Felt paper has been around the block and is probably the most cost effective barrier. I would check with your building department to see what they require. Around here they require the corrugated house wrap or the felt. Check also with the supplier of the stucco. Your warranty of the product will probably be effected by the wrap. I like the elastomeric Sto stucco and they recommend a paintlike barrier.

We've had hundred of customer aplly stucco to our SIP's (including my own home). felt paper works fine. The other products generally fall under the category of 'vapor barriers' and will do the same job just fine too. Remember, your stucco is not adhearing to this layer anyway, but to the foam and chicken wire.

Craig Boydell

KC Panels

www.kcpanels.com

Talk with your panel rep on stucco applications also. Some manufacturers will only continue warranty if specific brands or approved installers are used.
Also double check your moisture levels before applying.
I've heard nightmares of tearing down or repairing the stucco because of a 'poor install' or applying during higher moisture levels.