Greater London · England
Holborn External Mastic
Problem with your movement joints in Holborn? We remove the old material, prepare the joints and seal them properly, with a 12-month guarantee.
- Failed sealant between panels on a façade
- Plants rooting in failed movement joints
- Water getting into walls through failed joints
DIY versus a professional finish
If you’ve already had a go yourself, that is fine. We cut it out and start again, so just mention it when you contact us.
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.
How we handle external mastic in Holborn
Short cuts in external joints show up within a season or two. Overfilled joints, missing backing rod and sealant laid over old sealant all tend to fail early. We strip the joint back and start again. We’re often asked to deal with leaking joints around cladding and façade panels and moss and dirt in joints with no sealant left, across copings & trims, façade panels and concrete & block.
Modern London flats rely on sealed movement joints and cladding joints. Older terraces have their own weak points: gutter joints, roofline trims and the joint where an extension meets the original wall.
Whatever the size of the job, it’s backed by our 12-month guarantee.
- Where
- Holborn (WC1X, WC1N, EC1R)
- Wider area
- Greater London
- Cover
- A year, on every job
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
When it is not the sealant
We will not take on work that won’t last, so here’s what sealant can’t put right:
- Failed render or damaged cladding panels
- Cracks in the bricks or render themselves, away from the joints
- Damp that isn’t coming from the joint
Not sure which it is? You can call 0345 464 0079 or send us an email and we’ll tell you honestly before you book.
Surfaces we seal
- Brickwork movement joints
- Façade panels
- Render & cladding joints
- Joints between brick and frames
- Copings & trims
- Concrete & block
The process
There’s no need to move everything out, only the area right around the joints. We protect the rest, and the work takes a few hours to a few days, depending on the length of joint and the access for a typical job. In Holborn, flats, stairs and shared entrances are part of the routine. If the building has a concierge, managing agent or access rules, tell us when you book.
- Each joint is checked and the colour of the new sealant agreed.
- Failed sealant is removed back to clean, sound faces.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- Mention any tricky access
- Let us know about earlier repairs to the joints
- Mention any sign-in or site rules at work premises
Ask for a quote
Call for a quick quote, or email us if that is easier. Describe what needs sealing and we will talk you through the work and send you a clear quote.
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Do you need external mastic in Holborn?
If plants are growing out of a joint, the sealant has normally failed or was never there. Roots and dirt hold water against the wall and speed up the damage.
The problems people normally mention when they call include:
- Gaps where render, brick and frames meet
- Rigid filler in a joint that should flex
- Joints with sealant missing in places
- Damp patches traced to an open external joint
Managing a site like St Alban's Church of England Primary School? Then its movement joints, gutters and trims need looking after like any other building’s.
What your quote should include
- Is the old sealant removed completely?
- Which colour the sealant will be
- The length of the guarantee
- How the surfaces are prepared before sealing
For landlords and businesses
Whether it’s one flat or a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a 12-month guarantee.
We also work for businesses, from offices to washrooms and kitchens. For commercial premises, we can talk through working times when we quote.
External mastic in Holborn: local notes
In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking. Historic houses like Dr Johnson's House (about 0.4 miles south-east) are a reminder that the area around Holborn has older buildings as well as new. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
For landlords with property near Farringdon station, failed wall and movement joints let damp in, so they’re worth checking between tenancies. For an older house near a landmark such as St Alban's Church, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Holborn is about 2 miles north-west of London, in Greater London. Every kind of property in Holborn can book us for external mastic, old or new, large or small. The work is guaranteed for a year. Across Greater London, we cover 764 places, and Holborn is one of them.
We cover every part of the WC1X, WC1N and EC1R postcode area for external mastic. You’ll find streets such as Shoe Lane, Drury Lane and New Square, and we cover them all. Holborn sits on or near the A4 and A40. If you’re just outside Holborn, we cover Farringdon (1 mile east), St Pancras (1 mile north-west), Clare Market (1 mile south), Smithfield (1 mile east) and Temple Bar (1 mile south). Within a short drive, we also cover Kensington (4 miles west), Walthamstow (6 miles north-east), Hampstead (4 miles north-west), Ruislip (13 miles west), Brompton (3 miles south-west) and Stockwell (4 miles south).
Around Holborn
Typical jobs here are in homes near The Yorkshire Grey pub, British Library of Political and Economic Science and City Academy. Other local landmarks include Elizabeth Garrett Anderson School (0.9 miles north) and Lincoln's Inn Fields (under half a mile south-west). There’s a railway station in Holborn itself: Farringdon station. Nearby you will also find Montfichet's Tower (0.7 miles south-east) and Brunswick Centre (0.5 miles north-west). The countryside around Holborn includes Barnsbury Wood and Ludgate Hill.
Places near Holborn
More services for Holborn
FAQs for Holborn
Can parking be tricky for a visit in Holborn?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
Is Holborn in your area for external mastic?
Yes. Our work covers London and the South East, and Holborn is part of that. Just call 0345 464 0079 or send us an email with a few details of the job.
Is it messy?
Very little: the area around the joints is protected first, and we clear up the old sealant and our materials before we leave.
Do you seal joints where cladding meets other materials?
Yes. Where different materials meet is one of the most common joints we seal. We use a flexible sealant suited to both surfaces.
Do I need to be at home?
We need access to the joints, so we will agree that with you when we book. Indoors, that generally means someone at home.
Do you do commercial work?
Yes. We work in offices, washrooms, hotels and other commercial premises. Working times can be discussed when we quote.
Why do you put foam in the joint first?
That’s backing rod, a closed-cell foam. It keeps the sealant at the right depth and bonded to the sides only so it can flex with the joint.
Are you fully insured?
Yes. We’re fully insured for domestic and commercial work.
How we quote for external mastic
Call for a quick quote. What matters most is:
- The amount of work
- Whether old sealant or filler has to be cut out
- The type of sealant required
- Any mould that needs treating
No two jobs are quite the same, so each one gets its own quote. Size, access and the product the joint needs all play a part.
What to tell us for a quote
When you contact us, it’s useful to know:
- Access, such as stairs, a lift or height
- Any previous sealing or DIY work
- The address or postcode of the job
- The rough size of the job
Asking for a quote is easy: let us know the job and the location and its rough size. Photos by email help us understand the job.
Why it’s worth doing now in Holborn
It often makes sense to reseal all the failing joints on an elevation together. Joints of the same age tend to fail together. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in Holborn, the repair is bigger than a sealant job.
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. The price is agreed before we begin.
Why choose Mr Mastic in Holborn
- Any old sealant cut out fully, not covered over
- Fully insured
- Quality sealants from Arbo and Everbuild
- 12-month guarantee on every job