While dimensional shingles have many advantages. They also have their disadvantages, so before making your decision, be sure to weigh them out. One disadvantage is that due to being raised, they are prone to gathering damp leaves, which may result in mildew. Therefore, they must be cleaned off regularly. It is also important to make sure your roof support is sturdy enough to hold the heavy dimensional shingles. Be particularly careful if you live in an old property. Finally, the initial cost of buying and installing dimensional shingles is more expensive than other roofing alternatives. Many people believe it is worth it, as they can last up to 50 years, which is longer than most other roofing materials.