Hertfordshire · England
Nup End Green External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for Nup End Green, backed by a 12-month guarantee. Call for a quick quote.
- Plants rooting in failed movement joints
- Joints where the bead has come unstuck
- Old sealant gone brittle and cracked
How we handle external mastic in Nup End Green
For buildings in Nup End Green, we reseal external joints of all kinds, from brick movement joints to cladding panels. The preparation is the same whatever the wall: clean joint faces and the right depth. Typical jobs include sealant pulling away from one side of the joint and failed seals between different materials, across brickwork movement joints, joints between brick and frames and copings & trims.
In a village or hamlet like Nup End Green, older cottages and farm buildings often stand in the open, so walls and rooflines take the full force of wind and rain. Joints on those walls need a sealant that moves with the building and stays in place.
All of our work is guaranteed for twelve months, and the guarantee is the same wherever you are.
- Location
- Nup End Green (SG3)
- Wider area
- Hertfordshire
- Guarantee
- A year, on every job
- Quotes
- A clear price before work begins
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
How we quote for external mastic
The quote reflects the job in front of us. We take into account:
- When we can work, for business premises
- The old material and how stubborn it is
- How many rooms, windows or areas are involved
- Any mould that needs treating
No two jobs are quite the same, so we quote each one individually. Size, access and the product the joint needs all make a difference.
Helping us quote
When you contact us, these details help:
- The rough size of the job
- Whether it has been sealed before
- Where the property is
- How we’d reach the joints
There’s no standard price list. Instead, your job gets its own clear quote. To get started, phone 0345 464 0079 or drop us an email.
Towns and villages near Nup End Green
What else we do in Nup End Green
When to call us in Nup End Green
Some movement joints have been pointed up with mortar by mistake. The joint cannot move, so the wall cracks somewhere else instead.
People usually contact us when they notice something like this:
- Plants rooting in failed movement joints
- Sealant that has lost its bond to the brick or render
- Movement joints filled with mortar instead of sealant
- Movement joints with cracked, split or missing sealant
For landlords with property near Knebworth station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
What to look for in a quote
- How the colour is chosen
- Whether they’re fully insured
- Which sealant they’ll use, and why
- Who turns up on the day
What the job involves on each surface
Cladding and façade panels
Metal and composite panels move a lot with temperature, so the joint sealant has to cope with frequent movement. The sealant is chosen with that in mind.
Brickwork movement joints
Vertical joints in long brick walls let the brickwork expand without cracking. We reseal them with a low-modulus sealant over backing rod in a colour to suit the brick.
When it is not the sealant
Honest advice matters more to us than a booking, so here’s what new sealant won’t do:
- Cracking across the wall rather than at a joint
- Movement that is more than a sealant joint can take
- Adding movement joints to masonry that has none
If in doubt, phone 0345 464 0079 or email us and we’ll say what we think.
Surfaces we seal
- Copings & trims
- Concrete & block
- Façade panels
- Render & cladding joints
- Joints between brick and frames
- Brickwork movement joints
Your questions about external mastic in Nup End Green
Do you cover smaller places like Nup End Green?
Yes, Nup End Green is covered. We work across London and the South East, and smaller places are part of that. Longer journeys are simply planned in advance.
Is Nup End Green in your area for external mastic?
Yes. We work across London and the South East, and Nup End Green is part of that. You can ring 0345 464 0079 or send us an email and tell us what needs doing.
Can a movement joint be filled with mortar?
No, not if it’s a movement joint. Pointing it stops it working. A flexible sealant is the right fill.
Do you hold any approvals?
Yes. We’re ARBOMaster approved, the scheme for applicators of Arbo sealants.
Do the sealants smell?
That depends on the sealant. Some smell for a while, some hardly at all.
I’m a tenant. Can you help?
Yes. Check with your landlord; we can send the quote to them too.
How often do external joints need resealing?
It varies from wall to wall: joints on exposed walls or with a lot of movement age sooner. Check them each year and reseal when they split or harden. Every job carries our 12-month guarantee.
Do you work at height?
That depends on how high the joints are and the ground below. Ground-floor joints are simple; for higher work, tell us about the building and we’ll confirm what’s needed.
Looking after it afterwards
How long the joints last depends on use and care. Here’s what we suggest:
- Keep water from gutters off the wall
- Have failed joints looked at early
- Walk round the building once a year and look at the joints
- Keep soil, plants and ivy away from the joints
Do not paint over the new sealant unless we’ve said the product is paintable. Many exterior sealants aren’t designed to be painted, and paint can crack as the joint moves.
Water getting behind cladding or render can go unnoticed for a long time. When it finally shows inside, the joint may have been open for years so early resealing is worth it.
Why act early in Nup End Green
Pointing a movement joint with mortar might seem a neat fix, but it stops the joint moving. The movement then cracks the brickwork or render nearby. The correct repair is a flexible sealant with the right backing. Older cottages and farmhouses around Nup End Green can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
The cost depends on how much there is to do, how hard the old material is to remove and how easy the joints are to reach. We give a clear quote before work begins.
Why book with us
- Homes, businesses and hotels
- You choose the colour before work begins
- 20+ years of sealant experience
- Anti-fungal sanitary silicone in wet areas
Read what affects the cost and our reviews.
Outside joints around Nup End Green
Historic houses like Knebworth House (about 0.6 miles north-east) are a reminder that the area around Nup End 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, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
For an older house near a landmark such as Church of St Mary and St Thomas, an extension built onto an older house moves differently, and the joint between them takes the strain.
Nup End Green is about 3 miles south-west of Stevenage, in Hertfordshire. Across the SG3 area, we can carry out external mastic at your property. Across Hertfordshire, we cover 381 places, and Nup End Green is one of them. London is on our list too, around 26 miles away.
We work across SG3 for external mastic. Neighbouring places we cover for external mastic include Driver's End (1 mile west), Old Knebworth (1 mile north-east), Rableyheath (1 mile south-east), Pottersheath (1 mile south-east) and Codicote (1 mile south-west). We also work in nearby towns such as Hemel Hempstead (13 miles south-west), Stevenage (3 miles north-east), St Albans (9 miles south-west), Welwyn Garden City (5 miles south), Harpenden (6 miles south-west) and Hitchin (6 miles north).
What’s near Nup End Green
Locally, jobs take us to homes and businesses close to Robin Hood And Little John Public House and Knebworth Park. Nup End Green’s nearest station is Knebworth station, roughly 1.4 miles east. Nearby you’ll also find Benington Castle (4.9 miles north-east) and Lister Hospital (4.1 miles north). For a walk, there’s Mardley Heath.
The process
On the day, we start by going over the job with you, so there are no surprises. Surfaces next to the work are protected before any work begins. Most jobs take a few hours for a handful of joints, longer for a whole elevation. In a small place like Nup End Green, access is usually the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- First, the joints are inspected and the access agreed.
- We cut out the old mastic and rake out anything in the joint.
- The faces are brushed clean and primed where the product requires it.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
Preparing for the visit
- For indoor joints, keep the area dry beforehand if you can
- Keep children and pets away from the work area
- Let us know about earlier repairs to the joints
Get a quote
Asking for a quote is easy: let us know the job and the location, and roughly how big it is. A few pictures by email make the job easier to understand, and we will come back to you with a quote.