Greater London · England
External & façade joints in Longlands, Greater London
Problem with your movement joints in Longlands? We cut out the old, prepare the joints and apply the right sealant, and the work is guaranteed for a year.
- Gaps where render, brick and frames meet
- Panel joints letting water in
- Hard, crazed mastic that has stopped moving
How we handle external mastic in Longlands
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible exterior sealant takes up that movement. If you have water getting into walls through failed joints and gaps where render, brick and frames meet, we can put it right, on render & cladding joints, façade panels and brickwork movement joints alike.
Outside work in London starts with access: side passages, upper floors and where to park. For a home in Longlands, tell us how high the joints are and how to reach the back of the building.
The work is guaranteed for twelve months. If something is not right with it in that time, tell us and we will put it right.
- Where
- Longlands (DA15, DA14, SE9)
- Region
- Greater London
- Cover
- One year on every job
- Quote
- A clear price before work begins
- Call
- 0345 464 0079
- Updated
- 26 October 2026
What we cannot put right
Before booking, it’s worth knowing the limits too:
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Movement that’s more than a sealant joint can take
- Render that is blown, hollow or coming away
If you are not sure, just call 0345 464 0079 or send us an email and we will give you a straight answer before booking.
Where we work in Longlands
- Joints between brick and frames
- Façade panels
- Concrete & block
- Render & cladding joints
- Brickwork movement joints
- Copings & trims
Also near Longlands
Other services in Longlands
The process
The work is kept neat and contained to the joints we are treating. Expect the work to take a few hours to a few days, depending on the length of joint and the access. In Longlands, flats, stairs and shared entrances are part of the routine. Mention any building rules, key holders or managing agents when you book.
- First we look over the joints with you, agree which to renew and talk through access.
- The old mastic and anything lodged in the joint is removed.
- We clean both faces of the joint and prime them where the product calls for it.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
Getting ready for the visit
- On commercial sites, let us know about site rules
- Where the joints are inside, avoid wetting them before we arrive
- Mention any parking rules near the property
Ask for a quote
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is. Whenever you are ready, ring 0345 464 0079 or send us an email.
Read more
Longlands buildings and the weather
Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking.
If you live in an older home near Christ Church, old and new materials meet at the roofline and walls, which is where sealant earns its keep. Rented homes near New Eltham station change hands often, and failed wall and movement joints let damp in, so they’re worth checking between tenancies. If you look after a building such as Longlands Primary School, larger buildings have long runs of movement joint that eventually need resealing.
Longlands is about 1 mile west of Sidcup, in Greater London. We provide external mastic to homes and businesses in Longlands and nearby. We cover 764 towns and villages across Greater London. You can also see our page for London, roughly 9 miles from Longlands.
Our applicators cover all of the DA15, DA14 and SE9 postcode area for external mastic and the streets around it. We cover properties on Main Road, Alder Road and Sidcup Road. Longlands sits on or near the A211, which makes travel easy. Neighbouring places we cover for external mastic include Foxbury (1 mile south), New Eltham (1 mile north-west), Chislehurst (1 mile south-west), Coldharbour (1 mile west) and Blackfen (1 mile north). Larger places within reach include London (9 miles north-west), City of Westminster (12 miles north-west), Marylebone (12 miles north-west), Kensington (13 miles west), St Pancras (11 miles north-west) and Shoreditch (10 miles north-west).
What’s near Longlands
We work in homes and buildings around Waring Park, Chislehurst School for Girls and Ye Olde Black Horse Inn. Longlands’s nearest station is New Eltham station, about 0.8 miles north-west of the centre. A little further out are Queen Mary's Hospital (1 mile south-east) and Greenwich Castle (5 miles north-west). Not far away are Summer Hill and The Tarn.
How the job changes by surface
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. Their movement joints are sealed over backing rod with a flexible sealant.
Copings and trims
Metal and stone copings both move with temperature, so a flexible sealant suits them best.
Landlord and commercial work in Longlands
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Keeping joints in good order is simple maintenance.
Failed sealant is one of the commonest items on a check-out report, and it’s quick to put right between tenancies. Several properties can go on one quote.
What happens if it’s left?
An open joint keeps letting water into the wall with every downpour. Wet masonry is more easily damaged by frost near the open joint, so the damage spreads beyond the joint. In a flat in Longlands, failed sealant seldom stays inside your own four walls: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
What it costs depends on the size of the job, how hard the old material is to remove and how easy the joints are to reach. We give a clear quote before work begins.
Why book with us
- Any old sealant cut out fully, not covered over
- You choose the colour before work begins
- Anti-fungal sanitary silicone in wet areas
- 12-month guarantee on every job
Read our cost guide and customer reviews.
DIY sealant or a professional job?
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly, so tell us about it when you ask for a quote.
The difference is mostly in the preparation and the product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions, then guaranteed for a year.
Looking after it afterwards
After the cure time, these simple habits help:
- Make sure movement joints are not pointed over
- Ask before painting over external sealant
- Point out the joints to other trades
- Wash walls gently around the sealant
Don’t let soil, plants or ivy build up against the new joints. Anything that holds water against the joint wears it out sooner.
Gaps, plants or missing sealant in a joint are worth getting looked at. Early work is quicker and leaves a better finish.
Your questions about external mastic in Longlands
Can you do external mastic in Longlands?
Yes, Longlands is within the area we cover. We work across London and the South East. You can phone 0345 464 0079 or drop us an email and tell us what needs doing, and we will give you a clear quote.
Is parking a problem for a job in Longlands?
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 do commercial work?
Yes. Hotels, offices and other businesses use us and we are fully insured.
Can you quote for more than one area?
Yes. Tell us about everything you’d like done and we’ll quote it together.
Which products do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. We use products from Arbo and Everbuild.
Are you ARBOMaster approved?
Yes. We are ARBOMaster approved, the scheme for applicators of Arbo sealants.
Do you guarantee your work?
Yes. All our work carries our 12-month guarantee.
Are you insured?
Yes. We’re fully insured for domestic and commercial work.