Yes, if the changes are structural in character. The installation of a beam or lintel that affects the building's structural stability will also require permission. Any material change to an existing roof structure requires approval from the city. You should notify the city if you plan to make major repairs to your house. Major repairs include anything that would cause a significant change in the appearance of the property or could affect its safety for people or pets. Examples might be replacing all of the windows on a single floor or fixing up a badly damaged porch. If you're just putting up some shelves or adding another room to an already approved project, you don't need permission. However, be sure to follow any local building codes when making structural changes. For example, you shouldn't install a beam or lintel over an exterior wall without first getting approval from the city because this would create an unsafe condition if not done correctly. Lumber is the most common form of fuel used in residential construction. Therefore, if you want to replace your roof but don't want to go through the trouble and expense of getting licensed as a residential builder, you can use lumber as long as it's not priced above average. Of course, you'll also want to make sure the quality is good enough to last through at least one hurricane season.