Home Addition Considerations

March 10, 2023

There are many reasons why someone would want to add on to their existing home, such as adding an extra bedroom for a growing family or building more entertaining space for hosting parties. Whatever your reason for a building addition, proper planning is critical to success and ensuring the home expansion is as least disruptive to your ongoing lifestyle as possible.

Selecting the right contractor is essential and you should consider those that specialize in renovations and additions. Adding on to an existing home that is occupied by a family is very different than building a new home, and requires a different approach from all the craftsmen and tradespeople involved.

Listed below are some of the issues which need to be considered, addressed, and resolved before any work begins:

Planning a Home Addition – What to Consider Before You Start

Building, Zoning, & Neighborhood restrictions

Check all the local regulations to make sure the addition you envision will be allowed. Zoning rules impose building setbacks (how far the structure must be from the property line) and some neighborhoods may have special restrictions as well (like a prohibition against removal of some trees). Building codes require escape windows from bedrooms – so an addition that creates an interior bedroom may be prohibited.

Roof, Wall, & Foundation Connections

An addition cannot simply be built next to your existing house. It must be connected structurally and preserve the environmental and thermal envelopes of the home. Roofs must be structurally framed together to act as one unit, so wind loads get properly transferred to the entire structure. Wood framing of old and new walls must be securely connected, so brick, stucco, or siding will need to be removed and replaced.

Flashing and vapor barriers must be maintained to protect the home against uncontrolled air, vapor, and temperature migration from the exterior. And concrete foundations must be securely joined to prevent uneven settlement, separation, or even failure.

planning a home addition

Increased Air Conditioning/Heating Loads on the Existing Systems

Most people would not build an addition for a small closet, so it’s a pretty sure bet that any addition will exceed the capacity of your existing air-conditioning or heating systems. You should plan on an additional system, with the controls, supply ducts, and equipment required (as well as the space needed and access to the equipment).


If the planned addition includes a new (or expanded) bathroom or kitchen, there may be new plumbing required. Remember, everything drains downhill, so you need to know where your sewer line exits the house relative to the new plumbing. If the addition turns out to be on the “high” end (farthest away from the sewer line exit) floor elevations and drain lines for showers or toilets may be a challenge.


Electrical panels may have extra room for more circuits, so adding a few to accommodate the new addition may be no problem. But, depending on the existing panel and the size of the addition, a secondary panel may be required.


Additions very often mean opening up the side of a house, leaving an unsecured hole in your castle while construction is ongoing. This exposes the inside of your home to the weather, insects, roaming neighborhood pets, or worse. This is also another reason to select a reputable, insured contractor who only uses tradespeople they know and trust to be in your home. Most contractors will secure openings as best as they can to prevent the elements from getting in.

All these issues can be successfully resolved to ensure the new addition provides comfortable and long-lasting space for your needs. Proper planning and competent professionals (like house plan designers and/or architects) involved in the beginning can make the process efficient, cost-effective, and timely.

Latest Articles

How To Prepare Your House for the Freeze

Has the Drought Affected Your House?

Winter Wonderland: 8 Cool Energy Efficient Home Ideas