Some of you may wonder if the new belle of the builder’s ball — a 3D-printed house — is really going to cost you less money to build than a traditional house in these times of stratospherically high lumber prices.
Experts tend to fawn over new techniques like this one, but they often highlight only the positive aspects and gloss over the negatives. This is nothing new, as decades ago lots of bold forecasts were made about supposed game-changers like geodesic-dome houses, A-frames and, more recently, straw-bale houses. All were flash-in-the-pan trends, and only time will tell what will happen with 3D-printed homes.
The only real difference between a basic 3D-printed house and one built with lumber is the exterior walls. For a 3D-printed house, a concrete mortar is created with sand and Portland cement. Layer after layer of this mortar is placed precisely by a computer-controlled machine, much like a pastry chef decorates a cake. The resulting solid-masonry wall takes the place of a traditional wood-framed wall.
As with any new technology, there may be hidden drawbacks with 3D-printed homes, and they may actually cause the price of the home to go up. If you’re considering a 3D-printed house, ask the builder these questions to avoid any surprises during or after the process.
1. Are there additional site requirements? Your builder will need to drive the giant 3D-printing machine to your job site, set it up, calibrate it and then take it all apart once the job is complete. Are there any extra foundation or site requirements to ensure the machine is completely stable as it operates? Is there enough room on your lot to place the machine? How level does the ground need to be?
2. How will energy codes be met? Masonry is a poor insulator, and heat is sucked into cold masonry very rapidly. How will your builder meet or exceed the energy code recommendations for your home’s solid concrete exterior walls? Do you have to build a wood-frame wall inside the exterior wall and then add fiberglass insulation? Do you glue closed-cell foam to the inside of the exterior walls?
3. How are electrical outlets installed in exterior walls? The National Electrical Code requires outlets every 12 linear feet on walls in rooms. How will the electric work be done for your house? Can metal conduits and boxes be screwed into the face of the printed walls?
4. What about the kitchen sink? It’s common to locate the sink below a window on an exterior wall. How will your builder install the plumbing drainpipe and vent pipe in the 3D-printed wall? I would avoid using an air-admittance valve (AAV) if your builder suggests it. These mechanical devices have moving parts that will eventually fail and possibly allow sewer gas to enter your kitchen.
5. Can I choose the appearance of my walls? Most of the 3D-printed homes I’ve seen have painted exterior walls. But what if you prefer a different look? Ask whether a brick, stone, wood, vinyl or anther exterior surface is available for your home.
When it comes to 3D-printed home costs, beware of the sizzling sales talk. Ask questions until you fully understand the process, and use common sense before you decide if it’s the right choice for you.
Tim Carter has worked as a home improvement professional for more than 30 years. To submit a question or to learn more, visit AsktheBuilder.com.