pressure treated plywood for floor of a metal shed

[patressa]

several people have told me that one should not build a metal shed on pressure treated plywood base, claim it speeds up rusting of metal, true or false?.purchased both pressure treated lumber and plywood

[Ed Pawlowski]

I don't know about sheds, but some fasteners will corrode from ACQ or CA treated wood. They are, of course, in direct contact. Perhaps a barrier of some sort is all you need.

[gfretwell]

I am really starting to question the concern. I am 3 1/2 years into a science fair project where I put CaC out in the weather with an assortment of metals and fasteners. So far I having no signs of external problems. I will be taking it apart at the 5 year mark to see what I have.

This is a Florida southern exposure to full weather.

[clare]

IF you put a layer of Blue-seal membrane between the shed and the PTP you should be OK as long as you use hot dip galvanized or stainless fasteners to hold the shed to the floor. Direct contact of metal to PTP is not good for the metal (steel or aluminum)

[clare]

The new ACQ is worse than the old stuff. There are ceramic coated" deck fasteners that seam to wotk well - otherwize hot dip galvanized or stainless are highly recommended. A friend's garage had aluminum cladding in contact with ACQ lumber and it corroded right through within 3 years. The steel hardware of the garage door is severely compromized about 7? years after install. The same hardware on standard SPF lumber is in good shape after 43 years (the house was

8 years old when I bought it 25 years ago)

[gfretwell]

ACQ is really not around that much these days. CaC seems to be the PT of choice for the upland crowd. I live close enough to salt water that I can still get CCA. 0,6 or 0.8 is going to last for decades if it is not submerged and 2.5 CCA will do 30+ years in tropical salt water if you wrap it. That is more like 50 years in direct burial, upland.

[DerbyDad03]

Common nails, aluminum nails and toe nails, oh my!