Water inside house :-(

[ga-hvac-tech]

Something I thought of the other day...

Along that wall where the windows are at grade level... when you slope the dirt away from the house... might add a few drains in the valley of the slope... with 6" pipe... to drain the water rolling down the hill.

The goal is to keep the water away from the house... and the little that does get there: both the waterproofing of the concrete and the french drain will keep it out.

Yeah... lots of work... however when it is over... the only biological growth in the house, will be your family... grin!

[Answer-Man]

I'm not a code freek, but the code books have a lot of handy information in them like: how to size these drains. The materials allowed, soil absorbtion rates, worst rain fall rates by city, how they are to be built, drain capacity tables. The "Book" can be used to verify the design you are thinking of using

[queequeg152]

thats not really true. but i guess it depends on your definition of porous.

is concrete like glass? no. but its not like sand either.

the problem with most concrete flatwork and concrete walls is that its not intended to hold back water in the first place.

trust me its WAY WAY WAY cheaper to design a concrete wall to just handle the lateral earth loads and put in a drainage system to handle the hydrostatic loads.

look at concrete aeration basins and concrete clarifier basins... concrete CIP lift stations etc. they can be basically waterproof without a coating, its just a matter of quality concrete with the right rebar schedule to prevent shrinkage cracking, right bonding agents... ad mixtures, quality waterstops, quality bentonite plugs, and wet curing etc.
there are concrete basins built way back in the 70's or 80's that are still uncoated from way back when the epa started first cracking down on waste water effluent... they are still going strong because they were engineered correctly to handle water.

look up the ACI 350-06... it detaiils concrete storage excellently.

[Answer-Man]

Queequeg Yes you are a smart man after all you are an electrical engineer and design HVAC support systems, correct?

The wall in question is not a foundation or structual member of the house, it is a retaining wall which happens to be hold quite a bit of water way from the wood wall by the pictures and descriptions posted by the owner.

If you place an untreated wood member up against concrete which has water (in whatever condition you may find it) on the other side, water will migrate and be transferred to the wood member and overtime those untreated wood members will rot and fail that is why the building code requires that all wood memebers that are in contact with concrete or the soil must be treated. In fact wood structures such as this by code must be 6" above the soil grade . This is what I am referring to. If you have an issue with that, your disagreement it is not with me talk to the code organizations.

Yes we use conrete containers everywhere to hold or channel water, slurries or a number of other liqidous materials but that does not mean water will not absorbed into the concrete and can evaporate from the oposite surface. Yes you can improve the conrete for your application by changing the mixtures, adding chemicals to it as it is being mixed. Adding tension members, rebar, troweling, power troweling can further improve the conrete for the application. But that has little bearing to water migrating into the wooden members that are below grade in this house. I have read nothing that Snapple4 plans on removing the 4ft high by 4" thick concrete wall that was poured against the wooden exterior wall of his house.

I have read nothing that indicates how this 4 Ft High by 4" thick retaining wall was built. Just a guess but I think it is pretty fortunate the concrete wall has not cuased the exterior load bearing wall to buckle inward as the house is most likely the supporting structure and keeping the wall from topling. But who knows there may be some purlons (deadmans) running back into the soil to hold the wall up. For being built in the 70" the amount of damage is minimal, just in my opinion.

Just a thought. The problem many engineers have (and I am not saying you do) is when they get to looking at a problem and begin figuring out a solution (because they know materials, tensile, shear and compression strengths, applicable temperatures, corosion and erosion, torque capability, current carring capability, etc... many times forget to look at the codes and standards that apply to the condition or situation to balance their repair to the rules that apply.

I'm not arguing, don't what to fight, nor mean any disrepect but I think you are just slightly of target for the situation

Hope you have a good afternoon

[queequeg152]

oh man, i am NOT an electrical engineer. lol man i barely passed 3rd semester physics which was all... magnetic flux this, and right hand rule that... i am terrible at that stuff. i remember exploding a capacitor in my face during this lab were we were trying to build a super crude diode rectified power supply... if i recall right the diode was just chopping off the bottom of the ac wave form and the capacitor was sort of bridging the gap between the voltage peaks... may have been a resistor in there too idk. i suck at electronics in a serious way.

no im a civil guy, and as all engineers will tell you... we are at the bottom of the respect totem pole. mechanical guys, chemical guys, electrical guys all dump on us lol. within the engineering discipline we are basically the equivelant of a communications major. anyway i dont consider myself smart at all, i just know what i know... ask me anything else and i probably wont have any clue. and i dont take offense at anything you said what so ever because its very true lol.

i understand what you are saying regarding the wall, but i just wanted to chime in regarding the liquid permeability of concrete because its an often cited thing thats just not true. the LIQUID permeability of concrete at normal temps and pressures can actually be in the same ball park as a monolithic granite with the right grain size and water to cement ratio and maby some admixtures.

i was not trying to say that his wall IS water tight or even that it could be water tight. i actually suggested the opposite earlier on in the thread, and i think we actually agree in how the solution should ideally be addressed.

yes, like you were saying concrete does indeed have vapor permeability issues, and the coeffieicnt of vapor permeability is usually a few orders of magnitude lower than for liquids( lower = more flow), so water vapor trapped inside the concrete will indeed slowly dry to the interior if allowed, and when one side of the wall is dryer than the other, you will develop a vapor pressure difference or gradient that will further drive moisture through the wall. this is why i suggested the waterproofing membrane and drainage composite earlier. i agree that a drain will partially address the issue, but again it may not solve it satisfactorily. the wall ideally should isolated from the surrounding soil completely with a vapor impermeable and water impermeable barrier or coating of some sort. as i said earlier though it will cost a grip to do all of this.

and regarding engineers and building codes, with the exception of MEP guys and structural guys, YES i totally agree. when i started out...i once spent hours and hours calculating the aeration requirements for a treatment plant only to find out that the state required X cfm as a function of a very rigid and very conservative calculation. what we are even worse at though... is designing stuff that is impractical, wasteful, or even possible to build. its little things that you have to learn to look for... like welds that are impossible to make in the field, designs that waste huge amounts of steel sheet, speccing bent bars that would require a 10k hydraulic bending machine rental, or speccing products that have like a 6 week lead time etc.

[Answer-Man]

Thanks for clarify I hope your afternoon goes welll

[WAYNE3298]

On a house if the foundation wall is only 4' tall the hydraulic overturning moment is small and is not a factor. Very few house foundation walls are designed to be water proof and as a result the walls do not have enough re-bar to minimize crack size to the point that coatings alone are 100% successful over the entire structure. That doesn't mean they will not work but their effectiveness depends on crack location and size.
This is illustrated clearly if you look at the difference between the design of a standard above ground house foundation and a totally underground house. If you build an underground or earth contact house like a standard foundation all you end up with is a soggy basement and that is just the start of your problems.

[queequeg152]

lol are you sure about that? have you done the math? i admit that i have not...

assuming 100% saturated soils all the way to the top of the wall... and assuming magical cohesive and permeable soil that would contribute 0 lateral earth pressure... you would develop around 2psi gauge pressure at the bottom of the wall. the centroid of that force triangle would be 1/3rd of the way up the wall or 4/3 feet from the top of the footing.

the average pressure over each 1' x4' wide vertical strip of the whole wall is = to (F sub 0elevation+ F sub 4' elevation)/2 *area

F = yh ( where y = specific weight of water in lb/ft3(62.2lb/ft3) , and h = height)

Pave = ( 0 + 62.2lb/ft3 * 4')/2 * ( 1'wide x 4'tall)
pave = 497.6lb/ft2 per 1' wide vertical strip.
let pave ~ 500lb/ft2.

moment at the intersection of the wall and footing = 500lb/ft2 * 4/3ft. = 666.6lbft per unit of wall length.

can a 4 or 6" wall resist that? it would depend on a number of factors, but i would not bet my livelyhood on that considering most of these walls are pissy no. 4 bars in a crappy 1.5" trapazoidal keyway. most of the time they are not even installing bonding agents or water stops... so they act almost as a leaky hinged joint which is why you will always see contractors putting in drainage and overhead joists on the foundation wall before they backfill lol.

[WAYNE3298]

Drainage is very important for several reasons. The hydraulic moment is 1/3 up from the bottom of the wall which on a 4' high wall is a lot less than an 8' wall. Block and rock walls are more vulnerable than concrete but once the weight of the house is on them normally stay put even without re-bar. Shifting earth moves more walls than anything else.
My main point was in support of the statement made here that the concrete walls were not designed to be waterproof. They are better thought of as water resistant but vulnerable to water infiltration mainly due to cracking.
I haven't run calcs on concrete structures in several years and don't care to do it now. That isn't meant in any way negative toward you I just don't have the desire to do it.

[madhat]

If it's a concrete block wall you can carefully cut a hole in one of the blocks above ground. Work two or three pieces of rebar into the wall cavity down to the footer. Pour concrete down inside the wall while wiggling the rebar to get the air bubbbles out. Brace a piece of plywood against the wall and pour concrete in to form the cap, while pushing the plywood against the wall. The Structural Engineer always had us use mixed concrete off a truck or use a mechanical mixer. No pan mixed concrete was allowed. BTW it took three of us to do a good internal pier build.

[WAYNE3298]

A wall mix is good for getting inside block. That works well especially where you put anchor bolts.

[Snaple4]

This topic has made some good conversation.

For clarification, on this specific house, the concrete wall in question is non-load bearing, is poured, is about 4" thick x 4-5' tall x 85' long. The slab has a retaining wall which is cinder block construction but that is on the other side of the house. No known details about construction quality or design.

I am going to pull all the dirt back away from the poured wall this week. I have a few questions. The guy doing it want to use a silicone roofing material (black jack premium) and lay 30lbs felt over it once the second coat becomes tacky. Then we will put the 2" foam against the felt.

I suggested going almost to the top of the wall (leaving enough for either clay or plastic for runoff) with the 3/4 washed gravel. He is suggesting just going up 1-2 feet above the perforated pipe then using regular dirt for the backfill. He said the rock wasn't necessary all the way up and would cost more than needed.

Anyone have any suggestions?

Also, I can't have the 2"foam on the top part of the concrete wall. Will this make a big difference?

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[ga-hvac-tech]

Question on the solution above...

What is the purpose of the foam? Does it actually hold the water out... or does it provide a mechanical barrier to absorb potential physical impact that could damage the coating on the concrete wall?

IMO: The gutters and french drain (and possibly a yard drain) are the major thing.
Having said that... given how much work it is to dig out the wall... I would NOT go cheap on the wall once it is dug out...

[Snaple4]

The foam is for insulating mainly. Help with preventing condensation on the inside of the wall. It also provides a protection for the water proofing.

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[queequeg152]

2" closed high density closed cell spray foam is a very very good vapor barrier, but its not proven to last more than 10 or maby 15 years.

if you go on the building science website you will see advocates of this technique touting it as both good insulation, and as very good vapor/ water barrier. however even they admit its only been done in the last 10-15 years. the oldest installations appear to be doing fine though, they foam just discolors from soil contact.

if you want to spend more for the foam, thats fine. its probably the best of both worlds, but just be aware that its going to require prep work and its not like... age old tried and tested? does that make sense?

foam kits are about a dollar a board foot... so take your total wall area and multiply it by 2, and that is what it will cost in foam kits... i think you will find that its not economical to do with kits, you will probably want to hire a contractor as they have access to much cheaper bulk drums of the foam monomer and blowing agent/activator stuff. make absolutly sure its high density CLOSED cell foam not the cheap open cell stuff.

cheap open cell is good for interior walls and especially against a roof deck where you have a hot humid climate... but its going to be close to worthless when in contact with soils.

also investigate one of the many coatings you can spray against the foam. most of these coatings are for extra fire rating... like say to get to a 60 minute wall with the foam exposed. but maby there is a coating geared for water proofing? IDK, but it might be worth looking into.

also regarding your question of only washed stone up a few feet? it depends on your soil.

if your soil water table is very, and remains very high after a heavy rain, then you need stone all the way up the wall to drain off the water against the wall and drop the water table.

if your soil water table is not terribly high after a heavy rain, then stone only a few feet up would be fine. just make sure the stone is wrapped over with geotextile AND make sure you get a proper drainage composite up against the wall to drain off the water above this stone.

if you waterproof all the way up, and put stone all the way up... you could probably omit the drainage composite, but its an extra barrier that could be useful in the long run as your stone collects super fine sediments. your corrugated pipe will also colellect fine sediments too btw, especialy if you have alot of alluvial soils you are excavating through. you should put in a cleanout at the end runs of these pipes so you could gently jet them out in like 10 years or so.

[Snaple4]

Started taking the dirt off the side. They did have some crappy drains put in (guessing 5-8 years ago) but they were clogged. Has a PVC pipe on top of footer but wasn't downhill so not doing much.

No water sealing on concrete wall.

Having to jackhammer the excess concrete to install a pipe next to the footer.

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[queequeg152]

oh wow man. nice work.

i wish i knew how to run an excavator =(.

how is your system shaping up? do yo have it all worked out now?

[Snaple4]

Nope. Actually hired my dad's friends step son to run the machine. Have to wait till tomorrow to finish. Crappy tires and the ground is still wet.

Have to put concrete patch at the bottom of the wall... They poured it on top of some dirt. The old drain pipe ran along the wall and footer but the footer is irregular and where it runs down (goes under the driveway) is higher than the rest of the footer.

Not sure how to handle it. I don't have enough money to have clean rock all the way up the wall so I m going to have to have only rock on the bottom. It is moving along though. Will be nice once all this is done.

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[BBeerme]

Nice !!

[Answer-Man]

Good job!The big thing is you have preserved the houses value, it will improve the inside qaulity. Keep some pictures as proof for if you ever sell the house.