OK, so I'm  interested in knowing what in the bejessuz you guys are talking about.

 When did concrete become a "wick" ?
 Or a "sponge" ?
 Or a "straw" ?

No offence intended, but I havn't seen any legitimate"building science" on this.

Got any?

I forgot to include LINK. Joe Lstiburek, Ph.D., P.Eng., has made a career out of studying the science of residential structures. He is highly regarded by many in the residential building industry.

For everything except ICF's btw guys, Joe is good with wood frame, however not so good with ICF's. He thinks they are a joke. He is the reason I got into building science, instead of architecture, I totally agree with his wood frame philosophies, however he has a very narrow mind, which is not so good.

Mark Ross

Interesting you should say that. His book, "Builder's Guide to Cold Climates" has, what I have always thought anyway, pretty good chapters for both ICF and SIP construction. Anyway, with regard to this thread subject, he illustrates capillary breaks in all footing to foundation configurations, not just ICF.

dmaceld,

The first quote about ground salts moving upward thru a 4000 psi floor mix would be a very rare occurrance indeed.Most slabs on grade are placed on elevated crushed gravel beds, above surrounding water tables.

In 25 yrs or so of concrete works, I haven't seen this occur. However, I have seen efflorescence in foundation walls above grade that are are batched with "hard water" and are subjected to many freeze thaws and severe weather. I would say the dew point within the wall moves, depending on the season.

Your second quote references masonry units and mortar, which in my humble opinion are highly porous.

I've poured many footings on "waterfront" lots ( high water tables) and haven't see any evidence of water wicking or siphoning upwards.

I'm not convinced at all.

Guys,

This is something I found. I believe it supports when Ben was doing...


LINK

Leonard

Bump.

Thanks Leonard, I can't get your link to work however, I was sent another link to fastfabric , or somesuch.

Nobody else stepped up to confirm the reality of capillary action...probably because it is a non starter.

To me this capillary thingie is really a "marketing ploy" creating a "need" to convince us to buy yet another useless product.

My rant..... Foundation drainage is critical to  the success of basement comfort and livability.
Properly installed weepers, air gap system, mechanical pumping capacity, underfloor rigid insulation,
and 6 mil poly, will go a lot further than trying to wrap a footing in fabric.
LOL.

Eric,

I will try this link to be clickable.  Works on my browser....

 

LINK

Leonard

Thanks Leonard. The link works.Anonymous author though :-)
The first pointer is laughable, placing poly between the footing and wall LOL.
However, the rest are what I would call good building practices. Thanks again.

Eric, are you disputing the idea of water wicking up through concrete, or arguing that concrete doesn't absorb/hold/pass moisture?

I do believe that most everyone would agree with your comment about foundation drainage, except maybe the part about "go a lot further".

Hope this link works.

http://www.heritage.nsw.gov.au/docs/maintenance2-1_risingdamp.pdf

.5mil poly sheeting is the modern common practice according to these guys/gals.....
The authors are listed at the bottom of the page.

Kevin

dmaceld:

Do you endorse wrapping footings with fabric to combat rising damp? 

I can't see the practicality, and I think it could be very difficult to do in a high water table situation.

A proper detailing of your drainage system and underfloor poly suits me fine. As noted above.

 I believe that we are sometimes victims of the marketing world,who create a need and hype for something, 
  that is essentially garbage. Sorry I repeat myself.

Boards like this are a perfect place to plant "marketing seeds" LOL.

I haven't decided yet! I had a conversation yesterday with my civil engineer cousin Ralph, who has spent 40+ years in concrete related construction projects of all sorts. He states unequivocally with no reservation whatever that concrete is permeable to water. He said he would take any doubters underneath a highway bridge and show them the wet underside of the concrete deck. Where there are cracks road salts will effloresce. Concrete, even with no cracks, is not waterproof. It's imperative to place a water barrier on the outside of basement walls, to keep ground water from permeating through the concrete.

Ralph said a concrete block is like a sponge, put the bottom edge in contact with water and eventually the entire sponge is soaked. Concrete will absorb and wick water.


That is the real rub. Ralph argues that poly sheet under any concrete is of little value. He said buildings move, concrete slabs move, and footings move. In time the poly gets ground away. He claimed a large industrial building he designed, and over saw construction of, had a poly sheet under the floor slab. Three years later when they cut a hole to install a machinery foundation there was no evidence the poly had ever been there! In fact Ralph maintains that even in crawl spaces a person is better off to not use a vapor barrier and have full time forced ventilation. Let the moisture come up through the ground and carry it away. Cuts down the probability of rot and mold. I'm not sure I'm ready to adopt that approach. I am considering using heavier than 6 mil poly just for durability, and sealing all the joints. In addition I'm thinking of installing a passive ventilation system under the poly to carry water vapor and soil gases out. Are soil gases present? I don't know, but after the house if built is a bad time to find out there is and then add the vent system.

The IRC does not require decay resistant wood in contact with concrete if the concrete is not in a wet location or if the wood will be more than 8" above the ground. So, how far does water move through concrete? I don't know.

As for me, I'm probably mostly inclined to say capillary action is real, footings and stem walls will have moisture moving through them, it's best to restrain that moisture from traveling freely through the crawl space, and carry it away with drains and vents. I definitely will have the ground vapor barrier go over all the footings, both exterior wall and pony wall, and at the very minimum, bring it up the inside of the crawl space wall 6" or so. I'm doing sealed and conditioned crawl space. Whatever water moves through the footing and into the ICF wall concrete will evaporate into the crawl space. I'm in a low humidity area so that vapor load from the walls probably won't be enough to worry about. On the other hand, I may smear an emulsified asphalt coating on the footing before I build the ICF wall on it.

As you say, a high water table area is the most difficult to work with, but that's also the case where water moving through the concrete into the basement or crawl space is mostly to occur and present the greater problem.

The big problem, in my opinion, is we have a situation here, water moving through concrete, but we don't have hard data that clearly characterizes that situation as a problem.

Now that's what I call a high quality response :-) Thank-you.
What I take away is still where I'm at. Fast fabric is fast money...for the manufacturer. Usefulness is doubtful.
Saturated concrete will allow moisture travel. Horizontally some...vertically..haven't seen it. hope I never do.
Control the water by dewatering systems and you elimininate a source of potential problems.

Eric, right or wrong I think this is a very debatable subject. I know if you take a tub with 2" of water and stand a CMU in the water it doesn't take long to wick. The main reason for Fab Form in my opinion would be to eliminate the need for footing forms and use 2x4 that can be used as roof truss bracing, or numerous other applications, and eliminate a concrete covered footing form that may have no application in a future home. At this point you are eliminating the potential for wicking. I understand if you wrap a CMU with fab and put it in a tub and it remains dry. Yes we sell this product but I'm not asking anyone to buy it from me, just trying to help point the way for future ICF growth.

Dave

Dave : Fabric forms have their place for sure..as forms :-)

And yes this is a very debatable subject , and I'm encouraged by the thought put into responses.

I'd like to kill off the CMU example tho, as most of us on this board pour concrete within ICF cores, and the focus of this discussion should be on that.

So guys the take away message is.....

Form-a-drain for the footers. Air gap membrane sheathing to cover the exterior wall (Dalta Platoon, ?sp). Key the footers for extra stability, apply spray on or brushed on waterproofing product, build the ICF and pour. Heavy poly (>6mil) for under the basement slab with rigid foam insulation. What do you all think?

Leonard

A few questions (for this scenario, of high water table):
1. How will act the ICF that is underground, with the presence of high water table? Maybe is better to have only concrete walls bellow grade and ICF above grade?
2. Will you consider the alternative of not using footings at all? For example Legalett has an engineered slab on grade that doesn't require footings. So water is no longer an issue. ( LINK)

Thanks!

Leonard:

Not sure formadrain is all its cracked up to be.

One problem with formadrain is that most suppliers carry the 8 inch. Now, 10 inch is available but not widely stocked, (also the 10 inch is thinner in width.)
So with a 12" inch thick footer, (pretty standard for our residential work) in effect one is soaking several inches at the bottom of the footer long term, with the water unable to be carried away. We see this practice as counterproductive. We have seen properly waterproofed basements without a cappillary break in the footing grow mossy mildew type growth on the interior lower portion of basement walls.
And so when we used formadrain, we still installed another perforated weeper around the perimiter to carry the water from below the bottom of the formadrain.
Also, because of the internal structure of formadrain and the thin width we see more possibility for silting and obstructions causing failure easier than conventional drainage tiles. Maybe we are incorrect, but for our protocols we have switched to use fabric forms and double perforated tiles for best results for our consumers.

Kevin