# Are there drywall screws made for ACQ treated lumber?



## miamicuse (Nov 13, 2011)

PT lumber is required when contact is made with concrete. So on a slab foundation the bottom plate has to be PT lumber, also on the inside of concrete wall the 1x2 furring strips are also PT lumber.

All I have ever seen everyone seem to be using regular drywall screws to attach the sheetrock to these lumber. I have never seen a rocker switch to use different screws when he is attaching to bottom plates or furrings over concrete walls.

Yet I kept hearing regular drywall screws would fail quickly on PT lumber.

I did a search and found a few people mentioned they use decking screws on drywalls...but decking screws is not as "flat" on the back side of the screw head and I don't think will seat as well as a drywall screw.

What is the best practice?


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## jlhaslip (Dec 31, 2009)

Most Drywall installers would continue to use the regular bugle head drywall screw and hope the baseboard will keep the board tight. 

It will be a few years before the regular screws will be rotted off, and their cheque will have cleared by then...


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## Windows on Wash (Aug 30, 2011)

+1

Can't say I have seen a deck screw used...or...a drywall screw fail. The lack or moisture in that assembly certainly mitigates the failure rate was well. 

There are plenty of counter sunk deck screw heads that will work fine if you want to go that route and you should only need s box at the most unless the basement is a whopper.


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## del schisler (Aug 22, 2010)

miamicuse said:


> PT lumber is required when contact is made with concrete. So on a slab foundation the bottom plate has to be PT lumber, also on the inside of concrete wall the 1x2 furring strips are also PT lumber.
> 
> All I have ever seen everyone seem to be using regular drywall screws to attach the sheetrock to these lumber. I have never seen a rocker switch to use different screws when he is attaching to bottom plates or furrings over concrete walls.
> 
> ...


use the dry wall screw that is white , i guess it is used for out side so belive fo be for wet use ?


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## joecaption (Nov 30, 2011)

It's the copper the wood is treated wood that's going to react with the steel screws and rust them out in no time. 
First warning sign will be rust bleeding through the paper tape, later on it will be cracked seams because the threads have rusted away.
Stick with the ceramic coated bugle head decking screws.


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## mikegp (Jul 17, 2011)

I used drywall screws into PT lumber to hold lattice on a concrete wall. They have survived 9 years of rain, snow, sun etc and not one has let go. I'd guess I used about 160 of them. Just saying. I'll pull some out and check to see how rusty they are one day. 

Also used regular nails on the ramset and those are also fine.


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## Bud9051 (Nov 11, 2015)

I've taken some decks apart that used the black drywall style screws and those were toast. If it were my home or my job they would be using the special screws anywhere they ran into PT. Homes are supposed to be built to last several lifetimes, using a screw to save a buck that will deteriorate to nothing in a few years is just shoddy work.

There are workarounds, like a double sill plate with PT on the bottom and regular lumber on top (treated nails of course). Cedar or metal strapping can work. Even cedar ledger boards may work in place of PT where flashing is an issue.

Bud


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## jflag (Oct 6, 2008)

As someone else mentioned you could use nails at the foot as well, probably a lot cheaper than screws in special finishes, or get the high dollar coated/dipped screws for decks and drive them proud(as someone else pointed out it will most likely be behind Baseboard). It does seem that the life of a regular dry wall screw would be very long because of the lack of moisture. Also last statement here, the best finish for going into PT is "Mechanically Galvanized" Zinc Coating - it is much better than just the zinc dip coated / yellow zinc dichromate coatings as far as being able to hold its own against the PT chemicals


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## RRH (Nov 24, 2016)

mikegp said:


> I used drywall screws into PT lumber to hold lattice on a concrete wall. They have survived 9 years of rain, snow, sun etc and not one has let go. I'd guess I used about 160 of them. Just saying. I'll pull some out and check to see how rusty they are one day.
> 
> Also used regular nails on the ramset and those are also fine.


So that was the old PT lumber that did not eat galvanized nails


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## RRH (Nov 24, 2016)

I have even seen a lot of the new coated ACQ approved deck screws rust in a couple of years.

Like a lot of contractors I have switched to stainless nails or deck screws. More expensive but it is the ONLY fastener you can be sure of in the new lumber.

But being indoors and having baseboard have not seen anybody use in drywall. If you were real picky then get Stains deck screws for the first row.


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## jflag (Oct 6, 2008)

RRH said:


> I have even seen a lot of the new coated ACQ approved deck screws rust in a couple of years..


I have seen deck screws that seem to be coated with a color keyed plastic like coating start to rust at the exact point where my bit stopped driving and must have broken the plastic like coating materials seal:biggrin2:


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## Gary in WA (Mar 11, 2009)

"PT lumber is required when contact is made with concrete. So on a slab foundation the bottom plate has to be PT lumber, also on the inside of concrete wall the 1x2 furring strips are also PT lumber."------------------- no. Any wood within 8"(?) of soil requires PT OR OTHER naturally durable wood- cedar, etc. *or* an impermeable vapor barrier to stop moisture (incl. under the slab though you need to prove it)- in most the "I" Codes. Code allows poly sheeting separating wood furring strips on the concrete walls, and many localities (check locally) allow foil-faced foam (or poly under XPS) board under the wall bottom plate for an air/moisture/thermal barrier; http://www.greenbuildingadvisor.com...ressure-treated-sill-plates-and-building-code

Do you really want more chemicals in your house...

Gary


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## Gary in WA (Mar 11, 2009)

If you do go PT; http://www.bayarearetrofit.com/wp-content/uploads/2014/07/ACQ_Fastener.pdf

Simpson doesn't like electroplated or mechanical bonded zinc; "Electroplated/electro galvanized and mechanically galvanized coatings should not be considered to be hot-dip galvanized. (Class 55, or higher, mechanical galvanizing provides galvanizing equivalent to the hot-dip galvanizing used on connectors and fasteners. Ref. ASTM B695 for additional information.)"---from "What metals and pro...."; https://www.strongtie.com/products/...rrosion-information/pressure-treated-wood-faq

Gary


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## weatheredwood (Aug 9, 2007)

RRH said:


> I have even seen a lot of the new coated ACQ approved deck screws rust in a couple of years.
> 
> .


I've always wondered about this. I noticed that when I back out a coated screw the coating is gone. I was thinking the act of even screwing them in removes most of the coating. I've never removed one after a few years to see if it is rusted out.


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## RRH (Nov 24, 2016)

weatheredwood said:


> I've always wondered about this. I noticed that when I back out a coated screw the coating is gone. I was thinking the act of even screwing them in removes most of the coating. I've never removed one after a few years to see if it is rusted out.


Even had a few the whole head rusted and broke off after 3 years.


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## clarenceboddick (Nov 30, 2016)

How well would Rock-On cement backer board screws work long term for corrosion resistance? How long do Tapcons last before they start rusting?


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## ront02769 (Nov 28, 2008)

Gary in WA said:


> "PT lumber is required when contact is made with concrete. So on a slab foundation the bottom plate has to be PT lumber, also on the inside of concrete wall the 1x2 furring strips are also PT lumber."------------------- no. Any wood within 8"(?) of soil requires PT OR OTHER naturally durable wood- cedar, etc. *or* an impermeable vapor barrier to stop moisture (incl. under the slab though you need to prove it)- in most the "I" Codes. Code allows poly sheeting separating wood furring strips on the concrete walls, and many localities (check locally) allow foil-faced foam (or poly under XPS) board under the wall bottom plate for an air/moisture/thermal barrier; http://www.greenbuildingadvisor.com...ressure-treated-sill-plates-and-building-code
> 
> Do you really want more chemicals in your house...
> 
> Gary


Gary, just finished up work on two houses slab on grade and am working on one with full foundation. Requirements in the three towns in ma and ri that I dealt with were for PT for the bottom plate (although maybe if we wanted to go broke we could have done cedar). And this was going on OVER top of a double layer of the sill seal that has a foam core encapsulated on t and bottom with plastic....making an "impermeable barrier". Different requirements for different areas I guess. Ton


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