Construction and new-build mastic in City of London
Sealant work in City of London for main contractors, managing agents and facilities managers: mastic packages for new-build and refurbishment projects, quoted at a fixed price.
- Sealant knocked or painted over by other trades
- Failed sealant in an existing building being refurbished
- Snag items on joints that need redoing before handover
Construction mastic across City of London
Tell us what needs sealing and where, with photos or drawings if you have them, and we’ll price it.
Your questions answered
Do you take on jobs in City of London where loading and access are tightly controlled?
Yes. Inductions, permits and timed loading are routine for us in London. The building manager’s rules go straight into our method.
Can work at a site such as Queen Mary's University West Smithfield Campus fit around teaching?
Yes. Tell us the term dates, vacation periods and access windows, and we’ll plan the work around them. Let us know which documents your site asks for, and we’ll confirm them alongside the quote.
How long does a job like this take?
The duration is planned around your programme and the access we are given. You’ll have an expected duration with the quote.
When can you be on site?
Give us your site hours and any access windows in your enquiry, and we will schedule the work to suit. You can reach the office between 8am and 5pm, Monday to Friday.
Is the mastic package guaranteed?
Each package is signed off with a 12-month workmanship guarantee. The guarantee covers our work, not later damage by other trades.
Do you take on mastic snagging only?
Yes. Send the snag list or photographs and we will price it.
Do you seal on top of existing sealant?
No. Sealing over old material is one of the classic causes of early joint failure, so everything comes out first.
Construction mastic in City of London, done properly
Mastic tends to be one of the final packages before handover. Mastic Doctor takes on mastic packages for main contractors and developers, sealing plot by plot or floor by floor as areas are released. Site teams most often ask us about internal caulk splitting as the building dries out and frame gaps too wide for sealant alone, on cladding and panel joints, floor and skirting junctions and internal decorators’ caulk. Facilities teams, main contractors and managing agents in City of London tend to want the same three things: a fixed quote, no surprises on site and a 12-month guarantee behind the result.
Around City of London, as across London, much of the work is refurbishing existing buildings as well as building new ones. Replacement windows, recladding and fit-outs leave perimeter and facade joints to seal, often next to people still using the building.
Guaranteed is the last step of every job. You get a 12-month guarantee on our workmanship, and the quote explains what it covers.
- Place
- City of London (EC4V, EC1A, EC2M, EC2Y)
- Region
- City of London
- Cover
- 12 months on our workmanship
- Price
- A fixed quote before we start
- Telephone
- 01277 525 020
- Updated
- 3 November 2026
What sets the cost
Your fixed quote is built from the real scope. It allows for:
- Site requirements such as inductions and permits
- Any access equipment needed
- Quantities, in metres or numbers
- Travel to remote or island sites
A quote for mastic packages depends on quantities, condition and access, and any specification that applies. Call for a quote.
What to include in your enquiry
Good information means a firmer quote. Helpful details to send:
- Whether an asbestos survey exists
- What the building is and how it’s used
- Photos of the joints, close up and from further back
- When you need the work done
Tell us about the building, the joints and when you need the work done, and a fixed quote will follow. To get it moving, speak to us on 01277 525 020 or send photos by email.
Maintenance after handover
For the best life from the joints:
- Keep scrapers and abrasive pads off new beads
- Flag uneven or tapered frame gaps early
- Ask for joint and product checks before the package is urgent
- Release areas for mastic once other trades have finished in them
Once an area is sealed, protect it from following trades. New beads should be left to cure before cleaning or decorating nearby; we confirm the time for each product.
Sealing outside when the joint is damp or too cold leads to poor adhesion. Holding off until conditions suit avoids callbacks, so we plan external work with that in mind.
Facades, frames and programmes in City of London
The area within 2 miles of City of London holds plenty of hotels. When hotels extend or refit, the work is typically squeezed between peak periods, mastic included. Every borough of Greater London is inside the ULEZ, and that applies to contractors’ vehicles on any job in City of London. London sites also mean booked deliveries and limited storage, which the mastic programme has to allow for.
Extensions at sites like St Bartholomew's Hospital (to the north-west of City of London) normally sit beside working departments, and the mastic follows strict access rules. University estates such as Queen Mary's University West Smithfield Campus (to the north-west of City of London) tend to have a rolling programme of new buildings and refurbishments, each with window perimeters and facade joints to seal.
City of London is about 1 mile north of London, in City of London. We cover commercial sites throughout City of London. We work across 7 places in City of London, from busy centres to rural villages.
Postcode districts covered here: EC4V, EC1A, EC2M and EC2Y. Buildings on Aldermanbury Square, Monkwell Square and Paternoster Square are within our area for mastic packages. Being close to the A1 and A3, City of London is easy to get to with materials and equipment. We also cover Barbican Estate (1 mile north), Bishopsgate (1 mile east), Finsbury (1 mile north), Aldgate (1 mile east) and St Luke's (1 mile north).
Near you in City of London
Locally, jobs take us to sites close to St Mary-at-Hill, Prior Weston Primary School and Children's Centre and Golden Fleece pub and the streets around them. You will also find Central Foundation Boys' School (0.8 miles north), Barts Health Archives (less than half a mile north-west) and St Alphage Garden (under half a mile north). There’s a railway station in City of London itself: London Cannon Street station. A little further out are Gabriel's Wharf (0.8 miles south-west) and London Mithraeum (less than half a mile south). Green spaces nearby include St. James's Park Lake and Barnsbury Wood.
Different surfaces, different methods
External facade and movement joints
Many facade substrates need a primer before sealing. Primer goes on where the sealant maker calls for it and work only when conditions suit.
Window and door perimeters
Inside, a paintable sealant or decorators’ caulk is used where the joint doesn’t move much. We follow what’s specified.
Signs you need construction mastic in City of London
Dust is the enemy of adhesion on a construction site. Dust, film adhesive, damp and grease on the joint faces prevent a proper bond.
What tends to prompt an enquiry:
- A long mastic snag list close to completion
- Failed sealant in an existing building being refurbished
- Early adhesion failures on new external joints
- Frame perimeters left unsealed or poorly sealed
New units and refits on sites such as Southwark Bridge Business Centre, 0.8 miles south of City of London, need their panel and perimeter joints sealed to the specification.
Before you book anyone
- Whether primer will be used where the manufacturer specifies it
- Whether old or failed sealant will be cut out, not overlaid
- How they’ll work around occupants
- How joint depth will be controlled
General trades versus a specialist
The visible bead is only part of the job. Correct depth, the right primer and a sealant matched to the movement are where general trades tend to cut corners.
Some joints are best left to specialists: fire-rated seals that must follow a tested detail, trafficked floor joints and external movement joints among them. Getting these wrong typically costs more in the end than doing them right.
Places near City of London
Also in City of London
How a job runs
Where the site stays busy, the work is phased so only one area is out of use at a time. Each section is protected, cleaned back and sealed, then handed back before the next one starts. The ULEZ covers the whole of Greater London, and parking near a job is rarely simple. Let us know about any on-site parking or loading arrangements when you send the job details.
- We start with the drawings, specification and programme.
- Quantities are measured and a fixed price returned.
- The sequence is agreed with the site manager.
- Each area is sealed when it’s released.
- Every joint is cleaned, set to depth and sealed with the specified product.
- Snags are cleared and the package signed off with our 12-month guarantee.
Getting the site ready
- Tell staff and tenants when we’ll be in
- Tell us which areas need to stay in use
- Make sure the joints can be reached
Ask for a quote
The quickest route to a quote is a few photographs and the site postcode. Send them through the quote form, or speak to us on 01277 525 020 or email a schedule or drawings to discuss it first.