Does pressure treated lumber rot non treated lumber when they are in contact with each other?

Question

I'm building a shed with pressure treated flooring. I was told that I could not place kiln dried framing on the pressured treated floor because it would rot the wood.

Answer 1

Both of your previous answers contain some truth. Pressure Treated will not cause any other lumber to rot. If you have rot it is because the elements got to the other lumber. Framing wall studs with pressure treated is not a good idea. PT is a much lower grade of lumber that is only to be used in areas susceptible to moisture contact.

Answer 2

No, that is absolutely false. Pressure treated wood and kiln dried wood are used together everyday. The bottom plate of many walls are made with pressure treated wood. The newer formula for pressure treating is copper based and will bleed a little bit of the green color on to the other wood, but it will not harm it. Make sure you wear gloves and wash your hands, PT wood is poisonous.

Answer 3

The pressure treated wood itself won't rot anything, but maybe they were thinking that moisture may migrate through the stable pt wood to the vulnerable wood above. Seems to me that you could isolate the two with either a membrane of some kind, like "building paper" or those rolls of foam they sell at HDepot or paint the top of the treated stuff before you install the deck or walls.

Answer 4

No, PT lumber does not cause anything to rot. I would use PT plate for the walls, but regular fir studs are fine...On the otherhand, why not use all PT lumber..it isn't that much more expensive, and it is all but termite proof. Make sure you block the walls well due to warp nature of PT lumber. Good luck

Answer 5

Yes, but it is best to let the new lumber season a little before you do so or the stain will not combine with the wood as it should. The substances that the wood is treated with will continue to "leach" out for a few weeks or months. I would give it a minimum of six weeks before staining.