Hertfordshire · England
Bell Bar External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for householders, landlords and businesses in Bell Bar. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Hard, crazed mastic that has stopped moving
- Failed sealant between panels on a façade
- Cracked joints where brick meets render or frames
External mastic in Bell Bar
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible sealant bridges the two where a rigid filler would soon crack. Typical jobs include rain getting behind render or cladding at a joint and joints where the bead has come unstuck, on concrete & block, brickwork movement joints and joints between brick and frames.
Outside joints can only be sealed when they’re dry, so work in Bell Bar is booked around the forecast. Let us know about access to every wall, plus any garages or outbuildings.
All our work is covered by our one-year guarantee, wherever you are in Hertfordshire.
- Place
- Bell Bar (AL9)
- Region
- Hertfordshire
- Cover
- A year, on every job
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
Outside joints around Bell Bar
Historic houses like Wyllyotts Manor (about 2.3 miles south) are a reminder that the area around Bell Bar has older buildings as well as new. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth. Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
For site and facilities teams at buildings such as Chancellor's School, its movement joints, gutters and trims need looking after like any other building’s. Letting a property close to Brookmans Park station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Bell Bar is about 2 miles north of Potters Bar, in Hertfordshire. Across the AL9 area, we cover external mastic for homes and businesses. Bell Bar is one of 381 places in Hertfordshire where we work. We also work in London, about 16 miles from Bell Bar.
Work in AL9 is quoted and booked the same way as anywhere else. Local streets include Bell Lane and The Drive. We also cover the places around Bell Bar: Brookmans Park (1 mile south), West End (2 miles north), Northaw (2 miles south-east), Essendon (3 miles north-east) and Little Berkhamsted (3 miles north-east). Larger places within reach include Watford (10 miles south-west), Hemel Hempstead (12 miles west), Stevenage (12 miles north), St Albans (6 miles west), Welwyn Garden City (5 miles north) and Harpenden (9 miles north-west).
Around Bell Bar
Typical jobs here are in homes near Brookmans Park, Brookmans Park Primary School and Cock Of The North pub. Bell Bar’s nearest station is Brookmans Park station, about 1 mile south-west. Other landmarks nearby include Queen Elizabeth II Hospital (3.6 miles north) and Potters Bar Museum (2.4 miles south). Open spaces near Bell Bar include Gobions Wood.
When to call us in Bell Bar
Poor preparation causes many early failures: joint faces that were dusty or damp, unprimed where they needed it, or still carrying old sealant. The sealant never bonds properly.
Most people get in touch after spotting one of these:
- Movement joints filled with mortar instead of sealant
- Failed sealant between panels on a façade
- Plants rooting in failed movement joints
- Damp patches traced to an open external joint
In the older streets around United Reformed Church Brookmans Park, the joints between older walls, newer extensions and the roofline need a sealant that can move.
What to look for in a quote
- Who does the work, and how experienced they are
- Are they insured?
- What preparation is included
- How the colour is chosen
What sealant work can’t fix
We won’t take on work that won’t last, so these are the limits:
- Cracks in the bricks or render themselves, away from the joints
- 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 drop us an email and we will give you a straight answer.
Surfaces we seal
- Concrete & block
- Render & cladding joints
- Copings & trims
- Brickwork movement joints
- Joints between brick and frames
- Façade panels
For landlords and businesses
Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements and we will quote.
Your questions about external mastic in Bell Bar
I let a flat near Brookmans Park station. Can you help?
Yes, we work for letting agents and landlords. You can call 0345 464 0079 or send us an email with the address and a few details, and we’ll give you a fixed price before work begins.
Is Bell Bar within the area you cover?
Yes, smaller places are covered as well as towns. We work across London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
Why do you put foam in the joint first?
We fit closed-cell backing rod wherever the joint depth needs controlling. It controls the depth and stops the sealant bonding to the back so the bead can stretch.
Are you an approved applicator?
Yes. We are an ARBOMaster approved applicator.
How do you reach high-level joints?
It depends on the building. Tell us the height, the number of joints and what’s below them, and we will confirm what access is needed.
Do you take out the old sealant first?
Yes. Sealing over the old bead is the commonest cause of early failure, so we never do it.
What colours does the sealant come in?
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.
Where do you work from?
Our base is in Crawley, West Sussex, and we work across South East England, London and Scotland.
What happens if it’s left?
Sealing over the top of old mastic does not hold for long. The new layer cannot bond properly to old, weathered material, so we always take the old sealant out. Where a wall is exposed, as many are in small places like Bell Bar, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
Some things make a job bigger or smaller: how much old sealant there is and how stubborn it is, whether mould needs treating, and whether we need extra access for height. We take all of that into account in your quote.
Why us?
- More than 20 years in sealant work
- Arbo and Everbuild products
- Domestic, commercial and hotel work
- We’re fully insured
Nearby places to Bell Bar
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What happens on the day
Most of a good job is in the preparation, and we do not rush it. Every joint is cleaned and dried before new material goes in. In total, it generally takes anything from a few hours to several days, depending on the building. For a village or hamlet like Bell Bar, the journey is planned in advance: let us know about lanes, gates and parking. Everything for the job comes with us, so a second trip is avoided where possible.
- We look at every joint and agree a colour to suit the wall.
- 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.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Getting ready for the visit
- Mention any parking rules near the property
- Mention any tricky access
- Let us know about earlier repairs to the joints
Get a quote
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To get started, call 0345 464 0079 or send us an email.
Read more
Should I try it myself first?
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
If you’ve already had a go yourself, that is fine. We cut it out and start again.
How we quote for external mastic
There’s no set price list, because no two jobs are the same. The quote depends on:
- The size of the job
- How much old sealant there is and how hard it is to remove
- When we can work, for business premises
- How many rooms, windows or areas are involved
Homes and businesses are quoted the same way: how much there is to do, how we reach it and what it needs, along with when we can work on site. Ask us for a quote and we will go through it with you.
What we need to know
When you contact us, these details help:
- Pictures of the joints, sent by email
- Access, such as stairs, a lift or height
- Any previous sealing or DIY work
- The address or postcode of the job
Need a quote? Please call 0345 464 0079 or email us with a few details. We will explain what we’d do and give you a clear price before we start.