Hertfordshire · England
External Mastic in The Folly
Sealing brickwork movement joints, render, cladding and façade joints for householders, landlords and businesses in The Folly. Fully insured, ARBOMaster approved and guaranteed for a year.
- Sealant that has lost its bond to the brick or render
- Leaking joints around cladding and façade panels
- Joints pointed up with cement by mistake
Landlord and commercial work in The Folly
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.
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements and we’ll give you a quote.
How we handle external mastic in The Folly
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 have brick movement joints where the sealant has split and sealant that has lost its bond to the brick or render, we can put it right, on joints between brick and frames, concrete & block and copings & trims alike.
Outside joints can only be sealed when they’re dry, so work in The Folly is booked around the forecast. Let us know about access to every wall, plus any garages or outbuildings.
Our work is backed for twelve months, and the guarantee is the same wherever you are.
- Place
- The Folly (AL4)
- Region
- Hertfordshire
- Cover
- One year on every job
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Also near The Folly
Other services in The Folly
How to look after the new joints
After the cure time, these simple habits help:
- Make sure movement joints are not pointed over
- Keep water from gutters off the wall
- Avoid pressure-washing directly into sealant joints
- Show decorators and builders where the movement joints are
Keep the joints clear of soil, plants and climbing growth. Anything that holds water against the joint wears it out sooner.
If you can see gaps, plants or bare sections in a joint, have it checked. Early work is quicker and leaves a better finish.
The Folly buildings and the weather
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. Historic houses like Shaw's Corner (about 2 miles north-east) are a reminder that the area around The Folly has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
Letting a property close to Harpenden station? Then outside joints that have cracked can let damp into a rental, so check them between lets. Homes close to St Helen's Church include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant. For site and facilities teams at buildings such as St Helen's Church of England Primary School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
The Folly is about 2 miles east of Harpenden, in Hertfordshire. Wherever you are in the AL4 postcode area, we cover external mastic for homes and businesses. Across Hertfordshire, we cover 381 places, The Folly among them. There’s also a page for London, roughly 24 miles from The Folly.
Work in AL4 is quoted and booked the same way as anywhere else. If you need external mastic at a property on Folly Fields and Lower Luton Road or anywhere close by, our applicators can take on the job. If you’re just outside The Folly, we cover Lea Valley (1 mile west), Amwell (1 mile south), Mackerye End (1 mile north-west), Blackmore End (1 mile north) and Batford (1 mile west). We also work in nearby towns such as Watford (11 miles south), Hemel Hempstead (8 miles south-west), Stevenage (8 miles north-east), St Albans (5 miles south), Welwyn Garden City (5 miles east) and Hitchin (9 miles north).
Around The Folly
We work in homes and buildings around Sir John Lawes School and The Cherry Trees pub, among other places. The closest station to The Folly is Harpenden station, about 2 miles west. Well-known places in the area include St Albans City Hospital (4.2 miles south) and Harpenden Museum (2.2 miles west). Green spaces nearby include Wheathampstead Local Nature Reserve.
Different surfaces, different methods
Render joints
Render has movement joints and stop beads that need sealing. We reseal them with a flexible exterior sealant that suits the render colour.
Joints between dissimilar materials
Brick against render, concrete against metal, stone against timber: every change of material is a joint. We seal the joint with a flexible exterior sealant so neither cracks the other.
Why deal with it now?
A low-modulus sealant is chosen because it moves without pulling hard at the edges. That matters on brick, render and concrete, which can be weaker at the face. Too stiff a sealant can pull at the edges and break them. Around The Folly, older homes often have timber in their floors and frames, where water from a failed joint can cause rot 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 we start, so you know where you stand.
Why us?
- A choice of colours where the product allows
- Domestic, commercial and hotel work
- Sanitary silicone with an anti-fungal additive in wet areas
- We agree the colour with you first
Take a look at how sealant jobs are priced and our reviews.
FAQs for The Folly
Can you help a landlord with a rental near Harpenden station?
Yes, landlords and agents are among the people we work for. Just phone 0345 464 0079 or send us an email with the address and what needs doing, and we’ll send you a clear quote.
Will you come out to The Folly?
Yes, The Folly is covered. Our work covers London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Do you have insurance?
Yes. We are fully insured, and we’ve been doing sealant work for more than 20 years.
Where do you work from?
We’re a Crawley-based firm, with over 20 years’ experience. We work across South East England, London and Scotland.
Can you reach joints on upper floors?
That depends on how high the joints are and the ground below. Ground-floor joints are simple; for higher ones, send details and we’ll confirm the access.
What does external mastic cost?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. You’ll get a clear quote before we start.
Can I add another job to the visit?
Of course. Combining jobs makes good use of the visit.
What colours does the sealant come in?
The aim is a neat, even joint in a colour that suits the wall. We will talk through colour options before any work starts from the range available.
When it is not the sealant
Some problems need a builder, plumber or other trade rather than us:
- Cracks in the bricks or render themselves, away from the joints
- Structural movement, which needs a surveyor or engineer
- Cutting new joints into brickwork, which is building work rather than sealant work
Not sure which it is? You can call 0345 464 0079 or email us and we’ll tell you honestly before booking.
Where we work in The Folly
- Render & cladding joints
- Concrete & block
- Joints between brick and frames
- Copings & trims
- Brickwork movement joints
- Façade panels
Quotes for external mastic in The Folly
You’ll get a clear quote before work begins. It’s based on:
- How much old sealant there is and how hard it is to remove
- The number and length of the joints
- The product the joint needs
- When we can work, for business premises
Commercial jobs are quoted on the same basis as homes: 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 explain what it covers.
Asking for a quote
To help us quote quickly, let us know:
- The address or postcode of the job
- Pictures of the joints, sent by email
- Any previous sealing or DIY work
- Roughly how big the job is
We quote each job on its own, so the first step is telling us about yours. Simply ring 0345 464 0079 or email us and describe the job.
What we do, step by step
At the end, we look at the finished work together. The work normally takes anything from a few hours to several days, depending on the building, depending on how much there is to do. Somewhere like The Folly needs a little journey planning: let us know about lanes, gates and parking. We bring what the job needs, so it can be finished in one trip where possible.
- First we look over the joints with you, agree which to renew and talk through access.
- We cut out the failed sealant and rake out any dirt or growth.
- Both sides are cleaned back to sound material and primed if needed.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
Getting ready for the visit
- Plan for the work area to be out of bounds to pets and children
- Let us know about parking restrictions
- Try not to wet indoor joints just before the visit
Get a quote
If you’re in The Folly and need external mastic, ring 0345 464 0079 or email us. Tell us what the problem is and where, and you’ll get a clear quote before any work starts.