My sisters and I bought the land next to mine to build a small house for my mother now that she's widowed. We're all in agreement about most decisions on the house, but we're split down the middle about fiberglass batt insulation vs. cellulose. We're aware that other types of insulation exist, but we've narrowed it down to these. Which of the two does a better job?

The short answer? Cellulose. Here's why: Both materials insulate well, but there's a difference in their typical performance. That's due to two reasons: First, the risk of air leaks is higher through fiberglass than through densely-packed cellulose. Second, and more importantly, it's very difficult for fiberglass batts to cover surfaces as thoroughly as cellulose does.

A fiberglass batt comes in specific dimensions and must be placed into a wall, floor, or ceiling cavity that has many obstacles, like wiring, that change the cavity's dimensions. Cellulose, which is typically blown in, fills-in more readily around these obstacles. So, cellulose covers surfaces more uniformly.

Regardless of the type of insulation you choose, be sure that a proper job of air sealing is done before insulation is installed. There's more to know about energy-saving insulation installation techniques in new construction.