Piling & Grade Beam Foundations For Home Additions

If you are planning a main-level home addition, most renovation contractors will ask if you are considering a full basement under your new addition. This will be a decision based on cost, living space requirement and construction equipment accessibility. The question will be – do you really need that extra square footage, despite significant extra cost and yard destruction?

If the answer is NO, you then have a few other less costly options. The first would be to excavate a four foot deep trench around the perimeter of the addition area, then install a concrete footing and “frost-wall”, then backfill. This is the most commonly used approach, but still a costly one, an invasive one and one that could require a complete rebuild of your yard.

The next option, and a much less costly and invasive one, is the piling/grade-beam foundation system. This system consists of the augering of a series of six foot deep holes which then are filled with concrete and rebar, with a three-ply 2×8” pressure treated grade-beam being placed on top of the piles around the perimeter of the addition.  Channel Custom Builders has been advocating and implementing this methodology for more than twenty years, with great success, while these engineered piles have been widely utilized in commercial construction (and less so in residential) for over one hundred years.

However now, with the advent of the helical “screw-pile”, we are beginning to save our Customers time and money by replacing the concrete piles with a series of engineered, thermal “screw-piles” that are simply drilled into the ground. No excavation, no muss, no fuss. The process is pretty much the same from that point on. The grade-beam is placed on top of the screw-piles, then a shallow “pony-wall” with the floor joists being placed over all to complete the basic foundation/floor structure. The interior of this shallow space (can’t really call it a “crawl-space”, as it will typically be very low in height) would have thick rigid insulation panels covering the grade area, with black poly sheeting over top that is then sealed to the grade-beam/pony-wall assembly. Fourteen mm. washed rock is then spread over all at a depth of approx. four to six inches to complete the insulation value required. The perimeter wall and joist-end assembly is then sprayed with two pound expanding foam to the R-value dictated by the building code.

You now have a clean, dry, sealed under-floor space that can be economically heated to maintain warm, comfortable floors in your new addition! Finally, everything from the floor up is standard construction where you can put more of your hard-earned cash into nicer finishings, instead of into the ground.

Contact a Channel Custom Builders representative today for more information about this slick new system!