Hertfordshire · England
External Mastic in Round Bush
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Round Bush and across Hertfordshire. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Cracked joints where brick meets render or frames
- Movement joints with cracked, split or missing sealant
- Rain getting behind render or cladding at a joint
How to look after the new joints
So the new joints stay in good condition:
- Tell anyone working on the walls about the movement joints
- Keep soil, plants and ivy away from the joints
- Never let anyone fill a movement joint with mortar
- Avoid pressure-washing directly into sealant joints
Keep the joints clear of soil, plants and climbing growth. Damp material against the sealant shortens its life.
Leave a failed movement joint and water keeps getting into the wall. Over time it can mean damp inside, stained render or frost-damaged brick, all bigger jobs than a reseal.
About our external mastic in Round Bush
On houses, flats and commercial buildings across Round Bush, we reseal joints in brickwork, render, cladding and façade panels. The preparation is the same whatever the wall: clean, sound faces and a controlled depth. We are often asked to deal with cracked joints where brick meets render or frames and panel joints letting water in, on render & cladding joints, copings & trims and brickwork movement joints.
External sealant needs dry, clean surfaces, so work around Round Bush is planned for dry weather. Tell us about access to all sides of the building, including outbuildings and garages.
The work is covered for a year after we finish. If there’s a problem with it, please call 0345 464 0079 or send us an email.
- Place
- Round Bush (WD25)
- Region
- Hertfordshire
- Guarantee
- 12 months on all our work
- Quote
- Quoted before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
Also near Round Bush
Also in Round Bush
Quotes for external mastic in Round Bush
There’s no set price list. The quote depends on:
- Any mould that needs treating
- Which sealant suits the joint
- Working hours on commercial sites
- The number and length of the joints
There are no prices on our website, because the cost depends so much on the job itself. Call for a quick quote and we will talk you through it.
What to tell us for a quote
When you contact us, these details help:
- Whether it’s a home or a business
- How many joints, rooms or windows are involved
- If someone has resealed it before
- Pictures of the joints, sent by email
We don’t publish a price list, because every job is different. Instead, we give you a clear quote for your job. To get started, call 0345 464 0079 or drop us an email.
What we cannot put right
We won’t take on work that won’t last, so here’s what sealant can’t put right:
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Cracking across the wall rather than at a joint
- Structural movement, which needs a surveyor or engineer
If you’re not sure, just phone 0345 464 0079 or email us and we’ll give you a straight answer.
Surfaces we seal
- Copings & trims
- Joints between brick and frames
- Brickwork movement joints
- Concrete & block
- Façade panels
- Render & cladding joints
Common questions in Round Bush
Do you cover Round Bush for external mastic?
Yes. Our work covers London and the South East, and Round Bush is part of that. You can ring 0345 464 0079 or email us and let us know what needs doing, and we will give you a clear quote.
I let a flat near Radlett station. Can you help?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or drop us an email and tell us about the property, and we’ll give you a clear quote.
Can a movement joint be filled with mortar?
No. A mortar-filled joint can’t move, so the movement cracks the wall elsewhere. It needs a flexible sealant over backing rod.
How long will you be here?
A typical job takes a few hours to a few days, depending on the length of joint and the access, including the preparation. We’ll confirm how long when we quote.
Can you reach joints on upper floors?
Each building is different. Send us photos and a rough idea of the height and we will confirm how they can be reached safely.
Will the new joint stand out?
We choose a sealant colour to suit the brick, stone or render. Exterior sealants come in a good range of colours.
Can you quote for more than one area?
Yes. More than one area can go on one quote.
Which products do you use?
Products from Arbo and Everbuild, among others, picked for each joint. We’ll tell you what we are using and why.
How the job changes by surface
Brickwork movement joints
People sometimes point up a brick movement joint by mistake. Where one has been mortared, we cut it out and reseal it with sealant where it can be done safely.
Render joints
Rendered walls have joints at beads, openings and changes of material. We reseal them with a flexible exterior sealant that suits the render colour.
DIY sealant or a professional job?
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it fails, we can still redo it.
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
External mastic in Round Bush: local notes
Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. With historic houses such as High Elms Manor (about 2.9 miles north-west) nearby, there’s older building stock in the area around Round Bush 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.
Rented homes near Radlett station change hands often, and outside joints that have cracked can let damp into a rental, so check them between lets. Homes close to Church of St John the Baptist include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant.
Round Bush is about 2 miles north of Bushey, in Hertfordshire. From the centre of Round Bush to the outskirts, we cover external mastic for every kind of property, from flats and houses to offices and hotels. 381 places in Hertfordshire are on our list, from the larger towns to small villages. There’s also a page for London, roughly 16 miles from Round Bush.
Every address in WD25 is covered for external mastic. Whether your property is on Round Bush Lane, Primrose Lane and Radlett Road or a nearby road, we can help. If you’re just outside Round Bush, we cover Aldenham (1 mile west), Kemprow (1 mile north), Patchetts Green (1 mile south-west), Letchmore Heath (1 mile south-east) and Radlett (1 mile north-east). Further out, we also cover Hemel Hempstead (7 miles north-west), St Albans (6 miles north), Welwyn Garden City (11 miles north-east), Harpenden (10 miles north), Hoddesdon (15 miles east) and Cheshunt (13 miles east).
Local landmarks in Round Bush
Typical jobs here are in homes near Garston Park, Three Compasses Public House and Queens' School and the streets around them. For rail, the closest station is Radlett station, about 1.5 miles north-east of the centre. Nearby you will also find Radlett and District Museum (1.4 miles north-east) and Shenley Hospital (2.7 miles north-east). The countryside around Round Bush includes Stanmore Common.
How the visit works
Our applicators work methodically: protection first, then preparation, sealing and a tidy-up. For most jobs that takes a few hours to a few days, depending on the length of joint and the access. Somewhere as small as Round Bush, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- We inspect the joints and agree which need resealing and how they’ll be reached.
- The old mastic and anything lodged in the joint is removed.
- 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.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
Preparing for the visit
- Where the joints are inside, avoid wetting them before we arrive
- Tell us about access, such as stairs, a lift or high-level joints
- Tell us about any water getting in
Ask for a quote
Getting a quote is simple: let us know what needs doing and where, and roughly how big it is. Photos by email help us understand the job, and we’ll come back to you with a quote.
Related advice
Do you need external mastic in Round Bush?
If plants are growing out of a joint, the sealant has normally failed or was never there. Roots and dirt hold water against the wall and speed up the damage.
Common reasons people contact us are:
- Brick movement joints where the sealant has split
- Moss and dirt in joints with no sealant left
- Old sealant gone brittle and cracked
- Cracked joints where brick meets render or frames
Schools such as Fair Field Junior School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
Comparing quotes
- Whether the sealant suits the joint
- Whether you can choose the colour
- How the surfaces are prepared before sealing
- What the cure time is