1 story or 2 story home? Which is efficient and cheaper to build?
Large lot so I have options. ‘
Which is less expensive to build? A single story ranch with 2,000 sq. ft. or a two-story home with 2,000 sq. ft. (1,000 sq. ft. per floor)?
Which is more energy efficient? The 1-story or 2-story?
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It's generally less expensive to build a 2-story home, as both the roof and foundation are half the size. Those tend to account for large portion of the home's expense.
In general a 2 story is more efficient, since there is less exterior surface to the building to lose/gain heat from. (Only 1o00 square feet of attic rather than 2000'.) If built in an air leaky fashion some of that is offset by higher rates of stack-effect infiltration, due to the taller "stack".
Two-story homes require a staircase and associated circulation space that you don't need with a single-story home on a slab foundation, so you save 80 to 160 square feet of space. If you have a basement with an interior staircase you lose that advantage.
A high-performing house with super-tight building envelope provide small differences in the energy efficiency question. We've compared energy bills for single vs. double story houses of the same size and same building quality and materials, and it shows very small difference in annual energy costs. Obviously, our findings are not scientific research, and a lot of it depends in owner occupancy, habits and ways of living, but not that far from a real world.
I would add another concept, which is, Universal Design. Depending on your age, or if this is your "last" home, or if there is any physical disability (now or future), or if at some point, your parents need to come and live with you, a single story is more advantageous.
Just a thought, before my 40 birthday, I had an accident that broke enough bones that made my life more complicated living in a two story house... tough lesson to learn. Since then, every single home I've designed in the last 20+ years, came with Universal Design criteria included, whether my clients had thought of it or not.
I haven't noticed enough difference in either the cost of construction or the energy consumption between the two to make it worth using them as a determinant as to which way to build.
I also think it's going at the process backwards. There are a lot of architectural decisions that lead to what type of house you want on a particular lot which have a much larger influence on whether the house will be an appropriate one that fulfills the owner's needs. Just using small improvements in efficiency to determine the form of a house is a really reductive way to make decisions.
Another reason why I am thinking of a 2-story is the expansive views. Once I get above the tree line, I have 360 degree views for 50-100 miles of mountains and valleys. So the 2nd story would give me incredible views.
Speaking of stack effect. With a 2-story home, one can flush a home out at night by opening windows on the 1st and 2nd floors, the cooler air on the 1st floor will flush the warmer air on the 2nd floor. Although this can be done with a 1-story with clerestory windows.
I agree. Roofing costs are increased with an expansive ranch design. More roof area to build, insulate and then cover with a roofing material. In my case, metal, and metal roofs are not inexpensive. The more roof you have the costs can easily double. It's not only the roof but the metal fascia and metal soffits that are needed.
The 160 sqft of space that is lost for a staircase is something very minimal. One can also create storage space underneath the staircase so that becomes a closet of sorts.
I thought about that also. I believe this will be my last earthly "home" for me before I pass away. That's why if I go 2-story, I will install a motorized scooter chair into the stairwell. It can come in handy if I should get injured or something. So that solves the problem with aging and stairs.
"Once I get above the tree line, I have 360 degree views for 50-100 miles of mountains and valleys. "
To me that alone would be a pretty convincing reason to go that way.
I've seen a lot of what you might call hybrid floor plans recently. The main floor contains all the necessary living spaces and a master-suite. The second floor has additional bedrooms and a bath. That way aging in place is already built-in
If you are surrounded by trees, which comment #6 indicates, then the 2-story option can improve solar panel options. Obviously, it depends on the site and the climate.
It’s easy to forget on a site like this which is so very much focused on the North American middle class norm of single family homes on expansive rural lots that the most resource efficient and environmentally responsible housing is found in attached townhomes on tiny slices of land with walkable access to life's important facilities of food, work, school etc. And yes, in these conditions where land use is considered important and valuable two or three story is of course the way to go. And I almost never get to design such homes because that’s not where the market is. Ah well.
If the walls are ICF, would it be better on a 2-story to go with wood floor trusses or a concrete flooring system for the 2nd floor? I know it terms of cost and ease of work, a wood truss 2nd floor would be better as the trusses can hang off the hangers that get drilled into the concrete ICF wall. My question is more in terms of strength. It's a Seismic Design Code C area.