Greater London · England
External & façade joints in Blackfriars, Greater London
Sealing brickwork movement joints, render, cladding and façade joints in Blackfriars, with a one-year guarantee on every job. Call for a quick quote.
- Rigid filler in a joint that should flex
- Brick movement joints where the sealant has split
- Leaking joints around cladding and façade panels
External mastic for homes and businesses in Blackfriars
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. If you’re dealing with movement joints filled with mortar instead of sealant and rain getting behind render or cladding at a joint, we can put it right.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. In Blackfriars, joints up high may need ladders or other access, which is worth talking through when you book.
There’s a 12-month guarantee on every job, large or small.
- Where
- Blackfriars (SE1, EC1M, EC1N)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- A clear price before work begins
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
What external mastic looks like in Blackfriars
With historic houses such as Dr Johnson's House (about 0.2 miles north-west) nearby, there’s older building stock in the area around Blackfriars as well as newer homes. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth. London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking.
Blackfriars is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. In the older streets around St Ann Blackfriars, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Blackfriars is about 1 mile north-west of London, in Greater London. Jobs in Blackfriars get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Our area takes in 764 places across Greater London.
Our applicators cover all of SE1, EC1M and EC1N for external mastic. External mastic is available to properties on Oat Lane, Bear Lane and Shoe Lane. Main roads around Blackfriars include the A4 and A40. We also cover Temple (1 mile west), Temple Bar (1 mile west), Bankside (1 mile south-east), Smithfield (1 mile north) and Clare Market (1 mile west). Further out, we also cover Kensington (4 miles west), Walthamstow (6 miles north-east), Hampstead (4 miles north-west), Ruislip (14 miles west), Brompton (3 miles south-west) and Stockwell (3 miles south).
Local landmarks in Blackfriars
In Blackfriars, that means homes and buildings near Barts Health Archives, St Mary-at-Hill and St Alban's Church of England Primary School, among other places. Nearby too are Bernie Spain Gardens (less than half a mile south-west), London Nautical School (0.5 miles south-west) and The Black Friar pub (under half a mile south-east). There’s a railway station in Blackfriars itself: London Blackfriars station. Well-known places in the area include Montfichet's Tower (under half a mile north-east) and St Brides Crypt Museum (less than half a mile north-west). The countryside around Blackfriars includes Barnsbury Wood and St. James's Park Lake.
The process
Before we leave, we go over the finished joints with you and tell you how long to leave it. The visit itself generally takes a few hours for a handful of joints, longer for a whole elevation, depending on how much there is to do. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- Backing rod sized to the joint goes in to set the depth.
- We apply the sealant, tool it and check the whole run.
Before we arrive
- Keep children and pets away from the work area
- Tell us about any previous sealing or DIY attempts
- Tell us if parking is tricky
Ask for a quote
We do not publish a price list, because every job is different. Instead, we send you a clear quote for your job. To arrange one, ring 0345 464 0079 or email us.
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What affects the cost of external mastic
There’s no set price list, because jobs vary so much. The quote depends on:
- The type of sealant required
- The number and length of the joints
- Mould in or behind the old joints
- Any working-time requirements on site
Doing several joints on one visit normally makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. You’ll get one clear quote for the whole job.
Asking for a quote
When you call or email, it’s useful to know:
- Access, such as stairs, a lift or height
- Whether it has been sealed before
- Photos by email, if that is easy
- Roughly how big the job is
If you are in Blackfriars and need external mastic, phone 0345 464 0079 or email us. Tell us what the problem is and where, and we’ll agree the price before any work begins.
Landlord and commercial work in Blackfriars
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Mouldy or split sealant often shows up at the end of a tenancy, and it’s quick to put right between tenancies. We can quote for more than one property at once.
Do you need external mastic in Blackfriars?
The wrong product in a moving joint is a classic cause. A stiff, general-purpose sealant can’t cope with a joint that moves a lot, so it pulls away from the edges.
The most common problems we see are:
- Joints where the bead has come unstuck
- Hard, crazed mastic that has stopped moving
- Movement joints filled with mortar instead of sealant
- Moss and dirt in joints with no sealant left
Managing a site like Mercers' School? Then its movement joints, gutters and trims need looking after like any other building’s.
Before booking anyone
- How the joint is cleaned and prepared
- How the colour is chosen
- What the cure time is
- What happens if the job turns out different
Blackfriars questions
Can parking be tricky for a visit in Blackfriars?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly.
Can you do external mastic in Blackfriars?
Yes, Blackfriars 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.
How long does external mastic last?
That depends on the wall, the weather and the movement. Look for splits, hardening or edges coming away.
Do you guarantee your work?
Yes: twelve months. If there’s a problem with our work in that time, tell us and we’ll put it right.
Are you insured?
Yes. We are fully insured.
What does external mastic cost?
Size, access and the old material all affect the cost. Call for a quick quote and we’ll talk you through it.
What do you need from me for a quote?
Let us know what needs doing and where, with photos by email if possible. We will ask anything else we need to know.
Do you work for letting agents?
Yes. Domestic, commercial and hotel work are all part of what we do, and we’re fully insured.
Surface by surface
Render joints
The face of render can be soft, so a sealant that stretches easily protects the edges. Priming is done where the sealant calls for it.
Cladding and façade panels
Metal and composite panels move a lot with temperature, so the joints work hard every day. We choose the product to suit.
Can I do it myself?
The difference is mostly in the preparation and the product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, then guaranteed for a year.
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it lifts and traps water and mould underneath. All the old material has to come out first.
When it is not the sealant
Before you book, it’s worth knowing the limits too:
- Cracking across the wall rather than at a joint
- Loose or hollow render, which needs re-rendering
- Movement that’s more than a sealant joint can take
If in doubt, phone 0345 464 0079 or send us an email and we’ll say what we think before booking.
Joints and surfaces we work on
- Façade panels
- Render & cladding joints
- Concrete & block
- Copings & trims
- Joints between brick and frames
- Brickwork movement joints