I've been building custom homes for over 30 years, and I've framed more than my share with a crew, swinging a hammer myself back before we had these new fangled nail guns. Along the way I've grown somewhat particular about how I like things done and I've worked off and on with the few framing crews who could wrap their brains around what has come to be known as Advanced Energy Framing advocated by Joe Lstiburek (pronounced Stee-brick). As I've gotten increasingly involved in the green building movement I've searched ever more vigorously for a better way to build homes especially when it comes to keeping the framing dry and reducing lumber waste and impact on the landscape at the building site. Here's why I've settled on Table Framing as a solution that fits my business.
There are a number of new wall alternatives on the market these days. I like the thermal performance of Structurally Insulated Panels (SIPs) but worry about their performance in a hurricane and I like the simplicity of being able to fill my walls with pipes and wires at will and add the insulation later. Insulated Concrete Forms (ICFs) are a really fabulous innovation and I'll probably continue to use them extensively for high performance foundations and for all our radiant slab applications but I do worry about the embodied energy content and cost of the concrete and steel and I'm, again, not thrilled about the need to remove the insulation (and concrete in some cases) to install pipes and wires. Aerated Autoclaved Concrete (Hebel) block is a fascinating material but many people have expressed concerns about it's permeability to water vapor and its lack of compressive strength. I look at the flashing systems used to install windows in AAC and have serious concerns about moisture intrusion. I'm personally appalled that anyone can seriously advocate steel framing as a green building system when we have so many better uses for recycled steel and wood is such a renewable and low embodied energy content resource.
So I keep coming back to wood Advanced Energy Framing, its economical cost, renewable source material, ease of access for wiring and plumbing and most importantly the ability to wrap the house with a durable and repairable water repellant membrane to manage moisture intrusion. I think it is the best of a number of imperfect alternatives. But I've been frustrated by the slowness of the site building process and the willfulness of framing crews who revert to the old "more wood must be better" way of building and end up wasting materials and time.
Table framing the walls off site minimizes lumber waste (computerized cut lists optimize lumber utilization and what little waste is produced at the plant is converted to wood I-joists and used in the next house) Building the walls indoors on a special table made for the purpose means all the walls are square and tight. Floor plates are marked by a computer pulling information directly from the blueprints, minimizing errors. Nail patterns are better managed and generally exceed code specs. When we ask for 3 nails in a 2x6 we generally get four. Code asks that plywood sheathing be nailed 4" oc at the edge and 8"oc in the field, we generally get 3" and 6" and the nails are placed by a computer driven auto-nailer. It's not dependant on the attitude and conscientiousness of the worker in the field.
But the biggest advantage I see is that I can build homes in densely wooded sites without needing to stockpile and protect large stacks of lumber on the job and without needing to manage all the piles of cut off lumber ends so my sites stay cleaner and safer and the jobs get a huge boost of speed with roofs going on faster and the interiors of the homes therefore being subject to much less weather damage.
I participate in third party green building certification through the NAHB and that system awards me points for lumber optimization and scrap reduction and for not beating up the jobsite environment. Take a look at the following images and you'll see what I mean about the speed and quality of construction. These images were taken between Thursday 3-13-08 and Wednesday 3-19-08. Six days from subfloor to tarpaper on the roof. By working off site we can schedule the walls to be built while the floor is being installed and have the roof trusses built and ready to go up as fast as the wall panels can be tilted up and made ready. We cut weeks off the build time and improve quality at no additional cost.
Table framing is not any less expensive than on site framing and it's not possible for every house but the improvement in quality and speed and reduction in lumber waste make it a better value from my perspective whenever we can make it work.
