Hi Mark,

I am not that keen on your suggestion to use Portland cement in connection with laying stone walls. Portland cement cures to form an impervious unyielding layer that traps water and can result in freeze / thaw movement damage plus if a timber frame stands on top of this it will cause rapid rot to any contact surfaces. If you need to use mortar then this should be simple lime mortar which will absorb / transmit / re emit water and will yield to slight movement and then re seal itself by water calcium carbonate soluable action. The old ways are the best.

Regards

Ken Hume

Looking back to see the way ahead !