We spoke with architect Eric Cobb about the process behind building a floating home.

This colorful floating home eschews maritime themes in favor of a clean and contemporary aesthetic. The interior pulls in views of Lake Union through floor-to-ceiling windows.

For his first floating house project, an elegant dwelling in Seattle built by G. Little Construction, Cobb extensively researched methods of retaining buoyancy. Here, in his own words, he shares his insights and the fundamental differences between building houses on land and houses on water.

The older floating homes are built on giant logs that float. These are the ones that are sagging; over time the buoyancy of the logs is reduced. Divers keep having to go underneath them to place pressure-filled barrels to lift the home.

This colorful floating home eschews maritime themes in favor of a clean and contemporary aesthetic. The interior pulls in views of Lake Union through floor-to-ceiling windows.

In the types of floating homes that are built right now, there are [two building options]. All floating homes now are built with concrete floats. In one, the concrete works as a giant floatation device with Styrofoam inside it, where the Styrofoam is floating and the concrete is forming an upside-down bowl over the Styrofoam. The Styrofoam does lose some of its buoyancy over time, and then the only recourse is to put barrels underneath. The other option is that the concrete float ends up floating because it’s displacing water. It’s a bowl filled with a void. This decision impacts how you’re going to build it and the whole process after that. 

The exterior of a floating house in Seattle is clad with fiber cement panels from James Hardie painted in three slightly different hues: Fiery Opal, Navajo Red, and Rich Chestnut by Benjamin Moore.

In the latter scenario, you have to keep water out of the float or it will sink. Unlike a house, where you’re on dry land and you might have damp soil that’s trying to work its way through your concrete foundation, here you have massive amounts of water pressure looking for any crack to power water into your displaced cavity. You have to use water-proofing measures [to prevent this].

Floor-to-ceiling windows in the main living space overlook Lake Union.

See the full story on Dwell.com: How to Build a Floating Home
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