Vapour Barrier Basement Floor

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Posted by: from London
2/28/2013 at 10:45:23 PM

Hi there,

I'm tiling my basement bathroom and am wondering if a vapour barrier is necessary. If so, what is recommended?


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Steve from Bath Revival in Oshawa
Date/Time3/1/2013 at 2:45:28 AM

Vapor and uncoupling membrane under the tile is often needed on a basement floor. There are uses and limitations depending on manufacturer. Kerdi is easy to use and can be installed to create vapour barrier.

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Date/Time3/1/2013 at 6:44:50 PM


Stewart here of Sct Floorcoverings. You do not need a Vapour Barrier for installing Ceramic or Porcelain tile over concrete in a Basement.

Best regard,


Sct Floorcoverings, Laminate Flooring and ceramic Tile

Mississauga Ontario,

Ph# 289-814-3023

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Date/Time3/2/2013 at 7:31:22 PM


Yes, you do. We always used DITRA from Schluter. Its more than a vapour barrier, if your basement concrete expands DITRA provides uncoupling through its open rib structure, which allows for in-plane movement that effectively neutralizes the differential movement stresses between the substrate and the tile, in that way eliminating the major cause of cracking and delaminating of the tiled surface.

Augusto Rubio

Portobello Tile inc

403 619 9962

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Date/Time3/3/2013 at 7:49:19 AM


Yes what you really need a a uncoupling membrem like DITRA from schluter industries. This will also act as a vapour barrier but most important will be like a shock asorber for you're tiles should the concreet want to shift or crack slightly.

Rene Rozon Construction

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Date/Time3/3/2013 at 2:56:17 PM

Hi Steve,

Stewart from SCT answered your specific question correctly. Vapour barrier is not required. The procedure of using Ditra underlayment would be considered an upgrade in your installation as it is not needed by the OBC but is beneficial with respect to potential movement in the subfloor.

Regarding vapour barrier, Ditra can be used more to manage potential vapour beneath it as opposed to it being used as an actual vapour barrier.

To answer your objective, go ahead and tile directly to the basement slab, if you want to spend some more money and time, install the ditra underlayment underneath first.

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Date/Time3/4/2013 at 12:17:07 PM


You don't need a vapour barrier under your tiles....

Ditra, by Schluter is an uncoupling membrane and is a premium installation.

When determining to use an uncoupling you must first consider on what substrate you will be applying the product.

As an example:

If the slab is new, there is a higher risk of shrinkage cracks in the slab. In this case an uncoupling membrane would be a good idea.

If the slab is old, then the risk of it cracking would be very small. Therefore, an uncoupling membrane would be unnecessary. However, consider hydrating the slab prior to applying mortar. You don't want the slab to suck all the moisture out of your mortar. A Ditra membrane may also be used if you want to raise your tiles, depending on the transition with the flooring outside the bathroom.

Good Luck.

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Andrew from A-Frame Construction in Angus
Date/Time3/26/2013 at 9:17:32 AM

I agree with steve stewart and augusto.

Here in ontario it is not required but I do suggest ditra as it will also help with warmth.

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