Yes, it can be worth screening a porch if you live in an area with beautiful weather, since it allows you to enjoy your outdoor space longer in the spring and summer. The additional protected space may even attract more prospective buyers if you intend to sell—especially if you add seasonal features, like a ceiling fan for summer or a heater to winterize your screened porch.

Building a sunroom is usually less expensive than the cost of building a home addition, but it depends on the type of sunroom. A four-season sunroom will cost more than a home addition because it’s basically a home addition with larger, more expensive windows. All other types of sunrooms will be more affordable than a home addition of an equivalent size because they don’t have insulation, heating, cooling, electrical connections, or plumbing.

Yes, you can build a sunroom addition to your home despite living in a cold climate. Make sure to use high-quality insulation and windows and to supplement with sufficient heating from your HVAC system. The windows in the sunroom allow enough natural light into the room to help heat it most times without having to use the furnace. Even a small electric fireplace can heat the sunroom well enough.

If you want to hire a professional to build a screened-in porch, a local sunroom or porch contractor is your best bet. If you can't find a local sunroom builder, another option is to consider hiring a general contractor to perform the work. 

If you're handy, you may consider building the porch yourself. Before you do so, make sure you understand the local permit requirements and building codes so that you don't have any problems with the safety or structure of the porch.