Hertfordshire · England
Chorleywood External Mastic
External mastic in Chorleywood from a team with over 20 years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Sealant pulling away from one side of the joint
- Water getting into walls through failed joints
- Leaking joints around cladding and façade panels
About our external mastic in Chorleywood
Movement joints let brickwork, render and cladding expand and shrink without cracking. The sealant in it has to stretch and squeeze for years, and when it fails, the wall takes the strain and water finds a way in. We work on render & cladding joints, brickwork movement joints and façade panels, and people most often call us about sealant that has lost its bond to the brick or render and hard, crazed mastic that has stopped moving.
Homes around Chorleywood range from older cottages to newer houses, with walls and rooflines of every type. Older homes need their gutter and trim joints kept tight, newer ones their movement joints.
We stand behind the work with a 12-month guarantee.
- Where
- Chorleywood (WD3)
- Region
- Hertfordshire
- Guarantee
- One year on every job
- Quote
- A clear price before work begins
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
How it works
Once we are on site, we check the joints match what you told us. If anything is different, we explain it before carrying on. Most jobs then take anything from a few hours to several days, depending on the building. Parking around Chorleywood is usually easier than in a town centre, but mention any lanes, gates or long drives. If the job is outside, tell us about side access and how high the joints are.
- First we look over the joints with you, agree which to renew and talk through access.
- The old mastic and anything lodged in the joint is removed.
- The joint faces are cleaned and primed where the sealant needs it.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
How to prepare
- Mention any leaks or damp you’ve noticed
- Keep pets and children clear of the area while we work
- Tell us about access, such as stairs, a lift or high-level joints
Getting a quote
For a quick quote, get us on the phone, or send an email if you’d rather. Tell us about the joints that need doing and we’ll talk you through the work before giving you a price.
Related advice
Common questions in Chorleywood
Do you cover smaller places like Chorleywood?
Yes, we do. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Is Chorleywood in your area for external mastic?
Yes. We work across London and the South East, and Chorleywood is part of that. Just phone 0345 464 0079 or email us with a few details of the job.
Should I point up the gap in my brickwork?
No. Cement or mortar can’t stretch, so the joint stops doing its job. Where a joint has been mortared, it can often be raked out and sealed properly.
Is it OK to seal over old sealant?
No. Fresh sealant doesn’t stick to old sealant, and anything trapped underneath, including mould and water, stays there. It all has to come out first.
Are you an approved applicator?
Yes. We are ARBOMaster approved, the scheme for applicators of Arbo sealants.
Do you remove the old sealant?
Yes. Sealing over old sealant is the main reason resealing fails early, and it’s something we never do.
Do you guarantee your work?
Yes. Each job is guaranteed for twelve months, wherever you are.
Does someone need to be in?
We need access to the joints, so we’ll agree that with you when we book. For inside work, that normally means someone being in.
Should I try it myself first?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and getting the depth right matters as much as the look.
Honest limits
Before you book, it’s worth knowing the limits too:
- Failed render or damaged cladding panels
- Damp that is not coming from the joint
- Cracked brickwork or render that needs a builder or plasterer
If you are not sure, just phone 0345 464 0079 or send us an email and we’ll give you a straight answer before you book.
Surfaces we seal
- Brickwork movement joints
- Façade panels
- Copings & trims
- Joints between brick and frames
- Concrete & block
- Render & cladding joints
For landlords and businesses
In hotels, rooms out of use cost money, so the work can be planned room by room. We have worked in hotels as well as homes and businesses.
Water getting past a failed joint can damage the building, which matters even more when someone else lives there. Resealing at the right time is simple maintenance that we can handle for you.
How to look after the new joints
After the cure time, these simple habits help:
- Keep soil, plants and ivy away from the joints
- Walk round the building once a year and look at the joints
- Avoid pressure-washing directly into sealant joints
- Make sure movement joints aren’t pointed over
Give the sealant the cure time we tell you before anything rubs against it. The surface skins over quickly, but full cure takes longer.
Gaps, plants or missing sealant in a joint are worth getting looked at. Earlier resealing means a smaller job and a better result.
Common problems we fix in Chorleywood
Many joints fail because they were sealed too deep or with nothing behind them. If the sealant sticks to the back as well as the sides, it can’t stretch and rips as the joint opens.
These are the problems we’re asked about most:
- Brick movement joints where the sealant has split
- Water getting into walls through failed joints
- Old sealant gone brittle and cracked
- Rigid filler in a joint that should flex
Rented homes near Chorleywood station change hands often, and failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Questions to ask before you book
- Who does the work, and how experienced they are
- Whether they’re fully insured
- What guarantee comes with the work
- What the cure time is
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. We choose the product to suit.
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.
Walls and rooflines in Chorleywood
London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. With historic houses such as Chenies Manor House (about 2.1 miles north-west) nearby, there’s older building stock in the area around Chorleywood as well as newer homes. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth.
If you look after a building such as Christ Church Chorleywood CofE School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. Homes close to Christ Church include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant.
Chorleywood is about 5 miles west of Watford, in Hertfordshire. Homes, rented property, offices and hotels in Chorleywood can book us for external mastic, old or new, large or small. The work is guaranteed for a year. Our Hertfordshire coverage runs to 381 places, and Chorleywood is one of them. London is on our list too, around 20 miles away.
All of WD3 is covered for external mastic. Streets in the area include South Cottage Drive, South Cottage Gardens and South Park Avenue, all of which we cover. Being close to the A404, Chorleywood is simple for us to get to for external mastic. If you’re just outside Chorleywood, we cover Heronsgate (1 mile south-west), Maple Cross (2 miles south), Chenies (2 miles north-west), Horn Hill (2 miles south-west) and West Hyde (3 miles south). We also work in nearby towns such as Watford (5 miles east), Hemel Hempstead (7 miles north), St Albans (10 miles north-east), Harpenden (13 miles north-east), Hatfield (14 miles north-east) and Borehamwood (10 miles east).
Near you in Chorleywood
We work in homes and buildings around St Clement Danes School, Rickmansworth Park and Black Horse Artichoke Dell pub, among other places. For rail, the closest station is Chorleywood station, about 0.7 miles west. A little further out are Harefield Hospital (3.2 miles south) and Chiltern Open Air Museum (2 miles south-west). Green spaces nearby include Chorleywood Common and Tumbling Bay.