We have talked repeatedly about flooring for out tiny house and have even asked for your advice and experience on our Facebook page. But what I realized last night was that we have been grossly overlooking an even more important step; sub flooring.

It seems many of us take it for granted. I know I am not even sure of the real importance of subflooring or at least I didn’t until I started doing a little research. I sort of looked at it as a way to stabilize your true flooring choice. Turns out there is several choices to be made when considering subflooring and purpose for each one.

It is safe to say that one of the most important parts of a tiny house and its structural integrity is the flooring system. The floor system sustains the weight of the interior walls, roof, interior furniture, appliances, interior flooring, and its occupants. Other than the trailer the floor structure should be designed and built in order to determine the overall weight of the tiny house trailer as well as how much weight the floor can carry. Without proper research, instruction, and construction, it is plausible that a tiny house may have weak foundation footings (read: support jacks), improperly spaced or sized joists, improperly nailed sub flooring, etc. These sort of innocent errors can lead to structural failures including – but not limited to – excessive movement, sagging, unleveling, floor separation, and squeaking.

The Four Main Types of Sub Flooring

Plywood. Growing up in a 60 year old home our subfloor was little more than sheets of 1/2″ plywood. Nothing fancy and nothing manufactured, per se. However, for the last 30+ years the type of plywood has changed to a CDX tongue and groove style that is made from thin sheets of southern pine veneer that are then cross-laminated and glued together forming 4′ x 8′ sheets in either 5/8″ thickness or 3/4″ thickness. Because the edges are T&G they interlock nicely providing a strong base for the finish flooring. This type of plywood subflooring typically provides a freedom from squeaks and give a nice level surface for your finish flooring.

Plank. Having gone into several old barns looking for wood to be repurposes I have come across plank flooring quite often. Originally used in pioneer days as a finish (and only) flooring plank has become a type of sub flooring since the mid-century. Usually comprised of 3/4″ x 4″-8″ wide southern yellow pine boards, plank flooring is installed by nailing these boards directly to the floor joists. Because this type of sub flooring is usually found in substantially older homes and can loosen up over time from the expanding and contracting of the wood, it is important to fasten these boards down with a solid 2.5″ or 3″ deck screw.

OSB (oriented stran board). The simplest and most cost-effective sub flooring is OSB sub flooring. It looks like a sheet of glued together litter chips pulled from a hamster cage. In actuality, it is. OSB is nothing more than wood chips compressed and glued together to form a 4′ x 8′ sheet. Installation typically involves gluing and nailing the OSB sheets to the floor joists. This is probably the easiest and least time consuming of the sub flooring options as well.

Concrete. I do NOT recommend this to any tiny house builder. But I felt it needed to be included as it is an often used method of sub flooring. Perhaps if you are building a more traditional, sticks ‘n bricks, type of tiny house this is a reasonable option. But for mobility sake I would not even continue reading this paragraph if I were building a tiny house trailer. Concrete slabs usually consist of a 4″-6″ thick of at least 3,500 lb. strength concrete. The water used in the mixing of the concrete can take anywhere from 48 hours to 3 months to fully dry out and the concrete to set. This is not an easy process and takes more than one set of hands for even a small concrete pour. If you want to read more about our experience with pouring concrete you can do so here.

What kind of subfloor did you choose for your build? Did you have a positive or a negative experience with the selection and installation? Don’t forget, if you enjoyed this post and others like it please Share it, LIKE it, or Tweet it out there. We rely on voices like yours!



Photo courtesy of Jeremy’s Tiny House