Thor74
New member
Hello,
I'd like some tips on control joint repairs on finished concrete slabs. This situation is analogous to a garage or shed installation, so I figured some members here might have some tips to share.
Here's the backstory. RI experienced tremendous flooding in April of 2010 with record rainfall at that time. Though I am located on high ground, the ground became completely saturated as the water table basically went to ground level.
My 50 y.o.home has a 30x30 ft footprint. It has a completely finished basement which is sunk in approx. 4 ft below ground level, allowing space for windows and light in the basement. About 1/2 of the surface area was living room/man cave, carpeted with particle board underlayment.
As the water table moved up, the water began seeping into the basement. The was no sump or sump pump hole ever cut and no water had ever leaked in from groundwater in 43 years.
With the flooring becoming completely soaked, I ripped out all the layers. Underneath was foam panel insulation tarred onto a rough concrete floor.
After cleaning the original slab up as best I could, there was about 2.5 - 3" of height difference between the main area and the kitchen and bathroom areas. We chose to pour a concrete cap onto the rough slab, and had it installed by an excellent local concrete contractor.
Further, we had the floor stained to a multi-color cola effect and finished. During this process the finisher cut "tile lines" to make it look like approx 2ft x 2ft tiles. One main control line the length of the 15 x 30 ft space was cut in the center and cross control joint cut about every 6 feet or 3 tile spacing.
I then finished the grouting myself with unsanded brown grout as recommended by the finisher. The finished effect was quite nice, and then with a few area rugs, very livable. And should groundwater ever be a problem again, this solution would allow for easy clean up with a shop wet vac. Problem solved. Or so I thought.
Six years later, the control joints have done exactly what they were supposed to do. The slabs expanded and contracted summer and winter and eventually the grouting has come loose in the control joints.
I cleaned the joints out recently and decided that a joint filler that had some elastic properties might be worth trying. Initially I used the basic Brown Dap latex caulk on a test area. The result was unacceptable with gassing out and shrinkage of the caulk. Btw, the grout line is probably close to an inch deep.
Next I tried the premium Dap caulk, Amerflex 230 or something like that. No gassing out, sides adhered to the joint, but the vertical shrinkage was at least 3/8" deep, pretty much requiring it be done twice.
I tried a couple of lines with GE Silicone II brown caulk. One line I did plain. One thing I noticed is that plain, the finished caulk shrinks about 1/4". It's WAY too shiny though.
I had a brainstorm and decided to lay a two foot silicone line and add grout. What I did was filled the line, then scraped the excess off. Then I dusted dry unsanded grout into the top of the line, brushed away the excess and then cleaned it as best I could. Tedious but looked more like the original grout lines.
The plain line I will either cut out or V cut it and put a thin line with dust on it on top. Not sure that is even possible.
Is there some more industrial material available that might be more suitable to provide an elastic and durable seal that is colorable or available in brown? Clear joints would just look horrible.
Any other suggestions? This on has me in trial and error mode, and the shrinkage really doesn't become apparent till the caulk has cured for a few days.
One other issue. This cap was at about the lower end of the thickness limit the contractor was comfortable with. I had no choice really and it's worked out ok so far. Now I notice that one of the "tiles" bounded by 2 control joints evidences a slight "rock" when stepped on. It's not going anywhere and when the caulk is redone it might stabilize a bit.
I was considering dripping some of that liquid Zap-a-gap that you find in model and hobby shops around the bottom of those adjacent joints, hoping the stuff will seep in under that section. Is that a viable option? Or am I wasting my time there.
The downside to that is that stuff stinks, and I will have to send Mrs. ThunderGoddess out shopping or something for the duration, which is another major expense in it's own right.
Any observations and opinions welcome and thank you in advance.
I'd like some tips on control joint repairs on finished concrete slabs. This situation is analogous to a garage or shed installation, so I figured some members here might have some tips to share.
Here's the backstory. RI experienced tremendous flooding in April of 2010 with record rainfall at that time. Though I am located on high ground, the ground became completely saturated as the water table basically went to ground level.
My 50 y.o.home has a 30x30 ft footprint. It has a completely finished basement which is sunk in approx. 4 ft below ground level, allowing space for windows and light in the basement. About 1/2 of the surface area was living room/man cave, carpeted with particle board underlayment.
As the water table moved up, the water began seeping into the basement. The was no sump or sump pump hole ever cut and no water had ever leaked in from groundwater in 43 years.
With the flooring becoming completely soaked, I ripped out all the layers. Underneath was foam panel insulation tarred onto a rough concrete floor.
After cleaning the original slab up as best I could, there was about 2.5 - 3" of height difference between the main area and the kitchen and bathroom areas. We chose to pour a concrete cap onto the rough slab, and had it installed by an excellent local concrete contractor.
Further, we had the floor stained to a multi-color cola effect and finished. During this process the finisher cut "tile lines" to make it look like approx 2ft x 2ft tiles. One main control line the length of the 15 x 30 ft space was cut in the center and cross control joint cut about every 6 feet or 3 tile spacing.
I then finished the grouting myself with unsanded brown grout as recommended by the finisher. The finished effect was quite nice, and then with a few area rugs, very livable. And should groundwater ever be a problem again, this solution would allow for easy clean up with a shop wet vac. Problem solved. Or so I thought.
Six years later, the control joints have done exactly what they were supposed to do. The slabs expanded and contracted summer and winter and eventually the grouting has come loose in the control joints.
I cleaned the joints out recently and decided that a joint filler that had some elastic properties might be worth trying. Initially I used the basic Brown Dap latex caulk on a test area. The result was unacceptable with gassing out and shrinkage of the caulk. Btw, the grout line is probably close to an inch deep.
Next I tried the premium Dap caulk, Amerflex 230 or something like that. No gassing out, sides adhered to the joint, but the vertical shrinkage was at least 3/8" deep, pretty much requiring it be done twice.
I tried a couple of lines with GE Silicone II brown caulk. One line I did plain. One thing I noticed is that plain, the finished caulk shrinks about 1/4". It's WAY too shiny though.
I had a brainstorm and decided to lay a two foot silicone line and add grout. What I did was filled the line, then scraped the excess off. Then I dusted dry unsanded grout into the top of the line, brushed away the excess and then cleaned it as best I could. Tedious but looked more like the original grout lines.
The plain line I will either cut out or V cut it and put a thin line with dust on it on top. Not sure that is even possible.
Is there some more industrial material available that might be more suitable to provide an elastic and durable seal that is colorable or available in brown? Clear joints would just look horrible.
Any other suggestions? This on has me in trial and error mode, and the shrinkage really doesn't become apparent till the caulk has cured for a few days.
One other issue. This cap was at about the lower end of the thickness limit the contractor was comfortable with. I had no choice really and it's worked out ok so far. Now I notice that one of the "tiles" bounded by 2 control joints evidences a slight "rock" when stepped on. It's not going anywhere and when the caulk is redone it might stabilize a bit.
I was considering dripping some of that liquid Zap-a-gap that you find in model and hobby shops around the bottom of those adjacent joints, hoping the stuff will seep in under that section. Is that a viable option? Or am I wasting my time there.
The downside to that is that stuff stinks, and I will have to send Mrs. ThunderGoddess out shopping or something for the duration, which is another major expense in it's own right.
Any observations and opinions welcome and thank you in advance.
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