Take a stroll above the insulation
I'd like to check the roof vents, furnace flue, and other penetrations through our attic, but the area was insulated with blown-in fiberglass that completely covers the bottom of the trusses. I'd like to build some kind of walkway up there, above the fiberglass, but I don't know how to go about it.
— Fred, Acworth, GA
Tom Silva replies: Basically, what you need is a simple platform that rests on top of the trusses' bottom chords, the horizontal members that act like ceiling joists. As long as the platform is used only occasionally as a walking surface and never for long-term storage (truss chords won't carry that kind of weight), it will be fine. By the way, while it's okay to attach things to a truss, never cut into one — you could do some serious structural damage.
For your platform, get some 2x stock that's wide enough to sit on the top edges of the bottom chords and extend above the level of the insulation. You'll also need some sheets of 5/8-inch plywood for the walkway, cut narrow enough to get up through your attic access hatch. Cut the 2xs to match the width of the plywood. Then cut some scrap 5/8-inch plywood to make gussets (one for each bottom chord) that run from the bottom of the chord to an inch or two below the top edge of the 2x. Now glue and screw a gusset to one of the faces of each 2x. Use deck screws, not brittle drywall screws.
With your materials at hand, and wearing gloves and long sleeves to prevent fiberglass itch, go up into the attic and clear away the insulation next to the chords. Squeeze some construction adhesive on the top and one side of each chord, and set the 2x extension and its gusset in place. Driving screws through each gusset and into the chord in a zigzag pattern will provide the stability you need. Finally, screw the plywood to the top edge of each 2x extension, making sure the end of each plywood sheet lands on a 2x and is held in place by at least four screws. Push the insulation back where it came from, and your walkway is now complete.