Hertfordshire · England
External & façade joints in Newnham, Hertfordshire
External mastic across Newnham and nearby, with old sealant always removed completely and a 12-month guarantee.
- Movement joints filled with mortar instead of sealant
- Hard, crazed mastic that has stopped moving
- Water getting into walls through failed joints
External mastic in Newnham
Many failed façade joints only get noticed once there’s a stain or a damp patch inside. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a colour to suit. We work on brickwork movement joints, concrete & block and copings & trims, and people most often call us about sealant pulling away from one side of the joint and weathered mastic that no longer stretches.
In a village or hamlet like Newnham, older cottages and farm buildings often stand in the open, where walls and rooflines take the weather head on. Joints on those walls need a sealant that moves with the building and stays in place.
Our work is backed for twelve months, and the guarantee is the same wherever you are.
- Place
- Newnham (SG7)
- Wider area
- Hertfordshire
- Cover
- A year, on every job
- Quotes
- A clear price before we start
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Common problems we fix in Newnham
Sometimes a movement joint was filled with mortar or a rigid filler, often by someone who didn’t know what it was for. With the joint locked solid, the movement turns into cracks elsewhere in the wall.
Keep an eye out for any of the following:
- Brick movement joints where the sealant has split
- Rigid filler in a joint that should flex
- Failed seals between different materials
- Joints where the bead has come unstuck
If you live in an older home near Church of St Vincent, the joints between older walls, newer extensions and the roofline need a sealant that can move.
What to look for in a quote
- Is the old sealant removed completely?
- What the cure time is
- Whether the sealant suits the joint
- What preparation is included
Keeping the joints in good condition
Good habits help new joints last longer. A few tips:
- Keep water from gutters off the wall
- Check external joints each spring
- Clear growth from the base of walls and joints
- Check the sealant is paintable before painting near it
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, often as cracks near the joint. Resealing it early helps prevent that.
DIY versus a professional finish
If you are set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it fails, we can still redo it.
The biggest DIY mistake is sealing over old sealant. Silicone doesn’t stick to old silicone, so it lifts and traps water and mould underneath. All the old material has to come out first.
What happens on the day
You do not need to clear the whole room or building, just the space around the work. We protect the rest, and the job takes anything from a few hours to several days, depending on the building in most cases. In a small place like Newnham, access is normally the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First, the joints are inspected and the access agreed.
- 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.
Before we arrive
- Mention any sign-in or site rules at work premises
- Where the joints are inside, avoid wetting them before we arrive
- Mention any tricky access
Getting a quote
For external mastic in Newnham, ring 0345 464 0079 or drop us an email. A short description of the job and where it is helps us quote, and you’ll get a clear quote before any work starts.
Related advice
Work for landlords, hotels and businesses
Hotels need rooms back in use, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance.
When something else is needed
It helps to know what we can’t do too:
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Cracks in the bricks or render themselves, away from the joints
- Structural movement, which needs a surveyor or engineer
Not sure which it is? You can ring 0345 464 0079 or drop us an email and we will tell you honestly before booking.
What we seal
- Façade panels
- Concrete & block
- Copings & trims
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
Questions from Newnham
Is Newnham within the area you cover?
Yes, we do. Our work covers London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
I let a flat near Baldock station. Can you help?
Yes, landlords and agents are among the people we work for, and several properties can be quoted together. Just phone 0345 464 0079 or drop us an email with the address and what needs doing, and we’ll give you a clear price.
Do you work for hotels and businesses?
Yes. We work in offices, washrooms, hotels and other commercial premises. Working times can be discussed when we quote.
How much does external mastic cost in Newnham?
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.
Can you seal over the old sealant?
No. We remove every bit of old sealant first, so the new joint bonds to clean surfaces.
How long before the joint can be used?
It depends on the product. We tell you how long to leave it before we go.
How do you reach high-level joints?
It depends on the building. Where joints can be reached safely, we will do them. Give us some details and we’ll confirm the access.
Can you match the colour of my brickwork?
We aim for a joint that suits the wall rather than one that jumps out. Colour is agreed with you before we begin, matched as closely as the range allows.
Places near Newnham
Other services in Newnham
What the job involves on each surface
Copings and trims
Joints in copings, parapets and trims are exposed to the worst of the weather. Each is resealed with a weatherproof, flexible sealant.
Concrete and blockwork
The face of concrete or block is often dusty, so preparation is key. We prime where the sealant needs it before the bead.
Walls and rooflines in Newnham
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. Historic houses like Hinxworth Place (about 1.4 miles north) are a reminder that the area around Newnham has older buildings as well as new. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth.
Managing a site like The Knights Templar School? Then its movement joints, gutters and trims need looking after like any other building’s. For landlords with property near Baldock station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Newnham is about 3 miles north-east of Letchworth, in Hertfordshire. For external mastic in and around Newnham, please call 0345 464 0079 or email us for a quick quote. We are based in Crawley and cover Hertfordshire, Newnham included. Newnham is one of 381 places in Hertfordshire we cover for external mastic. There’s also a page for Chelmsford, about 35 miles away.
All of SG7 is within our area for external mastic. You will find streets such as Ashwell Road and Caldecote Road, and we cover them all. If you’re just outside Newnham, we cover Caldecote (1 mile north-west), Bygrave (2 miles south-east), Ashwell End (2 miles north), Bury End (2 miles north) and Ashwell (2 miles north-east). Larger places within reach include Stevenage (8 miles south), Welwyn Garden City (15 miles south), Hitchin (6 miles south-west), Letchworth (4 miles south-west), Letchworth Garden City (4 miles south-west) and Benslow (6 miles south-west).
Near you in Newnham
Newnham’s nearest station is Baldock station, about 2 miles south of the centre. Nearby you will also find Bygrave House (1.5 miles south-east) and Fairfield Hospital (3 miles south-west). The countryside around Newnham includes Arlesey Old Moat and Glebe Meadows.