A mastic man is a tradesperson who specialises in sealant: the flexible joints that keep water, draughts and dirt out of the gaps between materials. You’ll also hear them called a silicone man, a sealant specialist, a sealant applicator or a caulking specialist. The name changes from place to place, but the work is the same.
Sealant looks simple, which is why it’s so often done badly. A good mastic man spends most of each job on the parts you don’t see: taking the old sealant out, preparing the joint and choosing the right product for it.
The jobs a mastic man does
Inside the home:
- resealing baths, showers, shower trays and enclosures, basins and wet rooms
- resealing kitchen worktops, upstands, sinks and splashbacks
- sealing skirting-to-floor joints and thresholds
- regrouting tiles and resealing the corners
Outside:
- replacing the mastic around window and door frames, sills and patio doors
- resealing brickwork movement joints and render, cladding and façade joints
- sealing gutter joints, fascias and roofline trims
- traditional sand mastic around sash and case windows in stone and brick
For businesses, landlords and developers:
- washroom, kitchen and welfare-area resealing in offices, hotels and schools
- fire-rated and intumescent sealant around service openings and door frames
- plot mastic and snagging on new builds
- concrete floor joints in commercial units
What happens on a typical job
- The joint is checked for movement, leaks or anything that isn’t a sealant problem, such as a cracked tray or a leaking valve.
- All the old sealant is cut out. New silicone doesn’t bond to old silicone, so sealing over the top fails.
- The joint is cleaned, degreased and treated for mould, then left to dry.
- Deep joints get backing rod so the sealant is the right depth. Baths are filled with water first.
- The right sealant for the joint is applied and tooled to a neat, even bead.
- You’re told how long to leave it before it gets wet or takes movement.
Mastic, silicone or caulk?
“Mastic” is used loosely for almost any gun-applied sealant. In practice a mastic man chooses between sanitary silicone for wet areas, low-modulus exterior sealants for frames and movement joints, hybrid (MS polymer) and polyurethane sealants where they suit, fire-rated sealants where fire stopping is specified, glazing silicone for glass, and traditional sand mastic on period windows. Decorators’ caulk is for filling non-moving gaps before painting and isn’t a substitute. Our guide to mastic vs silicone explains the differences.
Need it done properly? Mr Mastic covers the South East, London and Scotland, with a one-year guarantee on every job. Call or email for a quick quote.
Mastic man or handyman?
A handyman can run a bead of silicone, and for a small, easy joint that may be fine. A specialist earns their money where it gets harder: several layers of old sealant to remove, mould that keeps coming back, joints that move, outside joints that face the weather, commercial sites with lots of rooms, or anything that needs a specific product such as fire-rated or glazing sealant. If a joint has already failed more than once, that’s usually a sign it needs a specialist.
How long does it take?
A single bath or shower is usually a couple of hours. A whole bathroom and kitchen can take most of a day. Windows depend on how many frames there are and how they’re reached; commercial jobs are often planned room by room so the building can stay open.
What a mastic man doesn’t do
Sealant closes joints. It won’t fix a cracked shower tray, a leaking valve or waste, a failed double-glazed unit, a broken gutter or a roof leak. A good mastic man will tell you when the problem is something else, rather than reseal a joint that won’t solve it.
Quick answers
What does a mastic man do?
They remove old or failed sealant and reseal joints around baths, showers, kitchens, windows, doors, walls and floors, using the right sealant for each joint.
Is a mastic man the same as a silicone man?
Yes. Mastic man, silicone man and sealant specialist all describe the same trade.
Do mastic men seal over old silicone?
A good one won’t. The old sealant has to come out completely, or the new bead lifts.
Do you need a mastic man for a bath reseal?
Not always, but a professional reseal lasts longer because of the preparation. If mould keeps coming back or the joint keeps failing, it’s worth it.
Related services
More advice
- Mastic vs Silicone: What’s the Difference?
- How to Choose a Mastic Man: 10 Questions
- How Much Does a Mastic Man Cost? UK Guide
- All advice
This guide is general information about sealant work. It isn’t legal, fire-safety or structural advice; for those, speak to a qualified professional.