Best Sealant for Cracked or Broken Roof Tiles
What is the best sealant for cracked or broken roof tiles?
It depends on one thing: whether you intend to paint the tile afterwards.
If you are not painting the tile, Selleys Roof & Gutter Silicone is best for this repair. It is flexible, durable and easy to apply.
If you do plan to paint the tile, Selleys 3 in 1 is suitable and is paintable. 3 in 1 is not a silicone — it is a paintable adhesive, sealant and gap filler. It comes in white and clear, and white is the better choice for this repair.
The preparation and application technique
The method Selleys gives for this job is worth following exactly, because it solves the awkward part of the problem — how to get sealant into a break in a tile you cannot lift out.
- Make sure the break is clean and dry. That is the whole preparation requirement for the repair itself.
- Leave the broken tile where it is. Do not try to lift it out — a cracked tile usually breaks further when handled.
- Slide the tile above it out of the way instead. That exposes the top of the cracked tile and gives you access to the break.
- Apply the sealant into the break and bring the two surfaces together.
- Wipe the excess off with a rag soaked in a bit of mineral turps.
- Carefully pull the upper tile back into place.
The reason this sequence works is that it puts the sealant into the fracture from above, where gravity helps it into the joint, rather than trying to force it up into a crack from underneath.
The two products compared
| Property | Roof & Gutter Silicone | Selleys 3 in 1 |
|---|---|---|
| Technology | Neutral cure, 100% silicone | Moisture curing silyl modified polymer (SMP) |
| Paintable | No | Yes |
| Colours | Translucent, white, Colorbond-matched range | White (and clear) |
| Packaging | 300g / 310g cartridges; 90mL | 480g cartridge |
| Skin time | 5–10 minutes | 15–30 minutes (23°C, 50% RH) |
| Tooling time | 5 minutes | Approx. 15 minutes |
| Cure rate | 2mm / 24 hours | 3–4mm / 24 hours |
| Movement capability | ±25% | ±20% (ISO 9046 modified) |
| Elongation at break | 330% (ASTM D412) | >250% (DIN 53504) |
| Shore A hardness | 32 | 40 ± 5 |
| Tensile strength | — | 1.3 MPa (DIN 53504) |
| Service temperature | −60°C to +150°C | 0 to 70°C |
| Application temperature | +5°C to +30°C | 5 to 30°C |
| Wet surfaces | Surfaces must be dry | Suitable for wet or dry surfaces |
| UV resistance | Yes; 25-year guarantee | Yes |
Indicative data only, not intended for the preparation of specifications.
What the differences mean on a roof
Paintability is the deciding factor, and it is not close. Roof & Gutter Silicone is not paintable, and paint applied over it will not adhere. 3 in 1 is paintable. If the roof is going to be coated, using the silicone means either a visible bead in the finished job or a repair you have to cut out and redo.
Temperature range favours the silicone. A dark roof tile in Australian summer sun gets very hot. Roof & Gutter Silicone's service range runs to +150°C; 3 in 1's stops at 70°C. If the tile is not being painted, the silicone is the more comfortable choice for the exposure.
3 in 1 works on wet or dry surfaces, which is genuinely useful on a roof where you may be working between showers. Roof & Gutter Silicone requires the surface to be dry.
Working times differ considerably. The silicone skins in 5–10 minutes with a 5-minute tooling window; 3 in 1 skins in 15–30 minutes and tools for about 15. On a fiddly repair up a ladder, the longer window is easier to work with.
Movement capability. ±25% for the silicone against ±20% for 3 in 1. A tile crack does not move much, so both are ample — this matters more for a lap or a flashing joint than for a fracture.
Applying 3 in 1 to a tile you will paint
- Cut the tip and attach the nozzle, then cut the nozzle to the size you need.
- As a sealant, apply the product ensuring it is forced into the joint with good contact to the surfaces, and tool with a soap solution before skinning occurs.
- As a filler in a wider break, apply into the gap and smooth off with a spatula dipped in soapy water.
- Allow it to skin before painting with water-based paints.
- For neater work, mask the sides before applying and remove the tape before the sealant skins.
Limitations
Roof & Gutter Silicone:
- Not paintable; allow paint to dry at least 7 days before applying the sealant over it.
- Do not apply if the ambient or substrate temperature is below +5°C or above +40°C. A tiled roof passes 40°C early on a summer morning.
- Not recommended for continuous submersion or below-waterline use.
- Not for use on polyethylene, polypropylene or PTFE; pre-test other substrates.
- Avoid contact with high-plasticiser materials such as rubber and bituminous substrates.
- Requires atmospheric moisture to cure; curing slows in low humidity.
Selleys 3 in 1:
- Service temperature 0 to 70°C — a lower ceiling than the silicone.
- Application temperature 5 to 30°C.
- Ensure the surface is clean, dry and free from dust, grease and old or crumbling sealant.
A word on when a sealant is the wrong answer
A hairline crack in an otherwise sound tile is a good candidate for this repair. A tile that has broken into pieces, has lost a corner, or is one of several failing across a section of roof is a replacement job rather than a sealing job. Roof tiles are cheap; a sealed-up tile that fails again in a year has cost two trips onto the roof.
Take the usual precautions working at height, and walk on the tile battens rather than the middle of the tiles.
Common questions about repairing cracked roof tiles
Which product if I am painting the roof?
Selleys 3 in 1 — it is paintable, and white is the better colour for this repair. The silicone is not paintable.
Do I need to remove the cracked tile?
No. It is easier to leave the broken tile in place and slide the tile above it out of the way to get access.
How do I clean up the excess?
Wipe it off with a rag soaked in a little mineral turps, before the product skins.
Does the tile need to be dry?
For Roof & Gutter Silicone, yes. 3 in 1 is suitable for wet or dry surfaces, which makes it the more forgiving option on a damp day.
What colour 3 in 1 should I use?
White is the better choice for this repair. It also comes in clear.
How long before rain is safe?
Roof & Gutter Silicone skins in 5–10 minutes and is tack-free in 30. 3 in 1 skins in 15–30 minutes. Both cure through more slowly — 2mm and 3–4mm per 24 hours respectively.
Can I paint over the silicone if I change my mind?
No. Roof & Gutter Silicone is not paintable, and there is no way to make it so after the fact.
What about a leak at a valley or a flashing rather than a tile?
See emergency roofing repairs to prevent water damage, and Roof & Gutter Spray Seal for fine cracks and holes over larger areas.
How long does 3 in 1 take to cure fully?
It cures at 3–4mm per 24 hours, so cure time depends on the depth of product in the break — see 3 in 1 curing time.
What is the best sealant for cracked or broken roof tiles?
Selleys Point Works Gen III is the expert-recommended solution for cracked or broken roof tiles. It is a flexible roof pointing compound specifically engineered for bonding and finishing hip and ridge tiles, and it effectively seals roof tile surfaces.
Is there an alternative product to Selleys Point Works Gen III for sealing roof tile cracks?
Yes, Selleys Roof & Gutter Silicone Sealant is an excellent alternative for sealing cracks and gaps around roofing installations. It is a neutral cure, 100% silicone sealant that provides superior waterproof protection with excellent UV and weather resistance.
How should roof tile surfaces be prepared before applying sealant?
All surfaces must be clean, dry, and free from dirt, dust, oil, and loose rust. Old or crumbling sealant must be completely removed, and surfaces should be cleaned with mineral turpentine and wiped dry with a clean rag before applying the sealant.
What should be checked regarding the bedding when using Selleys Point Works Gen III?
The bedding should be free of all holes and defects, and it should be finished at least 3mm under the ridge tiles. Additionally, the edges of ridge tiles and roof tiles next to the bedding must be free of powdery bedding mortar.
What temperature range is recommended for applying Selleys Point Works Gen III?
Selleys Point Works Gen III should only be applied when the surface temperature is between 10-40°C.
How much working time do you have with Selleys Point Works Gen III before it skins over?
You have 10-20 minutes of working time at 40°C before Selleys Point Works Gen III begins to skin.
What thickness should Selleys Point Works Gen III be applied at?
Selleys Point Works Gen III should be trowelled to a thickness of 3-5mm, ensuring full contact with the roof tiles and under the tile edges.
What is the recommended technique for finishing Selleys Point Works Gen III after application?
Apply the product in small runs for a neat, clean finish, then use a wet trowel to create a smooth surface, cleaning the trowel regularly with water. Brushing or sponging should be avoided, as this damages the finished appearance.
How long does Selleys Point Works Gen III take to cure?
Selleys Point Works Gen III requires 24 hours for full cure. In good weather, 2 hours is sufficient for it to withstand light rain, but curing times extend in cold weather.