An enclosed porch should have walls of windows.Enclosing a porch makes the house interior darker, so spend the money on large windows so you can have glass walls. Provide a way to heat and cool the area so it is truly 4-season usable. If you want the porch open to breezes part of the year use windows that open. While a fireplace is nice, it blocks light that otherwise might make it into the house and it takes up floor space. Decide if you truly need a fireplace to make the room usable in the winter. Primary heating should be from some other source.
Try to arrange doors so one can get from the house to the outside without having to traverse the enclosed porch. The exterior door should face southerly to protect against winter winds when the exterior door is opened. If that is not possible, installing a vestibule/mud room may prevent excessive heat loss.
If the porch currently sits at grade it is a good idea to pour a foundation. Otherwise wet seasons are likely to seep through the floor and lead to mildew or rot. Use ceramic tile rather than wood or carpet for flooring.
You will likely need a permit to begin the project. As the homeowner you can probably do the work yourself, but you would be better off hiring a professional. The cost of tools alone makes professionals worth their pay. Their experience is priceless.
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9’4” ceiling. 13x20 room
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