Hertfordshire · England
External Mastic in Baldock
Professional external mastic in and around Baldock, with old sealant always removed completely and a 12-month guarantee.
- Joints pointed up with cement by mistake
- Damp patches traced to an open external joint
- Joints where the bead has come unstuck
How we handle external mastic in Baldock
External mastic is a job where short cuts show quickly. Overfilled joints, missing backing rod and sealant laid over old sealant rarely last long. We take the old material out and do it properly. Common call-outs are for gaps where render, brick and frames meet and brick movement joints where the sealant has split, across brickwork movement joints, façade panels and concrete & block.
Homes around Baldock range from older cottages to newer houses, with walls and rooflines of every type. Older homes need their gutter and trim joints kept tight, newer ones their movement joints.
There’s a 12-month guarantee on every job, large or small.
- Where
- Baldock (SG7, SG6)
- Wider area
- Hertfordshire
- Cover
- One year on every job
- Quotes
- A clear price before we start
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Your questions about external mastic in Baldock
Is Baldock in your area for external mastic?
Yes. Our work covers London and the South East, and Baldock is part of that. Just ring 0345 464 0079 or drop us an email with a few details of the job.
Will you come out to Baldock?
Yes. Baldock is within the area we cover, which takes in towns, villages and rural addresses. We work across London and the South East. Just mention lanes, gates or anything else about the route when you book.
Where is Mr Mastic based?
We work from Crawley. We cover Baldock and the rest of Hertfordshire.
Will there be a smell?
Sometimes, a little. It fades as the sealant cures.
Can tenants book the work?
Yes, though it’s best to check with your landlord first. Landlords are often happy for the work to be arranged.
Do you hold any approvals?
Yes. We are approved under the ARBOMaster scheme, the approved applicator scheme for Arbo sealants.
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. We will confirm how long when we quote.
Do you work for letting agents?
Yes, regularly. We can quote for several properties at once, and between tenancies is a good time for the work.
Also near Baldock
Other services in Baldock
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is.
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
Common problems we fix in Baldock
Sunlight, wet weather and frost wear exterior sealant down. In time it goes hard, crazes on the surface and stops stretching, so the joint eventually tears or comes away from one side.
The most common problems we see are:
- Plants rooting in failed movement joints
- Rigid filler in a joint that should flex
- Brick movement joints where the sealant has split
- Leaking joints around cladding and façade panels
If you look after a building such as Hartsfield Junior Mixed and Infant School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
What your quote should include
- Is the old sealant removed completely?
- What the quote includes, VAT included or not
- How much experience the applicator has
- Are they insured?
How it works
Most of a good job is in the preparation, and we do not rush it. Joints are cleaned back and dried before anything new goes in. All told, the work takes a few hours for a handful of joints, longer for a whole elevation. For a job in Baldock, we agree the time, the access and parking before the day. Outdoor jobs depend on a dry day, since sealant needs a dry surface.
- We start by walking round the building and agreeing the joints and the access.
- Every bit of old sealant and any mortar or debris is cut out.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- We apply the sealant, tool it and check the whole run.
Getting ready for the visit
- Let us know about stairs, lifts or work at height
- Keep pets and children clear of the area while we work
- Mention any parking rules near the property
How to get a quote
Call for a quick quote, or email us if that’s easier. Tell us about the joints that need doing and we’ll explain what’s involved before giving you a price.
Read more
What sealant work can’t fix
Honest advice matters more to us than a booking, so here’s what new sealant will not do:
- Subsidence or other structural problems
- Loose or hollow render, which needs re-rendering
- Cutting new joints into brickwork, which is building work rather than sealant work
If in doubt, phone 0345 464 0079 or email us and we’ll say what we think.
What we seal
- Façade panels
- Brickwork movement joints
- Joints between brick and frames
- Concrete & block
- Copings & trims
- Render & cladding joints
What happens if it’s left?
Sealing over the top of old mastic does not hold for long. The new layer cannot bond properly to old, weathered material, so we always take the old sealant out. In a smaller place like Baldock, wherever a wall is exposed, a failed outside joint is a real source of damp. Inside, a split seal lets water into floors and panels just as it would anywhere.
There are no prices on our 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 Baldock
- Homes, businesses and hotels
- Over 20 years’ experience
- You choose the colour before work begins
- Anti-fungal sanitary silicone in wet areas
See how sealant jobs are priced and our reviews.
Walls and rooflines in Baldock
The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Historic houses like Hinxworth Place (about 3.6 miles north) are a reminder that the area around Baldock 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.
Rented homes near Baldock station change hands often, and failed wall and movement joints let damp in, so they’re worth checking between tenancies. In the older streets around Church of St. Mary the Virgin, an extension built onto an older house moves differently, and the joint between them takes the strain.
Baldock is about 2 miles north-east of Letchworth, in Hertfordshire. From the centre of Baldock to the outskirts, we cover external mastic for every kind of property. Across Hertfordshire, we cover 381 places, Baldock among them. You can also see our page for London, roughly 34 miles from Baldock.
Jobs for external mastic in SG7 and SG6 is quoted and booked the same way as anywhere else. Whether your property is on High Street, Station Road and London Road or anywhere close by, we can help. With the A507 and B197 close by, Baldock is simple for us to get to for external mastic. We also cover the places around Baldock: Clothall (2 miles south-east), Weston (2 miles south), Wallington (3 miles east), Rooks Nest (4 miles south) and St Nicholas (5 miles south). Larger places within reach include Stevenage (6 miles south), Welwyn Garden City (13 miles south), Harpenden (14 miles south-west), Hitchin (5 miles south-west), Hertford (14 miles south) and Ware (14 miles south-east).
Local landmarks in Baldock
Typical jobs here are in homes near Norton School, The Knights Templar School and The White Lion Public House. There’s a railway station in Baldock itself: Baldock station. A little further out are Fairfield Hospital (2.8 miles west) and First Garden City Heritage Museum (1.8 miles south-west). Open spaces near Baldock include Purwell Ninesprings.
Different surfaces, different methods
Concrete and blockwork
Blockwork and concrete shrink over time and move with the seasons. We reseal their joints with backing rod and a flexible product.
Brickwork movement joints
Clay brickwork grows slightly over its life and moves with the weather. That movement goes into the joint, so the sealant in it must stay soft and stretchy.
Quotes for external mastic in Baldock
Call for a quick quote. What matters most is:
- Working hours on commercial sites
- The old material and how stubborn it is
- How many rooms, windows or areas are involved
- Whether there’s mould to deal with
What it costs depends on the size of the job, how much old material has to come out and access to the work. You’ll have a clear quote before any work starts.
What to tell us for a quote
You do not need to know the technical terms. Just tell us:
- The problem you’ve noticed
- Photos by email, if that is easy
- The rough size of the job
- Where the property is
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To arrange one, phone 0345 464 0079 or send us an email.