You can build a simple smokehouse with a wood box frame and simple board walls on a foundation of stone, concrete or concrete blocks. Use untreated and unpainted wood to avoid any potentially harmful chemicals. You can also use other materials such as concrete blocks for a non-flammable structure.
Wood smokehouses are fast to build and relatively inexpensive, but they are flammable. Builders need to carefully control how heat is distributed. Keep the fire at the bottom separated from the wooden walls on a gravel or concrete pad. Wooden smokehouse construction does not need to be exact; a leaky smokehouse is not a problem.
After constructing a simple wooden box frame for your smokehouse, cover the sides with wooden boards, and attach a wooden door to the front. Drill holes in the roof to vent the smoke. Add wooden bars or metal racks for food being smoked. Do not use galvanized metal, as it may give off toxic fumes.
Other more sophisticated smokehouses separate the firebox and the smokehouse into separate elements connected by a smoke channel. This arrangement allows for cold smoking.
Smoking meats and other foods can be a complicated process. Websites such as Meatsandsausages.com provide detailed meat-smoking instructions including how long to smoke meat, and at what temperature.