Maybe this should have been lesson #1 – it’s such a common mistake. The oft-neglected rule is this: not every house plans fits – or can easily be made to fit – on every site.
You’ve seen the sad, odd result of this mistake before – the one-level house precariously perched on a steeply sloping site. In the Midwestern and Southern United States it’ll be supported on stacks and stacks of concrete block; in the California hills it’s even worse – houses on stilts! But it does make for great video when a mudslide or earthquake takes one into the ravine below.
Most plan book houses are “designed” to be placed on flat lots, and granted, the majority of building lots are relatively flat. But many house plan buyers have more challenging properties and these lots require a design that responds appropriately.
You can buy “sloped lot” designs from some house plan sites, and these are a step in the right direction – if you know what to look for.
The Four “S’s” of Siting a House – Slope, Sun, Soil, and Sewer
Slope The slope of the property can have a big effect on the cost of your project – a house placed on a slope will most definitely cost more to build than on a flat lot. Does your house have to be placed on the slope? Perhaps it can be placed at the top or bottom – taking advantage of the views from the slope but not incurring the costs of building there.
Many owners of sloping lots want to take advantage of that situation by including a “walk-out” basement in the plan. It’s a great way to increase the space in your house for a relatively small cost. The steepness of the slope will partly determine how much excavation and/or fill is necessary to create the walkout.
But a walk-out basement will also require a few special details and some additional structural information to accomplish properly and to get permits from most building departments. Be sure your plan includes such provisions for a walk-out, or have someone make the necessary revisions to the plans for you.
Homes on sloped lots often require more (read: costly) gravel backfill material at the foundation; they might need expensive retaining walls to create a flat area for a driveway or hold back soil at the walk-out; and they usually have a full basement – whether you want it or not.
Looks for plans designed for sloped lots – they’re usually multi-level plans and are usually listed as “sloped lot plans” on house plan websites.
Here’s the bottom line – carefully analyze (with the help of a design professional if necessary) the impact that your sloped lot may have on your choice of house plans. Choose a house plan that’s appropriate for the lot without expensive modifications or construction techniques.
Sun Most homes are designed with the primary family living spaces at the back (kitchen, breakfast room, family room). These are the rooms you want sunlight in; the rooms with all the expensive windows. And you’ll get that sunlight through those windows, too – if the back of the house faces 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, isn’t going to get any direct sunlight at all. Or worse, your lot faces east, and the afternoon sun pours through that wall of west facing glass like a blast furnace – heating up the house and fading the furniture and carpeting.
Most house plan services will be happy to “flip” your plans for you if that will give the living spaces a better orientation to the sun. If the plan you’ve chosen is drawn on CAD (Computer Aided Drafting) software, then flipping the plan is easy. For hand drawn plans, you’ll have to make “reverse” prints yourself – easily done at your local reprographics (blueprint) shop. In Chapter #9 “Buy The “Right” Set Of Plans”, we’ll talk more about flipping floor plans.
Since we’re talking about sunlight, now’s a good time to bring up the subject of energy consumption. Houses use energy to keep heat in, and to keep heat out. The easiest and least expensive way to keep heat out of the house is with proper orientation of the windows and doors. The easiest way to keep heat in is to reduce the number of windows – so pay close attention to the number and location of windows in your house plan. A properly oriented plan can save you a lot in fuel bills.
Soil It’s amazing, every time a backhoe starts a new house foundation, how different soils can be from one building site to another. From loose sand to solid rock and everything in between, and sometimes on the same site!
Soil type can have a big impact on the cost of construction. Even if you know a lot about the underground conditions on 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’s relatively easy to learn the basic characteristics from your County Extension Service or local building department. You might also contact builders and excavators with experience in the area and ask them what they’ve encountered on other projects they’ve built near you.
House plan services that design all their own plans (like RTA Plans) often design them to fit the site conditions and building traditions of their local area. Some Southeastern plans, for example, have neither crawl spaces nor basements; they’re designed with foundations on multiple piers because of the low bearing capacity of the sandy soil. In areas with better soils this same system would be overkill.
A few of the plan services in the Great Plains and Texas design their homes on concrete slabs – there’s almost no foundation at all.
Some types of foundation systems that are popular in one region are unheard of in others. Typical practice in many areas is poured concrete walls – a potentially expensive option if your plans call for concrete block. It’s important to know what foundation systems are common where you’re building.
But even a house with the proper type of foundation for your site may need significant re-engineering to accommodate the local soils and the local building department.
Soils drain and retain water differently, and soils have vastly differently capacities to bear structural loads. In most areas, you’ll have to show the building department that your foundation is designed for the local soils conditions.
Don’t skip this step – if the plan you’re considering isn’t suited for the soil conditions on your site, you could spend thousands of dollars to have the plans modified accordingly.
Sewer The Plumber’s Credo – “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 front (usually) of the lot. The height of this pipe will determine the depth below grade of the basement slab since the effluent from the house must “flow downhill” to the sewer line.
Depending upon the soil conditions and slope of the lot, the sewer line may be too high to allow gravity flow from a basement, especially if you’re planning on having a bathroom in the basement. In such cases a “grinder” or “ejector” pump may be required to lift waste to the sewer height – at a cost of several thousand dollars.
An undeveloped lot is one where the utilities – electricity, water, gas, and public sewer – aren’t 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 at all. On such a lot, you’ll need some type of private sanitation system.
Several 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 widely in cost, and not all health districts allow all types. The choice of system will also be heavily weighted by the soil type and slope of the lot, and the available area(s) for the system. A typical leach field system will require a large clear area for a primary and second field.
Since a private sanitation system is more expensive than connecting to a public system, the cost isn’t typically considered in the “base” cost of building a house. A private sanitation system is usually an “extra”.
Put ’em all together At this point you’ve probably begun to guess that all of 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 indeed.
Will you be able to find that house plan on a website? Maybe – but perhaps just as important to you should be the desire to avoid purchasing a plan that won’t work on the property.