Peter writes from Manchester, United Kingdom: "How do I insulate under the stairs. The area under the stairs has an external door, which gives access to the utility meters etc under the stairs. The only access to the understairs area is from outside the property. So I'm looking to insulate the under side of the stair boards and probably the triangular solid bit of wall facing the door. What should I use, and should I worry about moisture (damp rather than a leak) getting behind the insulation?"

Answer: We recommend fiberglass insulation. Use the largest R-Value that will fit in the cavity. Most likely, that will be R-19 insulation.

If you have moisture issues now, you need to take care of that problem before installing fiberglass insulation. You may need more ventilation in the area.