Using Tapcons through the wood will negate the purpose of the dimple membrane. A kazillion holes in it?? Think about it. Why do you want to go to all this expense? If you are having moisture or water problems, this won't solve it. Adding XPS will only make the threshold at the sliding door inaccessible.

Others may advocate what you are doing, tub I would not want wood on a concrete floor. What will be your final flooring?

 

Thanks for the feedback. No water or moisture issues.
The thinking is the dimple mat gets me off the concrete by half an inch and creates a vapour barrier if there ever was any moisture. If there were ever a water leak event it gives 1/2” space for water to get to drains and dry. Also a 1/2” space that has to fill up before it gets up to the plywood.
Simply put, buys some time to respond to the water beetle detectors before there is 1-2” of water in the basement.
Final floor will be water proof LVP.

 

But drilling holes in the dimple mat won't keep it moisture free. Using waterproof LVP, like LIfeproof, will not gain anything by adding height. It is waterproof. Vacuum up the water and move on. If it needs removing so be it. It would need removing if you had the plywood, but now you have to remove the wet moldy plywood. Not a good way to go, IMO.

You could return the dimple mat and plywood, have enough money to buy good quality LVP, and go out to eat a few times.

 

But drilling holes in the dimple mat won't keep it moisture free. Using waterproof LVP, like LIfeproof, will not gain anything by adding height. It is waterproof. Vacuum up the water and move on. If it needs removing so be it. It would need removing if you had the plywood, but now you have to remove the wet moldy plywood. Not a good way to go, IMO.

The dimple mat is creating a thermal break and keeping any damp air out of the living space.
What would be your suggestion for subfloor to get up off the cold concrete, create an airspace, and give a solid subfloor for finished flooring?
Don’t say sleepers bc I’ve seen first hand what a flood does to that method.

 

Why not use a product like Dri-Core. Combines the 'dimple mat with the hard surface. I certainly wouldn't be putting rigid foam down as the surface that the finished flooring sits on.

 

IMO it is grossly over priced, not conducive to a concrete floor that has any height variations, and the osb it’s made of is about as unforgiving to moisture or a leak as it gets.
I’m not looking to put finished floor on ridged, but looking to put ridged between dimple mat and 3/4” plywood as added insulation.

 

I installed a lot of wood floors using a double layer of plywood over a sound barrier. This is similar to what you want to do. Install your dimple mat, then lay the first layer of plywood over the dimple mat. DO NOT FASTEN IT TO THE CONCETE. Lay the second layer of plywood over the first layer of plywood in the opposite direction, or on a 45-degree angle, using screws or staples that WILL NOT penetrate the bottom layer of plywood. Leave the required space next to any immovable objects, such as pipes and walls. By laying the second layer of plywood on a 45-degree angle you will be able to install a plank floor in either direction without having the plywood joints aligning with the joints of the finished new floor. You now have what we call a floating floor. The fasteners are not penetrating into the concrete, or dimple mat, and the plywood can expand and contract. It's possible to use two layers of 3/8", using an adhesive and screws if the height will be a problem. I prefer two layers of I/2". You can put a nail down, glue down, or floating floor on top. This is a very old method and has been working for years.

 

IF you are going to put that much weight on the dimple mat, why not just use 10 mil plastic as a vapor barrier? Dimple mat will flatten out with the weight.

 

This is what I’m talking about, but possibly adding 1/2” xps between the dimple mat and 3/4” plywood.

 

So you have a basement with no sign of water and no way to heat the floor and you are thinking of jumping hoops and spending money for what purpose?
Do any of these suggestions comes with a result like floor temperature when it is a finished living space?

 

So you have a basement with no sign of water and no way to heat the floor and you are thinking of jumping hoops and spending money for what purpose?
Do any of these suggestions comes with a result like floor temperature when it is a finished living space?

Not sure I understand your comment. I’m reno’ing a 35 year old home, including the the basement. That would include flooring. If you are suggesting I go directly on the concrete with finished flooring, that’s not going to work in a Canadian climate.
This is a popular subfloor method in cold climates.

 

I think you are already mindset on installing the mat and plywood with holes drilled all through it. I've already indicated you won't have the break you think you will with all the holes in the mat. So, I'll leave it to you to make the decision. Best of luck with it.

 

It really doesn't matter, if water is coming up thru the floor you do not start finishing. Screws would not hurt.
The problem with dimple board is that allows house are to get under the floor where the moisture can condense into water. Foam board between plywood and concrete would be a better idea but I have never seen proof that there is a cost benefit unless you are adding heat to the floor.

 

My worry wasn't about drilling holes in concrete. It was about drilling a kazillion holes in the mat, which would render it useless as a barrier at that point.

 

I took some time and watched the video above. I think that this video is another example of 80% or more of the videos that should be titled HOW I DID IT, not how TO DO it. If you didn't watch or listen closely you may have missed the part where he injects silicon into each hole after vacuuming the dust out of the hole. I happen to disagree with him. I don't think that 100% of the holes can be blocked well enough to stop moisture from coming through them. We all have our opinion.

 

I would contact the mfg. directly and see what they recommend.
All you get here is opinions unless someone has actually done it.....assuming THEY followed the mfg. instructions.
As joe954 eluded to, the internet is a vast wasteland of information.....some of it may be accurate, some not so much.
And watching it never tells you which is which.

 

I have only seen this product advertised and haven't used it, but it might be worth looking into for your use. Of course, you also have to consider what the flooring manufacturer will warranty.

DMX 1 STEP 2.0 ™ |Advanced Vapor Barrier |No Mold. No Cold. | The Famous Blue Rolls | Dimpled Underlayment

Or consider Joe's suggestion above.

 

Just a question for the OP, have you discussed the additional liability this additional work represents to your home owners insurance policy ? Remember, in the case of a broken water pipe they would need to remove all damage and hire contractors to rebuild. That work would be at contractor pricing, not your diy costs.
Bud

 

I have only seen this product advertised and haven't used it, but it might be worth looking into for your use. Of course, you also have to consider what the flooring manufacturer will warranty.

DMX 1 STEP 2.0 ™ |Advanced Vapor Barrier |No Mold. No Cold. | The Famous Blue Rolls | Dimpled Underlayment

Or consider Joe's suggestion above.

Looks promising, provided to OP is planning to install a hard floor.

If you are suggesting I go directly on the concrete with finished flooring, that’s not going to work in a Canadian climate.
This is a popular subfloor method in cold climates.

I've had three houses with finished basements that were carpet directly on the concrete (obviously, you need zero moisture issues) in central Ontario. All predated any kind of basement 'flooring systems'. I never found them to particularly cold. Most of the heat loss is through the walls. I read somewhere that only about 1% of the heat is lost through the floor and that the typical temperature is about 55F/13C. HVAC is basements is a bigger challenge to make them comfortable. Out current house is some kind of engineered floor but there is in-floor heating.

 

Can I ask what your final approach was? This is basically the same setup/issue I have - 40 year old house, a little bit of moisture wicking up through the concrete, I was thinking of some barrier layer/insulation ++ vinyl on top (to use the space as a gym). Currently, the previous owners laid LVF directly on the slab + kept a humidifier going, but that's not a long term fix.

Thanks!

 

Foundation 1/2” dimple mat (rated for interior use) on the concrete with all seams sealed with vapour barrier tape. The half inch gives airspace for any moisture to dry and provides vapour barrier between concrete and subfloor.

Then lay 3/4” tongue & groove plywood Subfloor on top and tapcon into the concrete. All holes pre-filled with silicone.

Then laid LVP with a cork backing.

Turned out awesome and basement is extremely dry, warm, and cozy. Temp stays within 1 degree of the main floor temp without supplemental heat.
Here’s a few pics: