I cleared efforescent and dried floor. Anything less (or nothing at all) is a recipe for myriad problems down the road. Each day, our editors assemble the latest breaking industry If you’ve ever had a problem with a basement floor (or any concrete floor), you know the kind of damage that too much moisture can cause. I’ve then had people suggest laying tile on it after it’s been diamond graded but that it could still come up through that but not be as bad because it will only come up through the grout. Overlay manufacturers typically recommend a moisture vapor emissions rate (MVER) of 3 pounds per 1000 square feet in 24 hours (see Reducing Bond Failures Caused by Moisture Vapor Transmission for more … PE-VRM can be used as a one-coat moisture vapor barrier coating suitable for various types of concrete. Hi, Hello, I don’t see much issue with slab degradation. I’ve also had the roof and windows inspected. What options do I have for vapor barriers/vapor mitigation? Thanks for any time and insight you may have it is appreciated. Thanks for the comments. I have opened the garage doors to dry it out and it gets even worse. These surface meters are meant to be used to identify suspect areas on a floor, not to make installation decisions. Finally, is bringing it up IN FRONT of the baseboard and behind the quarter round a smarter alternative? AND finally does it matter what we choose if we place a high performing barrier? I have a garage without moisture barrier beneath. I’m at a loss and have waisted so much money on each “fix.” What is the best way to deal with this? obviously we will lay plastic for the entire floor but thought would be double protection under the footing trenches and posts to protect from moisture. Vapor barriers are less permeable than vapor retarders. Personally, I would follow their guidance. What could be causing this? What do you suggest? I’m curious if I need to put visqueen and support wire down before I pour a 10 x 12 concrete floor on the west coast of Florida? I recommend a minimum 10-mil-thick polyethylene material, even if your local building code allows a 6-mil, as it lasts longer and is less prone to punctures. Your best bet is to have the installer provide the installation guidelines for the polyurea that will be installed. Which would be better? With the French drains, this may not be as critical, but you will usually see uniform coverage in a vapor retarder. A vapor barrier under your slab will also protect you from harmful ground pollutants like radon gas. Thank you for your time. Vapor barriers have been associated with certain concrete slab-on-grade problems including curling and cracking. I would contact https://www.stegoindustries.com/ And see if they have a viable option for you. Hi Jason, Hi, I live in Houston and have an outdoor patio that I had stained and sealed. Thank you for the question Gary. The concrete slab is the air barrier, and the ripped and torn and punctured polyethylene sheet is the vapor barrier. I am working on a project and the exiting mat slab is maintained and will have a new foundation next to it. (or possibly the contractor didn’t prep the floor properly or mix the thinset properly) so today i ripped up all the tile and halted the project until i can find answers…i really want to install tile again but my question is if I should use a painted sealer like redgard or something different to prevent moisture vapor to escape and ruin another attempt at tile! Is a vapor barrier necessary under a concrete slab with foam insulation and if so, where does go? that’s the reason of putting the sheet? Thanks for the message. This may help you in your process. Hi Jason, Should I be concerned about humidity build up between the vapour barrier and the concrete? Stego Industries is the leader in the below-slab concrete vapor barrier market. I would like to put down an impermeable class 1 vapor barrier on top of the slab before I put down any flooring. We would like to resolve the question of proper placement of vapor barriers under concrete slabs on grade. However, the vapor barrier under the slab must have a lower degree of permeance than the flooring (or floor covering) above the slab. As far as the “results” from the 6mil poly on the surface of the concrete, there is a reason this is not a flooring industry-recognized concrete moisture testing standard. Here’s what happens. Good luck. SPARTACOTE Moisture Vapor Barrier is a single-coat, 100% solids, liquid applied 2-part epoxy coating specifically designed for controlling the moisture vapor emission rate from new or existing concrete slabs. Don’t know which way to go! Thanks for the question. We have a home in Houston that has been flooded with the hurricane, and all flooring other than the travertine tile has been removed. What would be the best procedure to follow to remedy the issue. You should research them and look at warranties. The W. R. Meadows underslab vapor barriers are ideal for use under concrete slabs that come in contact with soil. You might also need a vapor barrier for liability reasons because most manufacturers of flooring include vapor barriers or retarders in their installation guidelines. Great information. any people are insisting i get rid of the carpet because it is a basement and they say it will always have moisture even with a dehumidifier running. We may share your information with our social media, advertising, and analytics partners. not even 2 weeks later the entire floor started to buckle. I don’t believe it’s capillary action from the water table because when I pull back an area of the plastic, that area dries out in a day or so. Always read the warranties. If we do this, is there a specific location that is best? Thanks much for your help. Be careful of who you hire dont trust what you read on angie’s list. I have a 40 X 20 pole-barn type building with a concrete floor, it was probably built in the mid 70’s. Our luxury vinyl floor was laid directly on top of it. My understanding is that we need some kind of vapor barrier to protect against radon (even though from my research it seems the Pacific NW has a low radon hazard), as well as needing some means of keeping the cement dry. Get Pro Builder in your inbox. At this point, the most-accepted method commercially is the American Society for Testing and Materials (ASTM) F2170 method. The slab is butted right against the outside wall of the building which is an old wooden country store with the wall opened up that has the normal reach in doors to the inside of store. He said with all the gravel and the French drains along the edges it was not necessary to have the membrane right up to the edges. So, in my opinion, you have two options: 1) They make VERY good products, intended to be put on top of the concrete slab, that restrict the moisture movement out of the concrete to a level that will not effect most flooring. Upon further investigation I found that the concrete walled sections of the foundation were covered with 1/2″ plywood over top of some type of other material and the plywood was covered on the outside with a latice wood material, purpose unknown to me. Being that this is a very specific, unique question, I am enrolling help from one of my industry counterparts from Stego. Good luck. I just bought a raised ranch modular home that sits on a poured concrete foundation on 3.25 walls. We had a moisture test done on the concrete with calcium chloride (72 hrs) and that showed no moisture in the concrete, it was just between the moisture barrier and wood. no cracks in it tho. We have a split home with typical family room downstairs that sits on concrete. I must also add that we find that most of the floor area other than where the defects are to have very low/no moisture. Guide to Concrete Floor and Slab Construction, http://www.elitebuilding.com/tile/ref/trowelsize.htm, https://www.tcnatile.com/faqs/71-thick-setthick-bed.html, https://www.concreteconstruction.net/how-to/new-slab-on-top-of-old_o, https://www.stegoindustries.com/stego-wrap-vapor-barriers?hsCtaTracking=d654940e-2168-473c-934d-ed294b689fe3%7C23dd2231-f515-494b-8e7f-b042972bd744, 3 Key Lessons about Moisture from an Old Concrete Floor. The downstairs had 12 x 12 tile, I replaced with 30 x 30 porcelain tile in November. Instead of going back and forth on this (I have questions), why don’t you just give me a call: Monday-Friday 7:30am-4:00pm at 800-634-9961 X235. Slabs that lack under-slab vapor barriers will nearly always have some water vapor emission from water below the slab, and newer slabs, even with vapor barriers, will need time to dry out. Hi Jason, I’ve always recommended placing an insulated vapor barrier beneath any new interior concrete floor. CONCURE 401 EPOXY VAPOR BARRIER is a 3-component water based epoxy system. Often, it's the concrete contractor who spreads it out just before placing concrete. If you just going to leave it as concrete, cosmetically, for now and the future, most probably wouldn’t utilize a vapor retarder. The Concure 401 Epoxy system has a superior cross-linking chemistry which creates an excellent adhesion to concrete.Installs in a two coat application, dries quickly between coats, stops moisture and vapor issues.Concure 401 Epoxy Vapor Barrier can also be applied to green and damp concrete as well as existing concrete. 2). That being said, I doubt some moisture (you didn’t say how much) would be a huge problem as long as you gave the flooring assembly ample time for the moisture to escape and dry, prior to installing a finished floor. However, strictly speaking, they aren’t the same thing. I would say you are on the right track with insulating the break between the cooler slab and the wood. I have no manufacturing information about the construction of the modular home back in 1990 and am not sure that any of the exterior walls of the modular have vapor barrier material on any of the exterior walls. My installer was half way through the job laying the tile when I realized some of the tiles were hollow to the tap…i pulled up some of these tiles to see that the thinset was not adhering to the slab (brittle actually) and in other areas it seemed to adhere fine…under one area of tile we noticed that the thinset adhered but the was some beading water in some of the thinset groves. If you think the concrete sealer is warranted, is there a particular product you recommend? I would like to install 12×24 tile on it but am wondering if I need to apply a vapor barrier or sealer of sorts prior to install? Two shorter run areas have screws that we have discovered that are supposedly to keep the floor from buckling and the screws are in about 24 ft runs. Good luck. I’ve also mounted a remote hygrometer on joist in crawl space near the slab. I would say that it really depends on the amount of moisture in the concrete as to which one would be best to utilize. • Vapor impermeable: 0.1 perms or less Hello, Is it possible that a temperature difference between the slab and room above the wood is causing condensation to build up under the floor? i put 6 inches of cement however i did not put any tarp or any vapor barrier underneath the slab . If you are unable to find the answer in their written documentation, I would call their technical center. My fear would be more about the floor being ruined than mold. It sounds like you may have a traditional mortar bed installation here. I’m just concerned that if something is stored in there that it could cause problems if the barrier is punctured. It makes me wonder if that may potentially be a perfect environment for mold growth. I need advice on a product that I can paint (or apply) to a cement floor on a porch that is being converted to a sunroom. The contractor removed the visqueen, poured the cement on the dirt in the crawl space, and then put the plastic back on top of the cement after it cured. Could this be caused by moisture in the slab or no vapor barrier? I have a contractor that says half of my garage reads a “5” on moisture gauge and wants to lay down a ristoleum vapor barrier for $1850. For an under-slab vapor barrier to be most effective, it should be in direct contact with the underside of the slab. I think if you were to read my other articles and/or view my video’s you would see my overarching opinion that concrete loves water, but it’s the flooring finishes that we use that don’t. There should be more than a 5 degree temperature variation between actual and calculated temperature to avoid condensation (sweating). Angie, We can’t afford to keep trying different things. I’m planning to build a shed, approx. Required fields are marked *. Each day, Pro Builder's editors assemble the latest breaking industry news, hottest trends, and most relevant research, delivered to your inbox. It’s a nice double garage and I want to use it more To further mitigate soil gas intrusion, install the vapor barrier over a 4-inch bed of level, compacted gravel before you pour the slab. Thanks for the email. Pro Builder is an advertisting supported site and we noticed you have ad-blocking enabled in your browser. The building inspector for my community says I need to apply a vapor barrier to the cement (it has none underneath) to avoid future mold problems. Enjoy the party barn. will it help? hi jason Google “epoxy moisture mitigation”. I have a slab foundation (on grade), and one room seems to have a moisture issue when it rains. In there, they should spell out “concrete moisture” maximums. The floor is generally dry, but I’d like to have some vapor barrier protection and the cushion. That being said, there are some coatings companies that use these devices in their installation documents. Lastly, here is a link to a tile size/trowel size guideline table: http://www.elitebuilding.com/tile/ref/trowelsize.htm. Newly poured concrete, given enough time, will eventually release sufficient moisture during the curing process to proceed with building construction and floor covering or a resinous floor coating system installation. I will assume cosmetic based on how you described it. SPARTACOTE Moisture Vapor Barrier exceeds ASTM F3010 standard with a perm rating of 0.052 grains/h/ft 2 /in. A neighbor asked if we installed a vapor barrier. Much of what you said I’ll agree with but not the part that water will hurt the concrete. thanks. I’m building my own house and I’m at the stage that my main floor has already been poly’ed, styrofoam installed, rebar done and finishing the loop for my radiant heating. That being said, yes moisture vapor can condense under the 6 mil, but the odds are it will be a constant flux of condense and reabsorption back into the concrete. Thanks for the question. Good luck. I need you help or is something I need to do around the Concret slab?? Thanks for the questions. unfortunately i did not . The house is on a concrete slab. I have a problem with my walk-in-beer cooler located in a convenience store in W. TN. You state the floor “sweats”. Our garage floor gets damp and slippery when it’s humid out which is often in WI. Some of these challenges include potential hydrostatic pressure (basement below water table) and the lack of a vapor retarder below the slab due to the age of the house. Does that sound right to you? Could the cover requirements be reduced? I would expect that you can successfully install carpet in this situation (or any other flooring product), but it is going to require that you find someone knowledgeable to work with that acknowledges the challenges you face in this application. Concrete Vapor Barrier. The concrete slab is then poured directly over the vapor barrier. Take care. Thanks for the question. A Low-permeance vapor Barrier or retarder can effectively keep below-slab moisture from reaching the flooring system. Thanks for the comment. I am sure you probably already have, but I would go back to the respective manufacturers’ installation documents and/or contact them directly with your situation and get their guidance. Rebar framework and equipment mounting studs will be built into the hole and then the hole filled with cement. Water is an important component of any concrete mix. You should be able to find some type of geotechnical service in your area that can perform a core sample test of the garage floor. The slab is in excellent condition and is 16 years since curing. Thanks for the question. This could be something as simple as varying temperatures and condensation forming on the tile. The wood lasted for a good while (old saw mill type) and we replaced the rotted wood almost 4 years ago. Thanks for the question. We have had carpet with a mold resistant pad for the past 6 years. If this was my project and I had done it multiple times without success, I would do a small test area first. (A mil is one-thousandth of an inch.) Before you can try for a solution, you need to know how big the problem is. Known for our flagship Stego Wrap line of below-slab vapor barriers and retarders, Stego has earned the respect, trust, and recommendation of architectural, engineering, and construction communities. 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