How to fix a broken tile
After leaving the factory, tiles continue to settle and cure and sometimes crack during this process. Replacing a broken tile is very easy and can be done by anyone with little or no experience. If you're unsure about your abilities, it may be better to get a contractor to do it for you.
The right tools to replace a roof tile
The most challenging part of replacing a broken tile is to walk on the roof without breaking more tiles along the way. This should not be a problem when you have a long enough ladder or ladders to aid you.
There are roofing ladders available for sale or hire that has wheels to enable you to push the ladder up the roof and hook it over the ridge without disturbing tiles along the way.
Alternatively you can buy a section with wheels and hook, which can be fitted to a conventional ladder. Professional roofers mostly use walk boards, depending on the type of roof. You may also consider hiring a scaffolding tower for the job.
How to Replace a Tile
Tiles won't break that easily, but you do get weak ones or you may simply be stepping on the wrong part of a tile. Rather choose a sunny day to work in, hot, but still comfortable, because some tile types are more flexible the hotter it gets. Never work in rainy or freezing conditions. Besides being dangerous, some tiles are guaranteed to break in cold conditions.
The first step is to look for some spare tiles that were left behind by the last roofer or builder. If not, you can take a sample with you and buy the replacements, or the closest match to it you can find. To obtain a sample, remove a broken tile as described below. If you don't like the contrast the replacement creates you can swap the new one with an old tile from another part of the roof that is most out of sight.
What you'll need is a flat pry bar and wedges to raise the surrounding tiles that overlap the broken one. When these are raised you can now lift the tile at the backside and slide it out. Tiles have a nudge at the back that hooks over the sheathing of the roof. The sheathing is the framework or skeleton on which roofing is laid. The new tile is now simply hooked over the sheathing as was the old one and the surrounding tiles lowered again. The tiles of some roofs may be nailed down, depending on the slope, which will make them more difficult to remove.
To remove an asphalt shingle, or tile, the same procedure is followed as described above, but these tiles are nailed down and it may be difficult to get a grip on the nails in order to remove them. Use a flat pry bar to gently lift the tiles above where they overlap the broken one. You will now see the nails that fasten the broken tile.
To remove the nails, four of them usually, use the pry bar - it must be a bent one - and position it against the edge of the nail's head. Give it a light tap with a hammer so the pry bar can dig slightly into the tile and get underneath the nail head. Pry out the nail as far as possible until you are able to use a claw hammer to pull out the nail.
Repeat this procedure with the remaining nails. Then lift the overlapping tile above with the pry bar to access the second row of nails. Use the same procedure to remove the second row and pull out the damaged tile. If the existing tiles are too brittle and won't lift high enough without cracking, tear out the damaged tile, cut v-notches in the new one to fit around the nails and slide it in place. Secure it now with four nails. You can also use asphalt roofing tar to seal around the nail heads and the gaps between the tiles.
If you can't replace a tile immediately and want a temporary solution to prevent water damage, you can use a caulking gun and bituminous sealant and seal the tile from below and above after cleaning it first with a wire brush. Try to force the silicon into the crack and press the parts together until some silicon get squeezed out. If you want to you can make this a permanent solution by camouflaging the fix. There may be some coloured granules that accumulated in the gutter. Sprinkle some of that on the fresh sealant and no one will know you fixed it.
Asphalt tiles that curls at the corners can be fixed by gluing them down using a caulking gun and sealant and forcing them down using a brick or any other suitable weight. Do this while the roof is hot.