Slight water wicking through clay. Any concern?

[zissou]

Recently had my pole building put up (40x60x16) and have been getting the drainage sorted before pouring concrete. It's come a long way already. We have some slope away from the building on all sides, it has gutters that I just buried and dumped well away from the building. Gutters were a massive help. However I still get a little bit of water wicking in through the clay after heavy rain. It's mainly from rain that hits the building and falls straight down on the backside of the shop.

Pictures after a rainstorm attached. Nothing dramatic, its gotten so much better as I've worked on drainage and grading. Am I worrying too much considering there is still 3/4" crushed rock to go on the pad + concrete? This would just be a little bit of moisture getting under the pad on one side. Other than this, it's been completely dry inside which is good considering its just a dirt floor and we get a lot of rain this time of year.

The other day I put some river rock I had sitting around on the backside for some backfill (as pictured) to bring it up to the metal and it sort of helped. Should I replace the river rock with crushed rock and compact it? I am going to bring in more rock for the backfill (its only about 1' off the building right now, planning to get it to 2-3').

 

[zissou]

Photos attached.

 

[zissou]

Original attachments were too big and wouldn't load. Fixed now.

 

[Youngandfree]

There's a reason people put vapor barrier down under a slab.

 

[rburke65]

And there’s a reason you’d usually have a water diversion plan BEFORE you start building!

 

[ConCretin]

I wouldn't be too concerned about it. Keep working on your perimeter drainage but if a little water seeps under your slab, it will be fine.

This isn't a reason to install a vapor barrier. While it's true that higher moisture levels under a slab could potentially increase water vapor transmission through the slab, this is only a problem if you intend to coat the slab with an adhered covering such as epoxy. If you intend to do so, you'd want a vapor barrier regardless of whether a little water was seeping in.

Take a look at my Guide to Floor Slabs in the link below for some additional thiughts on placing your slab. Good luck with the rest of your project. Looks great so far.

 

[Hank11]

Its a tall building and a lot of water will run down the sides. A much wider overhang would have helped some. But that’s a lot of wall area to drain.

 

[tarmy]

Around here clay swells when is get wet…not sure about where you are. I would look into a turn down edge of some sort to get that to stay dry. If you are really worried about heave or water intrusion a small subdrain or rock trough drain edge below the wall area would solve that issue.

 

[pcmeiners]

"this is only a problem if you intend to coat the slab with an adhered covering such as epoxy."

It is also an issue as condensation is an issue for metal tools rusting.

 

[MovingAlong]

I am going to bring in more rock for the backfill (its only about 1' off the building right now, planning to get it to 2-3').

If that were a basement, I'd be looking at drain tile... seems the principles and goals are same here. Before adding more rock around the outside, might consider putting a run of drain tile in/under the rock.

 

[BombShelter]

It looks like you need a larger gutter system, is the water coming in near the downspouts? I feel like you need at least one more downspout maybe two? There should be some online calculators to figure it out.

I'm never a fan of building up the grade unless you have outside water pooling, then fill in the low spots so you have a nice slope away but don't overdo it, 2-3' seems excessive. I tell a lot of people to take down the grade, dirt holds water. Code is 6" of separation from the framing to the grade, I don't know how they calculate it in your situation since since there's no slab or continous footing.

Great looking shop, I need one of those.

 

[pcmeiners]

"I am going to bring in more rock for the backfill (its only about 1' off the building right now, planning"

If you do that the gravel will do nothing to alleviate ANY moisture issue, unless your gravel absorbs water . Aside from gutters and increasing grading slope, the only other remedy is to buy powdered bentonite clay and spread it out 3-4 feet from the foundation at a minimum depth of a 1/2".

For the best moisture control concentrate your efforts at the slab level......

Add thick plastic sheeting to your slab base before you pour. Pounds of water permeate concrete every day if you do not use sheeting ( or additives) to control it, adding to moisture/condensation issues. Particularly with plastic sheeting, maintain a wet surface on the poured concrete for as long as practical up to 28 days, most importantly for the first full week.

 

[bb29510]

is it a concern ........ yes, if its a swelling clay like a yazoo clay. it will pick up the bldg and crack the slab, big time, sometimes three four inches

 

[Copymutt]

is it a concern ........ yes, if its a swelling clay like a yazoo clay. it will pick up the bldg and crack the slab, big time, sometimes three four inches

Both horizontally & vertically. Been there, done that. Replaced the slab through a living room window.