Felt Underlayment

This product comes in two sizes; 5′ x 50 (Felt 550™) & 5′ x 100 (Felt 5100™)

A question we regularly get about this product; Is this product the same thing as the roofing felt at Home Depot?

Felt 550™ & Felt 5100™ were designed to protect the DrySpace™ vapor barrier from punctures due to sharp rocks, concrete and metal in the crawl space. We highly recommend removing these items before encapsulating your crawl space, but that may not always be possible. Here’s an example- Let’s say someone in the past tried to fix a standing water problem in the crawl space. And, instead of doing it right they went to the local gravel pit and bought 10 yards of stone to put in the crawl space. The cheapest stone that day was crushed rock, which has very sharp edges. So with good intentions and terrible problem solving skills the crushed rock found its way into the crawl space (for the record that will not fix a standing water problem). So now the owner of the crawl space learns about DrySpace™ and wants to fix it for good. Instead of hauling all of the stone out of the crawl space you can install the Felt 550™ or 5100 onto the crushed rock and then install the DrySpace™ to control the moisture.
So what else does the Felt 550™ do besides protect your investment in the DrySpace™ vapor barrier?

Crawl spaces are harsh environments and with that comes considerations in air quality. One of the most serious is Radon Gas, because it is a killer. The Felt 550™ plays an important roll in Radon Gas Mitigation. The Felt 550™ creates an air gap between the DrySpace™ vapor barrier and the soil, enhancing the results of the active Radon fan(s). Allowing the fans(s) to keep a negative pressure on all parts of the crawl space floor and eliminating any “pockets” that seep the gas into the space.

The Felt 550™ also plays a key part in mitigating other soil gasses that cause odor. As we continue to do research on the best ways to fix the problems with air quality, energy loss and moisture levels we discover new problems and their solution. One of those new problems is soil gas odor(other than Radon Gas). This problem is not everywhere and it has nothing to do with DrySpace™ causing the smell (other plastics have been found to contribute depending on their makeup and additives). Like with Radon Gas the Felt 550™ enhances the results of the fan to mitigate the odor.