Ice shield is generally required by building codes to be placed from the roof edge flashing to a point up the roof slope 24" in horizontally from the inside of exterior wall.

In other words, if you measure from the inside wall where the roof rafters meet the top plate in toward the center of the room 24" horizontally....at that point vertically to the roof is the point to which ice shield must be applied.

For shallower slopes this equates to just a foot or two or ice shield. For steeper roof slopes, this can be several feet.

For a 2:12 roof slope with a 1 foot overhang, you would need slightly over 36" of ice shield to meet minimum code.

For a 12:12 roof slope with 1 foot overhang, you would need nearly 51 inches of ice shield to meet minimum code.

So 3 feet of ice shield is not enough in most cases and 6 feet surpasses minimum code requirements in most cases.

Felt must be at least 15# and for roof slopes of 2:12 to 4:12 must be double layered installed in a staggered 19" lap pattern over the lower course.

The two bids of 6' of ice sheild and 30# felt seem best all things considered.

Thanks for your reply.... is it safe to assume more is better for the ice shield and that 30# felt is always better than 15#? Thanks again...gp

More is not better necessarily.

30# felt is ever required unless specified by the shingle manufacturer but it won't hurt to have it.

Ice shield is only necessary within 6 feet of the eaves under most conditions since this is where ice dams form, but it can be prudent to use ice shield on the entire deck of some low slope roofs where wind blown water and ice can get up under the shingles.

One needs to balance 'need' with 'economic reality'.

One needs to get the most protection at the best price.

Adding more ice shield and using heavier felt does not always strike that balance.

Thanks for taking the time to help me understand! I appreciate it!