Panelization: An opportunity for efficiency
A few years ago, panelized construction was rarely used in B.C., and the companies in the province producing prefabricated homes were primarily focused on the export market.
Today, that's changing. Traditional demand in Asia has dropped (though it could rise again after the earthquake in Japan), while local builders are discovering the benefits of panelized construction, and adopting the techniques more widely.
To help you consider the benefits, and challenges of panelized construction, here are some things to consider.
Types of panelization
- Framing panels
Pre-fab framed panels (including exterior sheathing) are gaining adoption with larger home builders. Instead of building a 20-foot wall on site, it is built in a factory and craned into place, much as roof trusses are typically done.
- Framing plus insulation
A more elaborate option is framed, sheathed panels that have been insulated in some way (examples include exterior extruded polystyrene, or die-cut insulation panels that fit into wall assemblies). Typically, this system has the advantage of eliminating thermal breaks in walls, enhancing the home's energy performance.
- Framing, insulation, and finishing
More comprehensive types of panel systems transfer even more of the building process from the site to the factory. Panels may include exterior finishing, windows, and even interior finishing such as drywall panels. These near-modular systems are less common in B.C. to date.
Advantages of panelization
- Tighter construction, better quality
Cutting, joining and sealing components in a climate-controlled environment on a horizontal surface offers an opportunity for quality and tightly-joined components that cannot be matched by on-site construction where workers must deal with dirt, variable weather, and changing lighting conditions.
- Faster assembly
Although the cost of panelized construction may be similar to traditionally-built homes, the time required on-site for construction is significantly reduced. This can cut carrying costs by allowing a builder to have product ready for sale sooner.
- Energy efficiency
The tighter tolerances and pre-installed insulation options provided by panelized construction offer the possibility for highly efficient homes. The caveat here is that the home will only be as efficient as final assembly allows – so ensuring good sealing between panels is essential.
Good planning is essential
Transferring much of the piece-by-piece construction to the factory can mean on-site efficiency when it comes time to assemble the home. But it also means fewer opportunities to shift gears or fix problems during the assembly process.
And since assembly occurs with a crane standing by running up hourly costs, it is critical that good advance planning is done, and all necessary elements for smooth assembly are on-site before work begins.
For example, the panel provider or builder must ensure that panel intersections are well envisioned, with adequate material on hand for detailing and sealing, as there is only one opportunity to effectively complete intersections before the next panel is added.
Planning is also important since panel sizes must be manageable given clearances available at the site, as well as on all roads leading to it. Meanwhile, the advantages of climate-controlled panel construction can be lost if pre-fab panels are exposed to the weather during on-site delays.