Hertfordshire · England
External & façade joints in Sandon, Hertfordshire
Sealing brickwork movement joints, render, cladding and façade joints for Sandon, backed by a one-year guarantee. Ask us for a quote.
- Movement joints filled with mortar instead of sealant
- Rain getting behind render or cladding at a joint
- Weeds or debris growing in open joints
External mastic in Sandon, done properly
As ARBOMaster approved applicators, we choose exterior sealants to suit the joint and the surfaces. Some surfaces need a primer before sealing, and we don’t skip that step. Common call-outs are for weathered mastic that no longer stretches and movement joints with cracked, split or missing sealant, across render & cladding joints, brickwork movement joints and copings & trims.
Outside joints can only be sealed when they’re dry, so work in Sandon is booked around the forecast. Let us know about access to every wall, plus any garages or outbuildings.
All of our work is guaranteed for twelve months, and the guarantee is the same wherever you are.
- Where
- Sandon (SG9)
- Wider area
- Hertfordshire
- Cover
- A year, on every job
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Different surfaces, different methods
Cladding and façade panels
Metal and composite panels move a lot with temperature, so the joint sealant has to cope with frequent movement. The sealant is chosen with that in mind.
Copings and trims
Coping and trim joints face rain and sun head on. We reseal them with an exterior sealant suited to the material.
Why act early in Sandon
Water gets in through a failed movement joint. Dealing with it early keeps the repair to the joint, instead of the wall and finishes around it. In a small place like Sandon, homes can be exposed to wind and rain, which finds any gap, and older walls, once damp, take a long time to dry.
We do not show prices on the website, because each job is priced on what it involves. Call for a quick quote and we will talk you through it.
Why choose Mr Mastic in Sandon
- We leave the area clean and tidy
- More than 20 years in sealant work
- Rated 4.9 stars on Google
- Sealant colour chosen to suit
Other services in Sandon
Aftercare tips
Good habits help new joints last longer. A few tips:
- Make sure movement joints are not pointed over
- Check the sealant is paintable before painting near it
- Look over the joints every year, ideally after winter
- Tell anyone working on the walls about the movement joints
Don’t let soil, plants or ivy build up against the new joints. Damp material against the sealant shortens its life.
An open movement joint lets rain into the wall every time it pours. Over time it can mean damp inside, stained render or frost-damaged brick which cost more to put right than the joint.
Quotes for external mastic in Sandon
There’s no set price list. What we look at:
- Which sealant suits the joint
- Whether the work is at height
- When we can work, for business premises
- The amount of work
Rather than a set price list, we price the job in front of us: how many joints, what’s in them now and how we reach them. You’ll know the price before we begin.
Helping us quote
You do not need to know the technical terms. It helps if you can tell us:
- What the problem is, such as mould, gaps, leaks or cracking
- The type of property
- Whether it has been sealed before
- How we’d reach the joints
Every job is quoted individually. Simply ring 0345 464 0079 or drop us an email and describe the job.
Should I try it myself first?
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
A DIY attempt doesn’t rule out a professional job. We cut it out and start again, so just mention it when you contact us.
What happens on the day
All our tools and materials come with us in the van, so you do not need to buy or prepare anything. After a quick look at the joints together, we protect the area and start. It normally takes a few hours to a few days, depending on the length of joint and the access. Somewhere like Sandon needs a little journey planning: let us know about lanes, gates and parking. Everything for the job comes with us, so a second trip is avoided where possible.
- 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.
- We clean both faces of the joint and prime them where the product calls for it.
- Backing rod goes in next, setting the depth and keeping the sealant off the back of the joint.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
How to prepare
- Mention any leaks or damp you’ve noticed
- Where the joints are inside, avoid wetting them before we arrive
- Clear items away from the joints we’re working on
Ask for 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 will explain what’s involved and give you a clear price.
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Walls and rooflines in Sandon
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.
Rented homes near Ashwell & Morden station change hands often, and outside joints that have cracked can let damp into a rental, so check them between lets. If you look after a building such as Sandon Junior Mixed and Infant School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Sandon is in Hertfordshire. Across the SG9 area, our applicators can take on external mastic. Our Hertfordshire coverage runs to 381 places, and Sandon is one of them. Our Chelmsford page covers work nearby, about 30 miles away.
All of SG9 is covered for external mastic, from the main roads to the quietest streets. Streets in the area include Payne End, Rushden Road and Dark Lane, all of which we cover. Other places close to Sandon include Roe Green (1 mile south-west), Green End (1 mile south-east), Rushden (2 miles south-west), Buckland (2 miles east) and Chipping (3 miles south-east). Further out, we also cover Stevenage (7 miles south-west), Bishop's Stortford (13 miles south-east), Welwyn Garden City (14 miles south), Hitchin (9 miles west), Hertford (13 miles south) and Letchworth (6 miles west).
Around Sandon
The closest station to Sandon is Ashwell & Morden station, about 2.9 miles north-west. Nearby you will also find Clothall Castle (3.5 miles south-west). Open spaces near Sandon include Hawkins Wood.
Sandon: your questions answered
Is Sandon within the area you cover?
Yes, we do. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Can you help a landlord with a rental near Ashwell & Morden station?
Yes, landlords and agents are among the people we work for. You can phone 0345 464 0079 or email us with the details for a clear quote.
Do you do commercial work?
Yes. We work in offices, washrooms, hotels and other commercial premises. Working times can be discussed when we quote.
What sealant do you use?
Products from Arbo and Everbuild, among others, chosen to suit the joint. We explain the product when we quote.
Are you ARBOMaster approved?
Yes. We are ARBOMaster approved, the scheme for applicators of Arbo sealants.
When is the sealant fully cured?
Different products cure at different speeds, so follow the cure time we give you.
How much does external mastic cost in Sandon?
The cost depends on the size of the job, access and how much old sealant has to come out. Ask us for a quote.
How long does external mastic take?
Most jobs take a few hours for a handful of joints, longer for a whole elevation, including preparation and clearing up. Your quote will say how long we expect yours to take.
What we’re called out for in Sandon
UV, rain and frost all age exterior sealant. In time it goes hard, crazes on the surface and stops stretching, so the next time the wall moves, it splits or pulls away.
Any of these means the joints need attention:
- Sealant pulling away from one side of the joint
- Rigid filler in a joint that should flex
- Water getting into walls through failed joints
- Brick movement joints where the sealant has split
In the older streets around Church of All Saints, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
What your quote should include
- How the colour is chosen
- How the joint is cleaned and prepared
- Whether the sealant suits the joint
- When the joint can take water or movement