Greater London · England
External Mastic in Downe
Sealing brickwork movement joints, render, cladding and façade joints for Downe, backed by a 12-month guarantee. Call for a quick quote.
- Failed seals between different materials
- Weathered mastic that no longer stretches
- Leaking joints around cladding and façade panels
About our external mastic in Downe
Ground-floor and low-level joints are straightforward to reach. For joints higher up, give us some details of the building and we’ll confirm what’s needed to reach them safely. We’re often asked to deal with old sealant gone brittle and cracked and joints with sealant missing in places, across brickwork movement joints, concrete & block and copings & trims.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. For a home in Downe, tell us how high the joints are and how to reach the back of the building.
Every job comes with our 12-month guarantee.
- Where
- Downe (BR6)
- Region
- Greater London
- Guarantee
- One year on every job
- Quote
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What happens if it’s left?
Water gets in through a failed movement joint and can run behind render or cladding. Resealing early keeps the job to the joint itself, instead of the wall and finishes around it. In a London flat, a failed joint rarely stays your problem alone: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
Every job is a little different, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all make a difference.
Why book with us
- 20+ years of sealant experience
- White, clear, grey or another colour, product permitting
- A sealant colour to suit the surroundings
- Anti-fungal sanitary silicone in wet areas
See our cost guide and customer reviews.
How the job changes by surface
Render joints
Render is weaker at the surface than brick, so a sealant that stretches easily protects the edges. Priming is done where the sealant calls for it.
Copings and trims
Copings expand and contract through the day, so a flexible sealant suits them best year round.
How the visit works
On the day, there’s very little for you to do. Show us the job and we’ll take it from there. The job generally takes anything from a few hours to several days, depending on the building. In Downe, flats, stairs and shared entrances are part of the routine. If the building has a concierge, managing agent or access rules, tell us when you book.
- First we look over the joints with you, agree which to renew and talk through access.
- We cut out the failed sealant and rake out any dirt or growth.
- 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.
- We gun in a flexible exterior sealant in a colour that suits the wall and tool it neatly.
Before we arrive
- For business premises, tell us about site rules or sign-in
- Let us know about earlier repairs to the joints
- Tell us about any water getting in
Get a quote
Every job is quoted individually. Simply call 0345 464 0079 or drop us an email and describe the job.
Read more
How we quote for external mastic
We quote each job individually. This is what makes a difference:
- The type of sealant required
- When we can work, for business premises
- The size of the job
- Mould in or behind the old joints
Instead of a standard rate, we price the job in front of us: how many joints, what’s in them now and how we reach them. The price is agreed before we begin.
Helping us quote
You don’t need to know the technical terms. It helps if you can tell us:
- If it’s domestic, commercial or a hotel
- Any previous sealing or DIY work
- Roughly how big the job is
- The problem you’ve noticed
It all starts with a short chat. Describe the problem, the location and the size of the job, and we’ll explain how we’d tackle it. Whenever you’re ready, ring 0345 464 0079 or drop us an email.
What we are called out for in Downe
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.
If you can see any of these, it’s time to have the joints looked at:
- Cracked joints where brick meets render or frames
- Brick movement joints where the sealant has split
- Leaking joints around cladding and façade panels
- Moss and dirt in joints with no sealant left
If you look after a building such as Downe Primary School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Before booking anyone
- Are they insured?
- Whether all the old sealant comes out first
- Whether VAT is included
- The length of the guarantee
Towns and villages near Downe
Also in Downe
Downe questions
Is Downe in your area for external mastic?
Yes. We work across London and the South East, and Downe is part of that. Just phone 0345 464 0079 or send us an email with a few details of the job.
Is parking a problem for a job in Downe?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
Why is there a gap in my brick wall?
It’s a deliberate gap that lets the wall expand and contract without cracking. It should be filled with flexible sealant, never mortar.
What is backing rod for?
The foam is closed-cell backing rod. It keeps the sealant at the right depth and bonded to the sides only, which would stop it stretching.
Do you do commercial work?
Yes. Hotels, offices and other businesses use us and we are fully insured.
How long does external mastic take?
Most jobs take anything from a few hours to several days, depending on the building. Your quote will say how long we expect yours to take.
When is the sealant fully cured?
That depends on the sealant used, so please follow the time we give you when we finish.
Can you seal over the old sealant?
No. New silicone will not bond to old silicone, and it traps any mould or water underneath. We remove it all first.
Should I try it myself first?
A careful DIYer can reseal a simple joint, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
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.
What external mastic looks like in Downe
The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. With historic houses such as Down House (about 0.6 miles south) nearby, there’s older building stock in the area around Downe as well as newer homes. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth.
Downe is in London, so parking needs planning: let us know about parking bays, permits or a driveway. Letting a property close to Chelsfield station? Then outside joints that have cracked can let damp into a rental, so check them between lets.
Downe is about 4 miles south-west of Orpington, in Greater London. Our applicators cover external mastic for homes and businesses in Downe and nearby. Downe is one of 764 places in Greater London where we work for external mastic. Our London page covers work nearby (13 miles or so).
Our applicators cover all of the BR6 postcode area for external mastic and the streets around it. You’ll find streets such as High Street, North End Lane and Belle Vue Road, and we cover them all. Close by, we work in Farthing Street (1 mile north-west), Hazelwood (1 mile east), Luxted (1 mile south), Leaves Green (1 mile west) and Single Street (2 miles south). Further out, we also cover London (13 miles north-west), City of Westminster (15 miles north-west), Marylebone (15 miles north-west), St Pancras (15 miles north-west), Shoreditch (14 miles north-west) and Hoxton (15 miles north-west).
Around Downe
In Downe, that means homes and buildings near The Queens Head pub, Charles Darwin School and South Park. The nearest railway station is Chelsfield station, about 2.6 miles north-east of the centre. A little further out are Crofton Roman Villa (2.7 miles north-east) and Princess Royal University Hospital (1.8 miles north). Open spaces near Downe include Downe Bank Nature Reserve and Betsom's Hill.
Landlords, agents and businesses in Downe
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.
If you manage several properties in or around Downe, several properties can be quoted together. Just tell us the addresses and what each one needs, and pictures by email help.