Does SIPS Construction Make Sense for a Tiny House?

SIPS Tiny House

As a builder of tiny homes, I often get requests to build houses with SIPS, or Structural Insulated Panels. SIPS are large, pre-manufactured panels that come together in a short period of time to frame a home. Their primary appeal is that they are light weight, energy efficient and can expedite the onsite building process for larger structures.

That said, I have worked on several SIPS homes, and I can honestly say that for a tiny house, the SIPS model doesn’t really make sense. First, in terms of costs, I can complete the shell of a tiny house – meaning frame, sheathing and insulation – for less than the cost of a SIPS package which still requires installation at an additional expense.

SIPS typically require large equipment such as cranes and forklifts to install the panels. The need for this equipment and specialized operators adds costs to the construction process that otherwise would have been spent on local builders. Essentially, buying SIPS from a remote source exports jobs from our local communities and requires additional transportation (and related exhaust emissions) which isn’t a very green way to do business.

Essentially, buying SIPS from a remote source exports jobs from our local communities and requires additional transportation (and related exhaust emissions) which isn’t a very green way to do business.

Then there are the health concerns. If the SIPS panels are built out of OSB, or Oriented Strand Board – which most are – then the glue within the product is commonly a form of exterior glue that has tons of formaldehyde to help it with water resistance. The off-gassing of this formaldehyde ends up in the indoor air space of your home, where according to the EPA, it can cause coughing, wheezing, chest pains, and bronchitis. Some studies have also reported an association between formaldehyde exposure and lung and nasopharyngeal cancer.

In an uber efficient airtight home – which SIPS built homes tend to be – these toxic fumes are even more dangerous, so more venting is necessary. In fact, indoor air quality is an issue in any efficient tiny home, and I’ll write about this in detail soon.

SIPS are also harder to modify and customize than ‘stick built’. As anyone who has ever done any serious building knows, sometimes (or even a lot of times!) stuff just doesn’t fit, and you have to fix it on the spot as you go. I did a SIPS project last year that drove me crazy because the panels were built a thousand miles away from the building site, then shipped in for my crew to install. Despite several discussions and clarifications over the phone and by email, when the panels arrived, they didn’t fit the trailer or each other. That caused a ‘Significant Emotional Incident’ on the part of the owner and me because it totally kicked our schedule and added a lot of labor costs!

The OSB in SIPS is also highly water sensitive – it swells like cardboard or particle board when wet, and loses structural strength. If you have a plumbing leak or your washing machine floods the floor, you’re very likely looking at ripping out the floor and maybe even lower portion of the walls, destroying the structural integrity of your house. Remember, the SIPS package for a tiny house is the house – (like a box) everything else is sitting in it or on it. SIPS are really designed to sit on a level, concrete foundation for structural integrity and not a trailer.

SIPS blog post

{ Grinding a SIPS panel to make it fit the trailer. ARGH! }

That’s why SIPS don’t work well on a trailer. Most trailers are built with camber (a rainbow shaped curve) so they don’t buckle when they’re loaded. However, SIPS are made for that truly flat concrete foundation so you’ll have to scribe out the bottoms of the panels or shim them to make them fit flush. Neither is really a good solution. As the trailer flexes going down the road – which they’re designed to do, so they don’t get stress fractures – all of the joints between the panels are going to flex and probably ultimately crack out. The larger or longer the house the more likely this will happen.

So, bottom line, I’d recommend against using SIPS to build a tiny home. I just don’t see the advantage for an onsite building project, but I do see a lot of disadvantages.