Treated Lumber

[Mark W Pugh]

OK, I have this free standing deck that comes off my house. There are a few floor joists that need to be replaced. From what I can see, the original boards are not treated lumber. The boards were primed and painted. Now, I would like to replace these boards with treated lumber. A couple of questions.

1. How much does rested lumber shrink as it dries? What I don't want to happen is have bows in my decking when the lumber dries out. I know this would be years down the road, but I don't want to have to deal with it again.

2. Is there anything that can be put over fresh treated lumber so a paint can be used? Or, do I have to wait a year or so to let it dry out before I can paint it?

Thanks

[Stephen Tashiro]

I find the problem with treated lumber is that some boards twst and bow like crazy as it dries. Also if you have thin lumber subjected to constant force it will bend as it weathers- like a 2x4 post with the corner of a tarp pulling on it. A well designed treated lumber structure has each board held straight and braced by something else. The tendency of the lumber to bend with constant applied force can be helpful if you use parts of the structure to hold other parts flat.



There are opaque "stains" in colors such a white that are designed for treated lumber. To me, these "stains" look like paint.

[Ole Anderson]

Treated lumber can range from soaking wet to kiln dried after treatment. In general, my experience with wet treated lumber has been good. I had less than 5% of wet PT 5/4 deck boards twist and no significant problems with two bys used for framing. But you want to get moisture down to something reasonable before painting. To be safe, look for the kiln dried treated lumber. I have never found or used it though and if you can find it, it will be at a premium cost. If you want to be sure of zero twist and bow problems you need to look at something other than wood. Trex now has a steel framing system. Pricey I am sure.

[Kent A Bathurst]

If you can find a pace that sells KDAT [Kiln Dried After Treating] that is an excellent choice - well worth the $$, IMO. You will not find it at the BORG/big box stores - quality and price are too high for them to assign shelf space for it. You will need a regional lumber yard that caters to contractors.

There are two manufactures in the general region that I know of - Great Southern Wood [closest is in Fombell, PA], and Biewer Lumber [closest to you is Lansing MI]. You cannot buy from them, but they could tell you where the nearest distributor is. May be others that I don't know about - but it is a small % of PT producers that have kilns for KDAT.

But - I doubt you will be able to find it without a road trip.

In which case - I have no doubt the original deck was built with lumber - I have to bet on PT - that came from a local supplier. Coulda been in place for some time before they painted it. But - I don't know hte local code/practices, so cannot guarantee it.

There is nothing inherently wrong with the PT stuff - approximately 7.3 jillion decks built with it, and counting. It will warp and twist as it dries - some. NOt a huge deal, IMO. But that doesn't really invalidate it. Put it in place, nails at the joist hangers to anchor it, nails through the deck boards. Everything is tied together. You shouldn't have any dramatic bowing, etc. You can put in some X-type cross braces underneath to add more structural integrity, joist-to-joist. That's what I would do, for any type of free-standing deck construction, but that is just me.

As far as painting, staining, etc - on regular PT lumber, [B]forget you even thought about it for at least 1 year. SInce you are talking about joists, which are out of the sun, if it was me I would forget about it for 2 full years. Ain't nothing that you can do to it - the moisture in the product is going to exit.

You cannot redirect the laws of physics - they will laugh at you for your feeble, mortal, attempts to coat/seal the water inside the wood, and will strip off the paint just to get in your face, and prove the point.

[Rich Enders]

Three years ago I stored some of the new PT lumber from Home Depot outside awaiting a small project. It included about a dozen 2 X 6's and another half dozen 4 X 4's. About one year later it was all worthless. Twisted, cracked, and some rot. It was not covered, but neither is a deck.

It seldom rains here, but the sun and the heat are not bashful. I don't know if the new treatment is the weak link, but I wonder if you will have a deck left by the time yours is dry enough to protect with paint.

[Mark W Pugh]

Another option I thought of was using regular lumber and epoxy sealing it. After epoxy has cured, prime and paint. Using a borate product first to help preserve it. Any comments on that?

The reason I'm looking at it this way is I'm going to butt joint the new joists to the old floor joists inside. Then glue and screw support pieces (OSB) on both sides of the joint. If construction adhesive won't stick to new PT lumber, I need to go the epoxy route. I'm not a contractor so any other inputs appreciated.

[Mark Bolton]

I hope the butt joint your describing isn't to be structural (carries zero load).

[Dave Anderson NH]

Since I just completed a new deck over the weekend a few comments are in order.

1. Building codes have changed dramatically. in the last few years due to collapsing decks. In my area all joists must use hangers, cut ends in contact with the ground must be preservative treated, posts must be 6"x 6". A whole bunch more.

2. After the discontinuation of CCA pressure treating there are now 2 classes of PT lumber: Ground contact and non ground contact though I can't remember the exact names. Neither is as effective as the old chromated copper arsenate.

3. Here is the current and latest code on decks. I've linked because the pdf is too large to post here. www.awc.org/publications/dca/dca6/dca6-09.pdf (http://www.awc.org/publications/dca/dca6/dca6-09.pdf)

[Kent A Bathurst]

Three years ago I stored some of the new PT lumber from Home Depot outside..... About one year later it was all worthless. Twisted, cracked, and some rot. It was not covered, but neither is a deck................the sun and the heat are not bashful. I don't know if the new treatment is the weak link, but I wonder if you will have a deck left by the time yours is dry enough to protect with paint.

Rich - you were in the worst possible situation for that lumber. Sorry, but - pilot error - you flew it into the hill under full power.
Outside, uncovered, loose sticks, AZ sun and - more important - humidity that approaches zero.

Untreated lumber is delivered to the stores at max 19% MC - but they are all in the 16% - 19%. Had you done the exact same thing with untreated lumber, you would have had pretty much the exact same results. The humidity drop is unreal, and its effect on any wood is dramatic. FWIW - I have personal, professional experience on exactly this topic in Chandler - your neighbor.

The same thing occurs in pretty much any climate - but AZ, So Cal, etc are the most impressive. Buy it when you are ready to use it. Once it is framed together, you have an integrated structure. IF it is going to take you 4 weeks to complete the project, go to the store 4 Saturdays in row, or store it inside in a humidity-controlled environment. That integrated structure will be fine until dry for paint. In AZ - you would not need to wait a year or more. 6 months that include the summer would be more than enough in that climate.


Another option I thought of was using regular lumber and epoxy sealing it. After epoxy has cured, prime and paint. Using a borate product first to help preserve it. Any comments on that?

The reason I'm looking at it this way is I'm going to butt joint the new joists to the old floor joists inside. Then glue and screw support pieces (OSB) on both sides of the joint. If construction adhesive won't stick to new PT lumber, I need to go the epoxy route. I'm not a contractor so any other inputs appreciated.

On the borate - waste of $$. Indoor product only. Primary use is Gulf Coast for preventing Formosan termites. Framing material - wall sill plates for sure, other wall and roof components depending on the region. Water/moisture washes it away - it does not chemically "fix" in the wood like regular PT chemicals. Not a treatment for general rot/decay prevention.

Next - the epoxy route sounds to me like one great dang big pile of $$$.

Last - it sounds like you will use OSB gussets to connect exterior deck joists to interior floor joists. IF so, that would worry me on any number of levels:
> Anything that goes wrong on the deck rehab can transfer to the home itself.
> The std way is to have a 2 x rim board around the inside joists, sitting on top of the foundation, and the inside joists attached via joist hangers or other mechanical connection. Then, galvanized joist hangers on the outside for the deck joists to connect to the rim board. The rim board is fully supported by the foundation.
> Please - look at a "How to build a deck" book at the BORG. Don't color outside the lines for joist install/connections. If it ain't in that book, don't do it.
> You are making me nervous, my friend - you maybe should throw down the bucks for a pro. THe downside can be ugly - if not for you while you live in the house, then for the inspector when you go to sell, and he laughs his butt off - then you will find out what a licensed GC costs for the repairs.


Dave - there are actually 3 classes in residential construction: Above Ground [fence pickets, deck flooring, etc] Ground Contact [fence and deck posts, etc.] Critical Structure [for things just like it sounds]. My understanding is that joists need to be GC or Crit Struct, and I am going to hazard a guess that the BORG carries the 2x joist material only in GC.

Then - you get into the marine applications - freshwater submersion, salt water submersion, etc.

[Kent A Bathurst]

Neither is as effective as the old chromated copper arsenate.

My pet annoyance, as I am sure you are well aware. What a political/policy fiasco, inflamed by faux science, hyperbole, and media-sponsored emotion.

The big joke is, of course - for some applications, CCA is still permitted, because the alternatives do not perform:
> Agricultural [fence posts, pole barns, etc.] Includes utility poles [some are creosote, though].
> Treated plywood - other chemicals will not work with the adhesive/binder chemistry.
> Water submersion. All those docks, decks, seawalls, piers, etc - all are CCA, with a very high concentration of chemicals - something like 10x that of Ground Contact deck posts.

[Mark Bolton]

Rich - you were in the worst possible situation for that lumber. Sorry, but - pilot error - you flew it into the hill under full power.
Outside, uncovered, loose sticks, AZ sun and - more important - humidity that approaches zero.

Kent, Im sorry but I have to disagree with you here on a few points.


Untreated lumber is delivered to the stores at max 19% MC - but they are all in the 16% - 19%. Had you done the exact same thing with untreated lumber, you would have had pretty much the exact same results. The humidity drop is unreal, and its effect on any wood is dramatic. FWIW - I have personal, professional experience on exactly this topic in Chandler - your neighbor.

First of all, this isnt really accurate. The 19% number is merely an industry standard. It can vary dramatically. The drying and heat treating standards vary wildly based on region. But the simple fact of the matter is that you will likely never see the wild movements in non-treated lumber (thought it wil of course still move) simply because the cells of the material are simply not exposed to the same stresses and processes that treated lumber is. The pressure treating process is one that is completely un-natural and can unleash a wild array of effects on the finish product. This process is simply not applied to non-treated lumber. So while you may still see some cup, twist, bow, it will likely never be at a level even remotely close to that of treated lumber. The simple term "loose sticks" is a problem. There is no amount of restraint that is going to stop a member of any size from doing whatever it wants to do. Its going to go wherever it wants to go regardless of how much you try to hold it back. You cant hold it back. Its just that simple.

Its why hack deck builders will embed their posts in concrete to save time while a quality deck builder will pour their piers to ground level and use a more costly embedded anchor and a post base. Its because no amount of framing or structural connection is going to resist the rotational twist of that post drying. The post is going to wreak its havoc somewhere and none of us are wise enough to spot a post that will stay straight or twist. So you can be lazy and embed your post in which case all of the fury of said post(s) will be unleashed on the structure above (because the base of the post is fixed) or you can fix the top of the post (where it matters and all your pretty work is) and let the base of the post twist at will. If your customer pitches a fit about the twisted post you can come back and change it with no damage to the deck above. The simple fact of the matter is no amount of loose or tight sticks is going to stop what is going to happen. Its been pre-determined by mother nature herself. Its just a wait an see game. You could park a tractor trailer on top of your freshly delivered PT lumber for a year and when you pull it off, the pile is going to spring into whatever shape it was intended to.

I have seen 6x6 posts rotate almost a full 90 degrees in ten feet. They are never simply twisting either, they are twisting AND bowing which will tear handrail loose and all sorts of other things. No amount of resistance to this will stop it.


The same thing occurs in pretty much any climate - but AZ, So Cal, etc are the most impressive. Buy it when you are ready to use it. Once it is framed together, you have an integrated structure. IF it is going to take you 4 weeks to complete the project, go to the store 4 Saturdays in row, or store it inside in a humidity-controlled environment. That integrated structure will be fine until dry for paint. In AZ - you would not need to wait a year or more. 6 months that include the summer would be more than enough in that climate.

This depends soley on the material purchased. Contrary to the post with regards to KDAT many of the homecenters specifically are handling material which has in fact been dried after treating to reduce their in-house loss. They have numerous bunks of material which may sit on their racks for prolonged periods with little sales. The last thing they want is whacky wood (no sales to the pickers) on those bunks so they going to great lengths to insure that every board on the rack stays straight.



Then - you get into the marine applications - freshwater submersion, salt water submersion, etc.

Most marine and commercial applications are still going to be CCA. The move to an alternative was for one reason and one reason only and thats because residential consumers and contractors chose to bury or burn the single best wood preservative process we've had to date (CCA) which took the option away from us all at an unbelievably high cost in materials and fasteners.

[Mark Bolton]

My pet annoyance, as I am sure you are well aware. What a political/policy fiasco, inflamed by faux science, hyperbole, and media-sponsored emotion.

You obviously didnt work in the subdivisions I did. Contractors were dozing all scraps, truckloads of sawdust, into the backfill on site. Numerous contractors, jack legs, and homeowners, having the "bright idea" of taking the scraps from their deck building projects, all made from this illustrious lumber than bugs either wont eat, or will die when they do eat, and packing it home to burn in their fireplaces, wood stoves, and back yard fire pits.

Rocket science huh? A board that nothing will eat. I wonder whats in it? Anyone wager a guess? Uh,.. maybe poison? Hey!!! Lets burn it!!! :p

"Hey... I have this board that no bug will eat, and if a bug DOES eat it, the bug will die... Hey kids,... lets have a marshmallow roast out in the back yard.. I'll go get some of these boards from the deck I hacked together today while I was laid off from work!!"

That event, combined with numerous others, cost us the material which yes, is still available today.

[Mark W Pugh]

Last - it sounds like you will use OSB gussets to connect exterior deck joists to interior floor joists. IF so, that would worry me on any number of levels:
> Anything that goes wrong on the deck rehab can transfer to the home itself.
> The std way is to have a 2 x rim board around the inside joists, sitting on top of the foundation, and the inside joists attached via joist hangers or other mechanical connection. Then, galvanized joist hangers on the outside for the deck joists to connect to the rim board. The rim board is fully supported by the foundation.
> Please - look at a "How to build a deck" book at the BORG. Don't color outside the lines for joist install/connections. If it ain't in that book, don't do it.
> You are making me nervous, my friend - you maybe should throw down the bucks for a pro. THe downside can be ugly - if not for you while you live in the house, then for the inspector when you go to sell, and he laughs his butt off - then you will find out what a licensed GC costs for the repairs.




Kent,

The floor joists on the deck are the floor joists from the inside. The inside floor joists extend out the side of the house, resting on the bottom plate/foundation. There are NO support posts on the deck. It is a free standing deck. A rim board attached to the outside wall would not provide any support. I can't see any other way to fix this. I only have about 3 boards that need replaced, and they are not together. Where am I wrong here? Thanks.

[Brian Elfert]

Kent,

The floor joists on the deck are the floor joists from the inside. The inside floor joists extend out the side of the house, resting on the bottom plate/foundation. There are NO support posts on the deck. It is a free standing deck. A rim board attached to the outside wall would not provide any support. I can't see any other way to fix this. I only have about 3 boards that need replaced, and they are not together. Where am I wrong here? Thanks.

It sounds like you have a cantilevered deck. I am currently having a small bay in my house rebuilt by a contractor. He is redoing it as a cantilever. He is sistering the joists back 8 feet into the house. The city required he go back 8 feet. A simple butt joint is unlikely to work for this.

[Mark Bolton]

It sounds like you have a cantilevered deck. I am currently having a small bay in my house rebuilt by a contractor. He is redoing it as a cantilever. He is sistering the joists back 8 feet into the house. The city required he go back 8 feet. A simple butt joint is unlikely to work for this.

Its surprising the city even allowed that (but great). It often seems building officials default to the "engineers stamp" option with regards to cantilevers.

I too wondered about the cantilever but "free standing" would make me think of a deck standing on posts with no structural connection to the residence (though it still may be attached). But then he says no posts so the cantilever comes to mind.

A butt joint scabbed with osb will be a zero in the strength column.

[Mark W Pugh]

It sounds like you have a cantilevered deck. I am currently having a small bay in my house rebuilt by a contractor. He is redoing it as a cantilever. He is sistering the joists back 8 feet into the house. The city required he go back 8 feet. A simple butt joint is unlikely to work for this.

That's exactly what I'm dealing with.

[Brian Elfert]

Its surprising the city even allowed that (but great). It often seems building officials default to the "engineers stamp" option with regards to cantilevers.


The bay is only two or two and a half feet out from the house. I think that is why it did not need to be engineered. It has to be way better than the horrible job the previous homeowner did that allowed the whole thing to start pulling loose from the house. The homeowner simply attached some short joists to the rim joist.

[Kent A Bathurst]

Kent, Im sorry but I have to disagree with you here on a few points.

First of all, this isnt really accurate. The 19% number is merely an industry standard. It can vary dramatically. The drying and heat treating standards vary wildly based on region.

We don't disagree all that much Mark.

On the MC 19% - that is the grading rule. No one intentionally leaves the lumber in the dry kiln longer than needed for a basic commodity item like framing lumber - wasted $$ cutting into a thin profit margin. If the lumber came from a region/season with very low RH, it could have dried further in storage or in transit on rail cars.




But the simple fact of the matter is that you will likely never see the wild movements in non-treated lumber.

Agreed. But - I have seen dramatic movement in untreated lumber in Phoenix area - when the operation did not properly care for it - the "loose sticks" problem.


The simple term "loose sticks" is a problem. There is no amount of restraint that is going to stop a member of any size from doing whatever it wants to do. Its going to go wherever it wants to go regardless of how much you try to hold it back. You cant hold it back. Its just that simple.

Perzactly my point - even untreated lumber is going to heck in that environment. Treated lumber even worse.




You could park a tractor trailer on top of your freshly delivered PT lumber for a year and when you pull it off, the pile is going to spring into whatever shape it was intended to.

Hence my point about buying only what you can get into it's assembled, installed, structural home ASAP.

[Kent A Bathurst]

You obviously didnt work in the subdivisions I did. Contractors were dozing all scraps, truckloads of sawdust, into the backfill on site. Numerous contractors, jack legs, and homeowners, having the "bright idea" of taking the scraps from their deck building projects, all made from this illustrious lumber than bugs either wont eat, or will die when they do eat, and packing it home to burn in their fireplaces, wood stoves, and back yard fire pits.

Rocket science huh? A board that nothing will eat. I wonder whats in it? Anyone wager a guess? Uh,.. maybe poison? Hey!!! Lets burn it!!! :p

"Hey... I have this board that no bug will eat, and if a bug DOES eat it, the bug will die... Hey kids,... lets have a marshmallow roast out in the back yard.. I'll go get some of these boards from the deck I hacked together today while I was laid off from work!!"

That event, combined with numerous others, cost us the material which yes, is still available today.


I have zero sympathy for the contractors or homeowners that refuse to follow basic safety standards, or choose to willfully ignore rules and regulations for proper handling of any type of materials - spent batteries, old CRTs, old cans of paint, or treated lumber scraps. Find 'em, fine 'em, and give them a good beating.

Proper disposal is landfill - put it in the trash can, or in the RO/RO hopper at the job site.

Same fools probably scraped old lead-based paint and ripped out old asbestos insulation. Darwin has a way of winnowing "incredibly stupid" out of the gene pool.