Fences not strong enough.

[sidvanhound]

I have the "Heavy Steel Fence" but some animals seem to able to smash them down fast.
There must be a better thing?

[Nederbeest]

There are three more versions which are slightely stronger you can unlock in the main campaign, namely "Heavy Electrified Steel Fence" (takes slightly more hits before it breaks), "Heavy Concrete Fence" (takes more hits before it breaks) and "Heavy Electrified Concrete Fence" (takes even more hits before it breaks).

But besides that, none of these do their job. Even the smaller herbivores can break the "Heavy Electrified Concrete Fence" if they want. Fences do nothing in this game, besides delay the inevitable or contain them long enough during a storm. The only way to keep animals inside is to make sure they are happy (social, environment requirements and size enclosure).

Another tip: make multiple layers of fencing for the predators that are prone to get freaked out during storms. That way they need to go through multiple layers and you have more time to sedate them with a chopper or jeep.

Keep in mind: Highly packed and dense building sites are the targets for tornadoes. These will always targets those areas during heavy storms. None of the fences are tornado proof. There is a way to circumvent this, but that's by using the game against itself.

[V0lcanF1re]

any dino can break any fench, the strongest fence in concrete electric, cost power as well.

mostly fench buy you time to tranquillize the dino and avoid a break out.
before heavy tornado storm you can tranquillize some carnivors that 'upset' fast through heavy storms.

light fench can to be destroyed easily by tornado storm, you want at least heavy steel fench or higher for good protection.
in some missions you can make circle of fench, a lot of fenches will take the carnivors longer time to break out to hurt the visitors.

remember any dino can destroy any fench just take more time to do.
send fast jeep or heli to tranquillize the dino.

[Nioell]

There are also mods that make the fences way stronger, because yes, they are kinda a joke when a tiny Struthio can headbutt through a heavy concrete wall...

[FTWO]

If you're playing a Campaign, you're going to have to used what you got so far until you unlock better things by progressing through the game and unlocking better enclosures.

Steps to get familiar with:
1. You will get a warning before the Storm actually hits, listen for it then Save Game, just in case.
2. Immediately begin sending out your AC Helicopter and Ranger Teams to tranquilize some of your dinosaurs, mainly your carnivores. If any are going to break out, they will be the first to do so.
3. As soon as you get the Storm Warning icon that it's finally here, open ALL your Shelters to protect your Guests.
4. If you need to, keep up with your AC Helicopter and Ranger Teams to continue tranquilizing dinosaurs, but if the carnivores are tranq'd and Guests are in Shelters, you can handle anything else that happens, so just sit back and wait until it's over.

This is mainly the strategy for dealing with Storm Warnings in any of the Campaigns. Now playing a Challenge Mode, mainly Jurassic difficulty, it is unbelievably hard to get to a 5 Star Rating with tornadoes smashing through your island every 30 minutes. But just like @Nederbeest mentioned, you can use the game against itself. There is a trick you can do, on your island, that will 100% stop any Storms from happening on your island throughout your Challenge. It's your choice to do it. I did it because I wasn't trying to get a good finishing time on a Challenge. I just wanted to complete them all on the hardest difficulty to unlock all the Skins. If you want to know what the trick is, you can easily look that up.

[BlazeD]

You don't need any fence beyond Light, except for cosmetic purposes.
Keep your dinos happy and they will not try to escape. No fence will stop an unhappy dino, as others have pointed out.

There are scripted events where dinos escape regardless of happiness. Use double or triple wall enclosures for those.

[FTWO]

Originally posted by BlazeD:

You don't need any fence beyond Light, except for cosmetic purposes.
Keep your dinos happy and they will not try to escape. No fence will stop an unhappy dino, as others have pointed out.

There are scripted events where dinos escape regardless of happiness. Use double or triple wall enclosures for those.

Whether you keep your dinosaurs happy 100% of the time, when a Storm Warning occurs, it doesn't matter if it's a Light, Heavy, or Severe Storm, MOST carnivores are going to break out, regardless. The point of better fences is for this purpose alone. Light Fences will take 1 hit and they're down, 2 hits if it's a weaker dinosaur. The reason for a better fence is so you have time to react to the dinosaur attempting to break out and tranquilize it and give your Guests time to escape to a Shelter, before it does break out. Only other situations that wont matter at all is like @BlazeD mentioned, when you're doing a scripted Mission that might require such chaos like a dinosaur busting down a fence in 1 hit regardless how strong a fence it is.

If you're playing a Campaign that doesn't have Storm Warnings OR if you're playing a Challenge and you glitch the Storms so they do not occur anymore, then absolutely, only use Light Fences, because as long as you keep your dinosaurs happy, they are not going to try to get out at all.

[BlazeD]

Yep. Thats pretty much the case for other fencing.

After one gets Wus genetics storms dont make them mad any more.

[sidvanhound]

Thanks for all the info everyone. Among Jeff Goldblum's Quotes should be :
"If you can't build a decent fence you should probably not be rearing Dinosaurs"

[FTWO]

Originally posted by BlazeD:

Yep. Thats pretty much the case for other fencing.

After one gets Wus genetics storms dont make them mad any more.

The only thing I hate about Wu's genetics is that they reduce the dinosaurs Star Rating while also reducing it's Vitality Rating by a lot... so it's like... awww come on! Well, the genetics that increase the "Comfort" zone, that is.

[nachums]

Everyone here is right, keep the dinosaurs happy and most of the time you'll be fine. Tranq the worst when there's a storm.

When you get concrete fences, you can avoid using electricity and just use those mostly in a couple of layers.

[BlazeD]

Originally posted by FTWO:

The only thing I hate about Wu's genetics is that they reduce the dinosaurs Star Rating while also reducing it's Vitality Rating by a lot... so it's like... awww come on! Well, the genetics that increase the "Comfort" zone, that is.

It isn't that bad. I'm likely to have several around the park so the value to me is not worrying about every aggressive dino in a storm rather than any rating hits.