East Sussex · England
External Mastic in Crowborough
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Crowborough and across East Sussex. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Rigid filler in a joint that should flex
- Weathered mastic that no longer stretches
- Joints with sealant missing in places
What happens if it’s left?
Low-modulus sealants stretch easily, so they put less strain on the joint edges. That protects surfaces like brick, render and concrete. Too stiff a sealant can pull at the edges and break them. In a family home in Crowborough, a failed seal around a bath or a frame lets water into places you can’t see, such as under the floor, behind a panel or into a wall. Whatever the joint, failed sealant only gets worse.
Commercial jobs are quoted on the same basis as homes: the amount of work, how we reach it and what it needs, plus any working-time requirements on site. Call for a quick quote and we will go through it with you.
Why book with us
- Experience in homes, commercial sites and hotels
- A choice of colours where the product allows
- Sanitary silicone with an anti-fungal additive in wet areas
- Tidy, careful work
See what affects the cost and our reviews.
How we handle external mastic in Crowborough
Failed sealant is cut out, the depth set with closed-cell backing rod, and the joint resealed with a low-modulus sealant made for outside. We pick a colour that sits well with the wall so the joint does not stand out. We work on copings & trims, brickwork movement joints and concrete & block, and people most often call us about movement joints with cracked, split or missing sealant and old sealant gone brittle and cracked.
Garage door frames, porches and roofline trims are all part of external work in a town like Crowborough. Where two materials meet, they move differently, and the sealant has to allow for it.
All of our work is guaranteed for twelve months.
- Location
- Crowborough (TN6)
- Wider area
- East Sussex
- Cover
- A year, on every job
- Quotes
- A clear price before work begins
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
How we quote for external mastic
You’ll get a clear quote before any work starts. It takes into account:
- The old material and how stubborn it is
- When we can work, for business premises
- Whether the work is at height
- The number of rooms or windows
Every job is a little different, so we quote each one individually. Size, access and the product the joint needs all play a part.
Asking for a quote
A few details help us give you an accurate quote. When you get in contact, it helps to mention:
- The address or postcode of the job
- Access, such as stairs, a lift or height
- The type of property
- Whether it has been sealed before
For a quote, call 0345 464 0079 or email us with the location and a short description of the problem. We’ll give you a clear quote before any work starts.
Crowborough questions
Is there a guarantee on external mastic in Crowborough?
Every job comes with our one-year guarantee, wherever it is. We’re fully insured, and an ARBOMaster approved applicator.
Do you cover Crowborough for external mastic?
Yes. We work across London and the South East, and Crowborough is part of that. You can call 0345 464 0079 or send us an email and let us know what needs doing, and we’ll give you a clear quote.
Will the old sealant be removed?
Yes. We cut out all the old sealant and clean the joint before resealing.
Are you ARBOMaster approved?
Yes. Mr Mastic is an ARBOMaster approved applicator, and we are fully insured.
Where do you work from?
Mr Mastic is based in Crawley. We cover Crowborough and the rest of East Sussex.
Can I do it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
How long before the joint can be used?
Most sealants are touch-dry well before they’re fully cured. We’ll tell you how long to leave the joint before we leave.
Is it OK to seal over old sealant?
No. The old sealant always comes out first, so the new sealant bonds properly.
How to look after the new joints
No joint lasts for ever, but care makes a real difference. Our tips:
- Don’t let climbing plants root in the sealant
- Make sure movement joints are not pointed over
- Keep high-pressure jets off the joints
- Walk round the building once a year and look at the joints
Keep pressure washers away from the sealant. A strong jet can damage the edges of the bead over time.
Leaks behind façade panels and render often go unseen. By the time there’s a damp patch, the damage can be well established.
Do you need external mastic in Crowborough?
Weeds, moss and debris in a joint are a sign the sealant has gone. Dirt and roots then trap moisture in the joint and speed up the damage.
People normally contact us when they notice something like this:
- Old sealant gone brittle and cracked
- Joints pointed up with cement by mistake
- Plants rooting in failed movement joints
- Movement joints with cracked, split or missing sealant
Letting a property close to Crowborough station? Then split movement joints are easy to miss on a rental until damp shows inside.
What to look for in a quote
- How much experience the applicator has
- Whether they seal over old material or remove it
- How the joint is cleaned and prepared
- What insurance they hold
Towns and villages near Crowborough
What else we do in Crowborough
How it works
A visit follows a simple pattern: we check the joints, protect the area around them, do the work and tidy away. Most jobs take a few hours for a handful of joints, longer for a whole elevation. Parking in a town like Crowborough is normally straightforward, but tell us if there’s a driveway or any restrictions, and mention if the work is upstairs, in a flat or high on the outside.
- We start by walking round the building and agreeing the joints and the access.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control the depth.
- The exterior sealant is applied, tooled and checked along its length.
Preparing for the visit
- Let us know if you’ve seen damp or leaks
- Let us know about parking restrictions
- Mention if the joints have been sealed before
How to get a quote
Need a quote? Please phone 0345 464 0079 or email us with a few details. We’ll explain what we’d do and give you a clear price before work begins.
Read more
Can I do it myself?
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.
The biggest DIY mistake is sealing over old sealant. New silicone won’t bond to old, so it lifts and traps water and mould underneath. Everything old must be removed first.
Walls and rooflines in Crowborough
The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. With historic houses such as Groombridge Place (about 4.6 miles north) nearby, there’s older building stock in the area around Crowborough as well as newer homes. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
Managing a site like St Marys Catholic Primary School? Then movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. Homes close to The Parish Church of All Saints include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain.
Crowborough is about 16 miles south of Sevenoaks, in East Sussex. We carry out external mastic for homes and businesses in Crowborough and the surrounding area. Across East Sussex, we cover 289 places, and Crowborough is one of them. There’s also a page for Crawley, about 16 miles away.
Every address in TN6 is covered for external mastic. If you need external mastic at a property on Church Road, High Street and London Road or anywhere close by, our applicators can take on the job. Crowborough sits on or near the A26 and B2100. We also cover the places around Crowborough: Jarvis Brook (1 mile east), Steel Cross (1 mile north-east), Boarshead (2 miles north-east), Sweethaws (2 miles south-west) and Marden's Hill (2 miles north-west). Further out, we also cover Lewes (14 miles south-west), Hailsham (14 miles south), Uckfield (6 miles south-west), South Malling (14 miles south-west), Heathfield (7 miles south-east) and Southover (14 miles south-west). Crowborough is among the bigger towns we cover in East Sussex.
Around Crowborough
Around Crowborough, our work takes us to homes and buildings near Beacon Academy and The Crowborough Cross pub. The closest station to Crowborough is Crowborough station, roughly 1 mile south-east. Nearby you’ll also find Crowborough War Memorial Hospital (0.5 miles west). For a walk, there’s Crowborough Country Park.
How the job changes by surface
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. We reseal their joints with backing rod and a flexible product.
Cladding and façade panels
Panels heat up and cool down quickly, so the joint sealant has to cope with frequent movement. We choose the product to suit.