Hello Breaktime
This is my first posting. Thanks for having this forum and thanks in advance for any help, comments, or heckling. I have a moisture problem in my basement and would like to know if anyone has a recommendation for waterproofing a concrete slab and the seam between the slab and the brick wall that was used as a form when they poured it. There are many more details below in case you are interested and have questions that might aid your analysis of the situation and a possible resolution. Thats the basic problem and if you do make it to the end of this post, thank you for your patience and perseverence in reading my aimless rambling.
I have a “raised” basement (slab on grade) home in New Orleans (approximately 100 years old). My house survived okay during and after Katrina, but I have either seepage from hydrostatic pressure or condensation on the slab under my laminate (3mm bamboo on plywood with aluminum oxide coating) glueless, floating floor. I used a dimpled plastic sheet (56′ X 5′ strips) as underlayment. The underlayment protected the floor as advertised, but my concern is the moisture and humidity caused by the water under the underlayment.
Let me describe the disaster that is the construction of the foundation. I’m not sure that it was ever intended to be living space, but that’s another story. It appears that a concrete footer was poured that extends about 8″ outside the wall on both sides and the back of the house. On top of this footer they built a brick wall three bricks high, end-to-end. On top of the bricks, they used 4X6 sills (sitting right on top of the bricks) as the base of the wall with the studs nailed to that sill.
Half of the interior walls are brick from the footer to the rafters supporting the upstairs with a thicker section to support the brick fireplace and chimney above. The rest of the walls were either made of 2X4s or barge board.
I don’t believe that any visqueen was put down before the slab was poured. Also, I think that the slab was poured in several thin layers (1-3″) over the years. The left side of the house has a relatively smooth finish to the concrete as well as the front room on the right side. They used the brick walls, sheetrock, and barge board as the forms when they poured the slab. I found sections of barge board and 2X4s in contact with the dirt under the slab. (This was the welcome mat for the termites that caused a significant amount of damage that I discovered and corrected as well as I could with new 2X12 pressure-treated joists). I
I think that I may have hydro pressure coming up through the seams between the different sections of slab and also through the seams where the brick meets the slab.
When I returned to my house last month after about six months away, I discovered that the slab was wet under the underlayment. I have pulled up all 400 sq ft of flooring. I also discovered that the mortar (I am guessing lime and sand mortar) seemed to be crumbling at the bottom of the brick wall in several places. I can easily remove the mortar above and below the level of the slab because it is so loose.
(I also have what appear to be cone-shaped burrow holes into the mortar. If anyone can take a stab at what that might be. The terminix guy had no idea and said he would ask his manager. He didn’t ask his manager and when I called, the manager had no interest in coming out to look. Leaves me wondering what it is I pay them for.)
Another piece of the puzzle is that my rain gutters on that side of the house are somewhat dilapidated and in need of repair. I have only one downspout on each side of the house, but each downspout goes into an underground drain. On that side of the house, the water stands up against the short exterior brick wall. But the water appears to be coming in near the interior brick wall.
In order to correct this problem, these are the things that I have already done:
1. removed the brick chain wall at the back of the house and replaced with a concrete chain wall
2. replaced 25′ of rotten 4X6 sill that was sitting on top of the brick wall on each side of the house
3. removed all of the dirt up against the brick wall on both sides of the house and painted waterproofing on the exterior of the brick wall
4. poured self-leveling concrete on the slab to prepare for the flooring
5. painted drylok waterproofing on the inside of the exterior brick wall
6. I used the same flooring in the rec room and attempted to seal the cracked floor with self-leveling concrete topped with Redgard. I don’t have any indication of problems back there.
Things that I intend to do:
1. replace the gutter system adding two downspouts on each side of the house with all tied into the underground drainage
2. repoint the interior brick wall with type “N” concrete (Fun, fun job)
And finally, (if you’re reading this, thanks for sticking with me) my questions:
1. Is there a waterproofing agent that I can apply to the floor and brick (part of the brick has already been painted with latex paint) that will stop any water intrusion and if so, do you have any recommendations?
2. Can I use type “N” mortar to repoint the brick wall below the slab or should I use something else?
3. Should I abandon my laminate flooring given the situation in my basement?
Thanks again for taking the time to consider my situation.
Mule
Replies
Well...
I would abandon the laminate flooring for something like this.
I believe that the source of the water problem is hydrostatic pressure, esp given you r location.
That means that you have water in the soil under the slab that is welling up from higher mearby ground water table. Water seeks its own level.
A common way of dealing with this sort of thing is going to upset you after having already poured more float over the old in #4 of your solutions donme so far. It is to run a grid of drain pipe under the slab leading to a sump pit where it is pumped out, or to daylight so gravity can handle it. You would need to remove the slab and dig drain tile into the soil, making sure that it is gravel type soil and not clay.
Then plastic and a new slab.
I suspect that you also have problems with your exterior perimeter drainage. We don't know where the water goes from your downspouts. The drops lead into the ground, but whether they are still clean and open leading away from the foundation or not is an open question. There are even ignorant builders who lead drains into the perimeter drain and introduce water instead of carrying it away. Some plumbning companies have cameras they can send into pipes to check it out. There might be other high tech gear too that I am ignorant of...
Being a mountain boy, my advice would be to move to higher ground!
;)
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mule.. i live on an island with high water tables.
i build homes with dry basements
i would concur with every word that piffen wroteMike Smith Rhode Island : Design / Build / Repair / Restore
Is sea level getting higher down your way too?
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I guess I'm a glutton for punishment.
If you don't mind, I'd like to pick your brain just a bit further. I had the slab exposed for several months last year before I put the floor down and I removed the floor over a month ago. With the slab exposed, I have never seen any water or moisture on the floor. It seemed to only be a problem with the plastic barrier down. The barrier has dimples which (in theory) create an air space that allows the moisture to mix with the ambient air and evaporate. Maybe it is not allowing that to happen.
With regard to higher ground, I am with you 100%, but I'm in the military and I go where I'm told. However, the area I live in is about 12' above sea level (which isn't much except that around here that IS higher ground). The river levee is about a quarter mile away and that would be the only place that I could really have hydro pressure coming from. Otherwise, it is almost completely flat or sloping away for the area within a mile of my house.
I can't remove the slab and put in drains and visqueen so I am somewhat stuck with trying to waterproof the slab from inside the house. Also, I have about 800 sq ft of the same stuff in a bigger room at the back of the house and have no signs of moisture or damage to the floor.
So, given this extra info, would you stick with your initial rec of ditching the laminate? (I'm guessing probably so.)
But, if I chose to march on with the laminate, do you have a recomendation for a waterproofing product to put on the slab?
And, laminate or not, I need to repoint the interior brick wall. The lime and sand mortar is not so good no more. I can easily dig it out below the slab. Do you have a recommendation for a product to use below the slab to replace that mortar? I have type N with sand, but I thought maybe I should use an acrylic crack sealer that might work better against any water intrusion there. The type N has a waterproofing agent in the mix, but I don't know if there is a more effective product I could use. thanks again for your help and consideration.
mule
I call my mason for pointing jobsFor the flooring - and understand that i am not there studying it - I would use pavers for a finish flooor.
if the plastic laminate is what I think, the bubbles are there to let moisture derain away and keep the top surface from wicking water into it by direct contact. I doubt it would ever allow enough air to "dry" it out.
By using a masonry finsh like the pavers, the ground moiusture could be able to evaporate thru it, and you would have a finished floor that would not rot. There is a reason why masonry materials were so common in humid Mediteranean climates
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thanks for the help.
mule
A couple of these, strategically placed outside the house with outlets down slope should take the water table down.
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Troy Sprout
Square, Level & Plumb Renovations
Edited 3/11/2006 11:31 am by Hackinatit
thanks Hackinatit