Building costs are closely tied to the number of square feet in a house. As the size of a house increases, the cost per square foot goes down as you're now able to spread the cost of excavation, the foundation and exterior envelope, heating and cooling systems across more square feet.
Building costs are also affected by the complexity of the house design. For example, in the photo to the left, rather than a room that's rectangular with 4 corners, there are at least 10 corners (7 visible in the photo) and that takes a lot more labor to build. You've got more measuring, cutting and installing of materials for each wall section – the horizontal joists, drywall and then the baseboard trim.
That's a fairly simple explanation of building complexity and it's hard to visualize if you're not familiar with home construction so let me use an example everyone is familiar with (and can easily try at home).
Let's start with a simple, brown grocery bag. Have you ever taken one of these bags apart? It's made from a single piece of paper cut, folded and glued just the right way. It's pretty amazing what engineers can invent with enough motivation which happens when they have millions of grocery bags to make. The point here is there's only one (1) vertical seam when the bag is done.
Challenges of Construction & Building Costs
How would you construct a bag, similar in shape to a grocery bag, with pieces of construction paper? Where would you place the vertical seams (corners in a house)? How would you overlap the paper to glue them together? Would all the pieces remain the same size or would you cut some? Getting a little complicated? Hopefully it provides some insight into the challenges and building costs of home construction as homeowners rarely understand how a simple change on paper can create unnecessary complexity when your a home builder has to translate some house plans to 3-dimensions with real lumber and nails.
Building Costs Start with Square Feet
Calculating square foot costs is a fascinating exercise as everyone uses different algorithms. Homeowners are most familiar with the square footage quoted in house listings on real estate's Multiple Listing Service (MLS). There are many calculations that go into building costs – linear feet for things like your foundation and siding, square feet for flooring but drywall must cover walls and ceilings, while heating and cooling are based on cubic feet as there's a big difference between 8 and 10 foot ceilings.
The house with 6 corners (house design below) might be cheaper than the house with 4 corners because there are fewer square feet inside to frame and finish (drywall, electrical, heating, etc). What you won't see is that the roof on your 6 corner house might cost the same or even more because your home builder might have to “stick build” part of the roof rather than using all prefabricated roof trusses, losing the cost savings of roof trusses.
Building costs impacted by corners
The complexity of your house design affects more than initial building costs. Using the roof as an example, every extra seam introduced by a “doesn't this look nice” architectural bump out or functional dormer, adds more risk that rain water will penetrate the roof and cause water damage that needs repair. The cost to replace the roof will also be higher so it's wise to understand …
Total Cost = Initial Building Costs + Maintenance and Repair Costs + Replacement Costs
Have you worked with building costs, carpentry and corners?
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