Greater London · England
External & façade joints in Lewisham, Greater London
Movement joints in Lewisham need attention? We cut out the old, prepare the joints and apply the right sealant.
- Leaking joints around cladding and façade panels
- Old sealant gone brittle and cracked
- Moss and dirt in joints with no sealant left
Your questions about external mastic in Lewisham
Can parking be tricky for a visit in Lewisham?
Parking in Lewisham, as in most of London, takes a little planning: a visitor permit or a bay close to the door helps a lot.
Do you cover Lewisham for external mastic?
Yes, Lewisham is within the area we cover. We work across London and the South East. Just ring 0345 464 0079 or send us an email with a few details of the job.
What is a movement joint?
Walls move with heat, cold and moisture, so long walls have planned gaps to take that movement. It’s closed with backing rod and a flexible sealant.
Will there be a smell?
There can be a smell while the sealant cures, but it fades. Ventilation helps.
Do I have to be there?
We need access to the joints, so we’ll agree that with you when we book. Indoors, that generally means someone at home.
Should I try DIY first?
You can, for simple jobs. The key is preparation: remove all the old material and work on a clean, dry joint. We can always put it right if it fails.
How long does the job take?
A typical job takes a few hours for a handful of joints, longer for a whole elevation, including preparation and clearing up. We’ll confirm how long when we quote.
What colours does the sealant come in?
The aim is a neat, even joint in a colour that suits the wall. We will talk through colour options before any work starts, matched as closely as the range allows.
How we handle external mastic in Lewisham
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible sealant bridges the two where mortar or filler would crack. We are often asked to deal with sealant that has lost its bond to the brick or render and joints pointed up with cement by mistake, across joints between brick and frames, render & cladding joints and façade panels.
Outside work in London starts with access: side passages, upper floors and where to park. For a home in Lewisham, tell us how high the joints are and how to reach the back of the building.
The work is guaranteed for twelve months. If there’s a problem with our work within the year, let us know and we will sort it.
- Place
- Lewisham (SE13, SE8, SE6)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quote
- A clear price before work begins
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Lewisham buildings and the weather
With historic houses such as Queen's House (about 1.4 miles north) nearby, there’s older building stock in the area around Lewisham as well as newer homes. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material. London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you live in an older home near St Stephen's Church, older walls, gutters and the joints where extensions meet them need a flexible sealant. Lewisham is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Lewisham is about 3 miles west of Eltham, in Greater London. Homes, rented property, offices and hotels in Lewisham can book us for external mastic. The work is guaranteed for a year. Across Greater London, we cover 764 places, Lewisham among them.
Here we cover the SE13, SE8 and SE6 postcode area for external mastic. External mastic is available to properties on Station Road, Lewisham High Street and Lewis Grove. You’ll find Lewisham on the B220, which makes it straightforward to reach. Neighbouring places we cover for external mastic include Ladywell (1 mile south-west), St Johns (1 mile north-west), Hither Green (1 mile south-east), Blackheath (1 mile north-east) and Lee (1 mile south-east). We also work in nearby towns such as London (4 miles north-west), City of Westminster (7 miles north-west), Marylebone (7 miles north-west), Kensington (9 miles west), St Pancras (6 miles north-west) and Shoreditch (5 miles north-west).
Local landmarks in Lewisham
Locally, jobs take us to homes and businesses close to St Joseph's Academy, Ladywell Fields and The Watch House and the streets around them. Lewisham has its own railway station: Lewisham station. Nearby you will also find Greenwich Castle (1.2 miles north) and Fan Museum (1.2 miles north). Open spaces near Lewisham include Knight's Hill and Brookmill Road Local Nature Reserve.
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Fix overflowing gutters above sealed joints
- Check the sealant is paintable before painting near it
- Check external joints each spring
- Don’t let climbing plants root in the sealant
Look over the joints once a year, ideally after winter. Splits, gaps at the edges or plants in the joint are early warning signs.
A joint that has stopped moving pushes the movement elsewhere, usually as cracking in the brickwork or render nearby. Catch it early and you reduce the risk.
What affects the quote in Lewisham
For a quick quote, just ask. The main things that affect it are:
- Whether old sealant or filler has to be cut out
- When we can work, for business premises
- Which sealant suits the joint
- Any mould that needs treating
A failed joint rarely gets cheaper to fix by waiting. If you’re not sure whether it needs doing, phone 0345 464 0079 or email us for an honest opinion and a quote.
What we need to know
Photos by email are helpful but not essential. Please mention:
- Any previous sealing or DIY work
- What the problem is, such as mould, gaps, leaks or cracking
- The address or postcode of the job
- Photos by email, if that’s easy
For a quote, call 0345 464 0079 or send us an email with the location and a short description of the problem. We will send you a clear quote before any work starts.
Surface by surface
Copings and trims
Joints in copings, parapets and trims are exposed to the worst of the weather. Each is resealed with a weatherproof, flexible sealant.
Concrete and blockwork
Concrete faces can be dusty and porous, so cleaning and priming matter. We prime where the sealant needs it before sealing.
What we do, step by step
A visit follows a simple pattern: we look at the joints together, protect the area around them, carry out the job and clear up. Most jobs take a few hours to a few days, depending on the length of joint and the access. In a London area like Lewisham, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- We start by walking round the building and agreeing the joints and the access.
- We cut out the old mastic and rake out anything in the joint.
- Joint faces are cleaned back and primed if the sealant needs 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
- Let us know about stairs, lifts or work at height
- Tell us about any previous sealing or DIY attempts
- Mention any leaks or damp you’ve noticed
How to get a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and email photos if that is easy.
Advice
Why deal with it now?
The longer a joint stays open, the more water the wall takes in. Wet masonry is more easily damaged by frost near the open joint, so the damage spreads beyond the joint. In a London flat, a failed joint rarely stays your problem alone: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
There are no prices on our website, because the cost depends so much on the job itself. For a quick quote, please call 0345 464 0079 or email us and we will talk you through it.
Why choose Mr Mastic in Lewisham
- Anti-fungal silicone where joints get wet
- Over 20 years’ experience
- Homes, businesses and hotels
- Every job guaranteed for a year
Places near Lewisham
Other services in Lewisham
DIY versus a professional finish
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and the joint depth matters as much as the finish.
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it fails, we can still redo it.
What we’re called out for in Lewisham
Poor preparation causes many early failures: dusty or wet faces, no primer where one was needed, or old sealant left in. The sealant never bonds properly.
If you can see any of these, it’s time to have the joints looked at:
- Leaking joints around cladding and façade panels
- Failed seals between different materials
- Rain getting behind render or cladding at a joint
- Weathered mastic that no longer stretches
For landlords with property near Lewisham station, outside joints that have cracked can let damp into a rental, so check them between lets.
Questions to ask before booking
- The length of the guarantee
- Is VAT in the price?
- Which sealant they’ll use, and why
- Is the old sealant removed completely?