Home building and Robots: now and then

WiseHomeBuilding - ZeroLabor Randek robots
ZEROLABOR® automates the construction process in high-end plans.
In a recent new deal with modular construction Katerra, Swedish firm Randek brings its automated workforce to the U.S. home building market.

Perfect squared walls and studs without any bowing. Window and electrical openings placed according to CAD in pre-fabricated walls. Conduits and insulation installed in a control temperature environment. Minimal waste to be handled. Yes, we are talking about the HOME BUILDING 2.0: an era of robots taking care of the home building business.

Despite the majority of home builders today can’t use this technology, it is already a reality for some companies that would like to work with this innovation. Faster process to build walls, roofs and trusses, with computer precision, maximizing the labor time. That’s the goal, and believe you or not it is starting to gain more and more adepts.

A perfectly framed wood home can be built by a team of two robots: precisely as designed by the architects and engineers, in record time, without delays or injuries.

ZeroLabor Robotic System® is one of this multifunctional application of mass-produced robotics with the ability to produce framed buildings. The first one was installed by  Moelven (a Norwegian forest products company) at its plant in the western Sweden in 2016, and the plant saw productivity increase by 5 times without any increase in staffing.

Photo from Randek website: http://www.randek.com/en/wall-floor-and-roof-production-lines/zerolabor

Swedish company Randek, which makes high-performance machines and systems for prefabricated house manufacturing in 36 countries and developed the world’s fastest wall line for Toll Brothers in 1992, is bringing its robotics revolution to U.S. production home building: Menlo Park, California (modular construction company Katerra recently purchased three ZeroLabor units, to be delivered next spring).

The robot screws, staples, nails, glues, and cuts out openings for windows and electrical as needed. It even straightens studs before nailing and marks building components using an inkjet printer. At the end of the task, the robot automatically separates waste and places it in the appropriate bins.

The future is coming, faster than we expected.

(OBS: to write this post we use information provided by the builders.com website)


How long does it take a slab to dry out before flooring can be installed?

This is a very important question. Moisture is a problem with fresh concrete slabs, and if you install your floor in a wet slab you will have a lot of problems in the future.

Basement Finished Superior Wall1
Concrete slab in the basement after finishing. We are now around 2 months after the installation. The concrete walls are already insulated (we used Superior Wall pre-cast foundations in this project)

Variables that affects the concrete moisture include:ambient relative humidity, concrete permeability, amount of water in the concrete when it is placed, slab thickness, presence (and thickness) of a vapor barrier in contact with the slab bottom, and method used to finish the surface.

Here you have the needs depending on the type of floor to be installed:

  1. Impermeable flooring (Vynil, for example): Internal relative humidity around 85% or surface moisture–vapor emission rates (MVER) of 3-5 pounds of moisture per square-feet over 24 hours
  2. Wood floors: 75% internal relative humidity and an MVER of 3 pounds of moisture per square-feet over 24 hours (National Wood Flooring Association recommendation)

In practical terms, just remember that to achieve the recommendations it takes time. In normal average conditions (relative humidity around 50% most of the time and temperature above 65F, concrete water-cement ratio of 50%) a 4-inch slab can take up to 3 months to dry before you can apply a floor there. But remember that this 3 month period starts only when the cement is dry.

You have some specific tests for that, that are too technical to describe here. Just to mention, the calcium-chloride test and the internal relative humidity test are tow that can be applied for this evaluation.

One of the most important features is the vapor barrier/vapor retarder. Without a vapor barrier the slab will never dry out. That’s why the construction codes put the obligation to use a 6 mils vapor barrier there. The 10mils and also the 15 mils poly sheet can better control the moisture. The best location for the vapor barrier is in direct contact with the bottom of the slab.

If insulation is used over the concrete slab a 4-month drying time should be respected before installing the EPS (normally the EPS absorbs 0.5% by volume).

To have more detailed information about that you can click here and check the Concrete Construction magazine

3 Easy Ways to Seal Air Leaks

Good insulation is the secret for a comfy house. Remember that the winter is coming again (every year we have it), and if you suffered last year and forgot to revise your insulation remember to check these topics:

Insulate around recess lights

The majority of the recess lights have vents that open into the attic. This represents a direct route for heated or cooled air to escape. Some houses can have more than 50 fixtures like that, and some researchers already pinpointed them as the leading cause of air leaks. Lights labeled ICAT (Insulation Contact and Air Tight) are already sealed – look for the label next to the bulb. If you don’t see it, assume yours leaks. An airtight baffle is a quick, 10-second fix (normally they cost around 10-25 dollars). Remove the bulb, push the baffle up into the housing, then replace the bulb.

Progress Lighting P88-ICAT
Picture of an ICAD recess light


Use the Foam in Medium-Size Gaps

Once the biggest attic gaps are fixed, move on to the medium-size ones. Low-expansion polyurethane foam in a can is great for plugging openings 1/4-inch to 3 inches wide, such as those around plumbing pipes and vents. A standard 12-ounce can ($5-6) is good for 250 feet of bead about 1/2-inch thick. The plastic straw applicator seals shut within two hours of the first use, so to get the most mileage out of a can, squirt a lubricant such as WD-40 onto a pipe cleaner and stuff that into the applicator tube between uses.

Related image
Great Stuff ® (is a well-known foam used for sealing

Caulk small gaps

Caulk is the best gap-filler for openings less than 1/4-inch wide. Silicone costs the most ($8-9 a tube depending on the brand) but works better next to nonporous materials, such as metal flashing, or where there are temperature extremes, as in attics. Acrylic latex caulk (around $2 a tube) is less messy to work with and cleans up with water.

If you have some time this weekend and would like to study a little bit more about air sealing we recommend the Department of Energy website (https://www.energy.gov/). They have great information about how to save energy and also you can learn a lot in their SAVE ENERGY, SAVE MONEY section. Enjoy.

Common spots for air leaking in a house