Surrey · England
External Mastic in Downside
Professional external mastic in and around Downside, with every bit of old sealant taken out first and a one-year guarantee.
- Cracked joints where brick meets render or frames
- Joints pointed up with cement by mistake
- Joints with sealant missing in places
How the job changes by surface
Brickwork movement joints
People sometimes point up a brick movement joint by mistake. If that is happened, we rake it out and reseal it properly if the joint can be cleared.
Concrete and blockwork
Wide joints in concrete need the depth controlling carefully. We size the backing rod to the gap so the sealant is not too deep.
How we handle external mastic in Downside
External mastic is a job where short cuts show quickly. New sealant over old, joints packed with mortar and beads with no backing all tend to fail early. We strip the joint back and start again. If you have rain getting behind render or cladding at a joint and movement joints with cracked, split or missing sealant, we can put it right.
Outside joints can only be sealed when they’re dry, so work in Downside is booked around the forecast. Let us know about access to every wall, plus any garages or outbuildings.
All our work is covered by a 12-month guarantee, wherever you are in Surrey.
- Where
- Downside (KT11)
- Wider area
- Surrey
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Other services in Downside
Common problems we fix in Downside
Buildings move more than people expect. Clay bricks expand slightly over their life, concrete and block shrink, and everything moves with temperature and wet. All of that ends up in the joint sealant.
Signs it’s time to call us include:
- Weathered mastic that no longer stretches
- Movement joints filled with mortar instead of sealant
- Sealant that has lost its bond to the brick or render
- Gaps where render, brick and frames meet
Managing a site like St Matthew's CofE Aided Infant School? Then larger buildings have long runs of movement joint that eventually need resealing.
What to look for in a quote
- Is the old sealant removed completely?
- Whether the sealant suits the joint
- What happens if they find a problem under the old sealant
- Whether you can choose the colour
Downside questions
Do you cover smaller places like Downside?
Yes, we do. Our work covers London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Do you work for landlords with property near Cobham & Stoke Dabernon station?
Yes, landlords and agents are among the people we work for, and several properties can go on one quote. You can call 0345 464 0079 or send us an email with the details for a clear quote.
Are you an approved applicator?
Yes. Mr Mastic is an ARBOMaster approved applicator and we’re fully insured too.
Can you seal joints between two different materials?
Yes. We cut out the old sealant, prepare both faces and reseal with a flexible exterior product. The colour is chosen to suit.
Is it messy?
Very little: the area around the joints is protected first, and we clear up the old sealant and our materials before we leave.
Is there a guarantee?
Yes. All our work carries our 12-month guarantee.
Does someone need to be in?
For indoor joints, yes, someone needs to let us in. Once we’ve agreed the job, you do not need to watch us work.
How long will you be here?
Typically it takes a few hours to a few days, depending on the length of joint and the access. Bigger jobs take longer.
How it works
There’s no need to move everything out before we come, only the area right around the joints. We protect the rest, and the work takes a few hours to a few days, depending on the length of joint and the access for a typical job. Somewhere like Downside needs a little journey planning: let us know about lanes, gates and parking. We bring what the job needs, so it can be finished in one trip where possible.
- Each joint is checked and the colour of the new sealant agreed.
- Failed sealant is removed back to clean, sound faces.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
How to prepare
- On commercial sites, let us know about site rules
- Move anything stored near the joints
- For indoor joints, keep the area dry beforehand if you can
Ask for a quote
Asking for a quote is easy: let us know the job and the location and its rough size. A few photos by email make the job easier to understand, and we’ll come back to you with a quote.
Related advice
Aftercare tips
Aftercare is simple, and it makes a real difference:
- Tell anyone working on the walls about the movement joints
- Have failed joints looked at early
- Clear growth from the base of walls and joints
- Keep water from gutters off the wall
Keep pressure washers away from the sealant. High-pressure water can lift the edges over time.
Once a joint can’t move, the wall finds another way, normally as cracking in the brickwork or render nearby. Catch it early and you reduce the risk.
DIY versus a professional finish
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly.
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.
Work for landlords, hotels and businesses
From a single let to a portfolio, the work is the same standard: old sealant fully removed, joints prepared properly and a 12-month guarantee.
Landlords and agents in Downside can book us as well as householders. Resealing between tenancies is a simple way to keep a property in good order before the next move-in.
What we can’t put right
We’d rather tell you now than do work that will not last, so these are the limits:
- Rising or penetrating damp from elsewhere in the wall
- Render that’s blown, hollow or coming away
- Cracked brickwork or render that needs a builder or plasterer
If you’re not sure, just phone 0345 464 0079 or send us an email and we’ll give you a straight answer before you book.
Joints and surfaces we work on
- Copings & trims
- Façade panels
- Concrete & block
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
Outside joints around Downside
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. Historic houses like Byfleet Manor (about 2.7 miles north-west) are a reminder that the area around Downside has older buildings as well as new. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth.
Homes close to St Michael's Chapel include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant. For landlords with property near Cobham & Stoke Dabernon station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Downside is about 4 miles west of Leatherhead, in Surrey. From the centre of Downside to the outskirts, external mastic is available for homes and businesses alike. Downside is one of 395 towns and villages in Surrey we cover. You can also see our page for Crawley, about 17 miles away.
Here we cover the KT11 postcode area for external mastic. You’ll find streets such as Downside Common, Downsview Close and Deacon Close, and we cover them all. Neighbouring places we cover for external mastic include Hatchford (1 mile west), Martyr's Green (1 mile south-west), Hatchford End (2 miles west), Whiteley Village (3 miles north) and Wisley (3 miles west). Within a short drive, we also cover Guildford (8 miles south-west), Woking (7 miles west), Camberley (14 miles west), Epsom (6 miles east), Horley (14 miles south-east) and Redhill (12 miles south-east).
What’s near Downside
We work in homes and buildings around The Plough Public House and Parkside School, among other places. The closest station to Downside is Cobham & Stoke Dabernon station, roughly 1 mile north-east of the centre. Nearby you will also find Epsom Cottage Hospital (5.1 miles north-east) and Send and Ripley History Society Museum (3.8 miles west). Open spaces near Downside include Jubilee Wood and Boldermere Lake.