Maybe this should have been lesson no. Mistake #1: It’s such a common mistake. The rule that is often overlooked is this: not all house plans fit, or can be easily adapted, in all places.
potential disaster
You’ve already seen the sad and strange result of this mistake: the one-story house perched precariously on a site with a steep slope. In the Midwestern and Southern United States, it will stand on piles and piles of cinder blocks; in the hills of California it is even worse: houses on stilts! But it’s a great video when a landslide or earthquake takes you into the ravine below.
Most blueprint book homes are “designed” to sit on flat lots, and of course most building lots are relatively flat. But many home plan buyers have more challenging properties and these lots require appropriately responsive design.
You can buy “sloped lot” designs on some house plan sites, and these are a step in the right direction, if you know what to look for.
The four “S” to locate a house: slope, sun, soil and sewage
Slope The slope of the property can have a big effect on the cost of your project: a house located on a slope will definitely cost more to build than on a flat lot. Does your house have to be located on a slope? Perhaps it can be placed at the top or bottom, taking advantage of the views from the slope but without incurring the construction costs there.
Many sloped lot owners want to take advantage of that situation by including a “walk-out” basement in the plan. It’s a great way to increase space in your home for relatively little cost. The steepness of the slope will partly determine the amount of excavation and/or fill needed to create the strike.
But a walkout basement will also require some special details and some additional structural information to get it right and get permits from most building departments. Make sure your plan includes such strike provisions, or ask someone to make any necessary revisions to the plans for you.
Homes on sloped lots often require more (read: expensive) gravel fill material in the foundation; they may need expensive retaining walls to create a flat area for a driveway or retain dirt at the driveway; and they usually have a full base whether you like it or not.
Look for plans designed for sloped lots; They are typically multi-level plans and are usually listed as “sloping lot plans” on home plan websites.
Here’s the bottom line: Carefully consider (with the help of a design professional if necessary) the impact your sloped lot may have on your choice of house plans. Choose a house plan that is appropriate for the lot without expensive modifications or construction techniques.
Sun Most homes are designed with the main family living spaces in the rear (kitchen, breakfast nook, family room). These are the rooms you want sunlight in; the rooms with all the expensive windows. And you’ll get sunlight through those windows, too, if the back of the house faces from the south. That’s where the sun is, remember? If your lot is on the south side of the street, great.
But what if your lot is on the north side? All that living space, all that glass, will not receive direct sunlight. Or worse yet, your lot faces east, and the afternoon sun pours through that west-facing wall of glass like a blast furnace, heating up the house and discoloring furniture and rugs.
Most home planning services will be happy to “flip” your plans for you if it gives the living spaces a better orientation towards the sun. If the plan you have chosen is drawn in CAD (Computer Aided Drawing) software, then flipping the plan is easy. For hand-drawn plans, you’ll need to make “reverse” prints yourself, easily at your local reprography (plan) shop. In Chapter 9, “Buy the ‘Right’ Floor Plan Set,” we’ll talk more about changing floor plans.
Since we’re talking about sunlight, now is a good time to bring up the subject of energy consumption. Houses use energy to keep heat in and out. The easiest and least expensive way to keep heat out of the house is with the proper orientation of windows and doors. The easiest way to keep in heat is to reduce the number of windows, so pay close attention to the number and placement of windows on your home plan. A properly targeted plan can save you a lot on fuel bills.
Soil It’s amazing, every time a backhoe begins the foundation of a new house, how different the soils can be from one construction site to another. From loose sand to solid rock and everything in between, and sometimes in the same spot!
The type of soil can have a big impact on the cost of construction. Even if you know a lot about the underground conditions at your site, it’s a good idea to keep a little cash in reserve to deal with potential surprises lurking under the turf.
How much do you know about the soils on your home site? It is relatively easy to learn the basics from your County Extension Service or local building department. You can also contact experienced builders and excavators in the area and ask them what they’ve found on other projects they’ve built near you.
House plan services that design all their own plans (such as RTA plans) often design them to fit the site conditions and building traditions of your local area. Some southeast plans, for example, do not have crawl spaces or basements; they are designed with foundations on several pillars due to the low bearing capacity of the sandy soil. In areas with better soils, this same system would be overkill.
Some of the plan’s services in Great Plains and Texas design their houses on concrete slabs; there are almost no foundations.
Some types of foundation systems that are popular in one region are unknown in others. Typical practice in many areas is to pour concrete walls, a potentially expensive option if your plans call for concrete block. It is important to know what foundation systems are common where you are building.
But even a house with the right type of foundation for its site may need significant re-engineering to accommodate local soils and the local building department.
Soils drain and hold water differently, and soils have very different capacities to support structural loads. In most areas, you’ll need to show the building department that your foundation is designed for local soil conditions.
Don’t skip this step – if the plan you’re considering isn’t right for the soil conditions at your site, you could spend thousands of dollars to modify plans accordingly.
Sewer The plumber’s creed – “everything flows downhill” is extremely important to remember when selecting a plan. On a developed lot, the municipal sanitary sewer line is buried near the (usually) front of the lot. The height of this pipe will determine the depth below the basement slab level since the effluent from the house must “flow downhill” to the sewer line.
Depending on soil conditions and the slope of the lot, the sewer line may be too high to allow gravity flow from a basement, especially if you plan to have a basement bathroom. In such cases, a “crusher” or “ejector” pump may be required to lift the waste into the sewer, at a cost of several thousand dollars.
An undeveloped lot is one where utilities (electric, water, gas, and public sewer) are not brought from the street to the buildable area of the lot. On larger undeveloped properties, there may not be any public sanitary sewer to connect to. On such a lot, you will need some kind of private sanitation system.
Various types of private sanitation systems are in use today, including the traditional septic tank and leach field, aeration systems, and “mound” systems. They can vary greatly in cost, and not all health districts allow all types. The choice of system will also be strongly influenced by the type of soil and slope of the lot, and the area available for the system. A typical leach field system will require a large cleared area for a primary and secondary field.
Since a private sanitation system is more expensive than connecting to a public system, the cost is generally not considered in the “base” cost of building a house. A private sanitation system is usually an “extra”.
Put Them All Together At this point, you’ve probably started to guess that the four critical site selection factors above can affect the same site. You’re right. A heavily wooded, steeply sloping property on the north side of the street with loose, sandy soil will require a very particular house plan.
Will you be able to find that house plan on a website? Maybe, but just as important to you should be the desire to avoid buying a plan that won’t work on the property.