Greater London · England
External & façade joints in Force Green, Greater London
External mastic for Force Green, by sealant specialists with 20+ years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Joints where the bead has come unstuck
- Damp patches traced to an open external joint
- Brick movement joints where the sealant has split
How to look after the new joints
To keep the joints looking good and working properly:
- Wash walls gently around the sealant
- Tell anyone working on the walls about the movement joints
- Get split or bare joints resealed while the damage is small
- Ask before painting over external sealant
Do not let soil, plants or ivy build up against the new joints. Damp material against the sealant shortens its life.
Water getting behind cladding or render can go unnoticed for a long time. By the time there’s a damp patch, the damage can be well established so early resealing is worth it.
How we handle external mastic in Force Green
Many failed façade joints only get noticed once there’s a stain or a damp patch inside. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a colour to suit. We work on render & cladding joints, copings & trims and concrete & block, and the jobs we see most are gaps where render, brick and frames meet and hard, crazed mastic that has stopped moving.
Newer London blocks are built with movement joints in brick and render, and with cladding joints sealed with mastic. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall, and both kinds of building are found across London.
A one-year guarantee comes as standard.
- Location
- Force Green (TN16)
- Wider area
- Greater London
- Cover
- A year, on every job
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Towns and villages near Force Green
Also in Force Green
The process
Our applicators work methodically: protect, prepare, seal, tidy. For most jobs that takes a few hours to a few days, depending on the length of joint and the access. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Force Green. A visitor permit or a nearby bay makes the visit run more smoothly.
- 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.
Before we arrive
- Let us know if you’ve seen damp or leaks
- Try not to wet indoor joints just before the visit
- Keep pets and children clear of the area while we work
How to get a quote
We don’t publish a price list. Instead, your job gets its own clear quote. To arrange one, call 0345 464 0079 or drop us an email.
Read more
Different surfaces, different methods
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. That movement goes into the joint, so its sealant has to stay flexible.
Cladding and façade panels
Where a cladding system has its own specified sealant, we follow it, or one the system allows. Tell us what the building has when you get in touch.
Force Green: your questions answered
Is parking a problem for a job in Force Green?
Parking in Force Green, as in most of London, takes a little planning: a visitor permit or a bay close to the door helps a lot.
Can you help a landlord with a rental near Oxted station?
Yes, rental work is part of what we do. You can phone 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before any work starts.
Where is Mr Mastic based?
Mr Mastic is based in Crawley. We cover Force Green and the rest of Greater London, along with the rest of our area.
Can you do several jobs on one visit?
Yes. Just list everything you need and we will quote it together.
Do you come to Force Green?
Yes. We work in Force Green and the rest of Greater London, as part of our work across South East England, London and Scotland. To book, phone 0345 464 0079 or send us an email.
What sealant do you use?
We choose the sealant for the joint, not the other way round. Movement, water and weather all affect the choice, and we will explain our choice.
Are you an approved applicator?
Yes. ARBOMaster is the approved applicator scheme for Arbo sealants, and we’re part of it.
How long does the job take?
Typically it takes anything from a few hours to several days, depending on the building. Larger jobs naturally take longer, and we will say how long yours will take.
What we are called out for in Force Green
Poor preparation causes many early failures: joint faces that were dusty or damp, unprimed where they needed it, or still carrying old sealant. The new sealant then lets go long before it should.
If you can see any of these, it’s time to have the joints looked at:
- Failed seals between different materials
- Movement joints filled with mortar instead of sealant
- Water getting into walls through failed joints
- Brick movement joints where the sealant has split
For landlords with property near Oxted station, outside joints that have cracked can let damp into a rental, so check them between lets.
Questions to ask before you book
- How hidden problems are handled
- How the colour is chosen
- Whether the sealant suits the joint
- When the joint can take water or movement
Can I do it myself?
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
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.
When it is not the sealant
It helps to know what we cannot do:
- Movement that’s more than a sealant joint can take
- Adding movement joints to masonry that has none
- Render that is blown, hollow or coming away
If in doubt, ring 0345 464 0079 or drop us an email and we will say what we think.
What we seal
- Concrete & block
- Render & cladding joints
- Brickwork movement joints
- Façade panels
- Joints between brick and frames
- Copings & trims
Force Green buildings and the weather
Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. Historic houses like Quebec House (about 0.8 miles south) are a reminder that the area around Force Green has older buildings as well as new. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
Homes close to Church of St Mary the Virgin include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant. As a London address, Force Green can be tricky for parking: let us know about parking bays, permits or a driveway.
Force Green is about 5 miles west of Sevenoaks, in Greater London. Force Green gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a one-year guarantee. 764 places in Greater London are on our list. For nearby work, see our Crawley page (16 miles or so).
Work in TN16 works the same way as everywhere else we cover. Close by, we work in Westerham (1 mile south), South Street (2 miles north-west), Moorhouse Bank (2 miles south-west), Tatsfield (2 miles north-west) and Titsey (2 miles west). We also work in nearby towns such as Orpington (7 miles north), New Cross (14 miles north), Thornton Heath (12 miles north-west), Croydon (10 miles north-west), East Dulwich (14 miles north-west) and Plumstead (14 miles north).
Local landmarks in Force Green
Around Force Green, our work takes us to homes and buildings near The Olde House At Home Public House, among other places. The nearest railway station is Oxted station, about 3.8 miles south-west. Other landmarks nearby include Tandridge Priory (2.7 miles south-west). Not far away are Dryhill Nature Reserve and Betsom's Hill.
Why deal with it now?
A failed movement joint lets water into the wall, behind render and cladding. Dealing with it early keeps the repair to the joint, instead of the wall and finishes around it. Converted houses in London often have a bathroom above someone else’s living room, and a slow leak from a failed seal can end up in the flat below. Putting it right early is much less trouble.
Some things make a job bigger or smaller: the old material and how easily it comes out, any mould to treat, and whether the work is at height. We take all of that into account in your quote.
Why us?
- Sanitary silicone with an anti-fungal additive in wet areas
- Tidy, careful work
- Full insurance on every job
- Over 20 years’ experience
See our cost guide and what customers say.