Build a log cabin Playhouse for under $300

Step 6 Secure the floor and Walls

You will most likely have to use some of those Cedar shim's since the stringers will most likely be a little thinner than the 2x4 treated lumber already there.
Put one 3" Screw directly through the floor panel stringers and shims into each of the 4x4's.

Setting the first wall
Screw one of the 2x4's into the side of the floor and part way into the other end of the 2x4.
Lean the back wall up and secure it with the 2x4.
Make sure the back panel is perfectly positioned since all other walls will key off this one. Screw the back panel to the floor with 3" screws by screwing at an angle through the bottom edge of each stringer "two screws each, pre-drilling through the stringers will make this easier".

Now just lean the side wall opposite the 2x4 support up, kick it so it is firmly against the back panel and screw it into place through the pack panel into both stringers.
Secure the bottom of the side wall in the same manner as the back.

Remove the 2x4 support and add the other side wall.

Now cut the remainder of the door out and screw it into place from the front.