Canadian Contractor

The product that keeps basement floor installations dry

A "Made in Canada" product you will want to install in your customer's basement

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December 16, 2012 by Robert Koci

I visited the manufacturing facility of DMX a few weeks ago and got the story on a new product named DMX One Step Underlayment made right here in Ontario. I wanted to take some pictures of the process to prove that this product is not actually made in China, but president Steve Sennik said if I published photos of the process, he’d have to kill me.

The next best thing is right here in this video. Learn its properties, and why you will want to use this product on every basement floor you install from now on. For a more detailed video on the installation process watch this video.


Robert Koci

Robert Koci

Rob Koci is the publisher of Canadian Contractor magazine. Tel. 647-407-0754
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63 Comments » for The product that keeps basement floor installations dry
  1. brian potter says:

    I need to shim my floor because it has a slope toward a drain. The gap is about 2 inches at the drain hole.
    Do I shim directly to the floor then lay the underlayment or do I shim on top of the underlayment.
    I do intend to lay a 5/8 board over the underlayment then my carpet or other finish.
    Any info would help.


    • Paula says:

      Hi Brian,

      We recommend the application of a cementitious self leveling compound on the top side of the concrete slab to bring the slope to within 1/4″ in 4 feet prior to the installation of the 1-Step membrane, the recommended standard slope for floors.

      This will direct any water that does get into the basement area to be drained to the outlets beneath the 1-Step membrane. Using a shim method to apply a top side correction for too much slope has not been successful for most do-it-yourself handymen if they are not experienced at using the proper tools and fasteners for this type of repair.

      In addition, this would most likely require some use of fasteners that pierce through the 1-Step membrane that would need to be sealed, something that adds work to the install.

      Should you have further questions we would be happy to answer.

      You can reach us at or me directly at

      Thank you,

  2. Tim Traplin says:

    We have a basement with a moisture issue. No puddling, or evidence of it when we did the ‘patch test’ in various areas, but enough that we had to remove and toss all the previously laid laminate due to mold and mildew build up underneath. Our contractor convinced us we did not need a vapour barrier underneath as the concrete needs to breathe and laminate is apparently totally waterproof. We have no leaks in the walls, and we have cut open sections of the wall to test for moisture and odours and found none. It all seems to be coming in through the floor. At present there’s a ‘wet dirt’ type of odour that becomes stronger during humid/rainy conditions. We’re also looking at possible causes of water build up under the house itself.

    We’ve since chemically sealed the floors throughout, painted (3 coats), added a portable dehumidifier, and are ready to redo the flooring. On average I’d say we have about 50-60% relative humidity down there without the dehumidifier running. I like the laminate for the fact that it shouldn’t hold moisture or odours like carpet would. Would it be okay to do a double layer of 6mm vapour barrier directly on the concrete, and this ‘DMX 1 Step’ on top of that as a sub-floor/extra vapour barrier insurance? Or would it cause additional potential problems? Allowing the concrete to ‘breathe’ into the basement in any way just leads me to believe it’ll ruin any flooring we try down there.

    • Paula says:

      Hi Tim,

      From the details described in your question, it does appear as though you may have ground moisture conditions that are affecting the home environment with too much humidity, as evidenced from the “wet dirt” type odours that you have noticed. If you have not experienced or seen evidence of leaks in the foundation walls, then there are some conditions which may apply to your home that are contributing to the high humidity;

      a) The age of the home, or the construction of the home may not have allowed for proper vapor control by the use of vapor barriers, ventilation fans in the bathrooms and kitchen areas, or the lack of use of these fans when needed.

      b) Ground moisture may be high in your particular area, meaning that you could be affected by a high water table level. This can cause excess vapor moisture to migrate upwards toward the dryer air in the basement and wicking through the pores or capillaries of the concrete slab, which can have an impact on the humidity levels in the basement

      c) The grading around the property may not be directing surface away from the building properly, which can lead to high moisture conditions in the soil around the foundation and high humidity levels in the living area due to what is termed “vapor moisture pressure equalization”. In simple terms this means that the high concentration of ground moisture is trying to equalize itself to the interior dryer air so both the interior and exterior environments have the same humidity levels.

      d) Improperly installed or lack of perimeter foundation drainage of ground moisture to a positive outlet can lead to high moisture conditions in the soils around the basement, and under the concrete slab, which can lead to high humidity in the basement area.

      There are others factors as well which can lead to high humidity in homes such as described in your question, but for the most part, the conditions above are the more common links to the reasons for the humidity.

      As for the use of a vapor barrier (flat sheet) on the top side of the concrete slab it is not recommended since any moisture condensation will collect and allow mold/mildew to propagate, and if you ever do get a leak in the foundation the water can build up under the poly sheet and stay wet for some time. This will have a negative effect on your laminate flooring and assist in the propagation of moisture induced damage to wood and other porous materials.

      The use of the DMX 1-Step provides the properties of a high quality vapor barrier material with the added advantage of providing drainage for leakage water to flow to the floor drain area, thereby not accumulating water of any quantity for an extended period of time. If your basement is not yet completed to the drywall stage, you can seal the 1-Step to the concrete walls using a limited expansion polyurethane foam to seal off any vapor moisture from finding its way into your living space.

      If your walls are finished to the drywall stage you could look to sealing the vapor barrier used to separate the bottom plate of the exterior wall framing from the concrete slab to the top of the 1-Step thereby creating a seal around the perimeter of the basement walls. This also would provide protection from vapor moisture traveling into you living space in the basement from beneath the concrete slab area. The use of an elastomeric sealant to seal the two membranes together would create the appropriate seal, which can be found at most building supply outlets.

      When dealing with high humidity levels in a home there are many factors that can influence the cause that need to be investigated and ruled out one by one in order to find the true source of the humidity input source. Basements are cooler than the rest of the home because of their location, and humidity shows up usually first in this area than in any other area of the home. Good ventilation and moisture controls are the first line of defense against most humidity related conditions within a home.

      Our technical person has given some information on conditions that may happen, but if you would like to be more specific you can contact me directly and we will get all your questions addressed.

      Thank you,

      • Hope says:

        I have the exact problem like you in my 60 years old house. I have done lots of research and talked to many builders. The way that DMX1 advises people to seal air tight the sheet around basement walls are terribly wrong and great way to have mold in your floor b/c floor drain is not in the middle of the house, if it is then you are in trouble breathing those stinky water. Floor drain is usually in the furnace room, if there is water running like river on the concrete slab, it would have to pass through many walls and you would get lots of mold and mushroom growing on these walls. You can use DMX1 but with the method of Dricore, you leave 1/4″ gaps around the walls for air to come in to dry out any moisture, the amount of moisture breaths through concrete is very little, slow and lesser quantity than your shower and washer, let it vaporizes into the air and dries out on its own through the gap. You can buy floor epoxy paint from contractors’ stores or ask HP, it works as vapor barrier but breath. Two coats is better than one..

  3. Mike says:

    Hi, can I lay vinal ( Allure ) planks directely over DMX or do I have to lay plywood between the vinal planks and DMX?

    Truly, Mike.

  4. Paula says:

    Hi Mike,

    We would suggest that you use a plywood or OSB board on top of 1-Step and if you are using a Vinyl flooring.

    The reasons we suggest this are as follows:
    – In most cases Vinyl is too flexible, and would move too much if laid directly over 1-Step, which would wear at the seams of the planks.
    – Vinyl may be too light. We have found that if a product weighs less than 1.8 lbs/sq.ft. it is too light to keep from moving too much.
    – Vinyl flooring also has an ability to telegraph the surfaces irregularities in the substrate through the vinyl planks over time. It would do this by settling into the negative void of the 1-Step, which would be a problem over time.

    I hope this does not deter you from using our product, however, with Vinyl planks we suggest using plywood.

    Thank you,

  5. Tim says:

    Hi, Paula

    i think i’ve had moisture issues through my concrete floor. i have no evidence of leaks anywhere. Before covering up my floor, i have never had any musty smell on the floor. When i finished my basement, i used a special underlay and then carpet. After a few months, my basement started smelling very musty even wtih a humidifier running. Since then i tore out the carpet and underlay and left it for a few months and there was no smell at all. So bizzare. I then did some research and was thinking i was getting some moisture through the floor when covered and was going to install drycore until i stumbled uopon DMX step 1. With the idea of allowing the floor to breath better, I installed the DMX product with 12mm lamminate on top and left the quarter rounds a couple mm above the lamminate to allow airflow. It has been almost a year with the DMX product but still notice a very light musty smell; probably because im paranoid and go looking for it. when i bend down to the baseboards/quarter rounds and put my noise to it, i can detect a slight musty odour; keep in mind I run a newer dehumidifier. Again the smell is no where as bad as when i had the last underlay and carpet. i was wondering if you recommend that i cut out vents around the perimeter every 10 feet (like as for drycore); exposing right down to the concrete and put vent covers to allow more airflow. Again, when the floor isn’t covered, there is never a smell. i am thinking that more airflow would help. i would appreciate your opininion. Note, i have several air ducts + a cold air return in the basement to aid in air circulation. Looking forward to your comments.

  6. Tristan says:

    We are looking at possibly using DMX One Step over a concrete basement floor. We are going to use vinyl planks as our flooring. Is there a certain size of plywood/OSB board you suggest. 1/4 or 3/8. We have ceramic tile that is laid by our doors and we want to try to match for a seamless transition between the two.

  7. glenn S says:

    I am looking at installing DMX 1 step under a hardwood floor. I want to float the hardwood floor. I assume that i will need to put down T&G plywood first on the DMX to get a good surface or could it be applied directly.

    • Paula says:

      Hi Glenn,

      Yes you are correct the T&G would need to go on top of the 1-Step in order to ensure that you have the correct surface for your hardwood.

      Thank you,

  8. Michael Albeser says:

    I see that DMX-1 is used on basement, but can this product also be used on a crawspace floor? If so, how would it be installed and what prep needs to done to the floor? At this time I have hardwood on the kitchen floor and plan to remove and install tile. Look forward to hearing back from you.

  9. Paula says:

    Hello Michael,

    Your question was very intriguing, so I included

    Crawl Space w/Kitchen over:

    1) Level out the floor of the crawl space (if it is dirt now), if concrete with self leveling compound.
    2) If the walls of crawl space are insulated, lift up insulation 12″ above dirt or concrete floor and tack with tape.
    3) Install the DMX AG (if it is dirt floor) over entire floor area, ensuring overlaps are 6″ minimum and taped with Tuck Tape.
    4) Install the DMX 1-Step (if it is a concrete floor) over floor area, ensuring butt joints are taped with Tuck Tape.
    5) In both cases, seal the membrane to the exterior walls using a polyurethane foam (from the can) to make the membrane vapor tight (see dwg on our web site).
    6) Return the insulation on walls (if it exists) back to the floor elevation, ensuring the vapor barrier over the insulation is intact (no tears or holes).
    7) Since the area is a crawl space, the plastic HDPE of the DMX membranes should not be left exposed and should be covered with a product such as wood paneling, steel sheeting, to protect it in case of fire as the plastic can contribute to smoke development in a fire situation and required chemical extinguishing not water when left exposed.

    Trusting this answers your question, good luck with your project. Get back to us if you should have additional questions.

    Thank you,

  10. Puneet says:

    Hi, we are planning to use DMX or Delta FL to apply directly to the concrete floor in the basement. We want to use laminate flooring. of 10mm or more. My question here is:
    1. What is the difference in using Delta and DMX
    2. Is it necessary to hae a plywood sub floor to be put on top of the DMX/Delta
    before laminate is installed?
    3. Should we use foam padding between DMX and Laminate

    Please advise

    • Paula says:

      Hello Puneet,

      1. DMX 1-Step has a foam on the base of our product, at the very least this will eliminate the clicking sounds of the rigid plastic from clicking on the cement. In the Delta installation video they suggest that you use a needle-punched geo-textile (landscaping cloth) below the Delta FL in order to eliminate this noise.

      2. With a 10mm or thicker Laminate you do not need to use OSB or Plywood, you would just need to ensure that your cement is within a 1/4 inch differential within a 4 foot radius.

      3. If you would like to use a foam padding in between DMX 1-Step and your Laminate this will add an additional layer of friction, however, you do not need this as protection for your floors as the DMX 1-Step is a vapor barrier.

      Please feel free to contact us again should you have more questions. Also on our website we have links to videos that compare us to our competition and more information about our product including testimonials from other customers that have used DMX 1-Step.

      Thank you,

  11. PA says:

    I want to install carpet in my basement. I am planning on using DMX 1-step and will put OSB on top. Can I put a tapcon through the DMX?


    • Paula says:

      Hello PA,

      You are absolutely able to use Tapcons to secure the OSB into the cement. We recommend that you predrill the OSB and the DMX 1-Step before you use the tapcon screws so that you can dip the tapcon screws in a butyl rubber or a polyethylene sealant in order to coat the DMX 1-Step and maintain the seal.

      There is more detailed information about this on our Frequently Asked Questions page on our website:

      Please feel free to contact us with more questions.

      Thank you,

  12. Matt says:

    I converted a garage into a playroom and the floor is cement. I put laminate flooring down; however, the floor gets so cold in the winter, it’s unusable because the floor is basically like a high powered air conditioning unit. Will DMX stop the cold. Should I put plywood down to further help insulate? Thanks

    • David says:

      Curious if there were a reply to Matt’s post. I am converting part of my garage into a home workout room. Trying to determine best application for the flooring, keeping it from being too cold, etc..

      • Paula says:

        Hello Matt, David,

        Yes DMX 1-Step provides a thermal break that will help increase the warmth of the floor.

        So you will definitely notice a difference if you use DMX 1-Step under a 10mm or thicker laminate or a 3/8 inch Engineered Hardwood, but there would be additional warmth from adding an additional layer like plywood.

        Thank you,

        • Zoubir says:

          Hi Paula,
          If I undestand it’s better if I use DMX 1STEP + Playwood/OSB + Laminate?
          Bcause I’m plannig to use DMX with laminated 12mm without Playwood/OSB.


  13. Antony says:

    I am planning to use it in Basement. In case, After flooded in basement(with DMX Underlay), Can i wash this product and re-use it ? Please explain test case scenario for this product ?

    • Paula says:

      Hi Anthony,

      Yes you can wash the DMX 1-Step and then relay it and use new tape for a new vapor seal.

      What type of test case scenario would you like explained Anthony?

      I would be happy to provide you with any specifics you would like. Feel free to post the specifics you are requesting or email me and I will provide it direct, whichever you are most comfortable with.

      Thank you,

  14. Oleber says:

    Hi Robert, Great product and great video, thanks to you guys.
    When can we see the next interview on the OCOT?
    If you go there, please do us a favor, let no stone un touch it.

    Good luck

  15. ck says:

    Hi there. . Looking to install allure vinyl tile and plank (click version) throughout a one floor 1150 building on concrete slab. Please explain best process from laying dmx to finished surface. Thx

    • Hi CK:

      When installing the LVP and LVT systems if is best if you install a T&G OSB or Plywood subsystem over the 1-Step first. The main reason is the support of the “click lock” joints system which should be supported over its full length.

      The 1-Step dimples create a void on the flat side of the membrane (dimples are always installed face down) and this will give way to potential stress issues at the click lock joint in these areas if the LVP and LVT systems are installed directly on the 1-Step without a subsystem (which is the same for all dimple sheet systems).

      For installing the subsystem visit our web site for drawings which shows how to do this. Once this is completed, you will have a much better experience with the finished product, and all the benefits that 1-Step offers over competitive dimple sheets.

      Good luck with your project.

  16. mm says:


    So I am looking to do a basement that is generally dry but gets some minor foundation leaks through the wall in the spring. I am not framed yet and i have seen the suggestion of running 1Step up the wall an sealing it. Can I do this and then have spray foam insulation or am I going to have issues?

    Also I here lots of talk about hardwood, can this be used for real hardwood or is it just the engineered hardwood? is the a way to do ceramic over 1Step?

    Thx in advance

    • Hi MM: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      If your basement is not yet framed you are correct that you can install the 1-Step to the concrete walls and seal it to the walls as shown on our web site under the Installation Instructions section.

      If you intend to spray foam on the walls of the foundation you will not need to foam the gap between the 1-Step and the wall, since the spray foam on the wall will do this for you. Any water that does leak through the wall will drain between the foam and wall, then drain under the 1-Step to the floor drains or sump pits.

      For real nail down hardwood you can apply this over the 1-Step, but you will need to install an OSB or Plywood subsystem over the 1-Step first. This will become the nailing surface to fasten down the hardwood, whether it is adhered or nailed down. The best suggestion would be to install the OSB/Plywood after the foam insulation and 1-Step have been done, leaving a 1/4″ expansion gap between the wood subsystem and the foam insulation.

      You can build your wall on top of the OSB/Plywood panels without the need for a vapour barrier since the foam has a low permeance rating and does not need a separate vapour barrier. The wall you install on top of the 1-Step must only be non-load bearing, as we do not know the details of any load bearing from the main house to make any judgment call on suitability.

      Trusting this answers your questions, good luck with your project.

  17. bhush says:

    Just wondering if i can use DMX AG for underlayment in basement?
    If not why. If yes then what is the difference between DMX AG & DMX step-1

    • Hi Bhush: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      The DMX AG is only recommended for use on the exterior of foundations for two very good reasons:

      a) The material is made of recycled HDPE which has a tendency toward giving off an odour due to the raw material that is used (soap bottles, milk bottles, etc) to make the material.

      b) The material does not have the sound deadening benefits of the 1-Step such as foam adhered to the dimple sheet. This can cause a clicking sound when you walk across the floor through contact the dimples make with the concrete floor slab.

      The odour is not harmful to you, but is an annoyance to many especially if you are prone to allergies or irritants. There are other benefits that 1-Step offer as well that are not provided by the DMX AG product.

      If one chooses to use the DMX AG as an underlayment DMX is clear that they will take no responsibility for any issues related to your flooring should you have problems. In addition DMX provides no warranty for the DMX AG when used as a flooring underlayment.

      We trust this answers your question and provide you with the information you need to make a decision on the proper underlayment for your project.

  18. Stephanie says:

    Hi! Do you recommend the use of 1-Step with ceramic tiled flooring, in the basement, and if so how would you suggest that I do this? We want the tiles to be warmer, and match-up in height to the carpet that will also be installed in the basement.

    • Hi Stephanie: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      The installation of ceramic type tiles can be placed over the 1-Step in much the same manner as the carpet by the installation of a T&G OSB or Plywood subsystem over the 1-Step first.

      The procedure for doing this is shown in drawing form on our web site in the Installation Instructions section of the site under the 1-Step product area.

      Trusting this answers your question, good luck with your project.

  19. Gerry Giorgi says:

    I am finishing my basement and plan on using laminate flooring on concrete. The concrete floor is slightly uneven in certain areas, 3/4 on an inch over a 5 foot radius. Can I use Dmx and shin in te low areas.

    • Hi Gerry: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      Yes you can install laminate flooring over the 1-Step underlayment without issue.

      To level the concrete slab floor area we recommend the use of a self leveling compound over shims as we have experienced clicking and crackling noises using shims under the low areas of the floor.

      There is an explanation for leveling the floor and how to go about checking the entire floor area before you start the installation of any leveling compounds.

      The following is a detailed procedure for checking the floor:

      To level a concrete floor the best approach is to use a string line, that is a piece of string or cord from a ball of general purpose cord. Cut the string line so that it is long enough to reach from corner to corner diagonally (X shaped) of the area or room you intend to level.

      Once you have the sting line, you will need a helper to take one end of the string, and using thumb pressure hold it on top of the concrete slab in one corner (wrapping some cord around their hand helps to position and hold the string in place), you take the other end and pull the string taught (firm and straight) with the string wrapped around your hand and placed on top of the floor using thumb pressure to hold the string taught.

      Identify the areas of the floor that appear to be lower than the highest point(s) in the floor (which will be in contact with the string). Locate them by marking on the floor the areas using a piece of chalk so that the total sum of the low area is more easily visible when you try to level the floor.

      Repeat the steps above for the alternate or opposite corners of the area, and after this just to be sure you have all areas covered, do the same procedure across the middle of the area in both directions (in a “+” form). This process is what is called “traversing” the floor.

      Once all areas are identified and marked, using a self leveling compound, which you can get from a builders supplier (or Home Depot), you spread the leveling compound over the low areas you marked with chalk in accordance with the manufacturers’ instructions which are normally found on the back of the packaging.

      Once the leveling is complete, you are ready to install the 1-Step underlayment and your finished floor. Good luck with your project.

  20. Brenda Walkeden says:

    We are using sheet vinyl in the basement. Can this be laid directly over 1-Step.

    • Hi Brenda: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      To install sheet vinyl over the 1-Step underlayment you will need to install a T&G OSB or Plywood subsystem over the 1-Step first. Sheet vinyl by itself would not be supported over the negative void of the dimples in the 1-Step, and the adhesive used to bond the adhesive would not work well directly on HDPE sheet.

      There is a drawing on our web site in the Installation Instructions section of the 1-Step area of our site which shows the installation of the OSB/Plywood panel system over 1-Step in detail. Once this is done you will be ready to install the sheet vinyl be happy with the installation.

      Trusting this answers your question, good luck with your project.

  21. Pat Kowal says:

    Hello, I live in northern MN and have built a 3 season (soon to be heated) porch on the back of our cabin. I have a 3/4″ treated plywood subfloor and wish to install your DMX 1 Step on top of it and vinyl plank flooring on top of your DMX. Good idea or not. Suggestions! Thank you.

    • Hi Pat: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      To install a LVP system over the 1-Step you will need to install a T&G OSB or Plywood subsystem over 1-Step first. The LVP system is not suitably supported at the click lock joints over the negative voids created by the dimples in the 1-Step.

      There is a drawing on our web site in the Installation Instructions section of the 1-Step area which shows how to install the subsystem over 1-Step for vinyl sheet goods (which would be similar to that needed for LVP systems).

      Once this is done you will be ready to install the LVP system.

      The use of a wood laminate system directly over the 1-Step would negate the need to install a subsystem over 1-Step, which could be a viable option for you since the area will be heated.

      Even in a cottage setting wood laminate should perform well as long as there is not excessive moisture built up during the winter months when you are not typically using the building much, especially if the building is well insulated.

      Trusting this answers your question, good luck with your decision and project.

  22. George says:

    Hi Paula, just I wander the perimeter of DMX 1 as it is mentioned above should be sealed (closed), my question is: if this will not create a moister/air trap and in time to develop moisture? Those bubbles are not designated to allow the air/moisture to travel and escape? Thank you!

    • Hi George: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      Good question George!

      If the 1-Step is sealed at the perimeter in a manner whereby the membrane is sealed to the foundation wall as shown in our drawing (which can be found on our web site in the Installation Instruction section for 1-Step) there should be no problems with moisture issues .

      Once sealed, the vapour moisture that gets through the pores in the concrete slab will saturate the air space under the 1-Step to a point where the air can no longer easily take on more moisture. At this point the vapour moisture stops trying to get to the air space above the top of the concrete slab since the air cannot hold any more moisture molecules, and is called “static equilibrium.

      If the soil and ground moisture content below the concrete slab changes seasonally and if the moisture content is dryer the moisture in the air space of the 1-Step will equalize by moving below the slab. This transfer dynamic is ongoing and mitigates situations where mold or mildew can set up.

      We have also provide a means of handling leakage water that gets in through the basement foundation walls, and directs this water under the 1-Step where it can’t damage your finished flooring.

      Trusting this answers your inquiry, good luck with your decision and project.

  23. Greta says:

    Hi Paula… thanks for all the tips… just wondering why there is no answer to Tim from November 2013… we are having dampness issues in our basement and looking at installing your product with Laminate flooring… Tim is saying he still smells a musty smell and wonders if he should install air vents in the floor… please advise.. thanks so much

    • Corey says:

      Paula, I am wondering if this product can be installed so that it is run up the wall an inch or two and sealed to the wall’s rigid foam insulation and then have floor vents cut every 10 feet or so like with other basement subfloor products. If not, please advise. Thanks

    • Hi Greta: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      After reviewing the issues that Tim (Nov. 2013) was experiencing, we addressed these issues the best we could given the information at the time that Tim provided. Without seeing first hand what the real problems are for some cases it is very difficult to be precise with our answers, and in Tim’s case we gave him a list of issues that could create his issue.

      Putting air vents in the floor is not necessarily the proper remedy for moisture and odour issues unless the vent system is evacuating the moisture to the exterior and bringing in conditioned fresh air to replace the moisture laden air. This type of air exchange can be very difficult and expensive to provide depending on the space available for a properly designed exchange system.

      To address your issue of moisture, if you place 1-Step over the concrete slab and seal it to the foundation walls (providing they are not already covered and framed to the drywall stage) using the method outlined in the drawing on our web site for performing this, you should not have issues with moisture.

      In fact our drawing also provides for leakage water that gets through the foundation walls to drain below the 1-Step and drain to a sump pit or other outlet/collection system.

      Depending on how a perimeter tile system was installed, it may have reached its expected service life and isn’t handling ground moisture as well as it did when first installed, which can lead to moisture build up in the soils around the house foundation. This ground moisture will drive to the interior of the basement more in the form of vapor moisture due to what is called “vapor moisture equalization”, which put simply is similar to “osmosis”.

      Depending of the time of year (rainfall amount, snowfall, etc.) this moisture can change and your interior humidity will change in direct proportion to the soil moisture content. Homes built in the late 1950’s to early 1960’s didn’t use good vapor barrier systems typically because the building materials weren’t available, and this moisture transfer process happened freely and frequently.

      Sealing the 1-Step in the basement (if your situation allows for it) will stop the transfer of ground moisture into the basement from the floor slab area for the total square footage of the footprint of the floor slab, which is usually equal to as much as 1.5 X the area of the foundation walls (using a foundation footprint of 60′ x 40′ x 8’ht).

      This ratio of protection will definitely have an impact on the reduction of moisture in your basement, however if other issues are at work (such as discussed in Tim’s original response) this benefit may or may not be negated until the full extent of the all moisture issues are corrected.

      Without knowing more about your home’s conditions such as age, style, location, and known issues you have experienced it is difficult to give you more precise pointers on what could be causing the moisture issues you are experiencing.

      If you get back to us we can look at the issues again and try to provide you with a more detailed response directed more at your issues. Pictures of the area in question also help to give us a “birds eye view” of the situation as well.

      Trusting this answered your questions.

  24. DIYfloorguy says:

    My old concrete floor in the basement has wet soil smell in the bad days. I did put 20″X20″ vapor barrier sheet and taped that down on the floor, no sign of any moisture coming up the plastic. What do you think if I use epoxy interior floor paint that the contractor recommended as paint on vapor barrier on concrete floor and DMX1 on top. I have heard that never sandwich the two layers of vapor barriers to trap air inside, what do you think of poxy paint on floor?

    • Hi DIYfloorguy: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      Before you consider doing any epoxy paint on the concrete slab it would be suggested that you perform a Calcium Chloride moisture test (ASTM F-1869-04) which can be done with a CaCl kit that you can purchase from Home Depot.

      This test was originally used for coatings applied to concrete slabs to determine if the coating would stay adhered to the concrete or not. The fact that you did a vapour barrier on the slab test (which is subject to many variables that need to be considered and monitored during the test) does not tell you if the vapour pressure coming up from the under the slab is < (3 lbs/1000 sq.ft./24 hrs) which is the limit for coatings per the ASTM test parameters.

      If you are getting a soil smell in your basement this could be caused by many factors, none on which you did not mention in your initial question details. The first thing I would look for is cracks or micro-cracks in your concrete slab, as these openings will allow soil smells to get into the basement.

      Damp soil conditions (which can be seasonally adjusted) can produce these odours and sealing the cracks is one way of stopping these odours from becoming nuisances. There are crack sealing materials which can be purchased form Home Depot or a building supply store.

      Without having more details on the home in question, and some specific details about the problems you have been experiencing which could cause these odoours it is difficult to be more precise with our answers.

      If you could provide more detailed information (pictures can also help) about the home and conditions we can attempt to respond with a more definite answer.

      Trusting this answered your inquiry.

  25. Eli says:

    I would like to put DMX over concrete on basement. My plan is to use engineered hardwood (3/8 or thicker) directly on DMX or put a layer of cork (1/4″) between DMX and engineered hardwood. Is that ok to use another level of underlay (cork, or another very thin underlay for sound/absorption etc.)

    I have two rooms/areas in basement, one of which I plan to use as workout room. I have a heavy treadmill and I like to do some free style exercise videos where I am going to be jumping etc. Will this setup hold up with all this activity (DMX + engineered hardwood) or (DMX + cork + engineered hardwood) ?

    • Hi Eli: We apologize for getting to your question later than usual, we had some issues with our Service Provider, but that is corrected now and we are back in business!

      The floor assembly you have proposed with the Cork overlay would work perfectly for your exercise area. It would provide you the benefits of the 1-Step with added sound attenuation with the cork overlay and a bit more cushion as well with firm support.

      Your treadmill will not harm the 1-Step and the laminate should carry the weight just fine.

      Trusting this answers your question.

  26. Trevor says:

    Hi, we are considering installing plank flooring that has a ribbed pvc base, the product is called press lock planks. They are 10mm thick. Could we install these directly over your DMX product?

  27. Chip says:

    I am reconstructing my once finished basement after a flood that soaked my Dri-core and started molding. After my entire floor is ripped up I want to replace it with anything that isn’t wood. There is a vinyl plank product out called Smartcore, that is thick like laminate but made of all vinyl. It is rigid and I was wondering if it could be installed on 1-step without the need of plywood. Could you advise me on this?

    Thank you

  28. Luis says:

    Dear all,

    Is it possible to install Allure Traffic Master with Grip Strip (self adhesive strip on the side of each plank) directly over DMX?

  29. James Abbott says:

    Can I lay 1/2 inch cork tile directly over one step. The tiles are constructed much like engineered wood with a millimetre of cork on the bottom? Also we have found some 1/2 inch thick waterproof vinyl tiles tat we would like to install directly over the Dax. Is this possible? The flooring store thinks that we can since they are as rigid as laminate.

  30. Peter B says:

    Hi there we would like to use the DMX Step one in our basement right over the concrete (no known water issues) and we have a 16mm laminate that we want to use. The laminate has a small under pad built onto it, but would like to know if you would recommend a cork floor underlay on top of the DMX and then my laminate that has the under pad on top of that. The idea is to try and add some extra warmth and cushioning but my wife is worried it might be too spongy when walking on it. Any advice on this is greatly appreciated.

  31. Cindy M says:

    I have installed DMX-1 Step and 5/8 OSB. I am going to build walls on top of the OSB. Do I nail the bottom plate into the OSB or through the OSB into the concrete?

    Thank you

  32. Paulette says:

    hi! I recently pulled the old rug and underlay off the concrete in our walk in our walk in basement. We have to use OSB on top of DMX 1step to ensure a proper moisture barrier and added warmth right? (The other tack boards for the old rug are right on the concrete).
    Just making sure before we try and get those nails out of a perfectly good concrete floor! Thank you

    • Steve Payne says:

      Hi Paulette:
      Reply below from DMX Customer Service…

      “You will need to remove the tack boards installed into the slab directly, since using them would compromise the intent and functionality of the 1-Step and the moisture control features of the membrane. Once the 1-Step is installed using OSB over, properly secured down with the recommended fasteners and sealants, new tack strips can be attached through the OSB panels and into the concrete slab. Tap-Con screws being the recommended fasteners to use for both the securing of the OSB panels and tack strips will afford you more control over the force necessary to hold the tack strips in place without pulling down too tightly on the OSB edges. This will make the perimeter edges more consistent.
      As we always recommend to our customers, bar far the biggest issue with installing any type of underlayment and finished flooring over a concrete slab is to check and ensure that the surface of the slab is level to within the tolerances that we specify on our web site, which is . From the Installation Checklist section you will find 3 different installation types which is fully explained and contains the instructions along with some drawings on installation tips and a full description of the floor level instructions.
      Most finish flooring manufacturers have a tolerance for floor level when it comes to installing their materials over a concrete slab, to ensure that you get a finish and fit that is considered “industry standard” in terms of finish and appearance. Check with your finish flooring manufacturer so see what their recommendations are, they may be more or less stringent. If less stringent we suggest following our tolerance requirement, if more stringent you should follow the flooring manufacturers requirements.
      You can download the complete instruction guide for the particular flooring type you are intending on installing from our web site. We recommend you do this before you start the project just to ensure that you familiarize yourself with the installation tips and guidelines of DMX Plastics Limited. This way you will be more prepared for what tools and processes you will be needing to get your project up and running, and finished in a timely fashion.
      1-Step provides a guarantee that any floor installed over the 1-Step will perform as intended (providedthat the complete installation meets the requirements of DMX Plastics Limited and the flooring manufacturers’ installation instructions) which covers the original cost of the flooring. Details of the warranty are available from our web site, we invite you to visit our web site to review this guarantee.
      Good luck with your installation project.”
      DMX Customer Service
      300 Walker Drive
      Brampton, Ontario

  33. Terri says:

    Can you use dmx1 directly under smart core laminate plank flooring? This will be on a concrete basement floor.

  34. david warneke says:

    I had a vinyl linoleum product ( 1’x2′ pieces that fit together like a laminate flooring) professionally installed. I chose this product because of it’s flexibility due to the fact my floor is not level. It looked great. About 6 months later I noticed moisture coming up thru the joints. Checked along perimeter and found the floor completely dry, so assumed moisture was coming thru the floor. Went back to the company and they informed me that the installation was done properly. I removed the entire floor and put down 2 coats of WATERTITE sealant. Reinstalled a portion of the floor. About 2 weeks later I checked under the installed floor and notice traces of moisture. Did an online search and game across your product. Would this product be something that would solve my dilemma? How does this product allow moisture to escape if you finish off the room with baseboard molding. I also have 4 support post that I need to go around. Your thoughts please.

  35. Walter says:

    I have used DMX AG on part of basement floor with no issues. Recently the product has a statement “not for indoor use” can I still use it or must I use the DMX 1-step ?

  36. David says:

    Sounds great Rob. Was just thinking the same thing using the DMX AG foundation wrap although they say not recommended for floors yet very close to the material of the 2’x2′ boards with the plastic backing.
    Truly would like to know why not recommended for basement flooring?

  37. Keith thomson says:

    Why is DMX AG not recommended for indoor use?

  38. Dave says:

    I am installing DMX one step in my basement. My floor drain is somewhat in the middle of the room and it drains into my sump pit. I plan on putting 19/32″ tongue and groove plywood on top of the one step. Can I go over the drain with the one stop and plywood? This should still allow and water under the one step to drain into the sump pit.