Master electrician Allen Gallant shows Kevin the new LED ribbon strip lights he's using under the cabinets in the kitchen and butler's pantry. Norm and Tom build the new mudroom storage system. Richard and Tom review the critical need for ventilation in the modern, super insulated building. Wallpaper hanger Mark Pehrson shows Kevin his technique for applying wallpaper to a ceiling in one girl's room. In another daughter's bedroom, painting contractor Mauro Henrique is setting up to paint decorative stripes on an accent wall. On ASK THIS OLD HOUSE, Kevin and Roger meet with meteorologist Jim Cantore to discuss Jim's biggest weather fear: lightning. Roger heads to Orlando to see a lightning protection system installed. Richard helps a homeowner install a reverse osmosis filter for drinking water. And the guys ask, "What is it?"