For every inch of rigid foam board, you typically get an R-value of 4, so 2 inches would have an R-value of 8. The foam board is light and shouldn't affect the garage door opener.

The average cost of home insulation is between $3,000 and $10,000 for a 2,000 square foot home or between $1.50 and $5.00 per square foot. Average Costs for Home Insulation ...

I use foam insulation. I’ve seen it come in 2-inch diameters (maybe a special order is required), which would have been the right size for the pipes in the heating system in our old house.

Tip the wall into place and fasten with concrete nails or screws. Pro tip: You need shims only about every third joist, but ...

This wall insulation system consists of four simple panels made from 1-inch-thick rigid insulation board. Your local fire codes may require rigid foam insulation to be covered with 1/2-inch gypsum.