Planning an Addition? Don’t Forget About Proper Massing


Some car owners love talking horsepower, torque, gear ratios and 0-60 times. They’re involved with their cars.

But other car owners just want their car to do whatever it is that cars are supposed to do, without having to think about it.

Turn key. Press pedal. Go.

If you’re going to add on to your house, you might like talking about massing, scale, proportion and detail.

Or you might just want your architect to get on with it, and skip the yada yada.

Design. Build. Enjoy.

But while there’s almost no meaningful input you can put into the design of your car (what you see in the showroom is what you get), your decisions about your house can have a huge impact on the quality of the design of your addition.

Massing basics

You don’t have to be an architect to improve the design of your addition: You can help make it better if you know a little bit about the basic elements of design.

Which is why today I’m going to tell you a little bit about massing.

With houses, massing comes in chunks. It’s about the boxes houses are made of, how many boxes there are and how big they are relative to each other.

When you add on to a house, proper massing is often the difference between “wow, that looks great!” and “hmmm … something’s not quite right”.

Good massing follows a couple of simple rules – good massing is proportional, and good massing is hierarchical (don’t Google that, I’ll explain!).

The good, the bad and the ugly

The two-story house below has simple massing; it’s one big box. A properly-massed addition to this house recognizes that the original house is the main mass — and is subordinate to it.


That’s hierarchical massing: The main house mass remains recognizable even after added on to. And for the house below, the massing sets up an easy path to a future addition just like this one, on the other side.

addition 1

It’s also important that the massing of the new addition be proportional to the main mass. “Proportional,” in this case, means that the shape of the addition is about the same as the original, even though it’s a different size.

The addition in the image above gets it just about right.

The massing of the addition below isn’t proportional to the original house. It’s too tall and narrow, and doesn’t look “right.”

two story

Another common mistake is working out all of the details of the floor plan before considering the massing. When that happens, you might get a functional — but unattractive — addition, like the one below.


When you focus on the floor plan alone, it seems natural to simply extend the house a little farther — a simple solution in 2-D, but in 3-D it ruins the character of the house.

Work on the massing while you’re working on floor plan, and adjust both to get the best overall design.

That’s how good design is done.

If the addition you’re designing doesn’t look quite right to you, it might be a massing problem. Make the addition subordinate to the main mass, and adjust the proportion, and you might find you’re back on track.

Is the massing of the addition you’re designing as good as it should be?

Richard Taylor is a residential architect based in Dublin, Ohio, and is a contributor to Zillow Blog. Connect with him at

Note: The views and opinions expressed in this article are those of the author and do not necessarily reflect the opinion or position of Zillow.

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