Hi, Kitchens and bathrooms always bring the biggest return. Be careful how much money you actually invest into the home as you may not see a return if the market doesn't justify a higher price for you. This will all depend on how much you paid for the home, when you plan to sell, and what the market is like at that time.
A deck extension may not be the best investment. Curb appeal is crucial because people judge your home by what they see on the outside. You might consider having an agent guiding you with market data and professional advice, we would need to see the home though.
Have a great day!
Accredited Buyer Representative
BenchMark Real Estate
100 Congress St
Portland Maine 04101