Water under deck

[Randy Rizzo]

Have a water problem under a deck. the area under the deck is another deck and a concrete retaining wall (see photo) The problem is water coming thru the upper deck collects in the area behind the retaining wall. In spite of a centrally located drain, footing drains, water that had saturated the soil behind the retaining wall froze and cracked the wall. We dug out all the soil behind the wall to the end of the window and replaced it with 1" gravel thinking the water would filter down to the footing drain. We replaced the broken cultured stone. Worked OK for about a year. This year it cracked again. I think there's two problems here. The first would be to eliminate the source of the problem, water. Have any of you used any of the various systems for collecting runoff from an upper deck, built one of your own. the second problem I see is the wall itself. Once cracked, I assume it will always be weak and subject to cracking any future replaced cultured stone. Methinks the concrete boys skimped on the rebar. Anyone ever reinforced a wall like this with angle iron, sheet steel, ?

[JohnT Fitzgerald]

Randy - I don't know what you can do to reinforce the wall after it's built, but you can try to improve the drainage. You need to drain not just the surface water falling from the deck, but also all the water that's in the earth behind the wall. You need to have gravel or sand begind the wall all the way down to the base, and then some sort of drains at the base (running along the wall, or through the wall onto the area just below it).

[Tom Godley]

Are you sure that the wall cracked because of the water? Sometimes they just settle and crack or they just crack :(

On my areas like this I have found that the surface drains that stick up above the surface work best for me.

I have also used products from Abatron to fix a variety of concrete problems - including an old concrete pool. They make a product to retrofit reinforcement in a crack - not cheap but the stuff works!

[Randy Rizzo]

Tom, I'm pretty sure water is the problem. Like I stated in the original post we removed all the dirt fill out to the end of the window right down to the drain tile and replaced it with 1" stone. When we were removing the original backfill it was just muck, the dirt was saturated with water. I though for sure the stone fill would allow water free flow to the footing tile. The photos don't show the stone fill because we added a couple inches of topsoil thinking we'd plant a shade ground cover. I want to eliminate the egress of water into the area from the overhead deck. I've seen several systems on the net that fit between the joists to funnel the water to a gutter making the area under the overhead deck dry. Just wondered if anyone has used any of these systems.

As for reinforcing the wall, I thought about bolting a 3 or 4" piece of angle iron, about 6' long to span the crack horizontally. I'll do some research on the product you mentioned though, thanks!

[Alan Lilly]

Here is my solution for capturing water. I think you might still have a problem because rain could come in from the side.

http://panofish.net/building-a-shed-under-a-deck/

[Brian Effinger]

Methinks the concrete boys skimped on the rebar.
That is definitely a possibility. Is the wall poured concrete, or concrete block? Also, are you sure that the footer is below the frost line for your area? It could be heaving just enough for the veneer to crack off.

[Frank Hill]

Wow, a non wood working question that I have a bit experience in.

If this were my problem, first I would identify the source of the offending water. If it is coming off the roof line, install gutters and downspouts. At the bottom of the downspout, install a transition, then flex pipe to this, run it underground away and below the trouble area and then install a surface drain. It will act in reverse fashion and let water out.

If the water is drainage from a higher area, install a french drain above the trouble area. French drains drain the area below the pipe by catching the water above it and diverting it from the lower area. One may not be enough. Also french drains are something I like to install unless I can personally supervise several different parts of the installation. There should be adequate rough stone above and below the pipe however the stone below the pipe must have a grade away from the area being drained. This is where I get involved. It doesn't take a transit and level to figure out if the grade is going the right way. Just a very long piece of clear flexible tubing, colored water and two stakes. If I can't personally check the grade with my little contraption, the contractor has to wait until I do. After the pipe is covered with rock, the rock should be covered with rolled roofing. Not straw, newspaper, cardboard or anything else. After that they can backfill.

It is always easier to deal with the water before it hits a problem area and then have to deal with it.

Now about your drains and grade. If surface water is still ponding then your overall grade is not uniformly to the drain. In my opinion if it were my job, I would have installed at least 3 if not 4 surface collection drains.
Where is the discharge? Pour some dyed water down the central drain and see if it comes out the discharge and also check for quantity of discharge. It won't won't be the same as you poured in but it should be reasonably close. If what comes out is grossly different than what you put in, your grades are running backwards or you have a belly in the pipe. A very common problem when the job is eyeballed.

If you dug out this area down to the drainage line and it was all muck (as in water dripping muck) then I suspect you have either a grade problem or a clogged line(s) or probably both since a poor grade increases the likelihood of a clogged line.

If you suspect that your drains are clogged and have a good pressure sprayer or no someone that does, you can purchase a jet fitting and run it up from the discharge end. This jet fitting will have one nozzle opening to the front and three side ones and because of the angle of the side jets, it will help pull itslef down the pipe. Don't play around with it as it will slice flesh (Been there done that and had stitches)

If all else fails and you dig it again in addition to the drainagel lines, dig a drywell with a vertical pvc pipe large enough to accommodate a sump pump. Lower the sump pump into the drywell via the pvc and make sure the discharge is away from and below the area.

Finally the hydraulic pressure of freezing water is immense. That's how our pioneers split those boulders in their farm fields to manageable size.

[Mac McQuinn]

If you want to investigate the concrete for this project, Try Design & Control of Concrete Mixtures by Portland Cement Association. Great book written in easy to understand terms with more info about concrete, admixtures, techniques, than you thought were possible.

Mac

[Lee Schierer]

As Frank pointed out, your problem is water. You need to identify where it is coming from and if you can't eliminate the source, then give it a path to follow that doesn't let it accumulate. Putting soil over the gravel in a french drain will fail in short order if you don't put down a geo-tex fabric to stop the migration of the soil into the gravel. Heavy duty professional landscape cloth works well for this, much better than felt paper as it will let the water through but not the soil.

I redid a french drain on a basement wall because the wall had been pushed in by the hydrostatic pressure. I had to support part of the house, tear down the wall, fix the drain slope, rebuild the wall and back fill the space with gravel within a few inches of the top. The wall had been rebuilt by the previous owner twice in 10 years. It's been 25 years since I rebuilt it properly and there isn't a crack in the wall. When it rains, the water starts coming out the french drain within minutes of a substantial shower.

[Josiah Bartlett]

I collect the rain water off the underside of my deck using plastic corrugated roofing. I installed spacers hanging from the bottom of the joists to slope the roofing toward a gutter mounted to one of the joists, which goes to a downspout that carries the water away to my rain barrels. The roofing is screwed through the peaks to the spacers. Its really just an upside down corrugated roof, and it works great. It is also inexpensive. I had 3 feet of snow on that deck last year and it didn't bother it a bit. Just make sure to leave some air space so that the deck joists are sitting in standing water.

My neighbor liked my idea so much she copied me.

[Randy Rizzo]

Thanks to all who responded. Some of the suggestions were already implemented. We put up gutters on downspouts once the logs had settled close to their final shrinkage. We do have drain tile at the base of the foundation and last year I drilled a few more weep holes. I'm pretty sure we have the footings deep enough. There is a miror image of the wall on the other side of the building and it's fine. The only difference is that area is covered by a shed roof over the deck above so any rain water does not tend to collect there. As most all have stated I think the egress of water from the deck above is the culprit. I just need to find a solution to directing water away. There have been a few solutions posted and a couple bear looking into.

[Doug Carpenter]

There are only two kinds of concrete....cracked and the kind that is going to crack.

I have concrete countertops in my house. when researching concrete I learned that there are something like 208 variables in a stanard mix design. It is difficult to contol all of them and all you need is one wrong and the concrete will crack.

If we are talking about poured walls and the crack hasn't shifted. You can use a polyurathane expanding foam product that will fill and seal the crack. It reacts with water so you install it when it is wet.

If the crack is tight it probrably isn't going anywhere....as long as you can stop water from getting into it. when it is full of water it will do damage as it freezes and thaws.

Rebar and wire don't prevent cracks per say. They do prevent shifting. and add strength. so the question becomes is it a normal crack or one caused by structural failure. since you have the water issue my money is on the normal crack. so with out seeing it I would say that reinforcement isn't what is need here.

If it is a block wall then all bets are off and some of it may need to be redone.

I think your water proofing efforts seem reasonable. If you are sure the water isn't from a leaky wall above or what ever. You can install a product to the underside of the deck above. It is used so that one can sit on a patio or deck that is directly under a deck above when it is raining. It looks like soffit material that will allow water to run out to the end of the deck anf into a drainage system. perhaps something like that would keep the water out away from the retaining wall. I still feel like your existing system should be able to handle the water but if the wall is cracked water will always take the easy route.

I think the combination of the crack filler (which can be done from inside so you don't have to dig it up again.) and the material under the deck to shed the water should help you problem.

If you have any questions feel free to conatct me. If I have misunderstood your situation I would gladly review more pictures and talk on the phone to help you solve your problem.

good luck, Doug

[Randy Rizzo]

Thanks Doug. It is a poured wall, 10" This is a shot of the footings before walls were poured. Looking at it now I woulda put in a lot more rebar.

[Doug Carpenter]

So the wall that is cracked is the retaining wall? Or are you just showing an example of their typical rebar installation.

[Randy Rizzo]

Doug, here's a better shot after the wall was poured. All the fill in the photo was removed down to the base of the perf pipe and re-filled with 1" stone. We did not seal the crack and probably should have. The perf pipe is pitched toward the hole in the wall. When we got done filling with stone we added a couple of inches of soil on top thinking we plant a ground cover. That may have contributed to the the problem. I plan on removing that and just leaving a decorative stone cover.

[Doug Carpenter]

Sorry Randy I thought you were having a problem inside the houe because of the water. Course if you do nothing you will have a problem inside the house.

I don't think you need to fill that crack with the product I mentioned. I suppose it can.t hurt but the product is costly. I guess if it keeps water from doing any more damage then it would be worth it. Is the side that is closest to the house still covered with decorative stone?

If not there is a super thick Ice Gaurd like membrane you could put on the whole wall to keep the backfilled portion from asbsorbing any moisture. We use it for insulated concrete forms for water proofing the wall before backfilling. I think it is called Miraflex. You could also use the roll on kind as well. Treat it like it was a wood planter so it holds the water like a bathtub.Then I think having the entire area woul benefit from the entire back fill being stone so you are sure there is no place for water to collect.

If the wall is covered with deorative stone then I suppose your best defense is the stone backfill and being sure the pipe is clear.

I assume the pipe is clear of any obstructions.

Doug