Mike's Blog

2007-04-21T14:38:00.000-07:00

Optimizing Panel Installation

By: Michael J. Murray

To help maximize the speed, quality and cost savings of wall and floor panel construction as well as achieve a seamless installation, take the time to prepare for the job prior to arrival of the panels to the jobsite. This discussion assumes that panels are large (up to 12 ft tall and 24 ft long) and sheathed with windows installed. Essentially the following suggestions could be put to use with panels that are less complete with fewer value added features.

Equipment Selection

It is easy to guard against damage occurring to the panels with timely unloading of the delivery truck(s). Also, to maximize employee safety, it is best that the following equipment be available on the jobsite.

Gradall – It is desirable to have a Gradall forklift on site for unloading panel packs with the greatest efficiency. The Manitou Combination Forklift/Crane may be used, but if a boom truck or other approach is selected, a separate Gradall forklift is necessary for unloading.

Crane – Whatever equipment is chosen by the installing contractor, it is important to have a 280-360 degree rotation. Since wall panels can weight up to 1,500 lbs or more and floor panels can be more than 3,500 lbs, the contractor should be sure that their equipment is rated well in excess of those loads at a 50 FOOT extension or more. Two examples of contractor selected solutions that were successful: 1) a Manitou Combination Forklift/Crane has been used as a lower cost solution and, 2) a knuckle boom truck was used to assemble a 3,000 square foot custom home in nine hours.

It is not recommended to use a standard, non-rotating Gradall for panel installation, because it presents a greater possibility of damage to the panels. In addition, the movements (forward and back to reposition) required of the Gradall when placing panels, may be detrimental to the safety of on-site personnel.

Rigging – The suggested rigging list below, allows the installing contractor to provide maximum safety for the jobsite employees while minimizing the chance for panel damage during installation.

Also, all panels should be rigged in a manner consistent with jobsite safety, using the installing contractor’s training and experience. If using a triangle rigging (a sling through two lift points on the panel and the eyes on the crane jib) the approach should be consistent with the contractor’s best judgment. These methods will minimize damage to the panels and increase control of the panels in the air. A rope secured to the end of the panel will allow a worker on the ground to help control the panel during placement.
I am not a crane or rigging engineer, but we have seen success with the following rigging present on the jobsite:

4 each ½ x 10 wire rope shockers (eye and eye swedge)
2 each 3” Nylon two ply 20’ eye + eye (1/2 twist)
2 each 3” Nylon two ply 10’ eye + eye (1/2 twist)
2 each 2” Nylon single ply 5’ eye + eye (1/2 twist)
6 each ¾” screw shackles

Plumb, Line and Panel Adjustment Equipment – After the wall panels are placed, prudence recommends that they be supported with the use of a turnbuckle (see below). The use of turnbuckle allows the installing contractor’s personnel to plumb and line the panels with the most accuracy, through turns of the screw rather than through manpower required on a 2x4 plumb stud. Accurate adjustments are possible while worker safety is of maximum concern; it is a very demanding task and potentially dangerous for one worker (or even two) to attempt to plumb a 1,500 lb, unsupported wall by hand.

Safety, speed and smooth installation of the building structure all depend on preparation and the proper equipment. The items listed above are, in my experience, a very good start.

2007-02-08T09:57:00.000-08:00

Energy Efficiency and Panelized Construction

The efficient use of energy has been a priority for our industry for a long time, but recent events (both regulatory and retail) have reinforced the need for constant improvement. Our customers are demanding it and the government (at all levels) is requiring it.

One of the best ways of increasing the energy efficiency of delivered houses is through the use of panelization and roof sheathing selection.

When using wall and floor panels manufactured offsite, a much more sealed and efficient envelope can be realized on site. In Sweden, panels produced using the Swedish System are required to pass a government test of zero air penetration of the structure at a 50 mile and hour wind. Such a standard can be met here using that system or a somewhat lesser standard can be met using others, either way superior performance can be delivered.

The key benefits that are delivered by properly produced panels include:

• Reduced air infiltration through a much tighter building envelope seal delivered from:
• Fewer exterior sheathing seams through the use of 4x10 or greater sheathing on all exterior walls, shear or not.
•The use of KD lumber maintaining tighter fits and delivering much less settlement and subsequent leakage.
• Much more accurate stud, module and sub-assembly cuts for better fitting panel-to-panel.
• Much reduced or eliminated sill seepage, with Plate Gasket seals between exterior walls and foundations, as well as between walls and second floor deck AND between wall panels end studs, where they are joined.
• With the use of a computer controlled saw and when possible, the use of engineered lumber, more precise cuts for exterior window and door openings and therefore more accurate opening wioth less leakage will result.
• Quality Jeld-Wen or other energy star windows with Low E glass, installed in the factory and flashed properly under controlled conditions. This should include the use of expansive foam in the window and door openings between the windows and the frame.

Additional energy efficiency benefits include:
• Better quality control overall through offsite manufacturing with indoor monitoring in controlled conditions.
• Additional points in the builders LEEDS certification process may well be realized, as well as meeting individual city or county development requirements.
Many, many fewer people driving to the factory than to the job-site during framing phase
• Much more efficient use of energy transporting material, as panels are a dense, high value product that require many fewer trip, in aggregate, that a series of materials deliveries required to site build the same structure..
• Significantly lower waste, 3% in the factory (most recycled) vs. 17-22% on site. This avoids the energy and other costs of producing materials and product that will just be wasted on the jobsite and then hauled away, requiring addition cost as well as gas or diesel consumption.

All these advantages should come at a price that is lower overall than site built solutions. Energy efficiency and a cost advantage to the builder as well as to the homeowner, what is not to like?

2006-11-18T18:00:00.000-08:00

Mike's Blog
Whole House Design – Get It Right the First Time

For a number of years the Wood Truss Council (www.woodtruss.com) has properly championed the potential benefits of designing the entire house in one seamless package (floor panels, wall panels and roof trusses), Whole House Design (WHD). Now that a builder can order an entire home package made offsite, the time has come for all those concerned with quality, cost and speed of construction to take Whole House Design seriously.

The use of prefabricated roof trusses has been a significant improvement in speed and cost on the jobsite, but has not delivered the benefits of Whole House Design, as the trusses sit on stick/site framed walls that may or may not match the WHD.

Now that it is possible to use Structural Building Components for the entire wood frame structure (house, multi-family, office or commercial), WHD comes into it’s own. The entire home is designed in CAD, from underfloor framing to floor panels, wall panels to roof trusses. All structural components such as beams, headers, posts and shearwall are specified in detail, down to the nail pattern. All wall heights and roof detail is laid out with grade changes and stem \walls accounted for. This allows a 3d model of the home to be constructed in the computer.

With WHD, the entire project (from Engineer to HVAC contractor) team can review the 3d model, identifying conflicts, laying out desirable HVAC chases, confirming window sizes and layout, and spotting architectural and engineering conflicts. If a load bearing wall is 6” off the foundation or a beam is hanging in mid-air (actual examples) the builder using WHD can make a decision about which room is larger or smaller and how to address the problem in a considered manner rather than on the fly. All these improvements, corrections and enhancements can be made before a single piece of lumber is cut!

Each panel and truss has an individual profile page that details framing, structural components and sheathing, with all materials marked, numbered and specified as to dimension and grade. Leading edge panels firms will generate machine controls (CAM instructions) to build the panels exactly as approved by the builder; less automated firms will at least generate the saw specifications and controls.

Whole House Design delivers homes that are of superior quality, go together faster and are much lower cost.

Superior Quality – Errors are caught before anything is constructed and on the fly solutions are eliminated. Floor, wall and roof intersections are clear and as desired, with wall heights established and the trusses seating clear in 3d.

Faster Construction – Panels go together much faster than stick frame and there is little or no on site delay due to errors in design, incorrect wall heights or roof specification.

Lower Cost – The significant portion of on site cost associated with errors and remediation is eliminated and materials are optimized to reduce waste from 18%= to less than 3%.

Whole House Design is here and it’s value is now fast becoming recognized. Builders who don’t move to WHD will be at a clear disadvantage.

2006-10-22T21:31:00.000-07:00

Panelization brings improved Quality to Building

While quality has long been critical for upscale custom home builders, both for them and for production builders the pursuit of building the best quality home has never been more important for an increasing number of reasons.

More Competition, More Choices – With the new buyer’s market, potential home purchasers have more choice of products, greater negotiating power when pursuing their chosen home.

Resale Value – As homebuyers are staying put less and moving much more, the average home stay is less than 7 years, resale value is a key concern to a potential home buyer.

Legal Liability - The dramatic increase in entrepreneurial plaintiff attorneys, actively pursuing direct mail and other methods to generate quality based lawsuits have dramatically increased rework, call backs and schedule delays.

J.D. Power and Branding – Most major production builders now compete actively for the “Quality Brand” and for the top J.D. Power Rating.

How Panelization Dramatically Improves Quality – Through the use of Panelization in construction of homes and multi-family units, builders can greatly increase the quality actually delivered in the final product.

CAD - All quality Panelized product requires CAD be performed prior to production of the panel packages. The Panel producer should then produce a 3d model of the structure for review allowing:

The identification of design errors/conflicts prior to any site construction activity, rather than on the fly during the course of construction. This assumes the errors would even have been identified during the course of traditional construction; this is often not the case.
Both Architectural and Structural details are implemented in detail, down to individual nail placement, and should include HVAC and plumbing subcontractors. Their chases and installations can be better accommodated through forward planning using the 3d model.

Kiln Dried and Engineered Lumber – The best producers utilized KD lumber for all panels, integrating as much engineered lumber as possible including I Joists for floor panels.

These produces are produced in exact dimension and do not dry in the wall or floor. Green lumber changes shape as it dries, ensuring nail popping, walls that warp an other problems that dramatically reduce the quality of the finished home. KD and engineered lumber have none of these problems and provide an exact dimension and a straight wall. Though both KD and Engineered lumber are a bit more expensive, efficient panel producers buy in such quantity and produce much less waste (3-6% rather than 18-22% on the jobsite), the actual delivered cost of better quality material for use in production is actually less costly.

Controlled Environment and Precise Production/CAM – By producing panels in a controlled environment to precise tolerances, the panels delivered are exactly as specified. The best results are achieved when the panels are produced using CAM (computer aided manufacture). Maximizing the use of automation ensures that the panes are produced exactly to the CAD designs approved by the project team, down to exact nail positioning, nail penetration and window opening. Optimally machines (rather than carpenters) should cut the lumber packs, do the actual framing, place and nail the sheathing, cut the window and door opening, and install the windows in the panels. Sheathing or Sheetrock should be installed on all panels (wall or floor) to ad value and (more importantly) ensure there is no racking of the panel during shipment or installation. If this approach is specified, it is possible to produce a 30’ long panel with sheathing and windows to a tolerance of a millimeter or two down it’s length.

Quality Promised, Quality Delivered - Panels produced following these guidelines provide product that provide;

Reduced inconsistency of on-site skilled and unskilled labor
Precise nailing and structural integrity
Window and door openings exact with no shimming required, installed in a controlled environment and flashed with consistency.
Each panel is coded for proper order in loading to install per plan layout
Records are kept to any future investigation of plan compliance
Speed of setting panels onsite reduces exposure to the elements
Panel consistency reduces errors by other trade contractors
Finish work of other trade contractors can be predictably consistent
Respected brand products are used in the factory production process, with the manufacture’s warranty passed on to the buyer where possible

Quality in Homebuilding will determine the successful builders in the future…!

2006-10-02T11:36:00.000-07:00

Green Building and Panelization - For Builder Architect Magazine
Responsible Value Delivered

As Green Building is becoming more mainstream and even recognized as an amenity by home buyers, it is becoming easier for builders to go Green. As a result of their processes, Panel producers are in a position to provide a Green product at little or no increased cost to the Builder.

Panel producers are Going Green in the factory, through two main areas; products integrated into the final panels and their own factory processes. In selecting the raw materials to be used in panel construction, Panel producers can easily select Green suppliers for most of their requirements;

Framing Lumber – at no significant increase in cost, lumber can be sourced from mills that are certified by either Forest Stewardship Council (FSC) or The Sustainable Forestry Initiative (SFI). This ensures that the mill and it’s suppliers “integrate the perpetual growing and harvesting of trees with the protection of wildlife, plants, soil, water and air quality”.
Engineered Lumber - Through increase use of Engineered Lumber, not only can panelized firms deliver increased quality (see my last months column on Kiln Dried and Engineered Lumber for details), Engineered Lumber uses smaller diameter and recycled material that in past times may have gone into a landfill. Engineered Lumber also reduces the need for large diameter trees to yield 4x or 6x headers and beams (replaced by Glulams or Timberstrand/LSLs), as well as for 2x12 floor joists (replaces by I Joists).
Oriented Strand Board (OSB) Sheathing – Through the use of OSB in wall and roof sheathing, a increase in the use of small diameter trees and recycled material is realized without a decrease in performance. PS2 rated OSB is an accepted substitute for APA rated Plywood for walls and roofs and delivers the Green solution.
Caulk, Sealants and Sub-floor adhesives – Low and no VOC products are available from many suppliers such as Henkel/OSI and others, in these areas. Though sold at a small premium, there is no degradation in performance and a significant improvement in “in factory” VOCs.
Zinc-Borate LSL Sill Plate – Through the sue of Engineered LSL – Zinc Borate Treated Sill Plate in wood to concrete applications, the need for use of Hot Dipped Galvanized anchor bolts, all thread rod, nails and seismic hardware is reduced or eliminated. This removes the need for a components of the building system that requires a significant environmental impact in the manufacturing process – hot dip galvanizing. This reduces emissions and increased workplace safety.

In their internal processes, Panel producers can deliver Green in many ways, including:

Zero Waste – Through optimization software used with framing lumber, to innovative use of sheathing material excess, Floor and Wall Panel producers can reduce the waste generated in producing a structure to less than 3%, which (the 3% waste) is then sold for uses such as horse paddock flooring and other manufacturing processes that use chipped or similar material. This is a dramatic improvement over the 15% to 22% waste we see on the jobsite, that all ultimately goes into landfills and creates a jobsite hazard in the mean time.
Kiln Dried Lumber and Engineered – Through the use of these plum, square and level produces, gaps are reduced and eliminated, providing a much superior building envelope with significantly lower air flow through the structure perimeter.
Sill and Panel Join Sealer – Through the use of a sealing strip between the walls and either the raised floor or foundation, as well as between panels as they are placed, the building envelope seal is greatly increased. In combination of the use of KD Lumber and Engineered (see above) the Panel producers in Europe have been able to achieve a standard of Zero Air Penetration at a 50 mile and hour wind.
Sawdust Capture and Recycle – Sawdust generated in the production process can be captured and recycled as well, eliminating landfill space as well as air borne particulates.
Packaging – The wood used to protect the panel packages in transit can be fully used during the backing and in fill frame portion of the construction process, eliminating the need to send packaging waste to landfills.

Working with a responsible panel producer allows the builder to represent to the city or county that they are committed to the community ands the environment, without increasing costs. The smart builder will also integrate the Green approach into their marketing material as presented to the ultimate home buyer. Form more information see www.formahomes.com and click on the Green Building link.

2006-09-27T15:44:00.000-07:00

Kiln Dried and Engineered Lumber in Panelization - For Builder Architect Magazine

In the production of quality wall and floor panels, selection of the proper raw material is critical.

The single greatest impediment to achieving a quality finished wood frame structure is the high moisture content and lack of consistent shape of the green lumber normally used in site framing. This lack of consistent lumber ensures a sill plate that does not provide a level base for floors and walls, makes it difficult to achieve a quality result when plumbing and squaring your walls, and requires door and window shimming. These problems are made even worse as the wood dries over time, changing shape, causing nails to pop, corners to crack, walls to bow and windows to leak.

In addition, the change from arsenic impregnated to copper impregnated Sill Plate now requires use of Hot Dip Galvanized fasteners, anchor bolts, hold downs and straps to combat the corrosiveness of the copper. According to the Simpson Strong-tie Technical paper T-PTWOOD06, the new copper process has a corrosion rating of over 3x, a significant increase over the ratings on previous methods of pressure treating wood, and one that demands more expensive hangers, fasteners and hardware.

In order to address the above problems, automate the manufacture process and to provide the superior quality that can be realized with manufactured panels, leading Panelization Firms use Kiln Dried (KD) lumber for framing lumber and have dramatically expanded the use of Engineered Lumber in their products.

KD lumber comes in exact dimensions, ensuring level, unbowed walls and greater quality delivered with no change in shape or form after the walls are placed. All lumber is #2 or better with no Standard or No-Grade lumber in use at all. When used in longer wall panels, up to 27’, the used of KD and of automation delivers a machine produced product that requires no on site adjustment. In fact, with a wall of this size normally site framed in three separate sections, with each section plumbed separately, the ability to place and plumb only one machine trued wall, delivers vastly superior quality at greater speed.

In many areas, the use of Engineered Lumber also greatly improves quality and performance. In floor panels, the use of I-Joist and Tongue and Groove (T&G) sheathing allows for longer spans and greater open space in the structure, while delivering minimal deflection and no squeaks. The Weyerhaeuser Silent Floor Systems, when properly utilized by a floor panel manufactured, provides a warranty that is passed all the way through to the Home Buyer (see www.ilevel.com for details).

To address the new wall Sill Plate requirement for Hot Dip fasteners, hardware and imbedded items, smart panel manufactures are using a Zinc-Borate treated LSL (Laminated S_ Lumber) Sill Plate. The use of this Engineered Product insured a straight, level and square base for the walls, but does not require any specially treated fasteners, hardware or imbedded items, dramatically lowering those related costs. Additionally, pneumatic (collated nail gun) fasteners can be used. A few leading panel firms are also experimenting with the use of LSL studs for window and door sub-components. As the Engineered Lumber does not expand, contract or change shape, window and door openings remain at the exact desired dimensions and no shims are required. Windows don’t leak from expansion and contraction of the wood cripples, trimmers and sills. Doors continue to open and close properly as well. Finally, the use of LSL lumber ensures better quality balloon framed walls, though these panels are typically only 10’ wide rather than the 27’ wide standard wall panels.

How are leading panel firms able to afford to use more expensive material like KD and Engineered Lumber, while still being cost effective? Efficient operators of wall and floor panel lines generate dramatically less waste than job-site framing does; 3-5% compared to 18-22%. This fact, combined with the very large amounts of lumber purchased (5-10,000,000 board feet annually) at one site, by panel manufacturers, provides lumber costs that are significantly lower than that available on the jobsite. This advantage allows quality panel firms to use higher quality KD and Engineered products to deliver quality at a cost that is lower then the less precise site built competition.

Be sure any panel firm you are considering uses KD lumber at a minimum and as much Engineered Lumber as possible, to ensure you receive the best possible product on your jobsite. Quality In, Quality Out.