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Question on using pressure treated lumber

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Forum topic by itsme_timd posted 05-13-2008 03:36 AM 5852 views 1 time favorited 14 replies Add to Favorites Watch
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itsme_timd

690 posts in 4474 days


05-13-2008 03:36 AM

Topic tags/keywords: question pressure treated

I’m helping a friend build an aquarium stand and the plans he has call for 4×4 posts with 2×4 cross supports to build the internal framework of the cabinet.

He purchased some supplies at HD and the only 4×4’s they had were pressure treated – the deck building type.

I don’t know the characteristics of working with pressure treated wood and we were wondering about any shrinkage or other considerations in using this lumber.

Any input is appreciated!

Thanks,

Tim

-- Tim D. - Woodstock, GA


14 replies so far

View Karson's profile

Karson

35212 posts in 5043 days


#1 posted 05-13-2008 03:55 AM

The wood is usually very wet and so it does shrink, It also has a tendency to warp. You should have also been able to find cedar 4X4’s they usually carry them. But, they are pricey.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Appomattox Virginia [email protected]

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Josh

119 posts in 4581 days


#2 posted 05-13-2008 05:27 AM

The only good thing about pressure treated lumber is the price. If it is in the budget I would look at using oak or another hardwood that holds up well to moisture. If you have to use pressure treated look for the dry boards and then let them sit in the shop for a bit. make sure to pick up a few extra boards. Like Karson said the stuff moves a lot.

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Napaman

5530 posts in 4720 days


#3 posted 05-13-2008 05:35 AM

here is a question not an answer—-is there any concern about using the pressure treated lumber indoors…and around the water of the tank…with food and chemicals being stored on top or inside of the stand???

i have heard that when you cut and use pressure treated lumber you should use gloves…so i cant imagine this being good on this type of project…but OTHERS will know better…

-- Matt--Proud LJ since 2007

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Chris

1880 posts in 4634 days


#4 posted 05-13-2008 01:05 PM

Great Question Matt!!!!

-- "Everything that is great and inspiring is created by the individual who labors in freedom" -- Albert Einstein

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Boardman

157 posts in 4404 days


#5 posted 05-13-2008 02:19 PM

They’ve removed the cyanide from the processing of pressure treated lumber, so it’s better than before. And frankly, I think society has become hyper-sensitive tp the potential dangers of many products, hence the gloves recommendation. But that’s just my opinion. Heck, I used to play around with loose mercury when I was a kid, and recently here, they evacuated a school because someone dropped a thermometer on the floor! Overkill if you ask me.

But about the project…pressure treated, and most all 4×4’s are cut from the very center of the log and will almost always split/crack as they dry out. It’s kinda ugly too. White oak would be a better choice as it’s fairly impervious to moisture – they make wine barrels out of it. And at least around here it’s pretty cheap and better looking, and being a lot stronger than PT pine, he wouldn’t need to go so large on the legs.

(hmmm…wonder if that mercury has anything to do with the 3rd arm growing out of my forehead?)

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Josh

119 posts in 4581 days


#6 posted 05-13-2008 02:29 PM

I use treated wood daily and don’t wear any hand protection. I have never seen anyone glove up when handling it. I have read you shouldn’t use treated lumber for picnic table tops because of the chemicals.

I don’t see it hurting the fish, or being a problem indoors, but I wouldn’t make a sandwich on it. I’m guessing in this case, the treated is used in the frame work and then hidden with other woods. I would not have any treated lumber, that my kids can touch, inside my house.

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Peter Oxley

1426 posts in 4517 days


#7 posted 05-13-2008 02:48 PM

There’s something about fasteners, and pressure-treated lumber … it’ll corrode regular fasteners so you have to use galvanized. Or does it corrode galvanized so you have to use regular? Oh, I don’t remember, but you might want to check on that.

-- http://www.peteroxley.com/woodworking -- http://north40studios.etsy.com --

View coloradoclimber's profile

coloradoclimber

548 posts in 4711 days


#8 posted 05-13-2008 04:45 PM

Tim,

We use pressure treated lumber for exterior deck superstructures all the time, around here it is required to meet code. Simpson Strong-Tie, probably the better known maker of lumber connectors, has a web page talking about the changes to the chemical treatments and the requirements for connectors. You need to use corrosion resistant, galvanized (probably what you’ll end up using) or stainless (super expensive)

Simpson Strong-Tie Corrosion Page

I personally wouldn’t use PT anywhere it would come in contact w/ people, animals, food, etc. It’s fine for wet / exterior, non contact applications. We do wear gloves mostly when we’re handling PT lumber. Mostly cause it is wet and leave a nasty residue all over your hands, gloves, pants, etc. Not something I’d want to rub up against in my house.

Why would your friend choose PT for his aquarium stand? Is he afraid it will be subject to continuous water exposure? If the stand is going to be finished / covered why not just use regular doug fir or pine? If it is not going to be finished you couldn’t hardly pick an uglier looking piece of lumber than PT.

I’d take all the PT back if it were me, get some regular pine/fir, or something prettier if it is not going to be covered.

View runngt's profile

runngt

120 posts in 4382 days


#9 posted 05-13-2008 07:00 PM

How big is this tank that calls for 4×4 corner post? I have a 125 gallon setting on a store bought stand and it only has 2×4 white pine corner post with two intermediate 1 1/2×1 3/4 support post. The top and bottom “rail” are 2×4. What is water per gallon….8.8# or so…that is 1,100# less a few gallon for rock and decorations setting on 2×4’s. WOW don’t lean on it ! : )

For the orginal question though, I would have no problem with PT pine as the frame work of the stand, heck it’s going to get wet sometime and that is what it’s for. The other option would be to screw two non-PT pine 2×4s together and adjust the plan dims.

-- It seem's I just make scrap wood and saw dust most of the time !

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Bra_DD

1 post in 4308 days


#10 posted 05-13-2008 09:46 PM

I am the Newbie with the fish tank. Tim is my neighbor. thanks for the help on this one. I think i might avoid the pressure treated wood now that i am looking at the comments. The only thing i am not to sure about is how to build the frame on 2X4’s. does any one have any ideas on a good load bearing design. i have a 75 gallon tank. most of the wieght is on the outside perimeter of the tank. the bottom glass doesnt even touch. after we create the frame we will panel the outside of it and put cabinet doors on the front so i am not to concerned with the apperance. would soft white pine from HD be ok to use?

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runngt

120 posts in 4382 days


#11 posted 05-13-2008 10:45 PM

The way mine was built is with 2×4 top and bottom perimeter laying flat (tank setting on wider side of boards) and mitered corners like a picture frame. The top frame is about 1/4 wider than the tank bottom for room to play.
At the corners take two 2×4 (height as desired) and make a 90 degree angle nailed together. Then just nail the support post onto the frame. The store bought was done with long staples and glue. I have come back and added front and side decorative framing out of base board but you can just router the edges as well.

My tank is six feet long so I think there are two support post in the middle. The cladding will give the side sway strength to the cabinet. I wish I had sketchup so I could post a picture (down loading is blocked here at work) because I am not sure this makes since reading it.

runngt

-- It seem's I just make scrap wood and saw dust most of the time !

View GMman's profile

GMman

3902 posts in 4340 days


#12 posted 05-14-2008 02:55 PM

I would not use pressure treated lumber it has a smell too it that last a long time, hard would will rot , I would go with red spruce which is tough and even left in water will not rot. Note: red spruce is also called tamarack

View dirtclod's profile

dirtclod

169 posts in 4503 days


#13 posted 05-15-2008 09:35 PM

If you have any concern with water or pressure treating chemicals then call a local sawmill and get cedar or locust. You’ll find the prices will be 1/4-1/2 the price of the big box stores. The big box stores are hard to beat on soft 2x material but that’s just a lure to get you to buy all the other things in their store.

-- Wonderful new things are coming! - God

View Dusty56's profile

Dusty56

11856 posts in 4331 days


#14 posted 05-16-2008 06:26 AM

PT is overkill for your aquarium…even if you use regular pine boards and spruce 2×4’s they will never rot enough to cause an issue with your tank. Yes , you will need special fasteners with PT , because the new ingredients in PT eat regular fasteners , even galvanized ones. I would imagine that you were going to paint or otherwise seal the areas that might come into contact with water anyway, so why even think about PT ? I know there is a chart online that will tell you the load bearing capacities of various framing lumber in both vertical and horizontal applications. You just might be surprised at how simple a frame you will really have to build !! Good luck and have fun : )

-- I'm absolutely positive that I couldn't be more uncertain!

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