Adjust for Altitude
High altitudes can also affect gluten-free ingredients. If your bread, cakes or cookies are a little off, experiment until you find the right combination for where you are. For example, reduce baking powder by 1/4 teaspoon for each teaspoon called for in the recipe if you are baking above 6,000 feet, recommends Jules Shepard, Maryland-based author of gluten-free cooking books and julesglutenfree.com. If you are baking higher than 8,000 feet, reduce by 1/2 teaspoon for each teaspoon in the recipe.