Greater London · England
Finsbury External Mastic
Professional external mastic in and around Finsbury, with every bit of old sealant taken out first and a 12-month guarantee.
- Weathered mastic that no longer stretches
- Joints pointed up with cement by mistake
- Movement joints with cracked, split or missing sealant
External mastic in Finsbury, done properly
Getting the depth right is half the job. Backing rod controls how deep the sealant goes and keeps it off the back of the joint, so it bonds to the two sides only and can stretch. If you have hard, crazed mastic that has stopped moving and sealant pulling away from one side of the joint, we can put it right, on façade panels, concrete & block and render & cladding joints alike.
Outside work in London starts with access: side passages, upper floors and where to park. For a home in Finsbury, tell us how high the joints are and how to reach the back of the building.
Each job carries a 12-month guarantee, whatever its size.
- Place
- Finsbury (EC1V, N1, EC2A)
- Wider area
- Greater London
- Guarantee
- One year on every job
- Price
- A clear price before we start
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Why it’s worth doing now in Finsbury
A low-modulus sealant is chosen because it moves without pulling hard at the edges. That matters on brick, render and concrete, which can be weaker at the face. Too stiff a sealant can pull at the edges and break them. In London conversions, one flat’s bathroom is often above another flat’s ceiling, and a slow leak from a failed seal can end up in the flat below. Putting it right early is much less trouble for homes in Finsbury.
The cost depends on the size of the job, how hard the old material is to remove and access to the work. You’ll have a clear quote before any work starts, so you know where you stand.
What you get with us
- We agree the colour with you first
- Old sealant always removed completely
- Tidy, careful work
- Sanitary silicone with an anti-fungal additive in wet areas
Read our cost guide or customer reviews.
Outside joints around Finsbury
With historic houses such as Mansion House (about 0.6 miles south) nearby, there’s older building stock in the area around Finsbury as well as newer homes. Where a home is older, 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, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
In the older streets around Jewin Welsh Presbyterian Chapel, the joints between older walls, newer extensions and the roofline need a sealant that can move. Schools such as Prior Weston Primary School and Children's Centre are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
Finsbury is about 2 miles north of London, in Greater London. Wherever you are in the EC1V postcode area, we can carry out external mastic at your property. 764 places in Greater London are on our list.
All of EC1V, N1 and EC2A is covered for external mastic. That includes homes and businesses on Oat Lane, Long Lane and Love Lane. With the A1 and A501 close by, Finsbury is easy for our applicators to reach for external mastic. Other places close to Finsbury include St Luke's (1 mile north), Barbican Estate (1 mile south), City of London (1 mile south), Bishopsgate (1 mile south-east) and Shoreditch (1 mile east). Within a short drive, we also cover City of Westminster (3 miles west), Kensington (5 miles west), Walthamstow (5 miles north-east), Hampstead (4 miles north-west), Ruislip (14 miles west) and Brompton (4 miles south-west).
Local landmarks in Finsbury
Locally, jobs take us to homes and businesses close to Artillery Ground, Barts Health Archives and Charterhouse Square School. Other local landmarks include The Jugged Hare pub (within half a mile south), St Mary-at-Hill (0.9 miles south-east) and Central Foundation Boys' School (within half a mile north-east). There’s a railway station in Finsbury itself: Old Street station. Other landmarks nearby include Honourable Artillery Company Museum (less than half a mile east) and Gabriel's Wharf (1.2 miles south-west). Not far away are Barnsbury Wood and Ludgate Hill.
Towns and villages near Finsbury
Other services in Finsbury
DIY sealant or a professional job?
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
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.
How we quote for external mastic
We do not publish a price list, because no two jobs are the same. The quote depends on:
- Whether old sealant or filler has to be cut out
- How much there is to do
- The number of rooms or windows
- Access and height
There are no prices on our website, because the cost depends so much on the job itself. Call for a quick quote.
What we need to know
Photos help, but a description is a good start. Please mention:
- Where the property is
- If it’s domestic, commercial or a hotel
- Pictures of the joints, sent by email
- How many joints, rooms or windows are involved
There’s no standard price list, as no two jobs are quite the same. Instead, we give you a clear quote for your job. To get started, phone 0345 464 0079 or email us.
What we are called out for in Finsbury
Sometimes a movement joint was filled with mortar or a rigid filler by mistake. With the joint locked solid, the movement turns into cracks elsewhere in the wall.
The most common problems we see are:
- Moss and dirt in joints with no sealant left
- Leaking joints around cladding and façade panels
- Weathered mastic that no longer stretches
- Gaps where render, brick and frames meet
As a London address, Finsbury can be tricky for parking: let us know about parking bays, permits or a driveway.
Before booking anyone
- Is VAT in the price?
- Is the old sealant removed completely?
- What preparation is included
- What product goes in the joint
Common questions in Finsbury
Is parking a problem for a job in Finsbury?
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 Finsbury in your area for external mastic?
Yes. We work across London and the South East, and Finsbury is part of that. Just phone 0345 464 0079 or email us with a few details of the job, and we will give you a clear quote.
Is it OK to fill a movement joint with cement?
No, not where the gap is a movement joint. Pointing it stops it working, and the wall may crack nearby. A flexible sealant is the right fill.
Is the work guaranteed?
Yes. There’s a 12-month guarantee on every job, wherever you are.
Will the old sealant be removed?
Yes. Sealing over the old bead is the commonest cause of early failure, and it’s something we never do.
I’m a tenant. Can you help?
We can work for tenants, landlords or agents. Just make sure your landlord agrees.
Can you reach joints on upper floors?
It depends on the building. Tell us the height, the number of joints and what’s below them and we will confirm how they can be reached safely.
Can you quote for more than one area?
Yes. Just list everything you need.
What we cannot put right
We’d rather tell you now than do work that will not last, so here’s what sealant can’t put right:
- Damp that is not coming from the joint
- Render that is blown, hollow or coming away
- Walls that need new movement joints cut into them
Not sure which it is? You can call 0345 464 0079 or drop us an email and we will tell you honestly before booking.
Where we work in Finsbury
- Joints between brick and frames
- Concrete & block
- Façade panels
- Copings & trims
- Brickwork movement joints
- Render & cladding joints
How it works
Our applicators work methodically: protect, prepare, seal, tidy. Typically it takes a few hours for a handful of joints, longer for a whole elevation, and the area is left clean. For a job in Finsbury, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- First, the joints are inspected and the access agreed.
- 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
- Try not to wet indoor joints just before the visit
- Let us know about parking restrictions
- Mention any sign-in or site rules at work premises
How to get a quote
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is, and add photos by email if you can.
Read more
How the job changes by surface
Cladding and façade panels
Cladding and façade panels are generally separated by sealed joints. Each joint gets a sealant that suits the panel and its movement.
Render joints
The face of render can be soft, so a sealant that stretches easily protects the edges. We prime where the product needs it.