Ditra instead of felt

[J L McCoy]

I'm building shower dry pack floor base and have extra Detra available.
Dry pack is for Kerdi membrane water proof. Would using Detra and no wire as vapor barrier UNDER dry pack instead of plastic/ or felt with lath be a bad thing?
I checked my drain position and preslope will work.

[cx]

I trust we're talking about Schluter Ditra, Jeffrey?

The purpose of the polyethylene sheeting or roofing felt under the drypack over a wood framed subfloor is to prevent the wood from sucking the moisture out of the mortar before it has a chance to cure properly. It is not intended to be a vapor barrier or even a vapor retarder, just a moisture barrier.

Ditra would be serious overkill for the application and I don't think it would serve the purpose of the expanded metal lath you should have there. But it's your shower and you can certainly do it in whatever manner you feel comfortable with.

Originally Posted by Jeffrey

I checked my drain position and preslope will work.

'Fraid I don't unnerstan that at all.

My opinion; worth price charged.

[Kman]

Welcome to the forum, Jeffrey.

If you're installing a Schluter Kerdi shower, you won't have a pre-slope, but just one single mud bed that incorporates the Kerdi drain.

[J L McCoy]

Thanks
I am using kerdi Membrane with a mud pack base. My choice of words are wrong.
Ditra I miss spelled.
I have ditra about 5x5 ft piece that I will never use. I was thinking Ditra alone as moisture barrier for dry pack. Or possibly Ditra with metal on top stapled to sub floor.
Don't have any felt but I do have heavy plastic, if it was your shower would you get and use felt, plastic, or use up Ditra

[Davy]

Ditra, is not designed for that. The Ditra won't hang on to the dry pack like lath will. A couple plastic trash bags stapled down will keep moisture away from the wood. No one knows if Ditra alone would cause a failure but why take the chance? If it failed, it would be a costly repair.

[J L McCoy]

Listening and will use felt
Thanks

[jadnashua]

As said, the plastic or roofing felt is there to help prevent the subfloor from sucking too much moisture out of the dry pack before it can cure properly...it doesn't take anything fancy. Pretty much any plastic material should work. Once the stuff has cured, it really doesn't provide any subsequent purpose.