Why Factory Installed Windows ...
Why factory installed windows? To add value and quality while saving money.
As most production and custom builders know, the windows can be the biggest single cause of callbacks and customer dissatisfaction. Whether it is leaks, missing screens, malfunctioning parts or poor installation, windows can create a negative impression well beyond their cost.
If your wall panel partner is doing the most to add value and save site problems, he will be offering window installation in the factory. This approach adds more value and greater quality to the panel, allows installation and flashing in a controlled environment and dramatically speeds up the completion of the home. The most significant advantages start with:
Rough Openings - if your panel manufacturer uses a highly automated system, rough openings should be true to within millimeters of tolerance. Ensuring a dimensionally correct and true opening in which to install the windows is something that often is not the case in the field. Properly done, no shims should be necessary, thus eliminating another source of potential error.
Kiln Dried or Engineered Headers, Studs, Trimmer, Sills and Cripples - the best possible results will be realized by using KD or engineered (LSL/LVL/GLB) for material for all parts of the window (and door) components. This will ensure accurate openings and will eliminate the change of dimension, shape and square that is experienced with green lumber. In addition, the space required around the window in the opening may be smaller (based on the window manufacturer’s recommendations), leaving less room for the potential air or water penetration intrusion.
Controlled Environment for Flashing and Installation - by installing the windows in the factory, far greater quality control is possible with consistency. Installers are not required to repeatedly climb ladders or scaffolds, and most windows can be installed with a window placement devise that ensures true and square installations. This combines robotics and vacuum lift technology to place windows within millimeters of the desired set and square. This approach allows the installer to start with an accurate opening and a properly placed window from the beginning. The flashing can be done to AIA guidelines, manufacture requirements or the builder’s preference, in a dry, controlled, dust-free environment allowing the installed membranes to adhere, set and cure well prior to any exposure to the environment, moisture or harsher weather.
Less Costly - the actual cost of the window installation should be less, if installed by the panel manufacturer. This is a function of the speed and controlled environment in the factory, as well as the fact that no installer needs to leave the ground. In addition, fewer workers and less job-site trade coordination is required as the machines should do much of the installation work.
Fewer Call Backs - the greater quality of the window, installation and surrounding materials should greatly reduce call backs and buyer dissatisfaction.
There are a few things that you need to be sure your panel manufacturer does for you to ensure a successful window program:
- Ship the panels with windows vertically. Be sure the screens arrive later, and preferably are installed by your panel manufacturer.
- All site work related to the install or repair, except where specifically called out in your supply contract, should be done by panel or window manufacturer personnel. The manufacturer should ensure that all windows function properly after panel placement. This should optimally be done at the time of screen installation.
- It is very important that window manufacturers’ warranties are arranged so that they flow through to your home buyer!
If you follow these few rules, a significant advantage can be delivered on your next project, whether you are building production housing or a custom home.
June 2007 Builder Architect Edition Issue
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Panels: Built to Order and Timely
For production of a panelized structure to deliver all its benefits (speed, cost and quality), preconstruction planning is critical. Proper advance planning with the procedures of a major panel manufacturer, as an example, may not be the only possible approach. Systematic preplanning allows the owner to create an accurate 3-D model and accurate panel layout and working drawings from which to place an order for the panels to be manufactured and delivered quickly. The process is as follows:
1. Receipt of the CAD plans (architectural and structural) activates the panel designers to utilize the CADworks program (other manufacturers may use different design software) to create the 3-D files for plan analysis by all who are involved.
2. The owner could have the foundation (if installed) inspected and surveyed, or as soon as possible after the pour to be sure the panel designs will fit properly; a field services rep visits the building location to make accommodations for site conditions.
3. A meeting in the panel manufacturer's design office or possibility via a computer WebEx session allows the owner, builder, architect, engineer, framing contractor, etc., to review the computer model of the home framing.
4. Once all necessary information, modifications and/or corrections have been incorporated, the owner signs the plans (while processing for final building de- partment approval), and the CNC/CAM drawings - or for other panel firms, manual shop drawings - will be completed.
5. Included with the panel drawings will be a "Suggested Sequence of Assembly for Panel Layout" that was determined in consultation with the owner, usually starting with an exterior or floor panel at the furthest corner of the building foundation and working towards to the closest point to the crane, unless working with unique building or site conditions.
6. The panel plan drawings and truss designs are prepared, reviewed and approved by the owner or owner's representative as designated in writing (if the foundation has been poured and surveyed, the order to build can immediately be put into the plant manufacturing schedule).
7. The panel plans are sent to the manufacturing facility as the panel materials are ordered.
8. It is possible for a panel manufacturer to partner with a lumber supplier which allows for the structured headers, beams, balloon walls, etc., to be cut to fit precisely in the manufactured walls or delivered to the site for field installation.
9. You should insist, at your panel supplier, that wall panels are arranged and programmed in "built order" for best manufacturing efficiencies as well as for best shipping order.
10. The owner is consulted regarding the number of panels to be included in each trailer delivery for the building site conditions and ability to unload, unpack and lift the panels into place on the building site.
11. The pre-planning effort for shipping is essential to build quicker and essential to in-fill projects with limited area to receive and install panels.
12. If the home is being constructed on a raised foundation, after the subfloor panels are set and secured, the exterior walls are best to install in the "Suggested Sequence" while setting the interior walls in predetermined zones which arrive bundled.
13. This floor and wall panel placement process is repeated for the second story, and third story, and so on.
An automated, systematic panel supplier will not only manufacture your building panels according to your home designs, but also deliver to difficult in-fill sites. Panel system suppliers, as described above, is the answer for built-to-order savings in cost, time, logistics, space management and improved customer satisfaction. Do not demand less of your supplier.
May 2007 Builder Architect Edition Issue
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Optimizing Panel Installation
To help maximize the speed, quality and cost savings of wall and floor panel construction, as well as to achieve a seamless installation, take the time to prepare for the job prior to arrival of the panels to the job site. The following suggestions assume that panels are large (up to 12 feet tall and 24 feet long) and sheathed with windows installed, although they could also 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 job site. 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- to 360-degree rotation. Since wall panels can weigh up to 1,500 pounds or more and floor panels can be more than 3,500 pounds, 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 as 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 job site employees while minimizing the chance for panel damage during installation.
Also, all panels should be rigged in a manner consistent with job site 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 job site:
- 4 each 1/2 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 3/4" 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. This 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; it is a very demanding task and potentially dangerous for one worker (or even two) to attempt to plumb a 1,500-pound, 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.
April 2007 Builder Architect Edition Issue
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Energy Efficiency and Panelized Construction
The efficient use of energy has been a priority for the building industry for a long time, but recent regulatory changes and increased market demand 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 to increase the energy efficiency of building new homes is through the use of panelization and roof sheathing selections.When using wall and floor panels manufactured off site, a much more sealed and efficient building envelope can be realized. 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-an-hour wind. Such a standard can be met here using the same system or a somewhat lesser standard can be met using others; either way superior performance can be delivered. The key benefit delivered by properly produced panels is 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, shape changes 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; Equally important, these gaskets should also be used between wall panels end studs, where they are joined;
- 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 openings with less leakage;
- 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/doors and the frame.
Additional energy efficiency benefits include:
- Better quality control overall through off-site manufacturing in controlled conditions;
- Additional points in the builders LEEDS certification process, as well as meeting individual city or county development requirements;
- Far 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 fewer trips, then a series of material 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 costs of producing materials and product that will just be wasted on the job site and then hauled away.
An even greater improvement in building envelope seal and heat retention is possible when, in addition to using properly constructed wall and floor panels, radiant barrier plywood or OSB is used to sheath the roof trusses. The added cost is minimal and the energy savings is significant. If the builder is reluctant to incur the cost, this sheathing can be offered as an upgrade to the home buyer with an attractive analysis of return on investment. An ancillary benefit to the builder is the ability to include more window area in a given home. The energy benefits of radiant barrier sheathing will allow the builder to meet the State of California Title 24 requirements with greater window area in the home, increasing the homes appeal, value and salability.
All these advantages 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's not to like? Increased profits and greater energy savings, doing well while doing good.
February 2007 Builder Architect Edition Issue
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Whole House Design - Get It Right the First Time
For a number of years, the Wood Truss Council 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, multifamily, office or commercial), WHD comes into its own. The entire home is designed in CAD, from underfloor framing, to floor panels, wall panels and 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 3-D model of the home to be constructed in the computer.
With WHD, the entire project (from engineer to HVAC contractor) team can review the 3-D 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 panel 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 3-D.
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 its value is now fast becoming recognized. Builders who don't move to WHD will be at a clear disadvantage.
For more information, visit www.forma-homes.com.
January 2007 Builder Architect Edition Issue
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Green Building and Panelization Responsible Value Delivered
As green building is becoming more mainstream and is recognized as an amenity by home buyers, it is becoming easier for builders to go green. 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 - green products integrated into the final panels and their own green-oriented 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 - 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 its suppliers "integrate the perpetual growing and harvesting of trees with the protection of wildlife, plants, soil, water and air quality."
- Engineered lumber - Through increased use of engineered lumber, not only can panelized firms deliver increased quality (see my last column on kiln-dried and engineered lumber in the October issue), 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 (replaced by I joists).
- Oriented strand board (OSB) sheathing - Through the use of OSB in wall and roof sheathing, an 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 use 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 rods, nails and seismic hardware is reduced or eliminated. This removes the need for hot dip galvanizing, a component of the building system that requires a significant environmental impact in the manufacturing process.
Panel producers can deliver green in many ways in their internal processes, 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 percent, which is then sold for uses such as horse paddock flooring and other manufacturing processes that use chipped or similar material. This is a significant reduction over the 15 percent to 22 percent waste we see on the job site, which creates a job site hazard and ultimately goes into landfills.
- Kiln-dried (KD) lumber and engineering - Through the use of plumb, square and level products, gaps are reduced or eliminated, providing a much superior building envelope with significantly lower air flow through the structure perimeter.
- Sill and panel joint sealer - With the use of sealing strips between the walls and the raised floor or foundation, as well as between panels as they are placed, the building envelope seal is greatly increased. In combination with the use of KD lumber and engineering, the panel producers in Europe have been able to achieve a standard of zero air penetration at a 50 mph wind.
- Sawdust capture and recycle - Sawdust generated in the production process can be captured and recycled as well, eliminating landfill space as well as airborne particulates.
- Packaging - The wood used to protect the panel packages in transit can be used for backing and the in-fill frame portion of the construction process, eliminating the need and cost of sending 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 and the environment, without increasing costs! The smart builder will also integrate the green approach into their marketing material presented to the home buyer.
December 2006 Builder Architect Edition Issue
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Panelization Brings Improved Quality to Building
Emphasis on quality has long been critical for upscale custom home builders, now production builders believe that building the best quality home has never been more important for an increasing number of reasons.
More Competition, More Choices - Today, it is a buyer's market! Home purchasers have a greater choice of products, amenities, features, types of financing and more negotiating power when deciding which home to purchase.
Resale Value - Home buyers are moving much more often, due to changing lifestyles, company relocations, career changes, etc. The typical California home buyer stays in their home less than seven years; thus, the resale value is a greater financial concern to a potential home buyer.
JD Power and Branding - Most major production builders now actively compete to be the "Quality Brand" with the JD Power and Associates Ratings.
Legal Liability - There has been a dramatic increase in "entrepreneurial" plaintiff attorneys, who actively pursue construction defect lawsuits. Using direct mail and other methods to generate lawsuits based on construction quality, has dramatically increased the attention to detail, correcting improper work when discovered to minimize scheduling delays and avoiding callbacks.
HOW PANELIZATION DRAMATICALLY IMPROVES QUALITY
Custom and production home builders can greatly increase the quality of their final product through the use of "The Swedish System" of manufactured panels.
CAD - With quality panelized products, CAD plans are analyzed prior to manufacturing the panel packages. The CAD program can produce a 3-D model of the structure for review, which will allow the identification of design errors/conflicts prior to any site construction activity, rather than on the fly during the course of construction. In addition, both architectural and structural details are indicated down to individual nail placement. Framing, mechanical, electrical and plumbing trade contractors are included in the forward planning cycle so that their chases and installations are intergraded.
Kiln-Dried and Engineered Lumber - The best panel factories use KD lumber for all panels, including as much engineered lumber as possible, such as I Joists for floor panels. Green lumber changes shape as it dries. This causes nail popping, warped walls and other problems that dramatically reduce the quality of the finished home, while KD and engineered lumber practically eliminate these problems. Although both KD and Engineered lumber is a bit more expensive, efficient panel manufacturers buy in quantity and produce much less waste (3-6 percent rather than 18-22 percent on the job site).
Controlled Environment and Precise Manufacturing/CAM - By manufacturing panels in a controlled environment to precise tolerances, the panels delivered to the job site are exactly as specified. The best results are achieved when the panels are produced using CAM (computer-aided manufacture). Maximizing the use of automation will ensure that the panels are manufactured exactly to the CAD designs approved by the project team - to the exact nail positioning, nail penetration and window openings. With this approach, it is possible to manufacture a 30' long wall panel, with sheathing and windows, to within a tolerance of a millimeter or two.
Quality Promised, Quality Delivered - Panels manufactured using "The Swedish System" produces a product that provides:
- Reduced inconsistency of on-site skilled and unskilled labor;
- Precise nailing and structural integrity;
- Panels with exact window and door openings (no shimming required), all installed in a controlled environment and flashed in a consistent manner;
- Panels that are coded and loaded in the installation order per plan layout;
- A decrease in the time framing material is exposed to the elements;
- Less chance of errors by other trade contractors;
- Reduced supervision time spent coordinating subcontractors on site;
- Respected brand products used in the factory production process, with the material manufacturer's warranty passed on to the buyer where possible.
October 2006 Builder Architect Edition Issue
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Kiln-Dried and Engineered Lumber in Panelization
In the production of quality wall and floor panels, selecting the proper raw material is critical.
The single greatest impediment to achieving a quality finished wood frame structure is the high moisture content or the green lumber normally used in site framing. The lack of consistent lumber results in starting with a sill plate that does not provide a level base for floors and walls. This makes achieving quality more difficult when plumbing and squaring your walls, and also requires door and window shimming. These problems are made even worse as the wood dries, 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 plates now requires using 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, which is a significant increase over the ratings on previous methods of pressure-treating wood, demanding more expensive hangers, fasteners and hardware.
In order to address the above problems, automation of the process of manufacturing panels provides the desired superior quality. Leading panel production 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 with no change in shape or form after the walls are placed. All lumber is #2 or better without using standard or no-grade lumber. When using longer wall panels, up to 27 feet, the use of KD lumber and automation delivers a manufactured product that does not require job site adjustment. A wall this size would usually be framed on site in three separate sections. The ability to place and plumb only one-piece manufactured walls 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 without squeaks. The Weyerhaeuser Silent Floor Systems, when properly utilized by a floor panel manufacturer, 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 galvanized fasteners and hardware, the smart panel manufactures are using a zinc-borate treated LSL (laminated strand lumber) sill plate. The use of this engineered product ensured 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 subcomponents. Since engineered lumber does not expand, contract or change shape, window and door openings remain at the exact desired dimensions without shims. 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.
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 (i.e. 3-5 percent compared to 18-22 percent). This fact, combined with the very large amounts of lumber purchased (5 to 10 million board feet annually) at one site by panel manufacturers, provides lumber costs that are significantly lower than that available on the job site. This advantage allows panel firms to use KD and engineered products to deliver quality at a cost that is lower than 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 job site. Quality In, Quality Out!
September 2006 Builder Architect Edition Issue
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Reduce Construction Time Using Panelization
Whether building a custom home, a production home development or a multifamily project, construction cycle time is a critical driver. Any solution that lessens the time to "dry in" the building(s) also reduces construction interest costs, damage due to inclement weather and potential market changes, thereby increasing return on capital and reducing overall project risks. Through panelized construction, builders can reduce the on-site construction framing cycle time by 50 to 70 percent, thus receiving all these benefits in a dramatic way.
Through advanced planning, off-site construction and use of the largest and most complete wall and floor panels, construction cycle time can be significantly reduced. The time required to take buildings to the "dry in" stage can be reduced for a custom- home builder from 8 +/- weeks to days; for production builders, from several weeks to just a few days; and for multifamily builders, from months to only weeks.
Builders will experience quicker capital turns; thus, they will be able to increase production-building activity from 25 to 50 percent while utilizing the same base capital. Larger private companies with extensive developments will find their return on equity almost doubles while public companies will dramatically increase revenues, resulting in higher earnings per share.
Panels are designed, produced and marshaled for delivery before the foundation is poured. This eliminates the lumber pack delivery coordination (which often gets in the way of other trade contractors), on- site framing time and the majority of the on-site manual labor required to "dry in" a structure.
Advance planning, by utilizing CAD design, will produce more efficient plans, reduce design conflicts, as well as potential production problems by discovering errors earlier in the building design process. This also allows for the resolution of potential scheduling delays well before any site work is done. Problems are solved before other trade contractors arrive on site so "on the fly" troubleshooting and subsequent delays are eliminated.
On infill or other constrained sites, a half- day's production can be delivered without the need for the constant material handling and reshuffling that such sites currently require. Each panel is individually labeled and delivered in pre-determined building order, so it can be lifted from the truck directly to its installation position. This leads to maxi- mum efficiency on the building site, greater speed at reduced cost and less adverse effect on the neighborhood.
Using the most complete and the largest panels possible also dramatically lowers cycle time. The optimal wall panel is up to 27 feet in length, includes kiln-dried framed lumber, sheathing (at least on one side) and has the windows installed. This approach means that a wall of 27 feet can be completed with one panel, and the site labor required to assemble the structure is dramatically reduced. A small Gradall crane can easily lift and set the panels.
Examples of custom-home assembly time savings using a panel system of this type include a two-story, 6,000-square- foot home with raised floors in 14 days; a single-story, 3,800-square-foot, on a slab in five days; and a two-story, 3,000- square-foot duplex on an infill site in five days.
Panelized construction delivers superior quality, at a lower cost, in less time!
July 2006 Builder Architect Edition Issue
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Forma Homes
Prefabricated Building Systems - Faster Completion, Better Quality, Lower Cost
The basic process of constructing a home in the United States has not changed substantially in over 100 years, with the exception for the manufacturing of roof trusses. Unlike almost every other manufacturing and fabrication industry, the home building sector continues to rely almost entirely on manual labor.
In North America, we are now dealing with the challenges of higher labor costs, labor shortages and a consumer demand for better quality. With the introduction of the JD Power and Associates customer satisfaction ratings of major builders, as well as increased consumer litigation, the quality and consistency of new homes has become one of the top priorities in the new home industry.
These issues came to a head 15-20 years ago in Scandinavia, forcing the Swedes to begin exploring automation as a means of meeting these challenges. In Northern Europe, the short building season, increasing labor costs, demanding consumers and extreme governmental regulatory pressure a highly automated solution known as the Swedish System.
Today, the Swedish System dominates the marketplace in Scandinavia, Northern Germany, Ireland and the United Kingdom. Leading home builders in the U.K. and Ireland are producing large numbers of homes in a single plant (6,000 homes per year at one U.K. plant and 3,000 in another plant in Ireland). Recently, the concept was brought to the United States by Toll Brothers in Pennsylvania.
The additional benefits of prefabrication were confirmed with the "Framing the American Dream" demonstration, which was a joint project of the National Association of Home Builders (NAHB) and the Wood Truss Council (WTC). The project involved building two identical 2,600-square-foot homes, one stick-frame and the other panelized prefab. The panelized home saved 26 hours of framing time and 1,109 board feet of lumber. Builders in the field, on actual jobs, have experienced even more dramatic results. Recently, a 6,000-square-foot custom home had all the panels set and the roof sheathed in three weeks, using the panelized-prefab version of the Swedish System.
Using the panelized approach to produce a prefabricated structure allows for any new home design, eliminating the modular-building requirement of selecting a pre-engineered plan from a catalogue. Manufacturing of building panels starts with analyzing the CAD plans. This ensures the quality and integrity of design before a single stud has been nailed. The structure is divided into a series of panels (one or more per wall or floor section), with detailed specifications allowing for precise
The Swedish System (invented by Burmek-Sweden) exports the CAD plan to CAM (computer-aided manufacture) instructions that run a highly automated assembly line, which produces each panel. It takes only 10 minutes to produce a 30-foot exterior wall (exact to within a millimeter of tolerance), complete with studs, sheathing, insulation and windows.
Panelization allows the builder to deliver an assembled, closed-in framed home in one-quarter to one-half the time needed for traditional stick-built construction, while saving labor, time and project loan inter- est. The factory-manufactured product reduces the need for on-site skilled labor, improves coordination of trade contractors and reduces the number of customer service requests.
Finally, a framing cost savings of 10-30 percent can be achieved, as compared to stick-frame construction. Better quality, faster delivery and lower cost: what is not to like? There is no doubt, we will see an ever-increasing use of panelized construction in the future.
June 2005 Builder Architect Edition Issue