Free Draining Stone Retaining Wall?

[AA52AA]

I've seen many, what are supposedly (or started out as) dry stone retaining walls have mortar added to keep poorly laid stones from falling out. At what point is a dry stone wall no longer considered to be free draining when mortar is added?

 

[youngstructural]

I would say that it would be at the point at which a design level event flow of water would be impeded (ie: no longer flow freely through the wall) and build a surcharge pressure head behind the wall; However I will add a caveat that I have never seen a guideline on the issue, and have just given it a few minutes rational thought.

I'd be curious to hear how you choose to proceed.

Regards,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...