Insulating and Sealing Existing Concrete Slabs (AVOID Moisture Issues)

If you're planning to retrofit a slab on grade floor, it can be frustrating to see your new flooring buckling, warping, or mold on your interior finishes. In this video, we will discuss a strategy that you can use if you have a damp slab on grade and are unsure how to insulate it properly without risking potential moisture problems in the future by using a dimple mat and some rigid insulation.
Working with a damp existing slab on grade foundation can cause problems if you're planning to install moisture-sensitive interior materials like wood flooring, paper-faced gypsum or a new wood subfloor. Moisture moves from high concentrations to low concentrations to establish equilibrium. Poor drainage around the foundation and lack of a vapor barrier typically cause moisture to migrate up through the slab to the interior and be distributed to the moisture-sensitive materials. Water that accumulates around the slab edge is driven inside through hydrostatic pressure and wicked deep into the slab due to the high porosity of the concrete and lack of a proper capillary break.
To mitigate the effects of moisture on your interior finish materials, you need to provide a vapor barrier and a capillary break between the damp slab and the interior. This is where the dimple mat comes into play...
A Guide To Moisture Management For Residential Remodels (eBook) : asiri-designs.com/shop/ols/pr...
For more information on remodeling existing concrete slab floors, check out these articles: asiri-designs.com/resources-1...
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[@ASIRIDesigns]

*A Guide To Moisture Management For Residential Remodels eBook:* asiri-designs.com/shop/ols/products/moisture-management-for-residential-remodels

[@nenadpopadic2781]

i have yet to come across someone who explains it this simply and informs every choice for the design of a slab detail. Very good job!

[@Guishan_Lingyou]

These videos are great. I am going to buy your ebook right now. Love the free info but happy to pay for some good details and pictures. Edit: I wish I had had access to this information when I first started messing with this old dilapidated house.

[@MrBill99]

Great information for a critical issue.

[@macjusss]

Love these videos!! A lot of value!

[@Armineh11]

loveeee your posts

[@ASIRIDesigns]

Thank you so much! More coming every week.

[@Armineh11]

Can’t wait

[@glenhackbardt1354]

Great info, thanks for sharing. I appreciate the emphasis on "perfect" air sealing of dimple mat or it will not function properly. How many would haphazardly throw down the mat and not be meticulous about the seams, edges, plumbing penetrations etc.

[@waynesweeney176]

What changes would you make for an above-ground bathroom build to adjust for the additional moisture and tile? Would a Shluter DITRA uncoupling membrane followed by a KERDI membrane system be sufficient? Would cement board between the Advantech subfloor and the DITRA be necessary for tile or would you skip the Advantech and go directly to a cement board product for the subfloor, followed by DITRA and KERDI? I really appreciate the input!

[@cottagekeeper]

How do you attach the wood subfloor??? 🤔 I'm thinking you can't attach to the concrete because that would compromise the dimple mat, right??

[@LaJotaFranco]

So here with your example, the 2 layers of subfloors are glued and screwed to each other and then floating on top of the insulation ? Not screwing in down to the slab ?

[@ASIRIDesigns]

That's exactly right. We also adhere the insulation to the dimple mat. No fastener penetrations through the dimple mat.

[@LaJotaFranco]

@@ASIRIDesigns okay thanks! It works the same on a basement slab too right ?

[@ASIRIDesigns]

@@LaJotaFranco Yep! The only difference is that you need a sump pit and ensure it's sealed at that location.

[@LaJotaFranco]

@@ASIRIDesigns Thank you!

[@timrxn5414]

@@ASIRIDesignsI love your videos. Will buy your book on rehabbing an old house. Does that include details on how to seal dimple mat to sump system? Not sure how I would do that…. Thanks for your work

[@nofurtherwest3474]

Could this strategy be used on a basement floor?

[@ASIRIDesigns]

Absolutely! I specify this regularly for basement retrofits. The only difference is that you need a sump pit sealed to the dimple mat so that any water that leaks into that space can be pumped out.

[@nofurtherwest3474]

@@ASIRIDesigns Interesting, thanks!

[@adamliberman6767]

If the basement floor has Stegowrap and XPS under it, would you still recommend the dimple mat under plywood or Advantec subflooring?

[@coasttal123]

Wouldn't a ZIP R6,9,12 panel and one layer of Advantech work just as well, as what you have shown above?

[@ASIRIDesigns]

ZIP-R isn't designed or warrantied for floor or roof assemblies yet. Plus the compressive strength of their polyiso product is slightly lower than what you would want for this type of application.