The cost of a home extension is determined by various factors including the size (length, width, height), materials used (e.g., brick, wood), additional features (e.g., roof lights), and the location of the property. Different regions may have different pricing due to labor and material costs.

Home extensions in Greater London tend to be more expensive due to higher labor costs, increased demand, and often stricter building regulations and requirements in the city.

Yes, the type, material, size, and number of roof lights can significantly affect the cost. For instance, automated roof lights or those made of high-quality glass might be more expensive than basic models.

Opting for simpler designs, choosing cost-effective materials, and avoiding unnecessary features can help reduce costs. Additionally, obtaining multiple quotes and negotiating with contractors can also lead to savings.

There can be unforeseen costs related to site complications, changes in design, or unexpected regulatory requirements. It's always a good idea to have a contingency budget in place to cover any unexpected expenses.