Greater London · England
External Mastic in St James's
Sealing brickwork movement joints, render, cladding and façade joints in St James's, with a 12-month guarantee on every job. Call for a quick quote.
- Movement joints with cracked, split or missing sealant
- Leaking joints around cladding and façade panels
- Joints pointed up with cement by mistake
DIY sealant or a professional job?
A careful DIYer can reseal a simple joint, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
If you’ve already had a go yourself, that is fine. We remove it and do the joint properly, so tell us about it when you ask for a quote.
External mastic for homes and businesses in St James's
A movement joint is a deliberate break that lets a wall expand and contract. Its sealant has to flex with the building, season after season, and when it fails, the wall takes the strain and water finds a way in. If you are dealing with brick movement joints where the sealant has split and failed seals between different materials, we can put it right.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. For a home in St James's, tell us how high the joints are and how to reach the back of the building.
All of our work is guaranteed for twelve months.
- Location
- St James's (W1F, W1D, W1J)
- Wider area
- Greater London
- Cover
- One year on every job
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Nearby places to St James's
Also in St James's
Why deal with it now?
The longer a joint stays open, the more water the wall takes in. Wet masonry is more easily damaged by frost near the open joint, so the damage spreads beyond the joint. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble.
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, and we’ll explain the quote if you ask.
Why book with us
- A sealant colour to suit the surroundings
- Any old sealant cut out fully, not covered over
- Trusted Arbo and Everbuild sealants
- ARBOMaster approved applicator
Read what affects the cost and customer reviews.
Signs you need external mastic in St James's
A lot of failed joints come down to preparation: dusty or wet faces, no primer where one was needed, or old sealant left in. The new sealant then lets go long before it should.
Signs it’s time to call us include:
- Hard, crazed mastic that has stopped moving
- Joints where the bead has come unstuck
- Plants rooting in failed movement joints
- Joints with sealant missing in places
Letting a property close to London Charing Cross station? Then outside joints that have cracked can let damp into a rental, so check them between lets.
What your quote should include
- What insurance they hold
- Is the old sealant removed completely?
- Is VAT in the price?
- When the joint can take water or movement
The process
We bring everything the job needs with us, so there’s nothing for you to buy. Once we have agreed what’s being done, we protect the area and start. Most jobs take anything from a few hours to several days, depending on the building. In St James's, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- First, the joints are inspected and the access agreed.
- We cut out the old mastic and rake out anything in the joint.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
Getting ready for the visit
- Let us know about parking restrictions
- Plan for the work area to be out of bounds to pets and children
- On commercial sites, let us know about site rules
Ask for a quote
For a quick quote, get us on the phone, or email us if that’s easier. Describe what needs sealing and we’ll explain what’s involved and give you a clear price.
Related advice
What external mastic looks like in St James's
Historic houses like Marlborough House (about 0.3 miles south-west) are a reminder that the area around St James's has older buildings as well as new. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth. In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking.
If you live in an older home near St James’s Church, the joints between older walls, newer extensions and the roofline need a sealant that can move. St James's is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
St James's is about 1 mile south-east of City of Westminster, in Greater London. Every kind of property in St James's is covered for external mastic, old or new, large or small. The work is guaranteed for a year. St James's is one of 764 towns and villages in Greater London we cover for external mastic.
Every address in W1F, W1D and W1J is covered for external mastic, from the main roads to the quietest streets. You will find streets such as Duck Lane, Bruton Lane and Bridle Lane, and we cover them all. St James's sits on or near the A4 and A400, which makes travel easy. Neighbouring places we cover for external mastic include Chinatown (1 mile north), Charing Cross (1 mile east), Soho (1 mile north), West End (1 mile north-east) and Burlington Estate (1 mile west). We also work in nearby towns such as Kensington (3 miles west), Shoreditch (3 miles north-east), Walthamstow (7 miles north-east), Hoxton (3 miles north-east), Whitechapel (3 miles east) and Hampstead (4 miles north-west).
Landmarks near St James's
Around St James's, our work takes us to homes and buildings near LITE Regal International School, Tom Cribb pub and London Library and the streets around them. Nearby too are Harris Westminster Sixth Form (0.6 miles south) and St Anne's Churchyard (less than half a mile north). There’s a railway station in St James's itself: London Charing Cross station. Other landmarks nearby include The Museum of Practical Geology (less than half a mile north-west) and Montfichet's Tower (1.4 miles east). Not far away are St. James's Park Lake and Ludgate Hill.
What the job involves on each surface
Render joints
Water behind render can lead to blown patches. Resealing the joints early keeps water out and protects the render itself.
Joints between dissimilar materials
Wherever two materials meet, they move differently. We seal the joint with a flexible exterior sealant so the movement is taken up.
St James's questions
Do you work for landlords with property near London Charing Cross station?
Yes, landlords and agents are among the people we work for. You can call 0345 464 0079 or send us an email with the details for a clear quote.
Is parking an issue for external mastic in St James's?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. That way the visit can be planned around it.
What should I tell you?
A short description and the location, plus pictures if you have them. We will ask anything else we need to know.
Do you work in St James's?
Yes. We cover St James's and the rest of Greater London. For a quote, phone 0345 464 0079 or send us an email.
Where are you based?
Our base is Crawley. We work across South East England, London and Scotland.
Can you do several jobs on one visit?
Yes, and it often makes sense. Combining jobs makes good use of the visit.
Why do you put foam in the joint first?
Closed-cell backing rod sets the depth of the sealant and stops it sticking to the back of the joint. Then the sealant bonds to two faces and can move.
Are you fully insured?
Yes. We’re fully insured, and we’ve been doing sealant work for more than 20 years.
Honest limits
To be straight with you, there are a few things sealant won’t fix:
- Walls that need new movement joints cut into them
- Subsidence or other structural problems
- Damp that is not coming from the joint
Not sure which it is? You can call 0345 464 0079 or drop us an email and we’ll tell you honestly before you book.
Joints and surfaces we work on
- Render & cladding joints
- Copings & trims
- Concrete & block
- Façade panels
- Joints between brick and frames
- Brickwork movement joints
Landlords, agents and businesses in St James's
We also work for businesses, from offices to washrooms and kitchens. On commercial sites, working times can be discussed when we quote.
Housing providers, facilities teams and property managers book us too. Several sites can go on one quote.