In Ark: Survival Evolved you are able to upgrade your base without the loss of any structures in many cases. This guide and video will show you how to do it quickly and effectively.
The process for upgrading a base is pretty much the same as building it in the first place. For example, you can place a new wall exactly where the old wall was, and when you click to place it, the old wall will be demolished as the new wall is placed. You are, of course, refunded your materials for the old wall, though as with all demolishing, you don't get everything back. This should not harm anything you have built or placed inside a structure, unless you run into a glitch.
When upgrading your base the best place to start is with the foundation. In most cases you'll find that you don't need to demolish anything that you have built on the floor. I have run into a few bugs where I did have to do so, but I am sure that those are glitches.
Depending on how your base is built you may find that you have to do some of the upgrading from inside, though for smaller buildings the foundation is easier to replace from the outside as you can clearly see it.
I have found that upgrading Thatch to Wood is easy enough from outside, but for Wood up it seems like you have to stand inside and stare down at the segment you want to replace, without actually standing on the segment to be replaced. Otherwise it won't light up green.
If you run into a glitch and you are forced to demolish an object built on the floor, make sure you have storage nearby for the materials refunded by demolishing them. Also keep in mind that when you demolish an object and its inventory is dropped to the ground it will despawn very quickly. Picking up the items and dropping them can be a way to buy yourself time. It is also a handy method by which you can move large numbers of items over to nearby storage containers.
Upgrading the walls is fairly simple, though it is often easier done from the outside than inside. That way you will most often have a clear view and the wall will jump around less on the snap points if your camera angle is good.
For the door and door frame you should upgrade the door frame first, though it does not appear to matter at this time. Also note that it seems as though when you place the new door it will inherit the configuration of the one it replaces. If the old door was locked, the new one will be locked.
I have noticed the same is true with the pin codes on the doors. Always double check the setup of the door after you place it.
Upgrading the Roof is one thing that I find very easy to mess up if you're not careful. Unlike the other parts of a structure, roof segments can be placed much more liberally, including in positions where they overhang the outside of the building. Be very careful when placing roof segments. Make sure that you can clearly see it and that the item is exactly where you want it to end up. Also give it a moment before you click to make sure it isn't going to bounce around on the snap points.
Keep in mind that depending on how high up your roof is you may actually have to get on top of it to upgrade it. There is also an interesting issue with the sloped roof. I have found that I can upgrade the sloped walls most of the time, but the actual sloped roof has to be demolished before the new one can be installed. This doesn't cost more in resources, but is a bit more work.
Installing the Hatch Frame is a fairly simple process. The same goes for the Trap Door and the Ladder. But making it all play well together and not be a big problem with the current glitches, that's where the tricks come in.
First off you don't want to have it so that when you go up the ladder you run straight into a wall. This can result in going straight back down the ladder hole without using the ladder. In other words, falling. Of course you can say the same for having a railing to run into, and of course if there is just an edge up there it will be very easy to shoot straight up the ladder and off the edge.
The solution is to make sure you have a ceiling tile worth of space to land on when you go up the ladder.
Another problem is getting hooked on the trap door when climbing up. This can be a real pain and can be very glitchy. The solution is a bit hard to explain but I'll give it a shot.
Stand so that when you open the trap door it swings either left to right or right to left. Then from this position place the ladder either at the front or the back. Basically if the trap door is swinging to the side, and you put your ladder on the side as well, you can run into tons of trouble as you may very often clip into the trap door.
Just take a look in the video at how I have installed my ladder on the hatch frame in relation to the trap door. Oh don't worry, this can still be glitchy, but it should be far less glitchy and annoying.
Installing a Window Frame is as easy as installing a wall. You can even upgrade a standard wall to a Window Frame very easily simply by placing the Window Frame over the Wall and clicking.
The windows snap into the Window Frame as easily as the door snaps into the door frame or the trap door into the Hatch Frame. With the windows you get the same options as with doors. Lock, unlock, & Pin Code.
The Railings install exactly the same way as walls. Keep in mind that you can stack railings just like walls.