Damp looking mortar between cinderblocks

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  #1  
Old 07-20-16, 06:41 AM
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Damp looking mortar between cinderblocks

We have had numerous "experts" look at our basement walls, and all seem to be in a quandary about what has caused this. Of course we would like to find out before forking out thousands of dollars to excavate the whole perimeter of our home and having to remove 2 decks to do so, and retarring and waterproofing, as suggested by one contractor.

History:
The house was raised 27 years ago to put a basement in. 10 years ago the main level was renovated, and spray foam insulation put in the walls. 1 year ago the basement was completely renovated. There had never been any signs of water until vapor barrier and insulation was removed from one corner of the basement - northwest. We and the contractors determined that it was the grading just outside this area, the placement of down pipes and the fact that we had been heaping snow in that area in the winter. The water damage was minimal considering that the outside conditions hadn't changed in 27 years, and it hadn't pooled anywhere in the basement but showed dampness behind the insulation, which was about 4 feet wide by 6 feet high. We addressed the grading and down pipes. The basement is not damp, there is no condensation anywhere, summer or winter. We have central air conditioning and the basement is a little cooler than the main level.

The wet mortar marks, some with efflorescence, have been gradually showing more and more over the past 8 years or so (only on the outside of the block, not when looking at it from the inside), and are showing on 3 areas of the house that are either very shaded by decks, trees or facing away from the sun. They do not feel damp to the touch. The one wall facing the sun shows nothing. We have never seen to the parging in the 27 years that it has been on (our bad) and we have been told recently that it seems very thin in places. The parging is falling off in chunks in what seems like random areas. There is no sign of rising water "tide" marks in the blocks themselves.

I have attached photos of all sides of the house, and under decks. What's your take on the problem? If you have any questions ask away.
 
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Last edited by newsusy; 07-20-16 at 08:55 AM. Reason: Just a typo in title
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  #2  
Old 07-20-16, 08:49 AM
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And what the heck are all those squiggly marks on the left of the third photo??
 
  #3  
Old 07-20-16, 11:02 AM
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My first approach would be to get some measurements of the inside and outside humidity, RH. and record the temperature at each location at the same time. In some climates the moisture is coming from the outside humidity and in others it comes from the inside.

As for the basement and other places looking dry, that is common but does not indicate a lack of moisture. just that the moisture is evaporating before it accumulates. The efflorescence is an indication of this evaporation as it leaves the minerals behind. Also, the moisture you encountered behind the vapor barrier is a common occurrence with a vb. When it blocks the moisture movement that moisture vapor accumulates to form water.

Is the basement currently finished on the inside?

Since the original house was probably not built with moisture barriers under and around the footings, rarely done, the moisture in vapor form easily travels up the block walls or even through solid concrete trying to reach areas of lower moisture content.

Have to run, will check back later,
Bud
 
  #4  
Old 07-20-16, 12:54 PM
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Hi Bud - Thanks for responding. Yes, the basement is currently finished. It used to have drywall throughout and a drop ceiling. We had a tenant that tended to leave the doors and windows open even in the hot and humid weather, while the air conditioning was running, and at other times we found out she had also been using an electric fireplace quite often in the middle of summer. She had it on almost continually in the winter because I guess she still found it cool down there. She lived here for 5 years. The latest renovation was completed just under a year ago, wherein we removed the drop ceiling, and replaced it with drywall. The guy dry walling had to wait an unusually long time for the mud to dry and there was a ton of it, it was super humid those weeks and they left all the windows open, therefore the air conditioner was turned off. As soon as we set foot downstairs the humidity hit us, but with that job done it has gone back to normal. The past couple of years the weather has been particularly humid in the spring and summer. We've never had the need for a dehumidifier, and there are no smells or odors that you would associate with a damp basement either.
 
  #5  
Old 07-20-16, 01:02 PM
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Relying on your nose to kno what is happening inside the walls isn't reliable. Pick up a couple of inexpensive temperature and humidity gauges and let us know what is happening.

Give us your approximate climate area, unless I missed it.

Bud
 
  #6  
Old 07-20-16, 03:04 PM
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I will do that! I'm located just outside of Toronto, Ontario - so we are experiencing weather very much like yours. We use to vacation in Maine when I was growing up.
 
  #7  
Old 07-20-16, 03:05 PM
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Number one, the walls are cool enough for condensation to be present for an extended period of time. This is likely why there is no problem on the sunny side of the house. (That wall is not as cold, therefore not below the dewpoint.) Number 2, the water source is either humidity in the air outside condensing on/in the block and mortar or its moisture inside trying to dry to the outside. (Contrary to what you might think, concrete walls are not impervious to moisture on their own... unsealed blocks are a conduit for moisture, almost like a wick, albeit slowly.) Number 3, the coating on the exterior side of the block is likely trapping the moisture, making the problem worse by raising the moisture content of the concrete blocks.

There are many possible products you can use, but IMO, paint or drylock should not be one of them. A penetrating masonry sealer should be applied to the wall after the efflorescence has been removed and cleaned. The Aldon System is a good one. Not really sure how you plan to proceed, but to get the old finish off, shot blasting / sandblasting to get down to bare masonry would probably be a step in the right direction prior to treating / sealing the walls.

A dehumidifier is almost ALWAYS a good idea in any basement. It can run to a floor drain or sump pump if you don't like dumping it constantly.
 
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Old 07-20-16, 06:52 PM
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Thank you so much for your analysis. This is exactly where I started in this process but with so many varying views it was hard to know which way to turn. We were told just the loose parging could be removed and then reparging done to even out the surface. The fact that there would be remaining water under the parging that was left behind and ultimately covered over again didn't make sense to me, especially when the materials left behind didn't allow for breathing in the first place. We've been told everything from water coming down from under the siding and having to remove it to see what could be going on to water wicking up from the footings, digging and boring holes to see if water drains out and then digging all the way around, rewaterproofing etc. - both of which would be costly and painstaking endeavours when you really dont have proof that it is even necessary. Condensation has also been an expressed possibility, and it has been a common thread that has been mentioned by all different tradesman that I've spoken with but all the other possibilities have weighed on my mind. I am leaning back toward your suggestion and removing all parging. So thanks again for making this decision making process easier for us.
 
  #9  
Old 07-23-16, 02:00 PM
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Okay - now what? We got a moisture meter and checked the moisture at the top and bottom of the outside block walls. The average was about 28% at the top and 22% at the bottom. We came inside, and measured the moisture in the block above grade, from the inside, and it was at 25%, below grade as close to the bottom of the wall was at 75%. As you progress up the wall, it gets lower each course of block. This isn't looking good. What would your guess be, we have water entering the block at footing level, because the moisture is so much higher there? Ugh.
 
  #10  
Old 07-23-16, 02:41 PM
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One of the problems with block walls is those blocks can be hollow and they can fill up with water. So, your moisture readings may be coming from the footings below or old water that has accumulated inside those blocks. It will soak through and dry, but if it is being replenished from some exterior point it basically never dries up. Just a guess.

Bud
 
  #11  
Old 07-23-16, 03:18 PM
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Just to add to what Bud said, the interior slab is generally poured up to that first block so seeping groundwater can create a 4" deep pond inside the blocks before you would notice any leakage inside. No real way to know what is going on there, but a couple exploratory holes would not hurt anything. Like maybe a 1" hole near the base of the wall at the floor level, through one of the hollow cores... 4" from either end of a block.

A 1" hole would let you do your own detective work and inspect with a flashlight or camera, and is a small hole easily patched with a little mortar.

Basement waterproofing often involves drilling these type of drain holes as part of a perimeter drain tile and sump. Not saying you need that, but it a possibility. Google: "Interior Weeping Tile Systems - Perimeter Drainage" and notice the detailed illustrations of the process at the first website that isnt an ad.
 
  #12  
Old 07-24-16, 09:55 AM
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Do you know if the weeping tile can be accessed with a scope via an exterior floor drain at the bottom of a stairwell? It was attached and made to drain into the weeping system when we did the renovation on the stairwell about 5 years ago.
 
  #13  
Old 07-24-16, 11:42 AM
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No idea. There are exterior perimeter drains and interior perimeter drains. Generally the interior drains are less expensive to retrofit, and that's what I was suggesting might be needed if your blocks have standing water inside them.
 
  #14  
Old 07-25-16, 02:58 AM
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After crawling around under decks I have discovered at least three areas that I am certain have directed the water straight to the foundation walls. The rear deck is the width of the house, and after crawling to the far end, under a 3 foot high space, I discovered a huge piece of plastic, about 12' X 16' was laid out and right up against the wall - like a big trough.

Now, it is obvious why the blocks moisture content is so high. It's obvious the grading all around the house needs addressing, but now my question is, what would be the best way to address the existing high moisture content in the blocks? Is there a way to do it without breaking the bank? There is a finished apartment in the basement, but the area in which the most water would have seeped in, from under the deck, is not part of that apartment. Do you think it would work to take down the drywall, vapour barrier, insulation and tar paper covering the blocks in that room 12' X 12', and get a dehumidifier to get the moisture out? Do you think it would eventually pull moisture from in behind walls that aren't as accessible?
 
  #15  
Old 07-25-16, 07:33 AM
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Okay - latest development. We just had holes drilled into the block, from the inside, and there is no evidence of standing water whatsoever, so... the moisture is in the blocks themselves. Any thoughts?
 
  #16  
Old 07-25-16, 07:50 AM
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The moisture that is getting in may not accumulate for long. You want to check those holes after a heavy rain. But, I wouldn't delay making improvements to the exterior drainage.

As for drying up what is there, the lack of standing water is good and an indication you may be able to dry most from the inside. The areas that are covered with a vapor barrier will dry to some degree sideways and may dry completely over a longer time. The key step is to eliminate the source of the water, then re-evaluate the issue.

Bud
 
  #17  
Old 07-25-16, 08:06 AM
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Thanks for your input Bud. We actually had a heavy rainfall early this morning.
 
  #18  
Old 07-25-16, 06:48 PM
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Yep - I'm back with another question. There are a few hairline cracks in the parging that follow the concrete block pattern, so steps - does this signify that the blocks directly underneath and/or below grade are compromised or cracked as well? I am being told that I should be concerned, but tell me are the concrete blocks more porous than the mortar in between, and because they have absorbed so much moisture, and the parging is old and thin in places, is it really just a reaction to the drying of the moisture that is reaching up to the drier air, to dry themselves out resulting in the cracked parging? Hopefully this isn't too confusing. Please ask me to clarify if needs be.
 
  #19  
Old 07-26-16, 04:14 AM
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More opinion as opposed to expertise, but those step patterns are very common on block foundations and IMO, they do represent similar cracks in the mortar between the blocks.

One thing you have to accept, existing basements are always going to leak, they were never built to hold back moisture vapor (airborne water) or in many cases liquid water. When I started building long ago, that black tar below grade was standard and we believed it stopped all water. We were wrong and generations have moved into homes believing they can finish off all of that empty space into beautiful living space. The results in many cases have been disastrous, not all, but too many.

Today they do know how to build a dry basement, but it costs more so we don't see it being done very often.

If we cannot make our basements perfectly dry then we must shift our objective to managing the moisture that gets through. By eliminating all vapor barriers our walls are able to dry to the inside. Add a dehumidifier or air conditioning to remove that moisture and most of the related problems go away. If our landscaping and exterior drainage is good then we are only dealing with the moisture level in the soil and that is easily handled. If you have water getting into those walls, which seems to be the case, the dehumidifier approach will struggle, especially where there are vapor barriers.

I'm not the pro, they may disagree. but there are many articles from "Building Science Corp" on this issue and they may help you in your decision. Here is one link to get you started, but there are other links referenced from this one and others from there.
http://buildingscience.com/documents...ts?full_view=1

Bud
 
  #20  
Old 07-26-16, 08:02 AM
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Are concrete block foundations usually parged right down to the footings, and then tarred/waterproofed over? I thought the parging was more for aesthetics? I'm starting to worry about what I'm being told by a particular contractor.
 
  #21  
Old 07-26-16, 09:03 AM
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Again, not a pro, but from my experience the parging is only above grade to cover the look of the block foundation. Tar is below grade.

Bud
 
  #22  
Old 01-07-18, 02:13 PM
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Curious if you were ever able to completely resolve this issue. I have a similar issue. Instead of parge coat we have stucco, with mesh between the cinder block foundation and stucco. We have noticed moisture build up on the exterior of the home with efflorescence during the winter months when the temp is hovering between 25-40 degrees. IT is on the south side of the house. We have a half finished basement without insulated walls that is not used much during the winter months and a drop down ceiling. We were told its likely condensation as our grade seems to be sufficient around the home and we have never had an issue with water in the basement. I have attached a pic for any advice:
 
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  #23  
Old 01-08-18, 03:59 AM
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Well.... Jer5Wil. You're not going to like what you're about to read. As you know we had bought the moisture sensor and measured the humdity of the blocks and found it very high at the base closer to the footing. We went on to the next step and drilled holes in the blocks to see if there was any standing water within. I expected water to come pouring out which didn't happen - phew (at the time). So... on to the next least expensive step. We had our contractor dig a hole down to the weeping tile and brought someone in with a scope, and our worst fear came to fruition. It was an absolute mess, as the scope moved down the pipe we found that anything and everything that could be compromised was - quite a number of tree roots had penetrated the pipe, although the tree no longer existed, as we moved down the side of the house and to the corner there was standing water in the area that I had described earlier, where we piled snow every winter, the standing water went for at least 15 feet and at that point, just before reaching the worst damp looking area in the brick at the front of the house, they couldn't move the scope any further - the weeping tile had collapsed. We then decided to scope in the other direction, under the back deck and there was so much silt and dirt in it, that it was pretty obvious we were in it for the long, expensive haul. We had to have the perimeter dug, new weeping tile put in plus a french drain, window wells and a non-penetrable plastic membrane wrapped around the whole house. That meant taking down our front deck and dismantling 2 patios. In order to avoid the expense of taking down and replacing the back deck, which was the full width of the house, they were able to bring in a machine that a guy could stand on to bring out the dirt. In the process a gas line was cut, and the gas company quickly came to the site, blocked off the street from cars coming down and saw to the leak. Over a year later the grading was finished and sod layed, because we had to wait for the ground that was dug up to settle. We had to borrow money and renegotiate our mortgage but In the end we have peace of mind and saved an expensive basement apartment renovation that had been finished the year prior.
 
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