Hertfordshire · England
External Mastic in Garston
Our applicators work in Garston on sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly.
- Failed seals between different materials
- Brick movement joints where the sealant has split
- Plants rooting in failed movement joints
What we do, step by step
At the end, we look at the finished work together and tell you how long to leave it. The work normally takes anything from a few hours to several days, depending on the building, depending on the size of the job. For a job in Garston, we agree the time, the access and parking before the day. If the work is outside, the weather plays a part, as sealant needs a dry surface.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- The faces are brushed clean and primed where the product requires it.
- We fit closed-cell backing rod to control the depth.
- The exterior sealant is applied, tooled and checked along its length.
Before we arrive
- Tell us if parking is tricky
- Mention if the joints have been sealed before
- Keep pets and children clear of the area while we work
Get a quote
We quote each job on its own. Just ring 0345 464 0079 or drop us an email with the details, and photos are welcome.
Advice
External mastic in Garston
We are ARBOMaster approved applicators, and each external joint gets a sealant suited to it. Porous or awkward surfaces are primed where the sealant needs it. If you’re dealing with failed seals between different materials and panel joints letting water in, we can help, whatever the surface.
In a smaller place like Garston, some homes face open ground, and walls and rooflines facing the weather take the worst of it. Joints on those sides are normally the first to go.
All of our work is guaranteed for twelve months.
- Where
- Garston (WD25, WD24, AL2)
- Wider area
- Hertfordshire
- Guarantee
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Keeping the joints in good condition
No joint lasts for ever, but care makes a real difference. Our tips:
- Leave the joints unpainted unless we’ve said otherwise
- Never let anyone fill a movement joint with mortar
- Fix overflowing gutters above sealed joints
- Act on the first splits you see
Follow the cure time we give you before the joint is knocked or disturbed. The surface skins over quickly, but full cure takes longer.
A joint that has stopped moving pushes the movement elsewhere, often as cracks near the joint. Catch it early and you reduce the risk.
What affects the cost of external mastic
We don’t publish a price list, because jobs vary so much. What we look at:
- The amount of work
- The product the joint needs
- Whether old sealant or filler has to be cut out
- When we can work, for business premises
No two jobs are quite the same, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all play a part.
Helping us quote
Photos by email are helpful but not essential. Try to tell us:
- Photos by email, if that’s easy
- The rough size of the job
- Any previous sealing or DIY work
- If it’s domestic, commercial or a hotel
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is. When it suits you, call 0345 464 0079 or send us an email.
More services for Garston
Walls and rooflines in Garston
With historic houses such as High Elms Manor (about 1 mile north-west) nearby, there’s older building stock in the area around Garston as well as newer homes. In older buildings, 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, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
In the older streets around Stanborough Park Church, an extension built onto an older house moves differently, and the joint between them takes the strain. For landlords with property near Garston station, split movement joints are easy to miss on a rental until damp shows inside.
Garston is about 2 miles north of Watford, in Hertfordshire. Whether you are in the middle of Garston or further out, external mastic is available for homes and businesses alike, from flats and houses to offices and hotels. Our Hertfordshire coverage runs to 381 places, Garston among them. You can also see our page for London, about 18 miles away.
All of WD25, WD24 and AL2 is within our area for external mastic. Whether your property is on First Avenue, Third Avenue and Fifth Avenue or a nearby road, we can help. If you are just outside Garston, we cover Meriden (1 mile south), Leavesden (1 mile north-west), North Watford (1 mile south), Aldenham (2 miles south-east) and Watford (2 miles south). We also work in nearby towns such as Hemel Hempstead (6 miles north-west), St Albans (5 miles north-east), Welwyn Garden City (11 miles north-east), Harpenden (9 miles north), Cheshunt (14 miles east) and Hatfield (8 miles north-east).
Local landmarks in Garston
Locally, jobs take us to homes and businesses close to Francis Combe Academy and Garston Park. There’s a railway station in Garston itself: Garston station. Well-known places in the area include Leavesden Hospital (1.4 miles north-west) and Charter Place (2.3 miles south). For a walk, there’s Longspring Wood and Verulamium Lake.
Common problems we fix in Garston
If plants are growing out of a joint, the sealant has generally failed or was never there. Dirt and roots then trap moisture in the joint and speed up the damage.
People generally contact us after spotting something like this:
- Movement joints filled with mortar instead of sealant
- Failed seals between different materials
- Damp patches traced to an open external joint
- Moss and dirt in joints with no sealant left
Schools such as The Grove Academy are buildings too, and movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Before booking anyone
- Is VAT in the price?
- Whether the sealant suits the joint
- Whether you can choose the colour
- What the cure time is
Surface by surface
Concrete and blockwork
Big joints in concrete need careful depth control. Backing rod sized to the joint sets it.
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.
Garston questions
Is Garston in your area for external mastic?
Yes. We work across London and the South East, and Garston is part of that. Just call 0345 464 0079 or drop us an email with a few details of the job, and we’ll send you a clear quote.
Is Garston 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.
Do you work at height?
That depends on how high the joints are and the ground below. Low-level joints are straightforward; for higher work, tell us about the building and we’ll confirm what’s needed.
How much does external mastic cost in Garston?
There’s no set price, as it depends on the job: how much there is, what’s there now, how we reach it and what it needs. You’ll get a clear quote before we start.
Can a movement joint be filled with mortar?
No. Rigid materials cannot move with the wall. Where a joint has been mortared, it can often be raked out and sealed properly.
Will the old sealant be removed?
Yes. We cut out all the old sealant and clean the joint before resealing.
Do I need to be at home?
If the work is inside, we need someone to let us in. Once we’ve agreed the job, you do not need to watch us work.
What do you need from me for a quote?
The location, the problem and the rough size of the job. If you can, email a few photos.
Honest limits
Honest advice matters more to us than a booking, so here’s what new sealant won’t do:
- Adding movement joints to masonry that has none
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Cracking across the wall rather than at a joint
If you are not sure, just phone 0345 464 0079 or drop us an email and we will give you a straight answer before you book.
Surfaces we seal
- Copings & trims
- Concrete & block
- Render & cladding joints
- Brickwork movement joints
- Façade panels
- Joints between brick and frames
Why deal with it now?
Resealing a run of joints in one go is usually better than patching one at a time. They’ve weathered the same way, and access only has to be arranged once. In an older home around Garston, damp from a failed joint can get into timber and plaster, which is far harder to put right than the sealant itself.
Leaving a failed joint usually makes the job bigger, not smaller. If you are unsure, ring 0345 464 0079 or email us for an honest opinion and a quote.
Why us?
- Approved under the ARBOMaster scheme
- We leave the area clean and tidy
- Old sealant always removed completely
- Full insurance on every job