The closer to square you get, the more sq ft. you'll get for the given wall / roof size. Keeping the ceilings at 7' 6" (minimum allowable for habitable space) will decrease costs but a lot of people will find that unpleasant (I live in a 7'6" tract house right now).

Thanks Ronnatalie--We've been thinking square. We love the look of a foursquare with attached garage but it seems difficult to fit the master on main. My husband is tall and prefers a 9 foot ceiling, so we may aim for that. 8 foot would be a minimum. (I'm 5 foot 2 and Frank Lloyd Wright designed homes that feel right to me...but most people grow up tall around here and I wonder about resale with a low ceiling).

Mightyanvil--We're hoping to use local materials and simple finishes. Farmhouse styles fit in well here. Craftsman and prairie are popular too, but tend to be more expensive if done up right. Thank you for pointing out the importance of finishes and simplicity of design. The more we learn, the more we realize how complex is the process of home design. It is nice to pick up a little from the experts here.

We own the land and plan to build because home prices have not fallen here (overall they have slowly increased) and we are locked into a certain location because of job commutes. However, I wonder if big inflation is on the horizon and the increasing cost of building materials will outpace the cost of buying an existing home? I scan the real estate ads every week, just in case.

All the best,
Lizzie

In theory, 2ft increments on your exterior walls is more effeiceint than other dimensions since it allows a full sheet [4x8] of material to be cut in half and used, with none being wasted.

It is a difference that's not really going to make a difference, though: if the OSB layer comes out just right, the siding will have to be slightly more than 2ft since it goes around the outside of the OSB, and the drywall on the inside will be considerably under.

Not sure where my post went but it WAS on here.

mightanvil, I have to respectfully disagree with you about joists. If you increase a span across a home (let's say a home that is 40 ft wide across the front) and you make the house deeper such that it requires going from 2x10 to 2x12, that really adds up. Your second floor joists and roof joists also have to get upsized. Your rafter thus increases. More roof sheathing, shingles, etc. That's just lumber, not including the additional flooring, paint, etc.

As far as load bearing walls, our prior house had a 24 ft open span that required a steel beam. That was an expensive "must have" for the wife.

The topic of new vs existing cost depends on the geographical location. Where I moved too in Maine, there is a not that many homes that turnover at each price point and thus much less selection (really slim in winter). It's actually cheaper to build. In the Cary area of NC with so many existing homes, the converse was true.

To the original poster, I recommend that you figure out how large of a home you need and then work backwards. Put down everything that is "absolutely must have" and strip the layers of the onion back so to speak. You can look at comparable house sizes (new and existing) to see about where you land.

nc_lawn_nut
Increasing the floor area by about 15% would increase the cost by about 18% so there would be little additional cost per s.f. to increase the joist and rafter spans by 2 ft and increase the depth of the joists by 2 inches and the cost of sheathing and finishes per s.f. would not change. I am recommending that the OP not base important design decisions on cost savings of pennies per s.f. In the case cited I think it would be about 2¢/s.f.

anvil,
Your example is precisely why most builders don't use $/sq ft when giving a quote. Hence the OP's inquiry. Your example also shows the non-linear fashion of floor area vs cost increase. This is not a battle I want to wage. You win.

How builders might price the work is another matter entirely. We're talking about designing in the hope of reducing the actual cost of the work. In fact, a builder might bid what he thinks you will pay and take the savings for himself.

So far it has been established that smaller houses are cheaper. You need to decide how large the house needs to be and how the spaces will be used and then find an efficient way to frame it not the other way around.

If you tune the room sizes to be an odd number of feet plus 4 inches between bearing studs, there would be no waste of standard length joists (10-0, 12-0, 14-0, etc) but if you ignored that idea and made the room spans a foot larger, you could use the scrap for solid blocking but that adds an extra cut per joist. Avoiding spans between those dimensions might avoid wasting 4 to 8" per joist and save you between $8 and $16 per room (averaging in the attic joists and rafters) assuming you could get the rooms to layout with those dimensional constraints. You night be able to reduce the cost of the house by $80 to $160.

Of course, none of the perimeter framing dimensions would likely be in multiples of 16", much less 48", so the scrap sheathing would probably wipe out any savings.

After you've designed a few houses you don't think about room dimensions as potential cost savings opportunities unless you are building a one room house or planning to build a full sized house a hundred times.

Design the house the way you want to live in it and ask a competent professional to design a frame for it with minor modifications to the design. Better yet consult at the preliminary stage of the design.

Sure, long span beams are expensive but if you really want a big open space the cost might be well worth it and sometimes long span engineered joists can reduce or eliminate that additional cost. Sometimes the least efficient way to enclose a given floor area is to use relatively small spans if they require more bearing walls, beams and footings. If you can design an efficient basement and first floor structure the rest will fall into place.

Where I live attics are often heated for HVAC equipment and additional living space so insulation is usually installed in the rafter framing and the rafter sizes are usually determined by the insulation depth rather than the span. In other climates, roof trusses are often used.

There are many simple plan houses on the internet from architects but I would avoid the big plan mills.

Here is a link that might be useful: Rick Thompson

Another way of putting it is that designing spaces efficiently for their intended use (especially for multi-uses) can often allow them to be smaller. This kind of floor plan efficiency can save considerably more money than the potential loss from use of slightly less efficient joist sizes. The best way to save money designing a house is to be clever about how you use and arrange living spaces rather than designing for material efficiency.

Lizzie - where are you building in WI? We are also in Wi and building this spring as well. Now is an excellent time to build especially if you DIY. Amazing how you can get bids on several items and then when the contractor calls back to see if they get the job you mention that another company came in at this amount and the company on the phone just lowers their price instantly. We are building a 2400 sq ft ranch and we are get amazing deals. Got my framing down from $22K down to $12K and my drywall with rounded corners and knock-down down to $9K from $13K.

Hi missleah--

We are in Sheboygan. Where are you? It sounds like you are working hard and getting some great deals. We are aiming for about 2000-2400 square feet in a two story house. We have been slow to pick a floor plan. Are you using a builder's plan or did get a house plan some other way?

Good luck with your build!

Lizzie- we are in the Waukesha County Area (suburb of Milwaukee). We looked at a bunch of model homes to see what's in style and then I bought the Better Homes and Gardens design software and designed it myself at home (14 tries to get it perfect). The software was about $60 and was great to work with since it has 3D views and cool stuff so you can actually see the room you designed. Then I found a great inexpensive retired architect in the area and paid him about $500 to verify and re-print out my blueprints and add the structural stuff like the beams and correct roof pitches etc. His name is Rich Kowalski and his email is: kowalskiassociates@yahoo.com. Great guy to work with. We did everything through email so I never had to drive to meet him. His pricing was excellent for the prints since everyone else charges about $2000.

Good luck with your build and remember to work the contractor's for pricing. Right now is the best time to build!!

misleah--we have that program and I've started to play around with it. We'll see how it goes. Thank you for the name of an architect and the inspiration. Will you post details of your build in the spring? We'll keep our eyes open. Thanks again. Lizzie