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)

 

Engineered Wood Products: the new normal

Engineered wood products includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibers, or veneers together with adhesives or other fixation methods.

They can be divided in a lot of categories:

  1. Plywood: one of the most recognized and trusted wood building products for decades. Manufactured from thin sheets of cross-laminated veneer and bonded under heat and pressure with strong adhesives, plywood panels have superior dimensional stability and an excellent strength-to-weight ratio and are highly resistant to impacts, chemicals, and changes in environmental temperature and humidity. Suitable for a variety of end uses including subflooring, single-layer flooring, wall and roof sheathing, sheathing ceiling/deck, structural insulated panels, marine applications, siding, webs of wood I-joists, concrete forming, pallets, industrial containers, mezzanine decks, and furniture.
  2. Oriented Strand Board (OSB): widely used, versatile structural wood panel. Manufactured from waterproof heat-cured adhesives and rectangularly shaped wood strands that are arranged in cross-oriented layers, OSB is an engineered wood panel that shares many of the strength and performance characteristics of plywood. OSB’s combination of wood and adhesives creates a strong, dimensionally stable panel that resists deflection, delamination, and warping; likewise, panels resist racking and shape distortion when subjected to demanding wind and seismic conditions. Relative to their strength, OSB panels are light in weight and easy to handle and install. Also suitable for a variety of end uses (similar to plywood)
  3. Glulam: Glued laminated timber, or glulam, is a highly innovative construction material. Pound for pound, glulam is stronger than steel and has greater strength and stiffness than comparably sized dimensional lumber. Increased design values, improved product performance, and cost competitiveness make glulam the superior choice for projects from simple beams and headers in residential construction to soaring arches for domed roofs spanning more than 500 feet. Glulam has a reputation for being used in striking, exposed applications such as vaulted ceilings and other designs with soaring open spaces. In homes, churches, public buildings, and other light commercial structures, glulam is often specified for its beauty as well as its strength
  4. I-Joists: I-joists are strong, lightweight, “I” shaped engineered wood structural members that meet demanding performance standards. I-joists are comprised of top and bottom flanges, which resist bending, united with webs, which provide outstanding shear resistance. The flange material is typically laminated veneer lumber (LVL) or solid sawn lumber, and the web is made with plywood or OSB. The robust combination of structural characteristics results in a versatile, economical framing member that is easy to install in residential and light commercial projects. I-joists are used extensively in residential floor and roof framing. They are ideal for long spans, including continuous spans over intermediate supports. Because I-joists are straight and true, it’s easier for builders to avoid crowning and maintain a level framing surface.
  5. Structural composite lumber (SCL):  includes laminated veneer lumber (LVL), parallel strand lumber (PSL), laminated strand lumber (LSL) and oriented strand lumber (OSL). They represent a family of engineered wood products created by layering dried and graded wood veneers, strands or flakes with moisture resistant adhesive into blocks of material known as billets, which are subsequently resawn into specified sizes. Typical uses for SCL include rafters, headers, beams, joists, studs, columns, and I-joist flange material. Two or three sections of SCL can be joined together to form 3-1/2-inch or 5-1/4-inch members. These thicker sections readily nest into 2×4 or 2×6 framed walls as headers or columns

Source: APA website

OSB and Plywood: importance for a house construction

Oriented strand board (better know as OSB) is one of the main materials used in parts of our house construction. It is a type of engineered wood, formed by adding special adhesives and then compressing many layers of wood strands, in specific orientation. OSB looks like (and is) a bunch of wood chips glued together.

APA panels with trademark
OSB panel (photo from APA website: https://www.apawood.org)

Many constructors talk a lot about the differences between OSB and plywood, another important product that can be used in sub floors and walls. Building codes typically use the phrase “wood structural panel” to describe the use of plywood and OSB. Codes recognize these two materials as the same. Likewise, APA the Engineered Wood Association, the agency responsible for approving more than 75% of the structural panels used in residential construction, treat OSB and plywood as equals in their published performance guidelines. And wood scientists agree that the structural performance of OSB and plywood are equivalent.

Nonetheless the composition of each material is different. Plywood is made from thin sheets of veneer that are cross-laminated and glued together with a hot-press. Imagine the raw log as a pencil being sharpened in a big pencil sharpener. The wood veneer is literally peeled from the log as it is spun. Resulting veneers have pure tangential grain orientation, since the slicing follows the growth rings of the log. Throughout the thickness of the panel, the grain of each layer is positioned in a perpendicular direction to the adjacent layer. There is always an odd number of layers in plywood panels so that the panel is balanced around its central axis. This strategy makes plywood stable and less likely to shrink, swell, cup or warp.

Related image
OSB production (Wikipedia photo)

In order to produce oriented strand-board logs are ground into thin wood strands. Dried strands are mixed with wax and adhesive, formed into thick mats, and then hot-pressed into panels. Don’t mistake OSB for chipboard or wafer-board. OSB is different. The strands in OSB are aligned. “Strand plies” are positioned as alternating layers that run perpendicular to each other. This structure mimics plywood. Wafer-board, a weaker and less-stiff cousin of OSB, is a homogeneous, random composition. OSB is engineered to have strength and stiffness equivalent to plywood.

Performance is similar in many ways, but there are differences in the service provided by osb and plywood. All wood products expand when they get wet. The Structural Board Association (SBA), a trade association that represents OSB manufacturers in North America, has issued a technical bulletin outlining a plan to prevent this phenomenon. SBA correctly indicates that dry storage, proper installation, adequate roof ventilation and application of a warm-side vapor barrier will help prevent roof ridging, for example.

For the majority of the sub floor applications, both plywood and OSB are fine. Take care if you are thinking about using OSB as a sub-floor for tile. For wall sheeting both are good materials, and different builders will have different preferences. We prefer the use of OSB.

OSB products are improving a lot. Many companies are now reaching an excellent level of manufacturing, and you can avoid the problems from the past because of the new techniques involved in the process. But, until now, the worst enemy for the wood will continue to be the same: moisture and wet climates always will represent a threat for your house if your builder do not control the water exposure during the building process.

Reference: https://bct.eco.umass.edu/publications/articles/choosing-between-oriented-strandboard-and-plywood/

Prefab and Timber Frame Homes

Timber frame homes have a unique concept that brings the beauty of wood for your house. All or just part of the entire structure of the home can contain timber framing. Timber structures are drawn specifically for each house and can vary in style.princeton-for-timberframe-hq

Timbers are usually cut by a CNC machine based on the production drawings created from an original design, and that’s a very interesting point when you think about this type of home: precision with beauty.

Some companies that work with timber homes also offer panelized house projects, and this can be a good option to avoid high labor costs (mainly for framing and roofing)

This is a cross section of a timer house framing. WhatsApp Image 2018-04-15 at 9.38.46 AM

This week we visit Davis Frame Co, based in Claremont NH and had the opportunity to discuss projects not only on timber but also panelized home building. Steve and his team were great hosts and we are thinking about them for future work.

WhatsApp Image 2018-04-15 at 9.38.46 AM (1)

Mainly now that it is becoming more and more difficult to quickly find sub contractors for a lot of work in a normal building process, this option can definitely be a good opportunity.