New carpet...Does adding a pad create problems?

My first thought was:

1) The slide - make sure it will clear!

2) Second thought was the moisture that may get trapped into the pad - from coming in with wet feet or leaving the door open with dew or rain. I met someone this past weekend who actually had a linoleum floor laid and then the carpet on top to act as a barrier to the wood frame/joists and possibly prevent wood rot!

3) Will your doors clear the additional height?

Just a thought!