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Web masonry in crawl space


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I am buying a new house from a builder. The house is about to be closed. I found the masonry was wet after 0.35 inches of rain.

Please see the pictures. They represent different locations.

On the very same raining day, I checked the crawl space in my current 20 year old house. The soil and masonry around the perimeter of the house is completely solid and dry. No sign of moist and watermark on the masonry.

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My builder told me it is normal to be wet after raining event.

The house already receive certificate of occupancy form the local government.

Is it normal to be wet like this after 0.35 inches of rain?

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tn_20141120143726_close%20to%20the%20front%20porch.jpg

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tn_20141120143754_Under%20the%20garage.jpg

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I don't think that is too unusual. With a new house the soil adjacent to the foundation was excavated and backfilled. This will allow water to enter the soil. Also, is grass established and do you have proper downspout extensions that extend at least about 4 feet from the foundation walls.

It looks like the soil in the crawl space is quite damp and is clayey. Clay soils do not drain well and water can wick up into the block.

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Yes, soil in the crawl space is damp and is clayey even without rain.

The concrete blocks is dry most of time. But both soil and blocks get very wet after rain. I verified them twice in past three weeks. My inspector did not want to come back and check again. He only said that he seen many crawl spaces and most of them are dry even after rain.

The nearby down sprouts got extended at 10 feet away by the builder. There are plenty of vents in the crawl space. Grass were laid already just like carpet. Both walls are under a garage. These two locations are not on the house perimeter. Namely, the other side of walls are not connecting to any grade.

I am afraid the moist in soil and masonry watermark mean mold growing problem in the future. Is the a house a buy or not?

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I don't think that is too unusual. With a new house the soil adjacent to the foundation was excavated and backfilled. This will allow water to enter the soil.

This is very common. Rain falls through the fluff (backfilled soil) and seeps down until it hits the undisturbed soil, then is spreads outward. It can go on for years until the fluff compacts.

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When did the downspouts get extended? Once that is done, it can take some time for residual water from previous rains to dry out. Were you discovering the moisture before the gutter downspouts were extended? Does the exterior grade on all sides of the house have sufficient slope away from the foundation walls?

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Guys, his question was "Is it normal to be wet like this after 0.35 inches of rain?" The block should have been waterproofed on the exterior, there should be footing drains, (at a minimum). So even with the fluff, he should not be getting water through the block. Once water has a pathway to the interior it will be difficult for it to seal itself and become dry. They may not waterproof block in NC but they do here in CT.

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I would want to verify the presence of waterproofing on the exterior of the block wall, and a correctly installed drain tile that slopes to daylight. If rain makes the wall and the soil wet, that's not a good sign in my opinion. These problems do not get better over time, they get worse. Yes, the backfill will settle and compact itself slightly over time, but I doubt that moisture you're seeing is just percolating down through the backfill. What is the slope outside the house where that wet spot shows? Where do the utilities enter?

I am consulting on a house right now that is down a gentle slope, and is on clay. The builder cut a very long ditch down the hill to the corner of the house, and installed the water and power in it. He effectively created a french drain directly to the foundation. Of course there is now a lot of paving and planting covering the area.

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How is your positive slope at perimeter outside?

If there is equipment down there you should have "damp-proofing", parged block exterior and draintiles installed.

The grade close to that wall is not good and acutally it is flat. Because the top of soil is only barely four inches below the top of foundation. There is no room to make good slope, so the builder installed drain sump w/grate to guide water away.

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I would want to verify the presence of waterproofing on the exterior of the block wall, and a correctly installed drain tile that slopes to daylight. If rain makes the wall and the soil wet, that's not a good sign in my opinion. These problems do not get better over time, they get worse. Yes, the backfill will settle and compact itself slightly over time, but I doubt that moisture you're seeing is just percolating down through the backfill. What is the slope outside the house where that wet spot shows? Where do the utilities enter?

I am consulting on a house right now that is down a gentle slope, and is on clay. The builder cut a very long ditch down the hill to the corner of the house, and installed the water and power in it. He effectively created a french drain directly to the foundation. Of course there is now a lot of paving and planting covering the area.

I wish I could check the presence of waterproofing on the exterior of that block wall. Like I said above, the block wall is under a garage. Its exterior is not adjacent to any outside grade. To check its exterior, the garage's concrete floor needs to be cracked open. There is no utilities enter or exit near where the wet spot shows.

Yes, there is a drain tile passing by and along that wall about 1 foot away. The builder said the drain tile is functioning right without any issues.

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The builder installs a sump and a grate. Warning #1.

He says no room to change the grading. What, is the property line that close?

He tells buyer no problem, drain is working. Should be no moisture if that's the case.

I suggest buyer needs help from someone that can take a good look, not just these pics.

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I post the house layout. Now you can see that the sidewalk limit the grade slope between front porch and garage. Please note, the front concrete block between the front porch and garage is dry. So where is moist from?

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tn_2014112204858_Layout.jpg

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Good drawing.

I had something very similar with my house. The water was simply oozing out of a seam in the clay soil. A spring or underground stream, if you will.

I ran drain tiles to the wet spots and haven't had a problem since.

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The builder installs a sump and a grate. Warning #1.

He says no room to change the grading. What, is the property line that close?

He tells buyer no problem, drain is working. Should be no moisture if that's the case.

I suggest buyer needs help from someone that can take a good look, not just these pics.

My hired inspector did not want to come back. He told me this is a problem. My builder said the watermark is normal and its hired 3rd party inspector said the moist is within normal range.

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I post the house layout. Now you can see that the sidewalk limit the grade slope between front porch and garage. Please note, the front concrete block between the front porch and garage is dry. So where is moist from?

Click to Enlarge
tn_2014112204858_Layout.jpg

24.26 KB

Good drawing.

I had something very similar with my house. The water was simply oozing out of a seam in the clay soil. A spring or underground stream, if you will.

I ran drain tiles to the wet spots and haven't had a problem since.

The drain tile is next to the block wall already...

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That helps a lot.

I'm still trying to figure how that upper drain tile actually drains when the discharge end seems higher than the sump. That's what it looks like according to the drain slope arrows.

Marc

I had the same question. I guess the drain is just dug deeper to the right side.

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I post the house layout. Now you can see that the sidewalk limit the grade slope between front porch and garage. Please note, the front concrete block between the front porch and garage is dry. So where is moist from?

Click to Enlarge
tn_2014112204858_Layout.jpg

24.26 KB

Good drawing.

I had something very similar with my house. The water was simply oozing out of a seam in the clay soil. A spring or underground stream, if you will.

I ran drain tiles to the wet spots and haven't had a problem since.

The drain tile is next to the block wall already...

I had a drain tile only about a foot from the wet spots as well. I extended the existing drain right smack dab to the wet spots and they disappeared.

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That helps a lot.

I'm still trying to figure how that upper drain tile actually drains when the discharge end seems higher than the sump. That's what it looks like according to the drain slope arrows.

Marc

I had the same question. I guess the drain is just dug deeper to the right side.

But it won't drain until it comes to the surface and only if that point is at an elevation that's lower than the sump.

Could it be that rainwater is actually flowing the wrong way?

Marc

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That helps a lot.

I'm still trying to figure how that upper drain tile actually drains when the discharge end seems higher than the sump. That's what it looks like according to the drain slope arrows.

Marc

I had the same question. I guess the drain is just dug deeper to the right side.

But it won't drain until it comes to the surface and only if that point is at an elevation that's lower than the sump.

Could it be that rainwater is actually flowing the wrong way?

Marc

The drain was the second attempt that the builder did to address the issue after my complaints. It made slight improvement but still can not get rid of the watermark completely.

I will find it out during next rain event on site.

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