I once saw a magician, ‘The Amazing Rudolfo’ or something like that, make an entire house float on thin air! He cautioned viewers not to try this at home. That’s good advice, even if you’re considered to be amazing and have your own T.V. special. If the magic you want to perform is actually living in your new log home, I’d plan to put it on something more substantial like a foundation or a slab.
This is one of the most important construction elements you’ll consider since it’s the portion of your home that will interact directly with the ground, not only holding the building up but also anchoring it down! Foundation systems, when properly designed and constructed, allow you to erect a structure that can withstand the powerful forces of nature such as soil pressure, water, ice, expansion, contraction, wind, fungus, insects and even the effects of gravity. When a foundation is poorly designed or weak, very little else can sentence your home to an earlier grave.
In certain areas, people build on a treated wooden platform for economy. That may be acceptable for a small vacation cabin but not a permanent, year ’round dwelling. If economy must prevail or the terrain prevents basement excavation, a poured concrete slab is both strong and durable. This is basically a single layer of concrete that’s several inches thick. It is poured thicker at the edges to form an integral footing and then rods are placed to strengthen the edges. The slab is poured on a bed of crushed gravel to improve drainage and a wire mesh is placed into the concrete to reduce the chances of future cracking.
The ideal choice, for my money, is a full-fledged foundation which provides a roomy cellar and a solid base to support the massive weight presented by the logs. Of the various materials and systems available, here are three of the more common foundation types:
Cinder or Cement Block is the least expensive but often takes the most time to erect. Typically, cement footings are poured below the frost line, then the blocks are stacked and mortared together on top of the footings. Holes or channels are filled with cement and reinforced with steel rods (rebar). Cinder block, especially, is porous and tends to hold moisture which doesn’t hurt the block but tends to encourage a damp basement. Still, block is strong and offers many of the advantages of other foundation types for only slightly more cost than a slab.
Poured Concrete comes at a higher price but is seamless, doesn’t retain moisture like block and should give you a nice, dry area for storage or finishing. It tends to be more labor intensive, therefore takes longer to build, but its strength and durability are second to none. Footings are poured below the frost line, much like with block construction. Then aluminum or insulated wall forms are placed on top of the footings, into which concrete is poured and reinforced with rebar for added strength. After a week or so, the concrete has cured enough for the walls to stand on their own and the molds [unless insulated] are removed. When they discover the ruins of an old town and decide to restore the buildings, they often use the original foundations … which you can bet were made from either stone or poured concrete.
Pre-Cast is the way we decided to go when we built our home. Why? Speed, strength and drainage. Pre-cast systems appealed to us for a number of other reasons, too. The walls are poured under controlled conditions in a factory using 5,000 pound per square inch (PSI) strength concrete instead of 2,500 to 3,000 PSI concrete like most walls poured on-site. The pre-cast walls are cured at the factory so they are guaranteed to achieve the intended design strength. Since they are manufactured square, if the site has been properly prepared the foundation will be plumb, level and square once it is assembled. Most pre-cast systems have an inch or more of foam insulation built into the walls. This minimizes cold conduction problems and provides a warmer basement in climates like the Northeast where we live. Should you decide to finish your basement, nailers are incorporated into the wall structure making it easier to add more insulation and construct your interior walls.
If you’re in a hurry, as we were, one of the biggest attractions of a pre-cast system is that it’s not weather dependent and can usually be erected in less than a day. The panels are bolted together and the seams waterproofed with special high performance urethane caulks. Building on an average 20% grade such as we did, an important feature was the unique ability for drainage offered by these systems. Because they are erected on gravel instead of a traditional footing, we were able to run several drains to empty a good distance from the house. Technically, a sheet of water coming down the hill would pass under the house and never rustle a pebble. So far … nine years worth of bone dry basement. Oh, at first I wondered about the gravel footing instead of solid cement but, after being compacted, it’s hard as a rock!
It was not my intention to lean more heavily toward pre-cast than other foundation types but, since that’s what Vigi and I chose for our own house, it only seemed fair to tell you why. Everyone has different needs, budgets and preferences. As with anything you do, it’s a matter of selecting the right tool for the job; for us, pre-cast turned out to be the right tool. Whatever you select as the foundation for your new home, just be sure to use something more grounded than the hovering hocus pocus of ‘The Amazing Rudolfo!’