Hertfordshire · England
Walkern External Mastic
We cover Walkern for sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly and a one-year guarantee.
- Plants rooting in failed movement joints
- Failed seals between different materials
- Leaking joints around cladding and façade panels
External mastic in Walkern
Short cuts in external joints show up within a season or two. New sealant over old, joints packed with mortar and beads with no backing rarely last long. We strip the joint back and start again. We work on copings & trims, façade panels and brickwork movement joints, and the jobs we see most are rigid filler in a joint that should flex and joints where the bead has come unstuck.
Older homes in small places like Walkern may be stone, brick or timber-framed, often with later extensions. Where one material meets another is where water usually gets in.
Your job is guaranteed for a year, as with all our work.
- Location
- Walkern (SG2)
- Region
- Hertfordshire
- Guarantee
- One year on every job
- Quotes
- A clear price before we start
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Walkern questions
Will you come out to Walkern?
Yes, we do. 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.
Can you do external mastic in Walkern?
Yes. We work across London and the South East, and Walkern is part of that. Just phone 0345 464 0079 or send us an email with a few details of the job.
Can you seal over the old sealant?
No. Fresh sealant doesn’t stick to old sealant, and it traps any mould or water underneath. It all has to come out first.
Are you insured?
Yes. We’re fully insured, and we’ve been doing sealant work for more than 20 years.
How long does the job take?
It depends on the size of the job, but as a guide it takes a few hours to a few days, depending on the length of joint and the access. We will tell you when we quote.
How much does external mastic cost in Walkern?
Every job is different, so each one gets its own quote. To get one, ring 0345 464 0079 or drop us an email with a short description of the job.
I’m a tenant. Can you help?
Yes, but check with your landlord or agent first. Many landlords are glad to have it sorted.
Is the work guaranteed?
Yes, always. There’s a 12-month guarantee on every job, large or small.
What happens if it’s left?
A failed movement joint lets water into the wall. Resealing early keeps the job to the joint itself, rather than the wall around it. Where a wall is exposed, as many are in small places like Walkern, wind-driven rain gets into any failed joint, and older walls, once damp, take a long time to dry.
What you pay reflects the work, not guesswork. That’s why we ask a few questions first and agree the price before starting.
Why book with us
- 20+ years of sealant experience
- Anti-fungal silicone where joints get wet
- Full insurance on every job
- Sealant colour chosen to suit
See how sealant jobs are priced and our reviews.
How we quote for external mastic
We quote each job individually. These are the things that affect it:
- How much old sealant there is and how hard it is to remove
- Any working-time requirements on site
- Mould in or behind the old joints
- The type of sealant required
Homes and businesses are quoted the same way: how much there is to do, how we reach it and what it needs. Call for a quick quote and we will explain what it covers.
Helping us quote
The more you tell us, the more accurate the quote. When you ask for a quote, tell us:
- If someone has resealed it before
- How many joints, rooms or windows are involved
- The address or postcode of the job
- Access, such as stairs, a lift or height
Getting a quote is simple: let us know the job and the location. Photos by email help us understand the job, and we will take it from there.
Walls and rooflines in Walkern
With historic houses such as Aston Bury (about 2.9 miles south) nearby, there’s older building stock in the area around Walkern 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. 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.
Managing a site like Walkern Primary School? Then its movement joints, gutters and trims need looking after like any other building’s. For an older house near a landmark such as Parish Church of St Mary the Virgin, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Walkern is about 2 miles east of Stevenage, in Hertfordshire. For external mastic in and around Walkern, it’s easy to get a quote: please phone 0345 464 0079 or email us. We cover Hertfordshire from our Crawley base, Walkern included. We cover 381 towns and villages across Hertfordshire, large and small. For nearby work, see our London page (29 miles or so).
Postcode districts we cover here for external mastic: SG2. That includes homes and businesses on High Street, Walchra Court and Yew Tree Close. Neighbouring places we cover for external mastic include Aston End (2 miles south-west), Chells (2 miles west), St Nicholas (2 miles west), Stevenage (2 miles west) and Pin Green (3 miles west). Larger places within reach include St Albans (14 miles south-west), Bishop's Stortford (13 miles east), Welwyn Garden City (9 miles south), Harpenden (12 miles south-west), Hitchin (6 miles west) and Hoddesdon (12 miles south-east).
Near you in Walkern
In Walkern, that means homes and buildings near The Nobel School and The Robin Hood Public House. The nearest railway station is Stevenage station, about 3.6 miles west of the centre. Nearby you’ll also find Lister Hospital (3.6 miles west) and Stevenage Museum (3.3 miles west). Green spaces nearby include Pryor's Wood.
Places near Walkern
Other services in Walkern
Can I do it myself?
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
What sealant work can’t fix
Some problems need a builder, plumber or other trade rather than us:
- Adding movement joints to masonry that has none
- Loose or hollow render, which needs re-rendering
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
If you are not sure, just call 0345 464 0079 or send us an email and we’ll give you a straight answer.
Where we work in Walkern
- Brickwork movement joints
- Render & cladding joints
- Façade panels
- Copings & trims
- Concrete & block
- Joints between brick and frames
What we’re called out for in Walkern
Some movement joints have been pointed up with mortar, often by someone who didn’t know what it was for. The joint can’t move, so the wall cracks somewhere else instead.
Signs it’s time to call us include:
- Plants rooting in failed movement joints
- Leaking joints around cladding and façade panels
- Gaps where render, brick and frames meet
- Sealant that has lost its bond to the brick or render
Letting a property close to Stevenage station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
What to look for in a quote
- How much experience the applicator has
- What happens if the job turns out different
- Are they insured?
- Which colour the sealant will be
Surface by surface
Render joints
The face of render can be soft, so a low-modulus sealant is kinder to the joint edges. We prime where the product needs it.
Concrete and blockwork
Wide joints in concrete need the depth controlling carefully. We size the backing rod to the gap.
What happens on the day
On the day, there’s very little for you to do. Point us to the joints and we’ll get on with it. The job generally takes a few hours for a handful of joints, longer for a whole elevation, including the tidy-up. In a small place like Walkern, access is normally the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- 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.
How to prepare
- For business premises, tell us about site rules or sign-in
- Keep children and pets away from the work area
- Tell us about access, such as stairs, a lift or high-level joints
Ask for a quote
If you are in Walkern and need external mastic, ring 0345 464 0079 or email us. Tell us what the problem is and where, and we will agree the price before any work begins.