Offer your clients building and expansion flexibility and flood protection with a raised foundation.
Raised floors provide many advantages throughout the life of the home, from lower flood risk to easier access to pipes and wiring. This technique can help you tap into project areas on slopes, in floodplains or on problem soil.
Start by educating your clients about their choices. People on tight budgets might be resistant to the additional building costs associated with raised floors. On the other hand, inhabitants of flood zones should consider the added protection a raised foundation would provide.
What are the Benefits of Raised Floors?
Raised foundations are usually more flexible than the alternatives, says Richard Kleiner, director of treated markets for the Southern Pine Council (SPC). For example, a wood-framed raised floor can be used on nearly any site and is particularly useful where slab-on-fill developments are restricted, on problem lots or on problem soils.
They also lend themselves to amenities like raised porches and decks, as well as protection from moisture and pests.
The SPC promotes awareness of such systems by highlighting the return on investment for the homeowner. Raised foundations can be removed in pieces to allow for cabling, wiring and plumbing systems to run under the floor space, as well as accommodating space for crawling in. That flexibility enables clients to add rooms without ripping up ceilings and floors to route new pipes.
Additionally, there are site-specific considerations, such as required base-flood elevations. Also, there is less of a need for grading and leveling on raised homes. “If a lot has to be built up 2 feet or more, you would [have to] look at raised as opposed to slab,” says Jeff Couvillion, president of Acadiana Group in Greenwell Springs, La.
According to the SPC, a raised floor system can be supported by a variety of foundation types such as open pier-and-beam, perimeter wall, or piles. The system is a simple assembly of beams, girders, joists and sheathing panels comprising various wood framing products.
One of the most common foundation types is the pier-and-beam foundation constructed of reinforced masonry and supported by individual, reinforced-concrete pad footings or by continuous, reinforced-concrete spread footings.
Another common type includes continuous foundation walls (stem wall foundations), which are often constructed of reinforced masonry or poured concrete and supported by a continuous, reinforced-concrete spread footing.
The most common footings types are:
- Spot footing: Typically a 2-feet-by-2-feet square pad used to support a single point of contact, such as under a pier or post.
- Continuous spread footing: Used to provide a stable base around the entire perimeter of a structure.
- Grade beam footing: A continuous reinforced-concrete member used to support loads with minimal bending, frequently constructed by digging a trench that spans the distance between supports.
One advantage of raised homes is their curb appeal. Kleiner describes the foundation as a “pedestal” that gives the home a commanding presence on the site. Some homeowners worry that the under floor spaces might attract pests, but Kleiner says detaching the floor system from contact with the ground actually makes entry from termites and other pests more difficult and allows easy inspection.
Finally, inform your clients that locating and repairing a plumbing leak in homes built on slabs can be very costly. If a leak is below the slab, it can drive moisture into the living area and can ruin flooring and cause more serious problems like mold.
Potential Drawbacks and Incentives
“I think the biggest challenge is just the mindset of people,” Couvillion says. If they aren’t used to seeing raised homes, they’re more resistant to the idea.
Still, pricier materials and additional man-hours can dissuade customers. But some advantages of raised floors are not immediately visible.
Supply air ductwork isn’t required, for example, and some homeowners with raised floors pay lower insurance premiums. Kleiner also notes that, during construction, builders can avoid delays from plumbing inspections required before a slab can be poured.
Installing a raised floor “might take a little more time and thought for a builder unfamiliar with the system, but you’re going to give your client more value and livability,” he says.
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