Prefab construction offers faster renos. But are they more affordable?
Prefab building is the way of the future. Wall assemblies, which include framing, vapour/air control layers, insulation and windows, are built in a factory and installed quickly on site. It’s ideal for custom builds and some additions to existing homes.
They certainly have their appeal for builders like me. I recall working on an addition last year in subzero temperatures. We used scaffolding, which got very icy. Contending with that and a snowstorm was not fun. The work was dangerous and slow.
I’ve had several clients interested in prefab. In all cases, it was deemed not appropriate. Why, when there are so many advantages?
One advantage is speed. Project activities can happen concurrently rather than sequentially. While the foundation is prepared and poured on site, the wall assemblies are built elsewhere. What may be a ten to twelve month project can be reduced to five to seven months. Technically, this helps reduce a project’s budget.
Another big advantage is quality control. Prefab wall assemblies are built in a controlled environment. Highly specialized labour works on every step. They can be factory tested for air tightness.
Not all wall assemblies are built the same and not all are environmentally friendly, however. As I’ve written before, foam insulation, which is a petroleum product, is high in embodied carbon. Wall assemblies that are insulated with cellulose-based materials are nontoxic with a much lower overall environmental footprint.
I’ve been very impressed with two companies that build prefab envelopes to Passive House standards – the highest level of energy efficiency, health and comfort. Tooketree Passive Homes is an award-winning company with offices in Toronto and Muskoka. Simple Life Homes is based in Brighton.
Fun fact – my company, Greening Homes, got its start almost 20 years ago when we built a prefab display home using straw-bale panels for a home show!
So why hasn’t Greening Homes used prefab wall assemblies yet in its home renovation projects?
For a city like Toronto, with its tightly packed residential areas, the logistics of installing prefab panels can be far more complex than in the suburbs, adding substantially to the project’s budget. You may have to close down the street to truck in the panels and bring in and operate a crane. You need to hire various companies to handle this work. There are added dangers too, of course, with panels dangling close above neighbouring houses.
For the projects we’ve reviewed, the installation and logistical costs unfortunately have outweighed the budget break from the time saved by building pre-fab.
Also of note, prefab generally offers up flat panels only. If you want walls that are rounded or have some other design flourishes, prefab may not be able to deliver.
Prefab is ideal for places with route access and generous space between houses. It’s great for new custom builds, particularly in suburbs. And it’s fantastic if you want to speed up your renovation. If you’re in urban Toronto, though, the speed of prefab may not deliver on a lower-cost build.
By Chris Phillips, Founder and President of Greening Homes Ltd.
Photo: A crane positions panels by Tooketree Passive Homes for a 3,150-square-foot home and music studio in Keene, Ontario. Photo Credit: Rick Zytaruk of Tooketree Passive Homes.