Hertfordshire · England
External Mastic in Kinsbourne Green
Movement joints in Kinsbourne Green need attention? We cut out the old, prepare the joints and apply the right sealant, with a 12-month guarantee.
- Weeds or debris growing in open joints
- Damp patches traced to an open external joint
- Old sealant gone brittle and cracked
External mastic in Kinsbourne Green, 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. We work on concrete & block, façade panels and joints between brick and frames, and the jobs we see most are hard, crazed mastic that has stopped moving and joints with sealant missing in places.
Around Kinsbourne Green, older buildings can be stone, brick or timber-framed, many with extensions added later. The joints where those materials meet are the weak points.
A one-year guarantee comes as standard, so you are covered after we’ve gone.
- Place
- Kinsbourne Green (AL5)
- Region
- Hertfordshire
- Cover
- One year on every job
- Quote
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
What happens on the day
Most of a good job is in the preparation, so that’s where we spend the time. Joints are cleaned back and dried before anything new goes in. In total, it normally takes a few hours to a few days, depending on the length of joint and the access. For a village or hamlet like Kinsbourne Green, the journey is planned in advance: tell us about narrow lanes, gates, long drives and where we can park. Everything for the job comes with us, so a second trip is avoided where possible.
- Each joint is checked and the colour of the new sealant agreed.
- We take out the old sealant until the faces are sound.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Getting ready for the visit
- Move anything stored near the joints
- On commercial sites, let us know about site rules
- Let us know about stairs, lifts or work at height
Getting a quote
Every job is quoted individually. Just phone 0345 464 0079 or drop us an email with the details, and pictures are welcome.
Read more
Surface by surface
Concrete and blockwork
The face of concrete or block is often dusty, so cleaning and priming matter. A primer goes on where the product requires one before sealing.
Joints between dissimilar materials
Each side of the joint may need its own preparation. We prepare both faces so the sealant bonds properly.
What affects the quote in Kinsbourne Green
Jobs vary more than people expect. What affects the quote:
- Mould in or behind the old joints
- When we can work, for business premises
- How many rooms, windows or areas are involved
- How easy the joints are to reach
What it costs depends on the size of the job, how hard the old material is to remove and access to the work. We give a clear quote before any work starts, so you know where you stand.
What to tell us for a quote
A few details help us give you an accurate quote. When you ask for a quote, tell us:
- The type of property
- What’s wrong with the joints now
- Access, such as stairs, a lift or height
- Where the property is
The more we know about the job, the more useful the quote. Let us know the location, the problem and roughly how many joints.
What we are called out for in Kinsbourne Green
Buildings move more than people expect. Brickwork grows a little over the years, blockwork and concrete shrink, and all of it moves with heat and moisture. The sealant in the movement joints takes that strain.
People usually contact us after spotting something like this:
- Movement joints filled with mortar instead of sealant
- Joints with sealant missing in places
- Old sealant gone brittle and cracked
- Panel joints letting water in
For landlords with property near Harpenden station, outside joints that have cracked can let damp into a rental, so check them between lets.
What to look for in a quote
- How hidden problems are handled
- Who turns up on the day
- Whether all the old sealant comes out first
- How the colour is chosen
Landlord and commercial work in Kinsbourne Green
We also work for property managers and facilities teams in Kinsbourne Green and across Hertfordshire. Several sites can go on one quote.
If you manage several properties in or around Kinsbourne Green, several properties can be quoted together. Send us the addresses and the work at each.
Your questions about external mastic in Kinsbourne Green
Do you cover smaller places like Kinsbourne Green?
Yes. Kinsbourne Green is within the area we cover, which takes in towns, villages and rural addresses. We work across London and the South East. Just mention lanes, gates or anything else about the route when you book.
Can you help a landlord with a rental near Harpenden station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or send us an email and tell us about the property, and we will give you a clear quote.
Is there a guarantee?
Yes, for a year. If there’s a problem with our work in that time, tell us and we’ll put it right.
Will the new joint stand out?
We choose a sealant colour to suit the brick, stone or render so the joint blends in. Exterior sealants come in a good range of colours.
How long should I leave it?
It depends on the product and the conditions. We tell you how long to leave it before we go.
What is a movement joint?
Most straight vertical gaps in brickwork are movement joints. It lets the bricks expand without cracking and needs a flexible seal, not mortar.
Can you do several jobs on one visit?
Yes. Several rooms, windows or areas can go on one quote.
How often do external joints need resealing?
It depends on the exposure, the movement and the product. Sealant is a maintenance item, so check the joints once a year and reseal when it splits.
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Fix overflowing gutters above sealed joints
- Point out the joints to other trades
- Check the sealant is paintable before painting near it
- Make sure movement joints are not pointed over
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They must stay as flexible joints, never rendered or pointed over.
If you can see gaps, plants or bare sections in a joint, have it checked. Early work is quicker and leaves a better finish.
What we cannot put right
To be straight with you, there are a few things sealant won’t fix:
- Walls that need new movement joints cut into them
- Cracks in the bricks or render themselves, away from the joints
- Structural movement, which needs a surveyor or engineer
If you’re not sure, just call 0345 464 0079 or send us an email and we will give you a straight answer before booking.
Where we work in Kinsbourne Green
- Render & cladding joints
- Brickwork movement joints
- Concrete & block
- Joints between brick and frames
- Copings & trims
- Façade panels
Also near Kinsbourne Green
More services for Kinsbourne Green
Walls and rooflines in Kinsbourne Green
Historic houses like Childwickbury Manor (about 4.1 miles south-east) are a reminder that the area around Kinsbourne 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. 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.
Homes close to Saint Mary the Virgin include some older properties, and the joints between older walls, newer extensions and the roofline need a sealant that can move. For site and facilities teams at buildings such as Wood End School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Kinsbourne Green is about 2 miles north-west of Harpenden, in Hertfordshire. Homes, rented property, offices and hotels in Kinsbourne Green is covered for external mastic, old or new, large or small. The work is guaranteed for a year. We cover 381 towns and villages across Hertfordshire. You can also see our page for London, about 26 miles away.
Every address in AL5 is covered for external mastic. External mastic is available to properties on Chamberlaines, Spring Road and Kinsbourne Green Lane. Close by, we work in Harpenden (2 miles south-east), Bower Heath (2 miles east) and Batford (3 miles east). Further out, we also cover Watford (12 miles south), Hemel Hempstead (6 miles south-west), Stevenage (11 miles north-east), St Albans (6 miles south-east), Welwyn Garden City (9 miles east) and Hitchin (10 miles north-east).
Near you in Kinsbourne Green
In Kinsbourne Green, that means homes and buildings near Roundwood Park School, Lydekker Park and The Fox Public House and the streets around them. Kinsbourne Green’s nearest station is Harpenden station, about 2.3 miles south-east of the centre. Nearby you will also find St Albans City Hospital (5.4 miles south-east) and The Mall Luton (3.5 miles north). Not far away are Wheathampstead Local Nature Reserve.