There are many adaptations for the lean-to shelter, depending on the circumstances and materials available.
In this case I used a horizontal ridge pole supported by two trees at either end with dead leaned against it and a piece of parachute material secured over to wick away any rain. The bed is made of spruce boughs.
Here we used Spruce boughs as thatching for the roof and this created a very effective waterproof cover. The bed is again made of Spruce boughs. The two logs across the front of the shelter prevent the occupant rolling into the fire when sleeping.
With this lean-to which I used on a survival course in Canada, I have incorporated a raised bed, lined with Spruce boughs. In this case I was sleeping in this shelter at -22 degrees, without a sleeping bag.