Hertfordshire · England
External & façade joints in Cottered, Hertfordshire
Our applicators work in Cottered on sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly and a 12-month guarantee.
- Weeds or debris growing in open joints
- Rigid filler in a joint that should flex
- Damp patches traced to an open external joint
Why it’s worth doing now in Cottered
A properly done movement joint is an even line in a colour that suits the wall. A hurried job with smeared edges and no backing looks worse and fails sooner, so it pays to do it properly once. Where a wall is exposed, as many are in small places like Cottered, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
The cost depends on the amount of work, how hard the old material is to remove and access to the work. We give a clear quote before any work starts.
Why Cottered clients choose us
- An ARBOMaster approved applicator
- Arbo and Everbuild products
- A choice of colours where the product allows
- Old sealant always removed completely
Read what affects the cost and what customers say.
External mastic in Cottered, done properly
Where two different materials meet, such as brick and render or blockwork and metal, they move at different rates. A flexible sealant bridges the two. If you are dealing with joints pointed up with cement by mistake and hard, crazed mastic that has stopped moving, we can help, whatever the surface.
Older homes in small places like Cottered may be stone, brick or timber-framed, often with later extensions. The joints where those materials meet are the weak points, and they need the right sealant at the right depth.
There’s a 12-month guarantee on every job.
- Where
- Cottered (SG9)
- Wider area
- Hertfordshire
- Guarantee
- One year on every job
- Quote
- A clear quote up front
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
What external mastic looks like in Cottered
The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you live in an older home near Parish Church of St John the Baptist, the joints between older walls, newer extensions and the roofline need a sealant that can move.
Cottered is about 5 miles north-east of Stevenage, in Hertfordshire. Cottered gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a one-year guarantee. Our area takes in 381 places across Hertfordshire, from the larger towns to small villages. You can also see our page for Chelmsford, about 28 miles away.
We work across the SG9 postcode area for external mastic. Whether your property is on Peasecroft, The Crescent and Warren Lane or a nearby road, our applicators can take on the job. Close by, we work in Throcking (1 mile north-east), Rushden (2 miles north-west), Chipping (2 miles north-east), Buntingford (2 miles east) and Aspenden (2 miles east). Within a short drive, we also cover Stevenage (5 miles south-west), Bishop's Stortford (11 miles south-east), Welwyn Garden City (11 miles south-west), Harpenden (15 miles south-west), Hitchin (8 miles west) and Hoddesdon (13 miles south).
Local landmarks in Cottered
Locally, jobs take us to homes and businesses close to The Bull Public House and the streets around them. Well-known places in the area include Clothall Castle (3.5 miles north-west). For a walk, there’s Hawkins Wood.
Signs you need external mastic in Cottered
Many joints fail because they were sealed too deep or with nothing behind them. Sealant bonded to three sides has nowhere to go and tears as soon as the joint widens.
Most people get in touch after spotting one of these:
- Movement joints with cracked, split or missing sealant
- Movement joints filled with mortar instead of sealant
- Sealant that has lost its bond to the brick or render
- Moss and dirt in joints with no sealant left
Managing a site like Freman College? Then movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Questions to ask before booking
- How long to leave it before use
- What happens if they find a problem under the old sealant
- What preparation is included
- Are they insured?
What happens on the day
At the end, we look at the finished work together. The visit itself usually takes a few hours for a handful of joints, longer for a whole elevation, depending on the size of the job. Somewhere as small as Cottered, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- Each joint is checked and the colour of the new sealant agreed.
- We take out the old sealant until the faces are sound.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- We prime the faces where required.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- Let us know about parking restrictions
- Let us know about earlier repairs to the joints
- For business premises, tell us about site rules or sign-in
Getting a quote
For a quote, ring 0345 464 0079 or send us an email with the location and a short description of the problem. We will give you a clear quote before any work starts.
Advice
FAQs for Cottered
Do you cover smaller places like Cottered?
Yes, Cottered is covered. Our work covers London and the South East, and smaller places are part of that. The journey is planned ahead, so it helps to know about access.
Is external mastic in Cottered guaranteed?
All our work, in Cottered and everywhere else, comes with a 12-month guarantee. We are fully insured, and an ARBOMaster approved applicator.
Do you hold any approvals?
Yes. ARBOMaster is the approved applicator scheme for Arbo sealants, and we are part of it.
What is a movement joint?
Walls move with heat, cold and moisture, and planned joints take up that movement. The gap is sealed with a flexible sealant over backing rod.
What does external mastic cost?
Every job is different, so each one gets its own quote. For a quick quote, ring 0345 464 0079 or drop us an email and tell us what needs doing and where.
Do you work at height?
It depends on the building. Where joints can be reached safely, we’ll do them. Tell us about the building and we’ll confirm what access is needed.
What sealant do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. Brands we use include Arbo and Everbuild.
Will you leave a mess?
Not at all. We work neatly, protect the area around the joints and tidy up afterwards.
When it isn’t the sealant
A few problems are outside what sealant work can do:
- Cracking across the wall rather than at a joint
- Movement that’s more than a sealant joint can take
- Damp that isn’t coming from the joint
If you’re not sure, just phone 0345 464 0079 or email us and we’ll give you a straight answer before you book.
What we seal
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
- Copings & trims
- Façade panels
- Concrete & block
What else we do in Cottered
What affects the quote in Cottered
Every job gets its own quote. These are the things that affect it:
- Any mould that needs treating
- How many rooms, windows or areas are involved
- Whether the work is at height
- How much there is to do
Commercial jobs are quoted on the same basis as homes: the amount of work, how we reach it and what it needs. Call for a quick quote and we will explain what it covers.
What we need to know
To make quoting easier, please include:
- If it’s domestic, commercial or a hotel
- Where the job is, and your postcode
- Photos by email, if that is easy
- What the problem is, such as mould, gaps, leaks or cracking
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is. When it suits you, call 0345 464 0079 or drop us an email.
How to look after the new joints
After the cure time, these simple habits help:
- Check the sealant is paintable before painting near it
- Keep high-pressure jets off the joints
- Deal with leaking gutters that soak the joints below
- Make sure movement joints aren’t pointed over
Keep the joints clear of soil, plants and climbing growth. Damp material against the sealant shortens its life.
Once a joint can’t move, the wall finds another way, often as cracks near the joint. Resealing it early helps prevent that.
DIY versus a professional finish
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it doesn’t work out, we can still put it right.