Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Flooring

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-24-2011, 09:25 AM   #1
Member
 
Join Date: Aug 2011
Posts: 59
Rewards Points: 0
Share |
Default

Concrete Slab on Grade - Moisture Issues, But How?


I have a concrete slab on grade foundation that's routinely testing at 6 - 7 lbs. per 1,000 sq. ft. in 24 hours using the calcium chloride test. There hasn't been a single drop of rain in over six months and the house was vacant with no lawn watering for two years. The lot is a cut and fill on a hillside with no springs or sources of moisture for miles. The neighbors uphill have a fairly dry, dead lawn, so I do not suspect their watering practices. The water meter shows no movement after a week.

I'm scratching my head at where this moisture can be coming from. If it's not a leak, and the weather has been hot and dry for months, where can it be coming from? I need to move in and want to install laminate floors, so I've had to purchase a very expensive vapor barrier product warranted by the manufacturer. I know this is a quick and dirty solution, but it doesn't cure the underlying problem. I do want to solve this mystery eventually.

I do see some areas around the house where water might gather in heavy rains, and I will regrade those areas before the next rains. A neighbor is also rebuilding the retaining wall downslope from me and will be installing a new French drain on my side of the wall. Hopefully those two things will dry me out.

BobSmitt is offline   Reply With Quote
Old 08-24-2011, 11:51 AM   #2
Pro Flooring Installer
 
rusty baker's Avatar
 
Join Date: Feb 2009
Location: SW Missouri
Posts: 3,857
Rewards Points: 2
Default

Concrete Slab on Grade - Moisture Issues, But How?


1. Do you know if poly was installed under the slab?


2 What is the interior temperature?

__________________
The ads in my post are there without my permission. I do not endorse any of the products.
Semi-Retired Installer
Installing since 1973
rusty baker is offline   Reply With Quote
Old 08-24-2011, 12:19 PM   #3
Member
 
Join Date: May 2010
Location: NJ
Posts: 211
Rewards Points: 0
Default

Concrete Slab on Grade - Moisture Issues, But How?


Do you have any mulch along side the house ?

Don't bring the Lam in till you solve the problem and get the room acclimated .

Any Photos ?
Floor Doc is offline   Reply With Quote
Old 08-25-2011, 03:22 PM   #4
Member
 
Join Date: Aug 2011
Posts: 59
Rewards Points: 0
Default

Concrete Slab on Grade - Moisture Issues, But How?


Quote:
Originally Posted by Floor Doc View Post
Do you have any mulch along side the house ?

Don't bring the Lam in till you solve the problem and get the room acclimated .

Any Photos ?
No mulch around the house. Just bare dirt on two sides and concrete slab on the other two.

I can't wait on the laminate. I have bare concrete floors and I'm out of money to pay for rent and a mortgage at the same time. I can't afford to carpet the place and move everything out later to install the laminate which is already purchased.

What would you like to see in photographs? I will take some, but there is no visible moisture or deposits. It's just the high test readings. When I pulled up the old vinyl floor it was damp underneath, but that dried out months ago and there are no other visible signs.
BobSmitt is offline   Reply With Quote
Old 08-25-2011, 04:06 PM   #5
Member
 
Join Date: May 2010
Location: NJ
Posts: 211
Rewards Points: 0
Default

Concrete Slab on Grade - Moisture Issues, But How?


have you taken any other cc tests lately ?
Floor is flat ?
Floor Doc is offline   Reply With Quote
Old 08-25-2011, 04:29 PM   #6
Member
 
Join Date: May 2008
Location: Near Philly
Posts: 2,038
Rewards Points: 8
Default

Concrete Slab on Grade - Moisture Issues, But How?


Could you have a plumbing leak under the slab?
bob22 is offline   Reply With Quote
Old 08-25-2011, 04:57 PM   #7
Member
 
Join Date: Aug 2011
Posts: 59
Rewards Points: 0
Default

Concrete Slab on Grade - Moisture Issues, But How?


Quote:
Originally Posted by Floor Doc View Post
have you taken any other cc tests lately ?
Floor is flat ?
Took one test in early July and one a couple weeks ago. Both had basically the same readings.

The floor is not flat. The living room is 29' long east to west and the east side is 3.75 inches lower than the west side. The floor is smooth and even, but sloped that direction. Oddly, that's the uphill direction of this cut and fill lot (meaning it slopes towards the cut and not the fill). There is a small crack running north to south across the entire slab at the west end of the living room which is where I imagine the break from level to sloping occurs. It is about 1/16 wide and doesn't have any signs of being wider as you get deeper. The moisture tests read the same no matter where on the slab they are taken. I don't suspect the sloping is related.

I do not suspect a plumbing leak since the water meter registers no water usage when the house was vacant for a week.
BobSmitt is offline   Reply With Quote
Old 08-25-2011, 06:55 PM   #8
Member
 
Join Date: May 2010
Location: NJ
Posts: 211
Rewards Points: 0
Default

Concrete Slab on Grade - Moisture Issues, But How?


If you don't correct the moisture , and flatness issues first you are going to have a floor failure .
Floor Doc is offline   Reply With Quote
Old 08-26-2011, 07:48 AM   #9
Member
 
Join Date: Aug 2011
Posts: 59
Rewards Points: 0
Default

Concrete Slab on Grade - Moisture Issues, But How?


Quote:
Originally Posted by Floor Doc View Post
If you don't correct the moisture , and flatness issues first you are going to have a floor failure .
That's why I'm here looking for ideas. The floor manufacturer, Armstrong, warrants their floor no matter what the moisture so long as you use their VapArrest product. It's just an epoxy coating. I imagine it should buy me some time to find the cause.

My only remaining idea is that it is due to the record rains we had earlier in the year, and that there were areas for the water to pool around the house. I just would have thought it would have dried out by now.

When I purchased the property in June I had a structural engineer out who was not at all concerned about any of the cracks in the slab. I don't believe he noticed the slope, though. You can't see it with the naked eye. It took a laser level to discover that. The doors and windows don't show any signs of a shifting foundation, so it seems that it has been that way for a long time.

Here is a rough diagram illustrating the cracks in the slab and the elevations at selected points. The uphill side is to the right (east).


Last edited by BobSmitt; 08-26-2011 at 08:44 AM. Reason: Add diagram
BobSmitt is offline   Reply With Quote
Old 11-18-2011, 03:56 PM   #10
Member
 
Join Date: Sep 2011
Posts: 166
Rewards Points: 0
Default

Concrete Slab on Grade - Moisture Issues, But How?


Hi!. Before getting to the wetness problem, I'm sorry to say the 3'' plus floor height difference in one corner of the house to another point is excessive and suggests severe failure of the slab. It's most likely been caused by too much fill not being properly compacted on the downward side, or the perimeter footings are sitting on expansive clay that is subject to wetting and drying, causing up and down movement with wetting and drying. Are you sure your levels are correct? With this magnitude of height variation, I would expect wide diagonal cracking in all walls and possibly ceilings. If doors won't close or jam and windows horribly out of square, then the problem is confirmed.

This is so serious, floor wetness is a distant secondary consideration. The remedy to the floor height problem is to demolish half, if not all the house and start again...diabolical.

Supposing you are not that bad by some quirk of fate, your wetness problem is ground or spring water. I know what you mean by this, as I built my house on the side of a hill and I have observed water running strongly 2'0'' below ground level at the point where the top soil sits on shale, the shale running parallel with the slope. When this underground water hits a wall footing & foundation, it can easily build up to slab level before it dissapates around the sides of the house. Your solution is relatively simple. Draw your sloping block in section and try to establish how far you can dig and how far up the hill you have to go to strike a horizontal line at least 1'0'' below the bottom of your slab, Then dig a trench 1'6'' wide across the back of the house on the uphill side, by the depth you have established. If the depth is more than 3'0'', you will need to provide two trench lines one at the higher hill level so the bottom of one relates to the top of the other. (This is like the way they terrace rice fields). This will give you 6'0'' of effective protection.

At the bottom of these trenches lay 4'' slotted agricultural pipe in a bed of 3/4'' crushed rock or screenings or scoria. Fill trench after checking Ag pipes are draining into stormwater runoff drains lower down the block are working properly with scoria or screenings to 6'' below the surface, and backfill top of trench to level with sandy top soil. You have effectively cut off water coming down the hill, and importantly, the underground stream. Your house will dry out eventually (6-12 months), but I don't know what you can do about the heaving floor except to live with it. At least it won't collapse..

I just reread your post and noted you say the windows work fine, then either it was built like that with the floor way out of level, or your lazer level needs checking. How did you do the transverse reading when you shifted the level? Did you allow for the level tripod being at a different height in the second reading? If the level was set up the level in the new position 3'' lower than elsewhere, your slab is in fact perfectly level. Take out a large ball bearing or marble, golf ball or bowling ball and place in middle of room. If it runs away quickly, your sloping floor is confirmed. If the floor is carpeted, this won't work, so find a hard floor surface to try it.

Cheers! from an architect in Oz.

JoJo-Arch is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fix or Replace Porch Concrete Slab Majoram Building & Construction 10 06-25-2011 02:45 PM
Carpet on grade level concrete slab JRP_24 Flooring 1 06-18-2011 09:04 PM
Tips For Pouring Concrete? Root issues? Thoughts? kronic24601 Building & Construction 5 02-14-2011 06:52 AM
engineer wood floor @ uneven Slab on grade gtimk4 Flooring 0 03-21-2010 06:29 PM
Concrete slab weeps moisture dale h Flooring 2 04-30-2005 10:29 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.