How to Build a One-Room House

Dig a hole in the ground roughly 25' x 25' with a two-foot depth bringing the foundation to below the frost line of the ground. This will be the crawl space for the house.

Lay out the forms for the footing for the crawl space using a measurement of 16” wide and 8” deep. Create a square 20' x 20'. Make sure the frame is squared to keep the house walls even. Build two square forms 3' x 3' each. Place these in the center of the floor about ten feet apart; level them off as best as possible. Pour concrete into these forms and allow it to set, use a 24 hour period to be certain.

Place metal posts on the two smaller squares and secure into place for your floor supports. These posts should be 4' high so that the floor is above the ground. Then build the walls to the foundation with cinder blocks. These are also 4' high.

Build the floor over the crawl space with 2 x 4 beams 10' long. Cut the board to size as you place each one. Create the frame around the top of the crawl space. Then place the cross beams in the center over the two posts. Now finish the layout of the floor using the sides and the cross beams as your ends, placing the boards 1' apart. This is your floor support. Finish the floor with a plywood underfloor.

Build the walls using 2 x 4s next. Build each wall with space for at least one window for enough natural light and heat to get in as well as cross ventilation. Remember to make one wall the front with the entrance.

Build a flat roof with a slight pitch of at least ten degrees. This allows water runoff and stops buildup of material during colder months. Make sure the roof has an overhang of at least one foot so anything that runs off doesn't affect the walls.

Install the windows and door. Be sure to follow the manufacturer's directions when installing to ensure proper fit and warranty coverage. After installation, open and close the windows, and the door, to make sure they work easily and close tightly to avoid trapping moisture or allowing drafts.

Place the electrical boxes and wiring. You will want two outlets per wall spaced at least five feet apart. Connect everything to the circuit box and test to make sure you have juice.

Lay out the plumbing for the kitchen wall and the bathroom. Have the main water line placed under the kitchen sink for easy access. Run the pipe from the kitchen to the bathroom. Run a continuous line to connect the bathroom sink, toilet and shower or tub as well as the water heater. Have another pipe running parallel to allow hot water to route itself back through.

Have the bathroom in one corner of the house. This way you only need to build two small walls. The bathroom should be at least 7' x 7' square to give enough space for use. Put the water heater in an unused corner of the bathroom to save space. Have the bathroom on the same wall as the kitchen.

After putting up the interior walls, install the flooring and the ceiling. You can use railroad ties or beams on the ceiling to give it a cabin look. Then, install the cabinets and appliances for the kitchen and the bathroom.