Haven homes can be built with a “slab on grade” style foundation or “raised” foundation. Our packages come with either option. For our model home, we determined that slab on grad was more appropriate for our site-specific needs. When camping, most of us have known the feeling of sleeping on the cold ground without an insulating pad. The ground drains heat from our bodies and, besides making us long for our soft beds, it makes us very cold! The same applies to your home when not insulated from the ground.
There are basically two different forms of foundation insulation; one for inside the perimeter stem walls, and sheet style used for under concrete slabs.
For the stem wall insulation, a standard rigid 2” thick insulation board with an R-value of 13 was chosen. Insulation boards cut to size are then fitted along the interior perimeter walls before backfilling. For Havens with framed floors, this insulation can be laid along the exterior of the stem walls and be just as efficient at preventing heat loss as laying it within the stem walls.
Under-slab insulation laid across freshly compacted ground serves to greatly reduce heat loss through the concrete floor. The insulation used for our Reno model Haven is a product
made right next-door in Carson City, called SlabShield. SlabShield is a “Low E” product, meaning that is allows for very little thermal energy, or heat, to pass through. SlabShield acts as a vapor and radon gas barrier for the Haven while also providing significant thermal performance because of its double layer of closed cell polyethylene foam, reflective layer, and overall R-value of 2.9. Then, to supplement the SlabShield, we used Visqueen in areas cut to allow utilities to pass though in order to create a thorough vapor barrier envelop for the Haven to rest in.
Below is a chart showing the difference in heat loss for insulated and un-insulated slabs. To read more about insulating your foundation, visit this great site where we found this simulation chart here.
(Simulation of a heated “slab on grade” with and without insulation. The temperature scale indicated in degrees Celsius (°C). Horizontal line with white markers is a reference plane at approximately 2.4m below the heated slab.)
What experiences do you have with insulating slab foundations? We welcome your questions, and comments regarding this important topic.