Sunroom Construction

A three-season room and what it is not

A three-season sunroom is a glassed-in room you use from spring into late fall, and on bright winter afternoons. It keeps out rain, wind, pollen and insects and holds the sun's warmth on a cool day. It is not heated and insulated like the rest of the house, and it is not meant to be. That is what keeps it simpler than a full addition.

If you want a room you can use in January, heated and insulated to the energy code, that is a four-season sunroom built as a new addition, and we cover it on the Sunroom Additions page. It brings foundations, insulation, heating and code requirements a three-season room does not need. We will help you decide which one fits how you plan to use the space.

For many families a three-season room is the right answer. It stretches the warm months at both ends, it adds no load to your heating system, and it can often use a footprint you already have.

It is also the room people tend to misjudge. A south or west wall of glass gets hot in July, so orientation, operable windows for a cross breeze and some shading are part of the design from the first sketch, not an afterthought once you have sat in it on an August afternoon.

Enclosing an existing porch or deck

Plenty of sunrooms start as a porch or deck the family already owns. That can be a good shortcut, but only if what is underneath is sound. Before we design anything we look at the footings, the framing and the ledger connection to the house. A deck built to carry people and furniture was not necessarily built to carry walls, glass and a roof.

Older porches in particular hide rot at the sills, the column bases and where the floor meets the house. Some were built on shallow piers that have moved over the years. If the structure needs new footings below frost, sistered joists or a rebuilt ledger, we tell you before we price the glass, so the decision gets made with the full picture.

Sometimes the honest answer is that the existing deck is not worth enclosing and should be rebuilt first. That conversation happens at the walkthrough, not halfway through the job.

When the existing structure is sound, enclosing it saves the footing and framing work a new room would need, and the floor already sits at a height that works with the door into the house. That is the real advantage of starting from a porch or deck.

You will know the sequence from the start, and you will hear from us when weather or a delivery shifts it.

Glass, framing and the roof tie-in

A three-season room is mostly glass, so the framing between the windows does the structural work. Posts and headers have to carry the roof and resist wind, and on the coast that wind load is real. The window or panel system gets chosen for how it opens, how it screens in summer and how well it seals in a driving rain.

The roof is where sunrooms most often fail. A shed roof that ties into the side wall of the house has to be flashed into the wall behind the siding, not caulked to its face. If the room meets an existing roof edge, the shingles, the ice and water barrier and the flashing have to be worked together so meltwater from an ice dam cannot find its way into the new ceiling. We detail that connection on paper before anything is cut.

Ceiling and floor finishes come last, chosen for a room that sees heat, cold and strong sun. Wood that is fine indoors can cup in a room that swings hard between a sunny afternoon and a cold night, so we steer material choices toward what holds up.

Screens matter as much as glass for most of the season. We look at how the screen panels store or swap, whether they can be cleaned without tools and how the bottom rails shed water, because those are the parts you handle every spring and fall.

Where the room meets the house

Adding a sunroom usually turns an exterior wall into an interior one. The door between the house and the sunroom stays an exterior door, since the sunroom is not conditioned, and it should seal like one. If you are widening that opening for French doors or a slider, the header work and the trim on both sides are part of the scope.

Outside, the siding, trim and gutters around the new room should look like they were always there. We match or complement the existing trim profiles and roof pitch where we can, and we make sure the new gutter does not dump water onto a walkway or against the foundation.

If the house predates 1978, cutting into the existing exterior can disturb lead paint, and we follow lead-safe work practices for that part of the job. In a local historic district, the commission may need to review the design before the building permit is issued.

Permits, inspections and the daily routine

A sunroom is a structure attached to the house, so it is permitted through your town's building department under 780 CMR and inspected as it goes. We prepare the drawings the department needs, pull the permit and are on site for the framing and final inspections. Any wiring for lights, a ceiling fan or outlets is done by a licensed electrician on its own permit.

You will know the sequence from the start, and you will hear from us when weather or a delivery shifts it. Glass packages usually have lead times, so ordering happens as soon as the measurements are final, and we keep you informed about where the order stands.

The work area is cleaned up every day, the inside of the house is protected with dust barriers when we open the wall, and the finished room is walked with you before we call it complete.

When something unexpected turns up, such as rot in the house wall behind an old ledger, we stop and show you before it is covered. You get the options and the price for the fix, and the work continues once you decide.

See the rest of our exterior work, or browse the gallery for rooms we have finished.