Hertfordshire · England
External & façade joints in Bygrave, Hertfordshire
Specialist external mastic for Bygrave: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Failed sealant between panels on a façade
- Old sealant gone brittle and cracked
- Moss and dirt in joints with no sealant left
External mastic in Bygrave
Failed sealant is cut out, the depth set with closed-cell backing rod, and the joint resealed with a low-modulus sealant made for outside. The colour is chosen to suit the brick or render so the joint doesn’t stand out. Common call-outs are for failed seals between different materials and rain getting behind render or cladding at a joint, across façade panels, joints between brick and frames and render & cladding joints.
Outside joints can only be sealed when they’re dry, so work in Bygrave is booked around the forecast. Tell us about access to all sides of the building, including outbuildings and garages.
A one-year guarantee comes as standard.
- Place
- Bygrave (SG7)
- Wider area
- Hertfordshire
- Cover
- 12 months on all our work
- Price
- A clear price before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
How to look after the new joints
To keep the joints looking good and working properly:
- Do not let climbing plants root in the sealant
- Look over the joints every year, ideally after winter
- Act on the first splits you see
- Make sure movement joints aren’t pointed over
Have a quick look at the joints each spring. Watch for splits, edges coming away or growth in the joint.
Gaps, plants or missing sealant in a joint are worth getting looked at. Earlier resealing means a smaller job and a better result.
Nearby places to Bygrave
Other services in Bygrave
What we do, step by step
On the day, there’s very little for you to do. Show us the job and we will take it from there. The job generally takes a few hours for a handful of joints, longer for a whole elevation, including the tidy-up. Somewhere as small as Bygrave, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
How to prepare
- For business premises, tell us about site rules or sign-in
- Where the joints are inside, avoid wetting them before we arrive
- Keep children and pets away from the work area
Getting a quote
It all starts with a short chat. Describe the problem, the location and the size of the job. Whenever you’re ready, ring 0345 464 0079 or send us an email.
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How the job changes by surface
Joints between dissimilar materials
Brick against render, concrete against metal, stone against timber: every change of material is a joint. A flexible sealant bridges the two.
Render joints
Rendered walls have joints at beads, openings and changes of material. We reseal them with a flexible exterior sealant that suits the render colour.
Why it’s worth doing now in Bygrave
An open joint keeps letting water into the wall with every downpour. In cold weather, frost can damage wet brick and render near the open joint, so the damage spreads beyond the joint. Where a wall is exposed, as many are in small places like Bygrave, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
Instead of a standard rate, we price the job in front of us: the amount of work, the old material and the access. The price is agreed before we begin.
Why choose Mr Mastic in Bygrave
- We never seal over old sealant
- We leave the area clean and tidy
- An ARBOMaster approved applicator
- Domestic, commercial and hotel work
Do you need external mastic in Bygrave?
Buildings move more than people expect. Brickwork grows a little over the years, blockwork and concrete shrink, and all of it moves with heat and moisture. The sealant in the movement joints takes that strain.
Signs it’s time to call us include:
- Movement joints with cracked, split or missing sealant
- Panel joints letting water in
- Old sealant gone brittle and cracked
- Damp patches traced to an open external joint
For landlords with property near Baldock station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Questions to ask before booking
- Which sealant they’ll use, and why
- How long to leave it before use
- What happens if they find a problem under the old sealant
- How the surfaces are prepared before sealing
Can I do it myself?
Sealing over old silicone is the commonest DIY error. 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.
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.
What we can’t put right
To be straight with you, there are a few things sealant will not fix:
- Cutting new joints into brickwork, which is building work rather than sealant work
- Failed render or damaged cladding panels
- Movement that is more than a sealant joint can take
If in doubt, call 0345 464 0079 or send us an email and we will say what we think before booking.
Surfaces we seal
- Render & cladding joints
- Joints between brick and frames
- Brickwork movement joints
- Concrete & block
- Façade panels
- Copings & trims
Bygrave questions
Do you work for landlords with property near Baldock station?
Yes, rental work is part of what we do. Just ring 0345 464 0079 or send us an email and tell us about the property, and we’ll give you a clear quote.
Is Bygrave in your area for external mastic?
Yes, Bygrave is within the area we cover. We work across London and the South East. You can phone 0345 464 0079 or email us and let us know what needs doing, and we will send you a clear quote.
Will the new joint stand out?
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.
What is backing rod for?
The foam is closed-cell backing rod. It keeps the sealant at the right depth and bonded to the sides only so it can flex with the joint.
Will you leave a mess?
Tidy work is part of the job. We protect what’s around the joints.
Can you seal joints between render and window frames?
Yes. Materials like render, brick, metal and uPVC all move differently, so a flexible sealant is needed where they meet. We choose one that suits both surfaces.
What information do you need?
Tell us what needs doing and where, with photos by email if possible. If we need more, we will ask.
What do you put in the joint?
It depends on the joint: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. We use products from Arbo and Everbuild.
What external mastic looks like in Bygrave
With historic houses such as Hinxworth Place (about 2.9 miles north-west) nearby, there’s older building stock in the area around Bygrave as well as newer homes. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material. 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.
If you look after a building such as The Knights Templar School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. In the older streets around Church of St Margaret of Antioch, an extension built onto an older house moves differently, and the joint between them takes the strain.
Bygrave is about 3 miles north-east of Letchworth, in Hertfordshire. Our applicators cover external mastic for homes and businesses in Bygrave, as part of our work across Hertfordshire. Across Hertfordshire, we cover 381 places, and Bygrave is one of them. We also work in Chelmsford, about 33 miles from Bygrave.
Here we cover the SG7 postcode area for external mastic. You’ll find streets such as Wedon Way and Ashwell Road, all of which we cover. Neighbouring places we cover for external mastic include Newnham (2 miles north-west), Caldecote (2 miles north-west), Ashwell (3 miles north), Ashwell End (3 miles north) and Bury End (3 miles north). Further out, we also cover Stevenage (7 miles south), Welwyn Garden City (14 miles south), Harpenden (15 miles south-west), Hitchin (6 miles south-west), Hertford (15 miles south) and Letchworth (3 miles south-west).
Around Bygrave
The nearest railway station is Baldock station, about 1.3 miles south-west of the centre. Well-known places in the area include Fairfield Hospital (3.6 miles west) and Stotfold Watermill & Nature Reserve (2.5 miles west). The countryside around Bygrave includes Arlesey Old Moat and Glebe Meadows.