Mr Mastic · South East, London and Scotland
External and façade joints
Brickwork movement joints, render, cladding and façade joints cut out and resealed with backing rod and a flexible sealant made for outside.
- Movement joints with cracked, split or missing sealant
- Water getting into walls at failed joints
- Hard, crazed mastic that has stopped moving
What external & façade joints involves
Buildings move with heat, cold and moisture, and movement joints are there to take it. When the sealant in them cracks, splits or goes hard, water gets into the wall and the joint stops working. We cut out the failed sealant, set the right depth with backing rod and reseal with a flexible exterior sealant in a colour to suit.
We work across the South East, London and all of Scotland from our base in Crawley. Every job comes with our one-year guarantee, and we’re fully insured and an ARBOMaster approved applicator.
Problems we put right
- Movement joints with cracked, split or missing sealant
- Water getting into walls at failed joints
- Hard, crazed mastic that has stopped moving
- Joints filled with mortar instead of sealant
- Weeds or debris growing in open joints
Where we work
- Brickwork movement joints
- Render & cladding joints
- Façade panels
- Joints between brick and frames
- Concrete & block
- Copings & trims
How it works
- We inspect the joints and agree which need resealing and how they’ll be reached.
- Old sealant and any debris are cut and raked out.
- The joint faces are cleaned and primed where the sealant needs it.
- Closed-cell backing rod is fitted to set the right depth and stop three-sided bonding.
- A flexible exterior sealant is applied and tooled, in a colour to suit the wall.
Why depth matters
A movement joint sealed too deep or bonded to the back can’t stretch and will tear. Backing rod sets the depth so the sealant bonds only to the two sides.
Access
Ground-floor and low-level joints are straightforward. For high-level joints, tell us about access when you ask for a quote and we’ll confirm what’s needed.
Why it’s worth doing now
A movement joint that has cracked or gone hard can’t do its job. Water gets into the wall behind it, and the movement it was meant to take ends up cracking the brickwork or render instead. Resealing is far cheaper than repairing walls.
What affects the quote
We don’t publish set prices, because every job is different. Call or email us with a few details and we’ll give you a clear quote before we start. The main things that affect it are:
- How many joints, rooms, windows or metres of joint there are
- How much old sealant or grout has to come out, and how many layers
- Mould, damage or movement that needs dealing with first
- Access: stairs, height, ladders or work outside
- The product the joint needs (sanitary, exterior, fire-rated, glazing or sand mastic)
- For commercial sites, working hours and phasing
What a good quote includes
- All the old sealant removed, not sealed over
- The product named for each joint
- How long the guarantee is and what it covers
- How long before the area can be used
- How your home or building will be protected
- Who is doing the work, and that they’re insured
Aftercare
Look at external joints once a year, keep plants and climbers away from them, and clear debris from joints near the ground. Avoid pressure-washing directly into sealant joints.
What customers say
Rated 4.9 on Google from 180+ five-star reviews. Read the reviews on Google.
“Called for a bathroom reseal and the mastic man showed up on time with all the right equipment. Brilliant attention to detail. The sealant looks perfect and they kept everything tidy.”
“We had old mastic that needed replacing throughout our kitchen and bathrooms. The mastic man professional was knowledgeable, quoted fairly, and delivered excellent quality work. Highly recommend!”
“Professional mastic man service from start to finish. They assessed the work properly, gave a clear quote, and executed the job perfectly. Very satisfied with the results.”
External and façade joints: common questions
What is a movement joint?
A deliberate gap in brickwork, render or cladding that lets the building expand and contract without cracking. It’s sealed with a flexible sealant, not mortar.
Can you match the colour of my brickwork?
We can use a sealant colour that suits the brick or render so the joint doesn’t stand out.
Do you work at height?
Where joints can be reached safely. Tell us about the building and we’ll confirm what access is needed.
Is the work guaranteed?
Yes. Every job comes with our one-year guarantee.
Do you give a price before you start?
Yes. Call or email us with a few details and we’ll give you a clear quote, so you know the price before any work starts.
Are you insured?
Yes. Mr Mastic is fully insured, and we’re an ARBOMaster approved applicator.
Page updated 26 October 2026
Near you
We cover the South East, London and Scotland. Find external & façade joints in your town:
- London
- Crawley
- Brighton
- Guildford
- Chelmsford
- Colchester
- Southampton
- Reading
- Oxford
- Edinburgh
- Glasgow
- Aberdeen
- Dundee