paper under hardwood ?

Hi guys, I am going to install maple hardwood floor (3/4'' by 2-1/4''). I already levelled and flattened my floor by adding 3/8'' subfloor on existing 5/8''. There is a crawl space under the room.
Do I need to lay paper (such as 30 or 60min asphalt-craft building paper) on the top of subfloor before installing the hardwood? So far, I have heard so many different opinions whether to install the paper or not, what do you recommend so I can avoid any future mistakes. Will this paper really help to protect the hardwood agaist moisture and sqeaking between the subfloor and hardwood? Is it really necessary to have this paper under the hardwood?
Thank you all in advance!!

Dimi

 

A 15# saturated felt paper is recommended as an additional barrier over subfloor beneath hardwood. If you are installing over a crawl space, you need a ground cover of 4-6 mil polyethylene (black plastic) as a moisture retarder over the soil. You need adequate foundation ventilation with no dead air spaces or standing water. Before delivery of wood, building must be closed in with heating/air conditioning running to control temperature and humidity at occupancy levels. Wood needs to be broken up into small lots and stored in rooms where it will be installed. Allow several days for wood to acclimate to temperature and humidity levels of the home before installation. This is very important as wood is kiln dried to very low moisture levels. Failure to follow installation safeguards may result in failure of the wood to perform properly.