My mother and I made insulation “pillows” to better insulate our house’s foundation during winter. We were successfully able to reduce the risk of our pipes freezing, lower heating costs and reduce wind flow under the house.
Our first step was to measure each of our foundation vents, because the interior sizes varied. We then purchased high-quality insulation, cut it to size, and folded it into pillow shapes. We wrapped the insulation pillows with shrink-wrap to make sure they held their shape. We placed our insulation pillows in the foundation vents and between the trusses in the vented area in the attic (of course, this was only after conferring with my contractor and HVAC engineer). The most important thing to remember is to add the pillows prior to the first freeze, and then remove them before spring to allow for proper ventilation.
Old Fort, North Carolina