Home Additions

What an addition actually involves on an existing house

Most people who call about an addition know the house is too small before they know what the new space should be. That is a fine place to start. An addition is a new piece of building that has to sit on its own foundation, carry its own loads, keep water out at every seam where it meets the old house, and stay warm without starving the rooms you already have. The purpose of the room can firm up while we work through those questions.

On a Massachusetts house the existing structure sets the terms. A postwar Cape has a low roof pitch and shallow eaves that limit how a new roof can meet it. An older colonial may be balloon framed, with studs running from the sill to the rafters and nothing stopping fire or cold air between floors. A split-level puts the new floor height somewhere awkward. On the first walkthrough we go into the attic and the basement, so the plan is built on what is actually there and not on what the listing said.

After that walkthrough you get a written scope: what we are building, what we expect to find when the wall opens, what the town will want to see, and who you will be talking to week to week. Usually that person is Steve. He has 20 years in the trade, has run Modern Remodeling for the last six, and holds an unrestricted Massachusetts Construction Supervisor License, the license that covers structural work on one- and two-family homes.

Zoning, setbacks and the permit before the design is final

Before anyone draws an elevation, we check what the lot allows. Every town sets its own setbacks from the property lines, a maximum lot coverage and a height limit, and some cap the size of an addition relative to the existing house. A corner lot has two front setbacks. An older house that already sits closer to the line than current zoning allows may need relief from the zoning board before the building department will accept the application.

Septic matters too. If the addition adds a bedroom on a property served by a septic system, Title 5 brings a design-flow review, and the existing system may have to be shown adequate or upgraded. Inside a local historic district, exterior changes go before the historic district commission. We find out which of these apply at the start, because each one adds a step and a meeting, and it is far better to learn that in the first week than in the tenth.

Once the design settles, the drawings go to the building department under 780 CMR, the Massachusetts State Building Code. Many towns have adopted the stretch energy code, which raises the insulation and air-sealing the new walls and roof have to meet. We handle the application and tell you when it is filed, what the department asked for, and when the permit is in hand.

We handle the application and tell you when it is filed, what the department asked for, and when the permit is in hand.

Footings, framing and tying the new roof into the old one

The foundation goes in first and it goes deep. Footings in Massachusetts sit below frost depth, commonly about four feet, so the addition does not heave in a hard winter and pull away from the house. Depending on the site that can mean a full basement, a crawlspace or a frost wall with a slab. Where the new foundation meets the old one we pay close attention to drainage and dampproofing, because that joint is where basements start taking water.

Framing follows, and the critical moment is the connection. The new floor has to land level with the old floor, which in a house that has settled for seventy years is rarely level itself. We shim and plane so the transition reads as one floor. Where the addition opens into the house, the old exterior wall becomes an interior one, and if it carries a load we size a header or beam and tell you about it before anyone swings a hammer.

Then the roof. The new roof has to shed water into or past the old one without creating a valley that holds snow. Ice dams are a fact of New England winters, and a badly placed valley over a poorly vented addition is exactly where they form. We work out the pitch, the flashing and the ventilation together, and run ice and water membrane wherever the two roofs meet.

Where additions go wrong, and how we head it off

The common failures are not dramatic. A siding line that does not quite match. A floor that dips at the old doorway. A heating system that was already working hard and now has to serve another room or two. A bathroom fan that dumps moisture into the new attic. Each of these comes from treating the addition as a separate project bolted to the house instead of part of it.

We look at heating and electrical capacity at the walkthrough. Sometimes the existing boiler or furnace can carry the new space and sometimes it cannot, and a separate system such as a ductless unit makes more sense. The electrical service may need an upgrade. Those calls are made with licensed electricians and plumbers, as Massachusetts requires, and they go into the written scope instead of showing up later as a surprise.

Older houses also hide things. When we open the exterior wall we may find rot under a window, knob-and-tube wiring, or lead paint on the trim of a house built before 1978. Lead is handled with lead-safe work practices. Rot and old wiring get photographed and explained to you, with the options and what each one changes, before we go any further.

How the job runs once we start

Steve started Modern Remodeling after years of working for guys that lacked communication, and the way we run an addition follows from that. You know who is on site each day. You get updates as things happen, without having to chase us for them. When something changes, because of what we found in a wall or because you decided to move a window, you get the change in writing with its effect on the work before we act on it.

Inspections run through the whole build: footings before the pour, rough framing, rough electrical and plumbing by the licensed trades, insulation, and final. We schedule them and tell you the results the same day. The site is closed up and cleaned at the end of each day, and the opening into the house is sealed with dust walls so the rest of your home stays livable while the addition goes up.

When it is finished, the addition should look as if the house was built that way. That is the standard we work to, and customers will tell you Steve does not put his name on work that is not right. We walk every room with you before we call the job done.

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