You haven't mentioned what type of wood it is and where in the building it will be used. If it's a sill that's one thing, if it's a post that's another and if it's a rafter that's a third place. As a sill, it might be ok without spiking. As a rafter, I wouldn't use it there. As a post, it might be ok depending on how many mortises and the placement of them. If the shake goes thru to both ends than I wouldn't use it for a post. Hopefully you'll get some more advice from this forum. Good Luck.