Press 'E' to pick up props.
Press mouse2 to nail a prop you are holding.
Press 'R' to unnail prop.
When holding the prop, hold 'SHIFT' to freeze it in place.

And next up, you also need to know
Do not, or atleast avoid, the practice of sh!t-cading!
sh!t-cading refers to a cade being so bad its close to unusable. It often meets following criteria (which it should not):

• Not being able to see through the barricade
  
• Not being able to shoot through the barricade
  
• Being able to go through holes that a barricade may have

If your barricade has any one of these criterias as true, restructure your cade or in short; fix any problems it has! Sh!tcading costs lives.

NEVER nail prop to prop.
The only exception is when you have to nail a prop but roof is to high AND [if more nails gives more health to prop] if a prop on the front of other props blocks the rest of the cade from damage, you can nail first prop to 2nd prop.


One from 2 exceptions where you can nail prop to prop

As a Barricader you should have some traits to make cading easier.

Traits
Iron Grip (on some servers it may have different name) is super important. It makes props you hold untouchable; zombies can't push the prop you are holding out of your hands. It's really usefull when you have to recade mid-wave.
On some servers you may need to buy Muscular trait. It lets you pick up big props (for example: Big Blue Shelf, Red couch)

Tools
Hammer is a unique tool which is used by a Cader. It needs nails to nail props. You can also repair with it just by pressing mouse1 and aiming at the prop you want to repair.

'Aegis' Barricade Kit' It's a kit with 5 boards which can be mounted on a wall, roof and floor.
Remember! On some servers you can't shoot through the 'Aegis' boards!

An example how boards should be mounted.

Small sidenote tip:
NEVER throw props at the front cade!!!
It makes cading so much harder.
Yes I know what's on the board reee

Do not leave props scattered around in the back cades!
Loose props can make it more painful to move around a cade,and with Shade being able to pick up and throw props on some servers,it makes everyone inside the cade an easy picking.
Sort out your props if you are going to use them later,and nail them to the roof or to the walls!

Finally! We can now talk about Barricades or shorter, Cade(s):

Normal Cade

It's a normal Cade, most of the time it's a Cade made out 2 shelves, benches, 1/2 doors and other props.
Examples:

How the normal Cade looks like


Another 'Type' of normal Cade

V Cade is a cade which is hard to hit by zombies. It forces zombies to go in, making destroying cade alot harder.
The V Cade has it's positives and negatives.

• Hard to hit by zombies.
  
• easy to shoot through.
  
• It can survive many waves without re-cading.

• Thin layer.
  
• It cannot be done in small rooms.
  
• It's The Tickle Monster Friendly. (Tickle can easily hit/kill you)
  

Examples:

how V cade should look like


Other 'Type' of V Cade

Map: zs_abandoned_mall_v6b

U Cade is characterised by a large number of props. It makes it even harder to hit the Cade.

• It is even harder to hit the Cade by a zombies.
  
• Easy to shoot through.
  
• It can survive many waves without re-cading.

• Thin layer.
  
• It cannot be done in small rooms.
  
• It's The Tickle Monster Friendly. (Tickle can easily hit/kill you)
  
  Examples:
  
  How the U cade should look like
  
  Map: zs_antarctic_hospital_v2c

Pixel cade is a cade that looks like you can go through, but you can't. It works well on servers with bots.

• Melee Friendly Cade.
  
• Hard to hit.

• Tickle friendly.
  
• Mostly has a thin layer.

Example:

This is how Pixel cade should looks like.

Tip:
Player width is 2 tiles (and maybe 1 unit more.)
So, if you are planning to make a pixel cade, find that floor texture, it will really help you at making the best pixel cades!

That's the player width in game.

Skycade is a cade that force zombies to go Fast zombie.
This type of cade is not allowed on some servers. Better read the rules or ask someone if it's allowed.

• It's hard to destroy.
  
• It's hard to spot if it's in the right place.
  
• Easy Last Human (It depends on the round)

• It takes so much time to finish it.
  
• Sometimes it won't work.

Examples:

The most common skycade, (Pro tip: Don't cade on this platform, it breaks)


That's the hardest skycade to destroy, the only way to kill it is going as a bonemesh or throwing poison.

Cross-Fire Cade, well; actually cades. They make zombies suffer - It's really powerfull. Zombies can't hide behind corners.

• Easy to shoot through.
  
• It can survive many waves without re-cading.

I can't find any negatives.. sorry I guess :p
An example how the Cross-Fire Cade should look like


Map: zs_Marsh_opt

Sandwich Cade is made out of thin props. It can accommodate up to 20 props in 1 entrance in extreme cases.

• Takes much time to destroy.
  
• It's a Anti Tickle Cade (not always).
  
• It can be a nice Melee Friendly cade.

• Hard to shoot through.
  
• Easily destroyable by a AoE zombies.

Examples:

This is how the normal sandwich cade looks like


Extreme case of sandwich cade, another 'Type' of Sandwich Cade
(I had to do it on sandbox becouse props that have been used here can be found only on Sandbox)

Map: zs_vector

Anti-Tickle Cade is characterised by a small gap betweeen props, so shooting through this cade can be sometimes really hard.

If you know that The Tickle Monster is incoming, use this prop to cover your team! You can shoot through that prop but tickle can't reach you.

• You're 90% safe in the cade (only poison and headcrabs can kill you).
  
• High amout of props in 1 entrance.

• It's hard to shoot through.
  
• It's not melee friendly.

That's a pretty nice cade isn't it? But there's a problem, Tickle can easily kill your team.



This prop fix that problem! Until Tickle destroys it.
Maybe it limits your visibility but it's worth it.


Examples:

The most popular Anti-Tickle Cade.


Another pretty popular Anti-Tickle Cade

Some Sandwich Cades can protect you from tickles range too.

Map: zs_trainstation_v5b

Tunnel Cade works well on bot servers. It's just a tunnel made out of props.

• Good on bot servers.
  
• It's hard to hit.
  
• Easy to shoot through.

• Thin layer.
  
• It's pretty bad compared to other cades.

How Tunnel Cade should looks like

"^" Cade is a really effective type of a barricade.

• Easy to recade mid-wave.
  
• Can survive many waves without recading.
  
• Easy to shoot through.

• Most of the time it isn't melee friendly.
  
• Easily destroyable by AoE zombies.
  
• Tickle friendly.

Standard 'Type' of a "^" Cade.



Another 'Type' of a "^" Cade.

15 or 45 Degree Cade is really, reeaaaaaally popular. You can do any Cade with there degrees. The most common 15 / 45 Degree Cade is a door cade.

• You can do any cade with these Degrees.
  
• You can make it a Melee friendly cade.

First door covers other doors, it's melee friendly and pretty solid.

Of course we cannot ignore the door/piano cade.
The Door Cade is probably the most popular Barricade in the entire Zombie Survival.

On some server doors are nerfed (less health).

• It's very strong.
  
• It can survive many waves without re-recading.
  
• it's easy to build.
  
• Thick layer.

• Easily destroyable by AoE zombies.

Examples:

Normal Door Cade 'Style'


45 Degree Door Cade, The best 'Type' of Door Barricade

Crouch Cade it's a really bad barricade. It forces zombies to crouch, AND It will work only on bots. It's easy to break and this is just not worth it to make this cade, just don't but still I'm gonna show you how it looks like.


This is how basic Crouch Cade looks like.


Map: zs_silenthill_v1b

Ladder Cades
Ladder cades are a special type of the cade. As the name suggests these are made on ladders.

Pro tip: Don't cade on Half-Life 2 ladders (those that makes you stick to them when E key is pressed). Instead, cade the CS:S ladders (those that lets you move to the left or right when stood on them).

• Easy to shoot through.
  
• Easy to recade mid-wave.
  
• Melee friendly.

• REALLY easy to destroy.
  
• Tickle friendly. (in this example.)

Standard type of the Ladder Cade.

• Easy to shoot through.
  
• Easy to recade mid-wave.
  
• Harder to hit (zombies have to turn around to hit a prop).
  
• Melee friendly.

• REALLY easy to destroy.
  
• Tickle friendly. (in this example.)

Another type of the Ladder Cade.

• Easy to shoot through.
  
• Easy to recade mid-wave.
  
• Melee friendly.
  
• Very hard to hit.

• Headcrabs can easily go through.
  
• Tickle friendly. (in this example.)

Probably the best type of a Ladder Cade.

Spiral Cade uses wooden tables or metal desks. It uses 6, max 8 props in 1 entrance.

• It's Melee friendly.
  
• Easy to shoot through.
  
• Easy to recade mid-wave.

• It's Tickle Friendly.
  
• Thin layer.

Examples:

This is how Spiral Cade should looks like.


Other 'Type' of Spiral Cade

Map: zs_snowedin

Now, there are many types of barricades out there, and hell, maybe you can even get creative and find a new way to cade a certain place or area. What really matters most in the end is that your barricade works and helps your team survive the waves!
We hope this small guide helped you learn the basics of barricading and the many different types of barricading (more soon to come!).

Thanks to DuffT for general help in creating this guide.