Moisture problems/laminate flooring in basement

I am converting a garage/workshop in a bedroom.

It is below grade. The floor is a concrete slab. It rains alot here in Squamish, B.C., but our exterior perimeter sunken drainage system works well and the concrete stays dry even during the worst rains,
Except, I have noticed that if I leave objects such as full duffel bags on the basement floor, when I lift them off a few days later, significant water has accumulated underneath. The bags seem to create an airtight seal under them, so I can't see that this would be due to condensation. Any ideas on why this happens and how to prevent.

This is important as I am planning to carpet some rooms and install lamintate wood flooring in others.

What precautions can i take to help keep moisture from either coming up throught the concrete or condensing under the flooring.

For the laminate, I plan to lay a closed cell foam, then install the floating laminate above it. Should I also lay down a plastic vapour barrier? Paint the floor with a latex paint first? Seal the concrete?

For the carpet, what are the correct procedures to preparing the concrete, and what needs to be placed under the carpet?

Thanks,
Sean

 

Unfortunately, what you describe with the duffle bags may be similar to doing this test. To get a better idea on your moisture issues, place a 2 ft. square of plastic on the floor or wall, sealing edges with duct tape, and check after 2 days for drops of water.

This test will determine to what extent you have problems. It may be that you apply a waterproofing sealer to the floor prior to installing any type of subfloor/finished flooring. Then you use a dimpled plastic sheeting which can also be placed over the floor and covered with rigid insulation and a tongue and groove plywood subfloor over this as you described. This forms a vapor retarder and drainage layer on the concrete floor.

Rigid insulation is placed on the floor and then covered with a decay-resistant plywood subfloor. This will be afew dollars but well worth it. For basements with severe problems, use of interior draing tile is suggested. In some cases, extending the dimpled plastic sheeting over the entire wall is recommended. The sheeting serves as a vapor retarder and it forms a drainage layer connected to the drain pipe below. This is particularly effective if the wall is to be finished. A second interior vapor retarder should be avoided, however, if batt insulation is used. There should be an interior air barrier (such as the wall finish material) sealed at the top and bottom plates and at all penetrations.

The dimpled plastic sheeting can also be placed over the floor and covered with rigid insulation and a tongue and groove plywood subfloor. This forms a vapor retarder and drainage layer on the floor. If a basement has moisture entering through walls or floor, covering it with any kind of wall finishing material or carpet is likely to make it worse unless the water is dealt with first. Wet carpet and moisture under wall coverings are excellent places for mold and mildew growth that can lead to health problems. Generally, when the relative humidity (RH) is above 60 to 70 percent, problems occur with mold and mildew growth.

A note about Mechanical Ventilation - Mechanical ventilation pipes connected to a suction fan can be fabricated to the dimpled sheeting. This draws moist air from beneath the sheeting and dries out the floor. It also assists in controlling radon and other soil gases.

One of our members did the following and was kind enough to provide great feedback,

"Before you go spend a lot of money, please look into this. I'm glad I did.
First I found this product called subflor, which appears to be very similar to the Dricore product.
http://www.subflor.com/
Then I found that they wanted $9 a 2x2 piece (4 sq feet). WHOA. So I got some rolls of Delta-FL
http://www.deltams.com/deltafl/index.html and 4x8 sheets of 5/8 OSB which came out to be about a buck per square foot. I'm sorry I can't remember the actual price per sq ft for the Delta product, but I do remember it being less than a dollar.... Screwed it down with some tapcons and I'm good to go! Made my own 'Subflor' for half price!
I've looked into these two products as well. And had one comment. The big difference between dricore and delta-fl is that the dri-core panels will 'float' with thermal expansion and wouldn't take as much effort to 'level' them to irregularities in the concrete. Dricore is a subfloor on is own, But with deltams you need install a sub floor on top of it before your final finish.
I installed Dri-core, solid, VERY EASY to install subfloor!!! It took me and my wife (yes, my wife) about
5 hours for 300 sq. ft., with some cutting around pipes support poles etc. I thought it went well anf it looks and feels great. Just follow the installation instructions and ther will be no problem...Need to do the other 1/2 next weekend...will be putting wall up after that..i will keep all informed on how it goes...But I would recommend this floor to anyone...Thanks for all your input..
I like the idea of putting the walls on top of the dricore, which i will be doing..Should I get any dampness, (which I shouldn't bu if), the walls and toeplate are off the cement. I used 1x3's as spacers and the 3/4" space is just right. . Dricore suggest fatening the toe plate to the flooring and then fastening the flooring to the concrete with 3 fasteners every 16 ft. I think itll work out nice. Let me know what you choose..and I'll keep you up to date on how the walls go up. In addition, i am not using baseboard heat so I did not have that worry, I am using a gas fireplace. Good luck..

I never contacted a flooring contractor about dricore. I bought 2 panels to show my General Contarctor, and he liked it, he had never seen it. From my understanding, it is made in Canada and is only available exclusively at Home Depot in the US. It is $4.97 for a 2x2 panel.

Advantages is that it is easy, solid, incorporates your vapor barrier and sub floor in one piece, allows the panel to "breath" underneath should you get dampness. I will now feel much more comforatble putting down carpet. Another point, it is dricore is only 7/8" high, where a true subfloor with sleepers etc is 2-2 1/4"..a big deal for me because of my ceiling height...

Had to use a few piece of leveling kit near the sump hole..$3.97 for a package of 20 pieces... "

Hope this helps!

 

I would like to ask Doug a question. I am also planning to add some flooring to my unfinished basement and the Dricore seems to be a viable product. However any idea how to deal with french drains in my basement? That is. should I lay the Dri-core flush with the masonry walls or on the edge of the drain?
Thanks in advance for your feedback.
-AKN

 

akn,

I have been asked this but I need to clarify your "french drain" condition. Is this a groove between the slab and wall?

If so, then what is your intentions for exterior wall finishes?

If you are placing a 2x wall, let's say 1 to 2 inches away from the wall, then your dricore would go up to this wall. If you are going to leave the walls exposed, I would not place dricore right up against them as it will destroy the dricore one the plys get wet. Other issues have to be addressed as well and this would include final flooring - hard to finish a floor and make a room look great if you have a space at the edge.

The issue is to plan your project through to the final finished look.

Then establish what products are required to accomplish that goal. Product choice will be determined by what your current site conditions are, how they can be used and what is the final goal. Making adjustments mid-stream can be costly and time consuming.

Best suggestion is review what products are available, where they can and cannot be used and for what purpose. A last note is that everything is based upon the budget for the project. This is where it get's interesting. Don't take shortcuts that could cost you later.

Hope this helps!

 

Doug,
Thanks for your feedback. The "drain" is a groove or a gully between the slab and the masonry wall. I do plan to install a wall. Do you think I should frame the wall first and then install Dri-core or can it be the other way around?
-AKN

 

AKN,

Frame and install all your EXTERIOR walls then do the subfloor application. Dricore for example is a "floating floor system". There is no problem setting interior walls on top of this system.

Good Luck!