The time is drawing near when decisions about flooring have to be made. The substrate for the first story floor is concrete while that of the second is tongue and groove OSB. When it comes to winter heating for our passive solar house, the difference in substrates dictates flooring choices, irrespective of the usual factors such as esthetics, durability, ease of installation, ease of maintenance, life expectancy and price. Following is the reasoning behind our final choices.
First Story
Deciding on the type of flooring for the first floor is a no-brainer -- either concrete as the finished floor or concrete overlaid with porcelain tile, either of which fits with our AGS design*. Porcelain tile is reasonably easy (but time-consuming) to lay, quite durable and there is an abundance of patterns nowadays mimicking wood grain in all price ranges.
Direct gain on an insulated concrete floor (the thick black border outlining the house represents insulation). |
Second Story
Flooring choices for the second story are less stringent because the amount of thermal mass is so limited. Having said that, there might be one instance in which it might be marginally important. If we were to overlay the OSB subfloor with a layer of cementitious board then install thinset-bonded porcelain tile, the cementitious board, thinset, tile and subfloor together would provide a thin veneer of thermal mass capable of absorbing a limited amount of heat on sunny days and re-radiating it at night. But, since the glass of all but two of the second story windows is translucent rather transparent, most of the winter sunlight is diffused rather than concentrated on hard surfaces like the floor. The diffused radiation, while it will not heat the inside air, will randomly warm the contents of the room, in which case, the floor would receive some of the energy and contribute slightly to a comfortable environment.
If we wish to overlook the slight thermal advantage of the tile floor, there are three other flooring materials that we might consider and one other that, for a green build like ours, should be avoided. First, the one to be avoided -- the popular solid laminate flooring. With a nod to its beautiful wood patterns and its DIY-friendly installation, it is a petroleum product that does not fit our commitment to sustainability.
That leaves three other choices -- bamboo, real hardwood and a new product, composite laminate flooring. Bamboo at first glance would seem to be a good choice from a sustainability standpoint since it comes from a rapid growing ubiquitous grass instead of mature trees. However, its embodied energy, mainly from manufacturing then transportation from the orient, makes it less appealing and its durability and life-expectancy is less than tile and real wood. Hardwood flooring would be a good choice if limited to native species (excluding old-growth stock) rather than exotics from distant lands. Wood composite flooring is the new kid on the block. It looks and installs like solid vinyl laminate but is a certified green product eligible for LEED points made mostly from post-industrial recycled wood chips. It also has all of the qualities of the best of vinyl products such as hardwood realism, stain and scratch resistance and 100% waterproof protection. Needless to say, composite flooring was easy choice for the second story.
Prices
Of the choices we would consider, hardwood is the most expensive at +/-$8 per sq ft DIY-installed and +/-$19 per sq ft contractor installed. Tile, even with the added expense of cementitious board, is least expensive at a little more than $2/sq ft if DIY installed (but +/-$10 sq ft, if professionally installed) Bamboo is intermediate. The DIY-installed composite laminate that we selected ran $2.75/sq ft.
What About Carpeting?
Until I read Mazria's book, I assumed that carpeting of any sort would have no place in a passive solar build where the floor is part of the thermal mass. However, Mazria makes sense when he says "Do not cover a masonry floor with wall-to-wall carpet. Carpet insulates the heat storage mass from the room. Scatter or area rugs, covering a small area of the floor, make little difference". We plan to use an area rug in the master bedroom and a few scatter rugs around the rest of the house especially after a year or two when the year-round temperature of the thermal mass has reached equilibrium._________________
*For those who have not followed the blog enough to know about the Annualized GeoSolar system that will provide year-round comfort in the absence of conventional HVAC, click on the title under "Featured Post" near the top of the left column.
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