Porches, decks and outdoor rooms built as part of the house.

The names get used loosely, so here is how we use them. A screened porch is a roofed porch with screens instead of windows: outdoor air without the bugs, on a deck-style floor that drains. A three-season room trades the screens for windows or removable panels; it is unheated, so it is comfortable from spring into fall. A four-season room is an addition with a lot of glass. It is insulated, heated and part of the house's conditioned space, which means it sits on a foundation and follows the energy code like any addition.

The choice comes down to how you'll use the room and how much structure you want to pay for. In Stretch and Specialized code towns, a four-season room counts toward the 1,000 sq ft of new conditioned space that triggers a HERS rating for additions. A screened porch does not, because it isn't conditioned.

Most porches that look tacked on fail on proportion, not materials. The roof pitch should relate to the main roof; the eave should line up with something on the house, a window head or a band of trim. Columns need to be stout enough to look like they carry the roof, and the beam above them deep enough to read as a beam. A painted beadboard ceiling finishes it.

The working details matter as much. A porch floor slopes slightly away from the house so rain runs off. Screen systems should come out for cleaning and repair without tearing up trim. Ceiling fans and lights get blocking and wiring before the ceiling goes up, not after. We draw all of it and render the porch against the real house before the footings are dug.

Most of our recent decks pair composite or PVC decking with pressure-treated framing, PVC trim and hidden fasteners, so the walking surface stays clean. Composite doesn't need staining, but the framing under it does all the work: joists at the spacing the decking maker requires, flashing where the ledger meets the house, and footings below the frost depth your building department sets. Near the water we use hardware rated for the exposure, because salt air eats ordinary fasteners.

To the state, a deck is structural work. Massachusetts lists decks among the projects that need a building permit, a registered home improvement contractor and a licensed construction supervisor. In Peabody we're rebuilding a deck now with framing for a hot tub, a load an ordinary deck isn't designed to carry.

A deck over a flat roof is two projects that have to agree: a roof that keeps water out and a deck that never punctures it. In Danvers we built a 16×25 deck over an EPDM roof on a tapered sleeper system with hidden fasteners. A sleeper system lets the deck sit above the membrane instead of fastening down through it, and tapering the sleepers keeps the deck level while the roof under it still slopes to drain.

The questions to answer first: can the roof framing carry the deck and the people on it, how will the membrane be inspected or repaired later, and does the railing work where the drop is real. Second-floor porches raise the same questions; in Danvers we're also rebuilding a second-floor porch and its stairs.

Plenty of North Shore backyards run down to a brook, a pond or a marsh. The conservation commission reviews work in a wetland resource area, within 100 feet of a wetland (the buffer zone), in the riverfront area, or on land subject to flooding. If you're not sure whether your project falls in its jurisdiction, a Request for Determination of Applicability answers that. If the work will alter a resource area, it takes a Notice of Intent, a public hearing and an Order of Conditions. More than 100 Massachusetts communities also have their own wetlands bylaws.

Design can keep a project small in the commission's eyes. In Peabody we're extending a landing beside protected wetlands as a cantilever, with composite decking and no new footings. Fewer holes in the buffer zone means less ground disturbed. Talk to your town's conservation agent early; it is a short conversation that can change the design.

A roof without walls is often the most-used outdoor space a house has: a pavilion off the back, a covered porch on the side, a portico over the front door. In Peabody we're building an attached backyard pavilion with a membrane roof now. Attached structures tie into the house's roof and walls the same way an addition does, with flashing at every joint and a roof that sheds water away from the house.

Out front, a portico is mostly about proportion: columns and a roof sized to the door and the facade, not the catalog. Exterior work in a local historic district needs a certificate from the historic district commission before a building permit can issue, and zoning setbacks can apply to porches and decks, so we check both before design. To see it before it's built, we model and render the porch against the real house.