New steel post in wet basement – loadbearing moisture break to prevent re-rusting
Hi…. I am about to set two replacement steel support posts in my wet basement, and I want to keep the new ones from rusting out too..
The footings will be level with the rough finished floor, except for a circular pedestal 2″ high (12″ diamater) built into each footing’s form. The purpose of the extra little step-up is to raise the steel base plate up off the flooor, which sometimes floods with a wide shallow sheet of water flowiing to a drain in the corner. Yeah I know…. we oughta install a drain around the inside of the foundation and add a sump. The way real estate is around here, we ain’t gonna do that. Outside grading etc has cut down the flooding but its not completely eliminated. So we gotta take care of our new steel posts and their baseplates without too much additional moola. Is there a loadbearing moisture break we can put on top of the pedestal before setting the new posts? We’ll be using PVC-coated L-shaped concrete anchors when I pour the footings. They’re holding up a 2 1/2 story four-square in snow country, nothing too fancy.. Thanks
Replies
Galvanize
I'd have the posts galvanized, or at least apply a bunch of galvalume.
Intermittent water submersion isn't that damaging. It is usually trapped water that causes problems.
Be sure to drill at least a couple of 1/4-inch holes, top and bottom, so any moisture that does get in the pole has an escape route.
I have seen UHMW Polyethylene used as bearing pads for bridge memebers, because it is smooth and hydrophobic. That was years ago, and I'm not sure they are still doing it.
You might be able to go "off lable" with some of the footing assemblies that Simpson makes for wooden posts.
I think if it were me, I would oversize the anchor bolts to give me about twice the area of steel that the column has, and double the thickness of the column base plate, then mount the column above some phenolic washers to provide an air gap.
Thanks for the input!
For most stuff I need to separate from concrete (like untreated plates or other wood contact) I use a width of Ice and Water shield, but for higher psi situations like yours I'd probably brush on a good layer of epoxy to both surfaces. If you're sold on the idea of some kind of spacer or whatnot, I'd use piece of thin stainless sheet the same shape as your base - proabably cost less than $10, but can be a pain to drill larger size holes like you need for the j-bolts unless you have bits that play well with stainless. You might be as well off with a sheet of galvanized steel, but it would have to have a good thick coat of zinc, not some electroplated cheap flashing.
Good ideas, thanks!