Hertfordshire · England
External Mastic in Sarratt
Sealing brickwork movement joints, render, cladding and façade joints for homeowners, landlords and businesses in Sarratt. Fully insured, ARBOMaster approved and guaranteed for a year.
- Weathered mastic that no longer stretches
- Leaking joints around cladding and façade panels
- Rigid filler in a joint that should flex
Can I do it myself?
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly, so tell us about it when you ask for a quote.
External mastic for homes and businesses in Sarratt
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible sealant bridges the two where a rigid filler would soon crack. We’re often asked to deal with weathered mastic that no longer stretches and joints pointed up with cement by mistake, on render & cladding joints, joints between brick and frames and copings & trims.
Somewhere as small as Sarratt, homes and farm buildings often face open ground, so walls and rooflines take the full force of wind and rain. Joints on those walls need a sealant that moves with the building and stays in place.
Big or small, it’s backed by our one-year guarantee in Sarratt and across Hertfordshire.
- Place
- Sarratt (WD3)
- Wider area
- Hertfordshire
- Cover
- One year on every job
- Quote
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Questions from Sarratt
Can you do external mastic in Sarratt?
Yes, Sarratt is within the area we cover. We work across London and the South East. You can ring 0345 464 0079 or drop us an email and let us know what needs doing.
Can you help a landlord with a rental near Chorleywood station?
Yes, we work for landlords and agents. Just call 0345 464 0079 or email us and tell us about the property, and we’ll send you a clear quote.
Are you fully insured?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
Do you guarantee your work?
Yes. Each job is guaranteed for twelve months, wherever you are.
What sealant do you use?
We choose the sealant for the joint, not the other way round. Where it moves, gets wet or faces the weather makes a difference, and we will explain our choice.
Will there be a smell?
That depends on the sealant. Some products have a noticeable smell, others very little.
Do you take out the old sealant first?
Always. Sealing over old sealant is the main reason resealing fails early, and it’s something we never do.
What is a movement joint?
It’s a deliberate gap that lets the wall expand and contract without cracking. It should be filled with flexible sealant, never mortar.
Honest limits
To be straight with you, there are a few things sealant won’t fix:
- Render that’s blown, hollow or coming away
- Cracked brickwork or render that needs a builder or plasterer
- Damp that isn’t coming from the joint
Not sure which it is? You can ring 0345 464 0079 or drop us an email and we’ll tell you honestly before you book.
Joints and surfaces we work on
- Concrete & block
- Façade panels
- Brickwork movement joints
- Joints between brick and frames
- Copings & trims
- Render & cladding joints
How the visit works
On the day, there’s very little for you to do. Show us the job and we will take it from there. The work itself takes a few hours for a handful of joints, longer for a whole elevation, including the tidy-up. In a small place like Sarratt, access is generally the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We start by walking round the building and agreeing the joints and the access.
- We cut out the old mastic and rake out anything in the joint.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
Getting ready for the visit
- For indoor joints, keep the area dry beforehand if you can
- On commercial sites, let us know about site rules
- Tell us about any water getting in
Ask for a quote
Asking for a quote is easy: tell us 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
Landlord and commercial work in Sarratt
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.
We also work for businesses, from offices to washrooms and kitchens. For commercial premises, we can talk through working times when we quote.
When to call us in Sarratt
Joints sealed without backing rod, or far too deep, rarely last. Sealant bonded to three sides has nowhere to go and rips as the joint opens.
The problems people generally mention when they call are:
- Movement joints with cracked, split or missing sealant
- Old sealant gone brittle and cracked
- Water getting into walls through failed joints
- Gaps where render, brick and frames meet
Managing a site like Sarratt Church of England Primary School? Then movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
What to look for in a quote
- Is VAT in the price?
- Whether all the old sealant comes out first
- What happens if the job turns out different
- Which colour the sealant will be
Also near Sarratt
More services for Sarratt
What happens if it’s left?
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 Sarratt, older homes often have timber in their floors and frames, and water through a failed joint can rot timber if it’s left.
Instead of a standard rate, we price the job in front of us: how many joints, what’s in them now and how we reach them. You will know the price before we begin.
Why Sarratt clients choose us
- We never seal over old sealant
- Anti-fungal silicone where joints get wet
- Tidy, careful work
- You choose the colour before work begins
Read how sealant jobs are priced or our reviews.
Looking after it afterwards
How long the joints last depends on use and care. We suggest:
- Don’t let climbing plants root in the sealant
- Keep water from gutters off the wall
- Check external joints each spring
- Make sure movement joints are not pointed over
Keep the joints clear of soil, plants and climbing growth. Damp material against the sealant shortens its life.
A joint that has stopped moving pushes the movement elsewhere, normally as cracking in the brickwork or render nearby. Resealing it early helps prevent that.
What external mastic looks like in Sarratt
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 Chenies Manor House (about 1.8 miles west) are a reminder that the area around Sarratt has older buildings as well as new. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
For an older house near a landmark such as Church of the Holy Cross, old and new materials meet at the roofline and walls, which is where sealant earns its keep. If you let a flat or house near Chorleywood station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Sarratt is about 3 miles north of Rickmansworth, in Hertfordshire. Every kind of property in Sarratt is covered for external mastic, old or new, large or small. The work is guaranteed for a year. 381 places in Hertfordshire are on our list. You can also see our page for London, roughly 21 miles from Sarratt.
Jobs for external mastic in WD3 is quoted and booked the same way as anywhere else. That includes homes and businesses on Alexandra Road, Downer Drive and The Briars and the roads around them. If you’re just outside Sarratt, we cover Micklefield Green (1 mile south-east), Bucks Hill (1 mile north-east), Chandler's Cross (2 miles south-east), Loudwater (2 miles south) and Chorleywood West (2 miles south). Further out, we also cover Watford (4 miles east), Hemel Hempstead (5 miles north), St Albans (8 miles north-east), Welwyn Garden City (15 miles north-east), Harpenden (11 miles north-east) and Hatfield (12 miles north-east).
Near you in Sarratt
Around Sarratt, our work takes us to homes and buildings near The Boot Public House and St Clement Danes School. Sarratt’s nearest station is Chorleywood station, roughly 2.3 miles south-west. A little further out are Chiltern Open Air Museum (3.8 miles south-west) and Leavesden Hospital (4 miles east). Green spaces nearby include Sarratt Bottom nature reserve and Tumbling Bay.