Hertfordshire · England
External & façade joints in Farnham, Hertfordshire
We cover Farnham for sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly.
- Brick movement joints where the sealant has split
- Joints pointed up with cement by mistake
- Sealant that has lost its bond to the brick or render
DIY versus a professional finish
The biggest DIY mistake is sealing over old sealant. Silicone does not stick to old silicone, so it peels away and traps moisture behind it. All the old material has to come out first.
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
How we handle external mastic in Farnham
We’re ARBOMaster approved applicators, and each external joint gets a sealant suited to it. Porous or awkward surfaces are primed where the sealant needs it. We work on copings & trims, joints between brick and frames and concrete & block, and common reasons people get in touch are moss and dirt in joints with no sealant left and rigid filler in a joint that should flex.
In a village or hamlet like Farnham, older cottages and farm buildings often stand in the open, 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.
Every job is covered by our 12-month guarantee.
- Place
- Farnham (CM23)
- Region
- Hertfordshire
- Cover
- A year, on every job
- Quotes
- A clear price before we start
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
What happens if it’s left?
It often makes sense to reseal all the failing joints on an elevation together. They’ve weathered the same way. In a small place like Farnham, homes can be exposed to wind and rain, which finds any gap, and damp in older walls is slow to dry out.
Rather than a set price list, we look at what your job involves: how many joints, what’s in them now and how we reach them. You’ll know the price before we begin.
What you get with us
- White, clear, grey or coloured to suit, where the product allows
- Approved under the ARBOMaster scheme
- Colour picked to suit the job
- Colour agreed with you before work begins
Take a look at how sealant jobs are priced or customer reviews.
What happens on the day
We keep the work tidy and contained to the joints we are treating. Expect the work to take a few hours for a handful of joints, longer for a whole elevation, and we explain the cure time before we leave. In a small place like Farnham, access is normally the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We start by checking each joint, agreeing the ones to redo and how we’ll reach them.
- 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.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
Before we arrive
- Keep pets and children clear of the area while we work
- For business premises, tell us about site rules or sign-in
- Tell us about any previous sealing or DIY attempts
Ask for a quote
For a quote, ring 0345 464 0079 or email us with the location and a short description of the problem. We will give you a clear quote before any work starts.
Related advice
Do you need external mastic in Farnham?
Poor preparation causes many early failures: dusty or wet faces, no primer where one was needed, or old sealant left in. The sealant never bonds properly.
Most people get in touch after spotting one of these:
- Movement joints filled with mortar instead of sealant
- Leaking joints around cladding and façade panels
- Failed seals between different materials
- Weathered mastic that no longer stretches
For an older house near a landmark such as Church of St Mary the Virgin, an extension built onto an older house moves differently, and the joint between them takes the strain.
What to look for in a quote
- How much experience the applicator has
- What product goes in the joint
- Whether they seal over old material or remove it
- When the joint can take water or movement
For landlords and businesses
We also work for property managers and facilities teams. Several sites can be quoted together.
If you manage several properties in or around Farnham, several properties can be quoted together. Just tell us the addresses and what each one needs.
Honest limits
To be straight with you, there are a few things sealant will not fix:
- Loose or hollow render, which needs re-rendering
- Cracked brickwork or render that needs a builder or plasterer
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
If in doubt, ring 0345 464 0079 or drop us an email and we will say what we think before booking.
Joints and surfaces we work on
- Concrete & block
- Brickwork movement joints
- Façade panels
- Render & cladding joints
- Copings & trims
- Joints between brick and frames
How to look after the new joints
How long the joints last depends on use and care. Here’s what we suggest:
- Keep high-pressure jets off the joints
- Check external joints each spring
- Make sure movement joints aren’t pointed over
- Ask before painting over external sealant
Avoid pressure-washing straight into the joints. High-pressure water can lift the edges over time.
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.
Common questions in Farnham
Is Farnham in your area for external mastic?
Yes, Farnham is within the area we cover. Our work covers London and the South East. You can phone 0345 464 0079 or email us and let us know what needs doing, and we will give you a clear price.
Do you cover smaller places like Farnham?
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.
Can you seal joints between render and window frames?
Yes. The old joint is removed, both surfaces cleaned and primed where needed, and a flexible sealant applied. The colour is chosen to suit.
What is backing rod for?
Backing rod controls the sealant depth and keeps it off the back of the joint. Then the sealant bonds to two faces and can move.
Do you take out the old sealant first?
Yes. We cut out all the old sealant and clean the joint.
Is it OK to seal over old sealant?
No. New silicone will not bond to old silicone, and anything trapped underneath, including mould and water, stays there. We remove it all first.
What does external mastic cost?
Every job is different, so each one gets its own quote. For a quick quote, call 0345 464 0079 or email us with a short description of the job.
How often do external joints need resealing?
It depends on the exposure, the movement and the product. Treat it as a maintenance item and look at it yearly and reseal when it splits.
What external mastic looks like in Farnham
Historic houses like Much Hadham Palace (about 4.2 miles south-west) are a reminder that the area around Farnham has older buildings as well as new. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth. 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.
Schools such as Farnham Church of England Primary School are buildings too, and movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. If you let a flat or house near Stansted Mountfitchet station, split movement joints are easy to miss on a rental until damp shows inside.
Farnham is about 2 miles north of Bishop's Stortford, in Hertfordshire. From the centre of Farnham to the outskirts, external mastic is available for homes and businesses alike, from flats and houses to offices and hotels. Our area takes in 381 places across Hertfordshire. We also work in Chelmsford, around 19 miles away.
Work in CM23 is quoted and booked the same way as anywhere else. We also cover Uppend (1 mile north), Mount Pleasant (1 mile north), Manuden (2 miles north-east), Bentfield Green (2 miles east) and Stansted Mountfitchet (2 miles east). Larger places within reach include Stevenage (14 miles west), Hoddesdon (12 miles south-west), Hertford (12 miles south-west), Ware (10 miles south-west), Baldock (15 miles north-west) and Broxbourne (13 miles south-west).
Landmarks near Farnham
In Farnham, that means homes and buildings near St Mary's Catholic School. The nearest railway station is Stansted Mountfitchet station, roughly 2.4 miles east. A little further out are Moated mound (1.7 miles south-west) and Herts and Essex Hospital (2.8 miles south-east). Green spaces nearby include Portingbury Hills and Aubrey Buxton Nature Reserve.