Greater London · England
External Mastic in Forestdale
Sealing brickwork movement joints, render, cladding and façade joints for Forestdale, backed by a one-year guarantee. Ask us for a quote.
- Sealant that has lost its bond to the brick or render
- Joints pointed up with cement by mistake
- Gaps where render, brick and frames meet
Quotes for external mastic in Forestdale
For a quick quote, just ask. The main things that affect it are:
- The number of rooms or windows
- The size of the job
- Working hours on commercial sites
- The type of sealant required
There are no prices on our website, because the cost depends so much on the job itself. Call for a quick quote and we will talk you through it.
Asking for a quote
Photos by email are helpful but not essential. Try to tell us:
- Any access issues, like height or stairs
- The rough size of the job
- If it’s domestic, commercial or a hotel
- Pictures of the joints, sent by email
For a quick quote, get us on the phone, or email us if that is easier. Describe what needs sealing and we’ll explain what’s involved and give you a clear price.
External mastic in Forestdale, done properly
A movement joint is a deliberate break that lets a wall expand and contract. The sealant in it has to stretch and squeeze for years, so once it splits or hardens, the joint stops working and water gets in. Common call-outs are for weathered mastic that no longer stretches and movement joints with cracked, split or missing sealant, across copings & trims, façade panels and joints between brick and frames.
Outside work in London starts with access: side passages, upper floors and where to park. In Forestdale, joints up high may need ladders or other access, which is worth talking through when you book.
All of our work is guaranteed for twelve months, in Forestdale and everywhere else we cover.
- Where
- Forestdale (CR0, CR2)
- Wider area
- Greater London
- Cover
- One year on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
How the job changes by surface
Brickwork movement joints
Brick walls have vertical movement joints to absorb expansion. They’re resealed over backing rod with a low-modulus sealant.
Concrete and blockwork
Blockwork and concrete shrink over time and move with the seasons. Their movement joints are sealed over backing rod with a flexible sealant.
Why act early in Forestdale
Water gets in through a failed movement joint, behind render and cladding. Resealing early keeps the job to the joint itself, rather than the wall around it. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble.
Instead of a standard rate, we look at what your job involves: how many joints, what’s in them now and how we reach them. You will know the price before we begin.
Why choose Mr Mastic in Forestdale
- ARBOMaster approved applicator
- We agree the colour with you first
- Rated 4.9 stars on Google
- Over 20 years’ experience
See what affects the cost and what customers say.
What happens on the day
At the end, we look at the finished work together and tell you how long to leave it. The visit itself normally takes a few hours to a few days, depending on the length of joint and the access, depending on the size of the job. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Forestdale. It helps if you can point us to a visitor permit or a bay close to the door.
- First, the joints are inspected and the access agreed.
- 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.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
Preparing for the visit
- For indoor joints, keep the area dry beforehand if you can
- Clear items away from the joints we’re working on
- Keep children and pets away from the work area
Ask for a quote
To get a quote, ring 0345 464 0079 or send us an email and tell us where the job is and what the problem looks like. You will have a clear quote before any work starts.
Read more
When to call us in Forestdale
The wrong product in a moving joint is a classic cause. A stiff, general-purpose sealant can’t cope with a joint that moves a lot, so it pulls away from the edges.
The most common problems we see are:
- Panel joints letting water in
- Sealant pulling away from one side of the joint
- Old sealant gone brittle and cracked
- Joints pointed up with cement by mistake
Forestdale is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Before you book anyone
- How the joint is cleaned and prepared
- When the joint can take water or movement
- How hidden problems are handled
- Who turns up on the day
External mastic in Forestdale: local notes
In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking. Rainfall in the South East is lower than in much 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 Francis, the joints between older walls, newer extensions and the roofline need a sealant that can move. If you let a flat or house near Sanderstead station, outside joints that have cracked can let damp into a rental, so check them between lets.
Forestdale is about 3 miles south-east of Croydon, in Greater London. Wherever you are in the CR0 postcode area, we cover external mastic for homes and businesses. We cover 764 towns and villages across Greater London, from the larger towns to small villages. London is on our list too, about 11 miles from Forestdale.
Our applicators cover all of CR0 and CR2 for external mastic. That includes homes and businesses on Courtwood Lane, Goldfinch Road and Bardolph Avenue and the roads around them. We also cover the places around Forestdale: Selsdon (1 mile west), New Addington (1 mile east), Addington (1 mile north), Farleigh (1 mile south) and Fickleshole (2 miles south-east). We also work in nearby towns such as London (11 miles north), City of Westminster (13 miles north-west), Marylebone (13 miles north), Kensington (13 miles north-west), St Pancras (13 miles north) and Shoreditch (13 miles north).
Around Forestdale
Around Forestdale, our work takes us to homes and buildings near John Ruskin College and Addington Park, among other places. Forestdale’s nearest station is Sanderstead station, about 2.4 miles west of the centre. A little further out are Warlingham Park Hospital (1.9 miles south) and Croydon Airport Visitor Centre (3.5 miles west). Not far away are Nore Hill and Hutchinson's Bank.
Nearby places to Forestdale
Also in Forestdale
How to look after the new joints
Good habits help new joints last longer. A few tips:
- Act on the first splits you see
- Point out the joints to other trades
- Make sure movement joints are not pointed over
- Keep water from gutters off the wall
Don’t paint over the new sealant unless we have said the product is paintable. Many exterior sealants aren’t designed to be painted.
Leaks behind façade panels and render often go unseen. By the time there’s a damp patch, the damage can be well established.
FAQs for Forestdale
Is parking an issue for external mastic in Forestdale?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
I let a flat near Sanderstead station. Can you help?
Yes, we work for landlords and agents. You can call 0345 464 0079 or send us an email with the address and a few details, and we will give you a fixed price before any work starts.
What do you put in the joint?
Quality sealants from brands including Arbo and Everbuild, picked for each joint. We explain the product when we quote.
Is it messy?
Not at all. The area is protected while we work and cleaned up afterwards.
What’s an expansion joint in brickwork?
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.
Can I add another job to the visit?
Yes. Several rooms, windows or areas can go on one quote.
Do you come to Forestdale?
Yes, we do. Our applicators work in Forestdale, and the service is the same as everywhere else.
Where are you based?
Our base is in Crawley, and we cover South East England, London and all of Scotland.
What we cannot put right
Sealant isn’t the answer to every problem, and we’d rather say so up front. It will not solve:
- Cracks in the bricks or render themselves, away from the joints
- Adding movement joints to masonry that has none
- Rising or penetrating damp from elsewhere in the wall
Not sure which it is? You can ring 0345 464 0079 or send us an email and we will tell you honestly before you book.
What we seal
- Copings & trims
- Joints between brick and frames
- Render & cladding joints
- Concrete & block
- Façade panels
- Brickwork movement joints