ICON is one of the most recognizable names in the 3D printed concrete business.
Their highly publicized East 17th Street Residences in Austin, Texas
are finally complete and I stayed overnight in one of them! In this video, we’re going to discuss
every aspect of the project, from the printing process to the architecture, interior design,
air quality and overall impressions. Before I begin, I want to thank Jarrett Gross for
organizing this stay and for inviting us. You’ve probably seen some of his videos on
3D printed concrete, but if you haven't, I’ll link his channel in the description beow.
The 4 houses are located in a rapidly growing neighborhood in East Austin.
They were designed by Logan Architecture and developed by 3Strands. Once concrete foundations
were poured, the exterior walls were printed with ICON’s Vulcan printer. They used a proprietary
cementitious material called Lavacrete. 1” tall and 2” wide beads of concrete were printed at a
rate of 5-7” per second. The exterior walls have 2 layers, while the interior wall has 1 layer.
All the starts and stops are hidden behind window and door openings. Excess concrete was used to
make sloped lintels and frames for the windows. Any concrete used in 3D printing isn’t actually
concrete, it’s mortar because it doesn’t contain gravel or coarse aggregates. I’m not sure how
strong Lavacrete is, because one page of ICON’s website says that it has a compressive strength
of 6,000 psi, but another page says that it is a more reasonable 2000-3500 psi.
The printed layers are pretty even on straight runs but they bulge out at the window and door
frames. This is because of the gantry wobble at turns. Some people might find it unsightly and
would prefer smooth walls, but I’m glad ICON didn’t try to “fix” the mistakes.
They embraced all the imperfections like small chips and wavy lines.
The concrete walls, door and window frames were painted with a white elastomeric paint.
This liquid paint hardens into a flexible, watertight covering. It can also bridge and
repair non-structural hairline cracks. I couldn’t find any visible cracking on the exterior
or the interior of the house. Only the first floors of the 4 houses have 3D printed walls,
the upper floors are made of traditional 2x6 wood framing. As I discussed in my previous
video on 3D concrete printing, walls are a small portion of a building. Even though it took 5 to 7
days to print the first floor of these houses, installing all the utilities and finishing the
exterior and interior took several months. The use of color on the exterior of the house
is very successful. The horizontally striated concrete walls on the lower level are painted
white. The wood construction on the upper level is clad in vertically striated black metal panelling.
This draws your eye upwards and makes the building seem taller than it is.
The wood walls overlap the concrete walls, which makes for a very clean transition.
It also marks a clear distinction between the two methods of construction.
Another important design decision is the use of curves and rounded edges on the lower level
and the sharp angles and traditional pitched roof on the upper level. It makes the building look
top-heavy, and gives off the illusion that it's actually a black house floating over the base.
Even though the materials and colors are contrasting, they meet in a way that they
complement each other. The buildings are very similar to ICON’s tiny houses
in Austin’s community first village. I think these houses are less successful from a design
perspective, because they tried to get a flush surface between the concrete and the metal,
rather than offsetting them. Lastly, every single house on this
lot is slightly different. Some have a red cedar siding, some have black siding. Their orientations
and entrances are different too. It keeps you interested and looking around for more variations.
As you can probably tell, I found the architecture very inspiring and successful.
The interiors are clean and minimalist. Claire Zinnekar, the interior designer, went for a “West
Texas” vibe or what I call Marfa chic. I think the exposed concrete walls are a classier version of
the overdone wood shiplap walls. The roughness of the concrete walls are contrasted by super smooth,
level 5 finish drywall. The kitchen cabinets, flooring, ceiling and even the furniture were
all a light wood finish with minimal texture. The unit that we stayed in had a half bath,
kitchen and living room on the lower level.
Upstairs, two bedrooms are separated by a full bathroom.
Since hanging any ornament on the concrete walls would damage them, sleek picture rails
are attached to the edge of the ceiling. Frames are hung from transparent plastic cables.
The designers came up with a creative solution to hide electrical wiring, plumbing and vents. They
bumped out this wall and ran all the utilities through it. Unfortunately, the kitchen is set
up against one of the 3D printed walls. Which could make remodelling difficult in the future.
Also, the joints at the uneven concrete walls are pretty rough. There are gaps at the edge
of the countertop, the cabinets, and even at the door frame. That’s just the reality of
3D printing right now, it’s not perfect. Even though the wind was howling outside, the
moment we stepped in and closed the front door, it was wonderfully quiet. The 3D printed walls
have a layer of open cell insulation in between, but also rely on thermal mass. Apart from the door
and window openings, the inner wall never meets the outer wall, which reduces thermal bridging. I
used a FLIR thermal imaging camera to see if there was any heat loss or gain through the walls.
The living room downstairs was very well sealed .There were no obvious leaks at the base of the
walls, the ceilings, or even around windows. Same with the kitchen. However, you could
definitely see some thermal bridging through the wood studs upstairs which is typical.
This shows us the advantages of concrete construction over stick building. The house
is very insulated and very comfortable. Positive Energy designed an ERV or Energy
Recovery Ventilation system for every house. It brings in fresh air continuously at a rate of
70 cubic feet per minute. An Air Handling Unit circulates this fresh air throughout the house.
The bathrooms don’t have a traditional exhaust because of the ERV system.
I spoke to the engineers who are fully confident in the sizing of the ERV system,
however, when Jarret Gross, a neighbor, my husband and myself had dinner together in the living room,
my Airthing sensor said that the CO2 levels spiked and remained elevated throughout the night.
The VOC levels were also high, probably because of the new furniture. Now, I was only there for
less than 24 hours, and these things take at least a couple of days to calibrate, but it’s something
I’m concerned about with air-tight homes. Now, the one thing that everyone is most
curious about, the cost. All 4 units have been sold and will be rented on Airbnb and VRBO.
2 bedroom 1.5 bath listed for 1,106 sq ft $450,000
4 bedroom 3 bathroom 1,521 sq ft $745,000 4 bedroom 3 bathroom 1,928 sq ft $795,000
which is comparable to the cost of other properties in the area.
Y’all know how cynical I am about the claims made by the 3D printed concrete industry, but these
houses really surprised me. I was very impressed. The entire project is very refined and well
thought-out. Every company involved really seems to care about its outcome, how it performs and its
future. They take pride in these homes and want the inhabitant to feel that same sense of pride.
ICON even embedded a medallion at the entrance to the home which says the home was designed with
love in Austin, Texas. The name of the printer used and the building number is also on it.
As much as I loved the architecture and site layout, I was disappointed that they printed
mostly straight walls. They didn’t explore the 3 dimensional capabilities of the technology.
These homes could have been made with CMU block walls or precast panels, but those
walls aren’t as enticing as 3D printed walls. Also, ICON seems to be pursuing refinement and
economies of scale rather than design exploration which is a legitimate business strategy.
I was also disappointed that they tried to integrate electrical wiring into the walls.
I know companies see it as a challenge, but it disturbs the continuity of the wall. I’d prefer
to see a freeform, undulating 3D printed wall, separate from interior partitions and utilities.
Because the concrete wall is uneven, some of the wall plates were loose.
They definitely need to improve the consistency and smoothness of the printing process,
but I can see this project becoming a “historic home” 50 to 70 years from now. I’m very interested
in seeing how these homes and all other 3D printed concrete ages, how they hold up over time.
I tried to address all the major points in this video, but if you have any questions about the
project, leave me a comment below. I’ll link my Patreon page in the description. If you
can support me, I’d really appreciate it. A big thank you to everyone already supporting me. Don’t
forget to hit the like button and subscribe to my channel. Thanks for watching. See ya.