The fallen tree or debris shelter is one of the simplest survival shelters to make. If you find yourself stuck out in the wilderness with no man made form of shelter like a tarp or tent and there are no other natural forms of shelter, then knowing how to build this shelter could be very helpful and lifesaving.
First survey your surroundings. You can either use a fallen tree where the tree is still attached, about 3-4 feet off the ground, to the trunk. It should look like a triangle on its side. If you do use the fallen tree method, make sure the tree is secure and you are not in danger of the tree coming loose and crushing you. The method I recommend and use is first find a generally good level spot where you would like to make camp. Next, look for a good sturdy tree with some good branches that will be low enough for the entrance of your shelter. Now go find a log for the ridge of your shelter. Make sure it is long enough so that you will be able to lie down in the shelter when you are done building. I am 6 feet tall so I generally try to find a thick log or fallen tree that is about 9-10 feet long. If you cannot find a good log or already fallen tree then you will have to cut a small tree to fit your needs. Try to find everything you use on your shelter from already fallen trees if at all possible.
Now lean the log on the tree so that one end of the log is still on the ground and the other is resting on top of a thick branch where it ties into the main part of the tree. Lay the log in the notch of the branch and trunk. If you have some sort of cordage it wouldn’t hurt to tie the log off for safety sake. You will now want to go find sticks or branches that are about as thick as your forearm and lean those out along the log you have leaning against the tree. Make sure you have a good steep angle to help run water off in case of rain. If you weave some thinner branches or vines trough the branches it will help make it sturdy.
If you are in an area with evergreen trees you can begin thatching the roof with evergreen branches. Keep the butt end of the branch up and start along the ground and keep piling them on until you reach the ridge log. Place a layer of evergreen branches along the ridge so that they overlap each sidewall and close the ridge up. Now just fill the inside with leaves or evergreen branches and move in for the night. You can also close in the front door with branches and leaves after you are inside. Make sure that you do have some vitalization though.
If you are not in an area with evergreens then you can supplement by building up piles of leaves and debris against the walls you built out of sticks. Place some small branches on top of the leaves and debris to help hold everything together and then place more leaves and debris on top of those branches. Completely cover the two walls and ridge. The more layers of leaves and debris that you have the warmer the shelter will be and you will be less likely to get wet in a rain storm. Place a thick layer of leaves inside the shelter for bedding. Climb in and enjoy all your work.
In the winter you can also place snow on the outside walls and ridge for insulation and to cut out any wind that might be blowing. I recommend that you test out building one of these shelters in your own yard or wherever you might be able to. It is easier to learn from any mistakes you make now than when your life might depend on it. There are also many modifications that you can make to this shelter as well. You can thatch the walls with birch bark, add a tarp or Tyvek underneath the thatching to make the shelter more water resistant and you can also thatch the roof with moss. Have you ever built one of these shelters and what modifications if any did you use? As always build at your own risk and never stop learning and fine tuning your survival skills. You are only guaranteed to have your knowledge and skills in a true survival situation. You may not have any man made tools or supplies when you most need them. So go out and enjoy the wonderful place we call the great outdoors and test your survival skills.