Hertfordshire · England
External Mastic in Potters Bar
Professional external mastic in and around Potters Bar, with every bit of old sealant taken out first and a one-year guarantee.
- Movement joints with cracked, split or missing sealant
- Failed sealant between panels on a façade
- Water getting into walls through failed joints
About our external mastic in Potters Bar
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible exterior sealant takes up that movement where a rigid filler would soon crack. Typical jobs include weeds or debris growing in open joints and sealant that has lost its bond to the brick or render, across joints between brick and frames, render & cladding joints and concrete & block.
Garage door frames, porches and roofline trims are all part of external work in a town like Potters Bar. Each joint between different materials moves in its own way, so the sealant has to cope with that.
Your job is guaranteed for a year, as with all our work.
- Where
- Potters Bar (EN6)
- Region
- Hertfordshire
- Guarantee
- A year, on every job
- Price
- A clear price before we start
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Keeping the joints in good condition
After the cure time, these simple habits help:
- Don’t let climbing plants root in the sealant
- Check the sealant is paintable before painting near it
- Never let anyone fill a movement joint with mortar
- Point out the joints to other trades
Make sure anyone working on the wall later knows where the movement joints are. They should be kept open and resealed, not filled.
A joint that has stopped moving pushes the movement elsewhere, generally as cracking in the brickwork or render nearby. Resealing it early helps prevent that.
Common questions in Potters Bar
What guarantee comes with external mastic in Potters Bar?
All our work, in Potters Bar and everywhere else, comes with a 12-month guarantee. We’re also fully insured and ARBOMaster approved.
Can you do external mastic in Potters Bar?
Yes, Potters Bar is within the area we cover. We work across London and the South East. You can call 0345 464 0079 or email us and tell us what needs doing.
Do you hold any approvals?
Yes. We are an ARBOMaster approved applicator, which is run for the Arbo sealant brand.
Can new sealant go over the old?
No. New silicone won’t bond to old silicone, and it traps any mould or water underneath. It all has to come out first.
Can you seal joints between render and window frames?
Yes. Joints between dissimilar materials are a big part of external work. The sealant is chosen to bond to both sides, primed where needed.
Can you reach joints on upper floors?
That depends on the building and the joints. Where joints can be reached safely, we’ll do them. Tell us about the building and we’ll confirm what access is needed.
How much does external mastic cost in Potters Bar?
Every job is different, so each one gets its own quote. To get one, phone 0345 464 0079 or send us an email and tell us what needs doing and where.
How often do external joints need resealing?
It depends on the exposure, the movement and the product. Treat it as a maintenance item and look at it yearly.
Can I do it myself?
A DIY attempt does not rule out a professional job. We remove it and do the joint properly, so tell us about it when you ask for a quote.
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.
Potters Bar buildings and the weather
Rainfall in the South East is lower than in much of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. Historic houses like Wyllyotts Manor (about 0.4 miles west) are a reminder that the area around Potters 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.
Homes close to St. Mary's Church include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep. For landlords with property near Potters Bar station, outside joints that have cracked can let damp into a rental, so check them between lets.
Potters Bar is about 7 miles north of Finchley, in Hertfordshire. Our applicators cover external mastic for householders, landlords and businesses in Potters Bar and nearby, as part of our work across Hertfordshire. We cover 381 towns and villages across Hertfordshire, large and small. We also work in London, about 14 miles from Potters Bar.
We cover every part of EN6 for external mastic. Whether your property is on High Street, Church Road and The Walk or anywhere close by, we can help. You’ll find Potters Bar on the A111 and B156, which makes it straightforward to reach. Other places close to Potters Bar include Bentley Heath (1 mile south-west), Northaw Valley (2 miles east), Hadley Wood (2 miles south), Monken Hadley (2 miles south) and Botany Bay (3 miles south-east). Further out, we also cover Watford (10 miles west), Hemel Hempstead (13 miles west), Stevenage (15 miles north), St Albans (7 miles north-west), Welwyn Garden City (7 miles north) and Harpenden (11 miles north-west).
What’s near Potters Bar
Around Potters Bar, our work takes us to homes and buildings near The White Horse Public House and Mount Grace School, among other places. Potters Bar has its own railway station: Potters Bar station. Well-known places in the area include Spires Shopping Centre (3 miles south) and Barnet General Hospital (3.4 miles south-west). For a walk, there’s Furzefield Wood and Lower Halfpenny.
How the job changes by surface
Render joints
The face of render can be soft, so a sealant that stretches easily protects the edges. Priming is done where the sealant calls for it.
Brickwork movement joints
Clay brickwork grows slightly over its life and moves with the weather. That movement goes into the joint, so the sealant in it must stay soft and stretchy.
How it works
When we arrive, we look over the joints with you first, so you know exactly what we’re doing. We protect the surfaces around the joints before any work begins. Most jobs take a few hours for a handful of joints, longer for a whole elevation. For a job in Potters Bar, we need access to where the work is and somewhere nearby to park. For outside work, let us know about side access, gates and any upper-floor joints.
- 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.
- We prime the faces where required.
- We gun in low-modulus sealant and tool it neatly.
Getting ready for the visit
- On commercial sites, let us know about site rules
- Let us know about stairs, lifts or work at height
- Mention any parking rules near the property
Getting a quote
Call for a quick quote, or send an email if you’d rather. Tell us about the joints that need doing and we will explain what’s involved before giving you a price.
Read more
Common problems we fix in Potters Bar
Every building moves. Clay bricks expand slightly over their life, concrete and block shrink, and everything moves with temperature and wet. All of that ends up in the joint sealant.
It’s worth asking for a quote if you see:
- Failed sealant between panels on a façade
- Movement joints filled with mortar instead of sealant
- Old sealant gone brittle and cracked
- Gaps where render, brick and frames meet
For site and facilities teams at buildings such as Ladbrooke Junior Mixed and Infant School, larger buildings have long runs of movement joint that eventually need resealing.
What to look for in a quote
- Is the old sealant removed completely?
- Which colour the sealant will be
- Is VAT in the price?
- Who turns up on the day
Why deal with it now?
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. In Potters Bar, as anywhere, most leaks start as a small gap in a joint, and they’re far easier to fix early.
Doing several joints on one visit is usually more efficient than separate visits. You will get one clear quote for the whole job.
What you get with us
- Any old sealant cut out fully, not covered over
- Domestic, commercial and hotel work
- Rated 4.9 stars on Google
- Tidy, careful work
Read our cost guide or what customers say.
Landlord and commercial work in Potters Bar
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Resealing at the right time is simple maintenance that we can handle for you.
If you manage several properties in or around Potters Bar, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs.