is included
New Cross: your questions answered
Do you work for landlords with property near New Cross station?
Yes, we work for landlords and agents. You can phone 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before work begins.
Can parking be tricky for a visit in New Cross?
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.
Do you use backing rod?
We fit closed-cell backing rod wherever the joint depth needs controlling. It sets the sealant depth and prevents three-sided bonding so the bead can stretch.
Do the sealants smell?
Possibly a little. Any smell clears as the sealant cures, and ventilation helps.
What do you need from me for a quote?
Where the job is, what the problem is and roughly how big it is. If you can, email a few pictures.
Should I point up the gap in my brickwork?
No. Rigid materials cannot move with the wall and the joint fails. If it has already been filled, we can usually cut it out and reseal it.
Does someone need to be in?
It depends on the job. Inside work needs someone to give us access.
Can you reach joints on upper floors?
That depends on the building and the joints. We work on joints that can be reached safely. Tell us about the building and we’ll confirm what access is needed.
How the visit works
When we arrive, we start by going over the job with you. Surfaces next to the work are protected before work begins. Most jobs 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.
- Each joint is checked and the colour of the new sealant agreed.
- We take out the old sealant until the faces are sound.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- Mention any parking rules near the property
- Mention any sign-in or site rules at work premises
- Try not to wet indoor joints just before the visit
Get a quote
For a quote, ring 0345 464 0079 or send us an email with the location and a short description of the problem. You’ll have a clear quote before we start.
Related advice
Keeping the joints in good condition
So the new joints stay in good condition:
- Have failed joints looked at early
- Check the sealant is paintable before painting near it
- Never let anyone fill a movement joint with mortar
- Don’t let climbing plants root in the sealant
Have a quick look at the joints each spring. Splits, gaps at the edges or plants in the joint are early warning signs.
Once a joint cannot move, the wall finds another way, often as cracks near the joint. Catch it early and you reduce the risk.
What external mastic looks like in New Cross
With historic houses such as Queen's House (about 1.5 miles north-east) nearby, there’s older building stock in the area around New Cross as well as newer homes. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material. In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts.
In the older streets around St James's Church, the joints between older walls, newer extensions and the roofline need a sealant that can move. Schools such as Myatt Garden Primary School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
New Cross is about 3 miles south-east of London, in Greater London. Jobs in New Cross get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. New Cross is one of 764 places in Greater London where we work.
Here we cover the SE8, SE14 and SE4 postcode area for external mastic. If you need external mastic at a property on Ivy Road, Mona Road and Avon Road or anywhere close by, our applicators can take on the job. New Cross sits on or near the A2209 and A2210, which makes travel easy. We also cover the places around New Cross: St Johns (1 mile east), Telegraph Hill (1 mile south-west), Deptford (1 mile north-east), Nunhead (1 mile south-west) and Lewisham (1 mile south-east). We also work in nearby towns such as London (3 miles north-west), City of Westminster (6 miles north-west), Marylebone (6 miles north-west), Kensington (8 miles west), St Pancras (5 miles north-west) and Shoreditch (4 miles north-west).
Around New Cross
In New Cross, that means homes and buildings near Wickham Arms, Fordham Park and Addey and Stanhope School. Also close by are St. Paul's (0.7 miles north-east) and Laban Centre (0.9 miles north-east). New Cross has its own railway station: New Cross station. Nearby you will also find Fan Museum (1.2 miles north-east) and Greenwich Castle (1.5 miles east). For a walk, there’s St. James's Park Lake and Tower Hill.
What affects the quote in New Cross
We don’t publish a price list, because no two jobs are the same. The quote depends on:
- The product the joint needs
- Working hours on commercial sites
- How much old sealant there is and how hard it is to remove
- How many rooms, windows or areas are involved
We do not show prices on the website, because each job is priced on what it involves. For a quick quote, please call 0345 464 0079 or drop us an email and we’ll talk you through it.
Asking for a quote
When you contact us, it’s useful to know:
- Any access issues, like height or stairs
- Whether it has been sealed before
- A few pictures by email, if you can
- The type of property
For external mastic in New Cross, ring 0345 464 0079 or email us. Tell us what the problem is and where, and you’ll get a clear quote before any work starts.