On a tiled roof, the right sealant depends on the job. Flexible pointing seals ridge and hip capping; flashing tape and storm seal waterproof joins at walls, valleys and penetrations; silicone suits small, targeted sealing around vents and flashings. No sealant fixes a cracked tile, crumbling ridge bedding or a rusted valley. Those need the part replaced, or the leak comes back.
The short answer
- Ridge and hip capping: flexible pointing, not silicone
- Walls, chimneys and penetrations: flashing, with sealant at the edges
- Valleys: replace rusted valley iron rather than coating it
- Silicone: small, targeted repairs and short-term protection
- Cracked tiles: replace the tile; sealant is only a stopgap
Types of roof sealant
| Type | What it is | Where it belongs on a tiled roof |
|---|---|---|
| Flexible pointing | A flexible compound applied over mortar bedding | Ridge and hip capping. Tested for wind resistance under AS 4046.8 |
| Silicone | A flexible sealant in a cartridge | Small gaps around vents, pipes and flashing edges; temporary protection |
| Flashing tape and storm seal | Flexible, self-adhesive or dressable flashing materials | Where tiles meet walls, chimneys, skylights and valleys |
| Polyurethane sealant | A tough, paintable sealant | Joints in metal flashings and gutters, not on tiles themselves |
| Liquid membranes | Brush or spray-on waterproof coatings | Flat and concrete roofs and decks, not pitched tiled roofs |
Where sealant is the wrong fix
- Cracked or broken tiles: sealant on a crack weathers in the sun and lets go. Replace the tile with a matched one.
- Crumbling ridge bedding: silicone over loose capping hides the problem until the caps move. The fix is a rebed and repoint.
- Rusted valleys: coating a rusted-through valley buys months, not years. Replace the valley iron.
- Whole-roof problems: if faults are everywhere, a restoration is better value than sealing them one by one.
Sealant over these problems can also trap moisture against the tiles and timbers, so the leak returns in the next heavy rain, often in a slightly different place.
Where sealant is the right tool
Around penetrations
Sealing the edges where vents, pipes and some flashings meet the roof.
Flashing laps and edges
Finishing a properly installed flashing so water cannot creep under its edges.
Small, targeted repairs
A small gap where the surrounding roof is sound.
Temporary protection
Holding off water until a permanent repair can be done.
See our silicone roof repairs page for how we decide between sealant and a permanent repair.
Not sure if sealant will fix it?
We will find where the water is getting in and tell you whether sealant or a permanent repair is the right fix.
Flexible pointing: the sealant your ridges need
Ridge and hip capping sits on sand and cement bedding, sealed with pointing. Modern flexible pointing moves with the roof as it heats and cools, rather than cracking like old cement pointing. It is the purpose-made sealant for capping, and the National Construction Code requires ridge, hip, barge and valley tiles to be fixed, so the capping has to be properly bedded and pointed, not glued. Read roof repointing for the signs it is due.
Sources: Monier: Flexible pointing technical data sheet; NCC 2022 Housing Provisions Part 7.3: Roof tiles.
What about waterproof roof paints?
Roof coatings restore colour and protect a weathered concrete tile surface, but Monier notes that painting tiles does not improve their waterproofing. A tiled roof stays dry because the tiles overlap and the capping, valleys and flashings are sound. Membranes sold as waterproof roof coatings are made for flat or low-pitched roofs, not pitched tiled roofs. See painting roof tiles for when a coating makes sense.
Sources: Monier: Roof cleaning and maintenance.
Applying sealant safely and properly
- Clean and dry the surface; sealant will not bond to dust, lichen or damp
- Use a product rated for outdoor and roof use, and follow the manufacturer’s instructions
- Work in mild, dry weather so it can cure
- Inspect it every year; sealant weathers faster than tiles and flashings
Sealing anything on a roof means working at height on slippery tiles. WorkSafe Victoria’s compliance code treats falls from roofs as one of the most serious risks in housing construction. Leave it to an insured crew with edge protection.
Sources: WorkSafe Victoria: Prevention of falls in housing construction.
Common questions
What is the best sealant for a tiled roof?
It depends on the job. Flexible pointing for ridge and hip capping, flashing materials where tiles meet walls and penetrations, and silicone for small, targeted sealing. Cracked tiles and rusted valleys need replacing, not sealing.
Can I use silicone on roof tiles?
For small gaps around penetrations and flashings, or as short-term protection, yes. On cracked tiles or loose ridge capping it is a stopgap that weathers and lets go.
Will a sealant fix a leaking roof?
Only if the leak is from a small gap that sealant genuinely suits. Most tiled roof leaks come from cracked tiles, ridge bedding, valleys or flashings, which need proper repairs.
Do waterproof roof paints stop leaks?
Not on tiled roofs. Monier notes painting does not improve the waterproofing of tiles. Waterproof membranes are designed for flat and low-pitched roofs.
How long does roof sealant last?
It weathers faster than tiles, flashings and pointing, especially in full sun. Check sealed areas every year and replace them as they crack or lift.
What is used to seal ridge caps?
Ridge and hip caps are bedded in sand and cement mortar and sealed with flexible pointing, a purpose-made compound that moves with the roof.
Related
Sources: Monier: Flexible pointing technical data sheet; NCC 2022 Housing Provisions Part 7.3: Roof tiles; Monier: Roof cleaning and maintenance; WorkSafe Victoria: Prevention of falls in housing construction.
Comments are closed