Hertfordshire · England
Bishop's Stortford External Mastic
External mastic for Bishop's Stortford, by sealant specialists with 20+ years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Rigid filler in a joint that should flex
- Leaking joints around cladding and façade panels
- Sealant that has lost its bond to the brick or render
Why deal with it now?
A failed movement joint lets water into the wall, behind render and cladding. Dealing with it early keeps the repair to the joint, instead of the wall and finishes around it. Draughts from a gap round a frame, damp under a sill or water behind a bath panel all start small, and they’re far easier to fix early.
Instead of a standard rate, we look at what your job involves: how many joints, what’s in them now and how we reach them. You will know the price before we begin.
Why us?
- Experience in homes, commercial sites and hotels
- An ARBOMaster approved applicator
- Sealant colour chosen to suit
- You choose the colour before work begins
Take a look at our cost guide or what customers say.
External mastic for homes and businesses in Bishop's Stortford
A movement joint is only as good as its depth. Backing rod controls how deep the sealant goes and keeps it off the back of the joint, so it bonds to the two sides only and can stretch. If you’re dealing with rain getting behind render or cladding at a joint and plants rooting in failed movement joints, we can help, on concrete & block, copings & trims and joints between brick and frames alike.
Bishop's Stortford mixes older houses and their gutters with newer estates of brick, render and uPVC trims. All of those joints move, so they need a flexible sealant rather than a rigid filler.
You get a one-year guarantee, the same in Bishop's Stortford as everywhere else we work.
- Where
- Bishop's Stortford (CM23, CM22)
- Region
- Hertfordshire
- Guarantee
- A year, on every job
- Quote
- A clear quote up front
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Honest limits
New sealant can’t fix everything, and we will tell you before any work starts. It won’t solve:
- Structural movement, which needs a surveyor or engineer
- Cracked brickwork or render that needs a builder or plasterer
- Render that’s blown, hollow or coming away
If in doubt, phone 0345 464 0079 or send us an email and we’ll say what we think before you book.
Joints and surfaces we work on
- Concrete & block
- Joints between brick and frames
- Render & cladding joints
- Copings & trims
- Brickwork movement joints
- Façade panels
What happens on the day
A visit follows a simple pattern: we look at the joints together, protect the area around them, do the work and clear up. Most jobs take anything from a few hours to several days, depending on the building. In Bishop's Stortford, parking is rarely complicated, though it helps to know about driveways or restrictions, and mention if the work is upstairs, in a flat or high on the outside.
- First we look over the joints with you, agree which to renew and talk through access.
- We cut out the failed sealant and rake out any dirt or growth.
- We clean both faces of the joint and prime them where the product calls for it.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- We gun in a flexible exterior sealant in a colour that suits the wall and tool it neatly.
How to prepare
- On commercial sites, let us know about site rules
- Plan for the work area to be out of bounds to pets and children
- For indoor joints, keep the area dry beforehand if you can
Get a quote
Need a quote? Please call 0345 464 0079 or email us and tell us about the job. You’ll know what we plan to do, and what it will cost, before any work begins.
Advice
How to look after the new joints
Joint life depends on how it’s used and looked after. We suggest:
- Tell anyone working on the walls about the movement joints
- Walk round the building once a year and look at the joints
- Clear growth from the base of walls and joints
- Leave the joints unpainted unless we have said otherwise
Follow the cure time we give you before the joint is knocked or disturbed. Most exterior sealants skin fast but take longer to cure right through.
Act while the splits are small. At that stage it’s a simple cut out and reseal.
Should I try it myself first?
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly, so just mention it when you contact us.
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Do you need external mastic in Bishop's Stortford?
Sunlight, wet weather and frost wear exterior sealant down. Over the years it hardens, cracks on the surface and loses its give, so the joint eventually tears or comes away from one side.
These are the problems we are asked about most:
- Water getting into walls through failed joints
- Weathered mastic that no longer stretches
- Movement joints filled with mortar instead of sealant
- Joints with sealant missing in places
If you live in an older home near Church of St Michael, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Before you book anyone
- What guarantee comes with the work
- Is the old sealant removed completely?
- What insurance they hold
- What the cure time is
Nearby places to Bishop's Stortford
What else we do in Bishop's Stortford
Bishop's Stortford questions
Do you cover Bishop's Stortford for external mastic?
Yes. We work across London and the South East, and Bishop's Stortford is part of that. Just ring 0345 464 0079 or drop us an email with a few details of the job.
What guarantee comes with external mastic in Bishop's Stortford?
All our work, in Bishop's Stortford and everywhere else, comes with a 12-month guarantee. We are fully insured, and an ARBOMaster approved applicator.
What is backing rod for?
We fit closed-cell backing rod wherever the joint depth needs controlling. It sets the sealant depth and prevents three-sided bonding, so the joint can move.
How long does external mastic last?
It varies from wall to wall: joints on exposed walls or with a lot of movement age sooner. A yearly look will tell you when they need doing. Our work comes with a 12-month guarantee.
Do you hold any approvals?
Yes. We’re approved under the ARBOMaster scheme, the approved applicator scheme for Arbo sealants.
What’s an expansion joint in brickwork?
Most straight vertical gaps in brickwork are movement joints. It gives the wall room to move and needs a flexible seal, not mortar.
Can a movement joint be filled with mortar?
No. Cement or mortar can’t stretch. If it has already been filled, we can usually cut it out and reseal it.
How long before the joint can be used?
Many sealants skin over quickly but take longer to cure fully. We will give you the cure time for the product we used.
What the job involves on each surface
Concrete and blockwork
The face of concrete or block is often dusty, so preparation is key. A primer goes on where the product requires one.
Cladding and façade panels
Cladding and façade panels are normally separated by sealed joints. Each joint gets a sealant that suits the panel and its movement.
Walls and rooflines in Bishop's Stortford
Historic houses like Much Hadham Palace (about 3.6 miles west) are a reminder that the area around Bishop's Stortford has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material. Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Schools such as St Michael's Church of England Primary School are buildings too, and its movement joints, gutters and trims need looking after like any other building’s. Rented homes near Bishops Stortford station change hands often, and outside joints that have cracked can let damp into a rental, so check them between lets.
Bishop's Stortford is in Hertfordshire. Whether you are in the middle of Bishop's Stortford or further out, external mastic is available for homes and businesses alike. Our Hertfordshire coverage runs to 381 places, Bishop's Stortford among them. There’s also a page for Chelmsford, roughly 17 miles from Bishop's Stortford.
Every address in CM23 and CM22 is within our area for external mastic, from the main roads to the quietest streets. Local streets include Market Street, High Street and Station Road, all of which we cover. Bishop's Stortford sits on or near the A120 and A1059. Neighbouring places we cover for external mastic include Thorley Street (1 mile south), Thorley (1 mile south-west), Birchanger (2 miles north-east), Great Hallingbury (2 miles south-east) and Bury Green (2 miles west). Larger places within reach include Stevenage (15 miles west), Hoddesdon (11 miles south-west), Cheshunt (14 miles south-west), Hertford (11 miles south-west), Ware (9 miles south-west) and Broxbourne (11 miles south-west). Bishop's Stortford is among the bigger towns we cover in Hertfordshire.
Near you in Bishop's Stortford
Locally, jobs take us to homes and businesses close to The Port Jackson pub and St Mary's Catholic School and the streets around them. There’s a railway station in Bishop's Stortford itself: Bishops Stortford station. A little further out are Herts and Essex Hospital (0.8 miles east) and Moated mound (2.4 miles north-west). Not far away are Rushy Mead and Portingbury Hills.