Building a New House? You Need to Start from the Ground Up
One of the items related to building your dream home that may not be keeping you up at night – but should – is your home’s foundation. It’s easy to get caught up in home décor elements, floor plans, paint colors, appliances, and landscaping, but you really have to start with the basics, and that includes house plan foundations.
There are a variety of factors that go into narrowing down the right foundation for your home. Some examples include whether the land on which your house will be built is made up of sand or clay soil and whether it is on wetlands, on bedrock, or is prone to flooding. In the end, though, the type of soil at your building lot will largely determine the type of foundation you’ll need to support your home.
This 3-bedroom, 2-bath Acadian style home plan is on an on-grade slab foundation, one of the most popular types of foundations across the country (House Plan #142-1094).
Things to Consider
What exactly are the reasons for determining the best home plan foundations?
1. First of all, the foundation needs to support the load of the house you’re putting on it. Depending on the type of home you’re building and the overall size and weight of the load the foundation will need to bear, the foundation must be strong enough to support the home or you’ll most certainly have issues with it. The designer of the house plan you choose will have taken all of these considerations into account when designing the home. If you choose a different foundation from the designer’s available options or have a modification done for a foundation not listed as an option on the plan details page, then again, the designer will make sure the foundation can support the structure. If you choose to purchase a house plan and handle the foundation on your own, be sure to have a qualified designer/architect or engineer sign off on the foundation before commencing your build.
2. Additionally, the foundation must be placed on soil that is settled and undisturbed to avoid shifts in support for the foundation that may result in the breakdown of the structure. A certified, experienced building contractor will make sure the conditions are right before digging and installing a foundation.
3. Another important factor to keep in mind when determining the best residential foundation is to be sure that the foundation will remain dry. Will groundwater have access to your foundation? A damp foundation is not a sound foundation. Most non-urban localities require a “perc test” of the soil before building a house to be sure the soil will percolate water through it properly for a septic system. Soil that passes a perf test should not have groundwater problems with a deep (basement) foundation.
4. In the absence (or even completion) of a perc test you can have a soil test performed by a local engineering sompany that will determine what kind of soil is present, its moisture content, and its compaction qualities. Passing a soil test ensures that your foundation will perform properly.
5. Installing gutters and downspouts to redirect moisture from the roof is a good way to keep excess moisture away from your foundation after building. Incorporating materials that provide drainage away from your foundation, such as gravel and sand, can help protect your foundation from dangerous moisture. If you want to take your foundation’s protection against moisture one step further, consider installing a subslab drainage pad. Consult your contractor on this. When you install a layer of polyethylene sheeting between the drainage pad and the foundation, you can block out water vapor and soil gases as well. It may even improve the air quality in your home.
Types of Foundations
Depending on the type of home you’re constructing and the geographical location of the area you’re building in, your need or desire for a basement may change. After all, you wouldn’t build a basement as part of your beachfront home, with its high water table levels, would you? Basements are mostly found in the Northeast or Midwest where the soil can support the structural compnents for one.
The construction of your basement home would likely begin with a hole eight or more feet deep. Often the foundation consists of footings placed below the frost depth and walls that enclose a 4-inch-thick poured-concrete slab. The walls of the basement could be formed by poured concrete (insulated or not), stacked concrete blocks (insulated or not), insulated concrete panels, or even pressure-treated wood and plywood (permanent wood foundation) to ensure a secure structure to support the rest of the home.
Because homes often have footings that anchor the structure, especially those that are in colder climates, builders will often add a basement inasmuch as they are already having to dig so deep to set the footings. This leaves the homeowner with some extra square footage for their own needs or increased future resale value. Insulating the slab and walls will be necessary for those finishing the basement space, as this will reduce mold and mildew in warm weather and improve all-season temperature control.
For those with lots that are sloped, a walk-out, or daylight, basement may be an even better option. These types of basements often have fewer issues with dampness and are overall more enjoyable as a living space because they let in quite a bit of natural light.
This full basement foundation has the sidewalls already insulated, ready for finishing as extra living space. The area has also already been ducted for heating and air-conditioning – see the register in the ceiling at upper left-center of image (courtesy HGTV/Candice Olson).
Not quite a basement, nevertheless a crawl space keeps the house’s structure elevated above ground level. Why would someone seek crawl space in their new foundation? Oftentimes, it’s to keep the plumbing and HVAC equipment accessible for the ease of future repairs in the absence of the basement space. If you’ve determined that crawl space would be the best foundation for your house plan, you may be wondering what is involved with constructing one.
In this type of foundation, footing and short foundation walls are poured. Usually they are 20 or more inches high, so the crawl space affords just that amount of maneuvering space. You’ll need to crawl on your stomach or hands and knees to reach the utilities if they do in fact need repair in the future. Contractors will often suggest placing a vapor barrier over the soil as well to avoid any mold issues. Adding a crawl space doesn’t typically protect a home from flooding as some might think, but it will make any major plumbing or air conditioning and heating repairs much easier than with a slab foundation.
Top:This well built and designed crawl space has a central support structure and plenty of maneuvering room for upkeep and maintenance (courtesy doityourself.com) Bottom: The illustration shows a cross-sectional view of a typical crawl space with important components and features called out (courtesy Basement Systems).
A slab foundation built directly on the soil without first digging deep for a basement is likely the most common type of foundation for a standard home built on a stable piece of land. The land must first be leveled and a space must be dug around the area where the foundation will sit. Typically, gravel or small stones are spread across the site and concrete is poured to form the 4- to 6-inch thick slab and perimeter and interior support footings (as support for walls and columns).
What are the advantages to using a slab foundation? It is usually lower in cost and easier to construct, which decreases the overall timeline of your home construction project. The only disadvantages would be if you have uneven or unstable soil underneath, which can cause the foundation to crack and break down over time. Also, plumbing and sometimes even HVAC systems may be buried underneath the slab, which can make them difficult to repair or replace. And of course, you lose any extra storage or future living space you may have had with a basement. Regardless of the disadvantages, slab foundations still tend to be the most popular for their low cost and ease of construction.
The slab foundation is the most popular – and probably easiest – residential foundation in the country. When the first large mass-produced residential planned communities were built (starting with post-WWII Levittown, New York, and others), most were designed with efficient slab foundations. A slab can be installed over just about any stable soil without conern over a high water table or the presence of large boulders or bedrock (courtesy Arm Concrete LLC).
For Homes with Difficult Land
If building a slab foundation is impossible because of the type of land you’re planning to build on, such as on a hill or on unstable soil or sand, what are your options? Pier foundations are often the best option for your house plan in these cases.
Pier foundations are laid with the use of square or circular pads of concrete at strategic spots around the perimeter of (and within the footprint of) the structure. The footing pads are dug and set in the soil, usually on bedrock or other subsoil feature determined by an engineer to be stable enough for support; then concrete or pressure-treated wood columns are poured or set on top of the footing pads and and connected by horizontal beams (girders) made of wood or steel. The beams support the walls and floors of your home. Your contractor can determine whether or not a pier approach is the best foundation for your house plan, depending on the type of land upon which it will be built. Some pier foundations elevate the house structure 8 or more feet, making them ideal for use in coastal, beachfront, or floodplain areas where flooding may be possible. They are also ideal for hilly or mountainous areas to compensate for the lack of a flat spot to locate the house.
Typical for beachfront or coastal homes, pier foundations allow you to build over the the earth below the structure. As long as the pier footings can reach stable earth below the surface, the foundation will be strong and sturdy. The piers themselves may raise the house structure anywhere from inches aboveground to several feet – protecting the house from flood damage or rising it above hilly or severely sloped building lots (House Plan #116-1003)
Here at The Plan Collection, we understand how important your home’s foundation is to ensure the safety and security of your house for decades to come. So it’s important that you select the best foundation for the houseplan you choose through The Plan Collection and can build your dream home with peace of mind!