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Help With Treated Wood Table

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Forum topic by BrandonR posted 484 days ago 1785 views 0 times favorited 24 replies Add to Favorites Watch
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BrandonR

56 posts in 892 days


484 days ago

Topic tags/keywords: treated wood furniture

Hello All-

I just got an a custom order from a client… They want me to build a harvest table style,

http://4.bp.blogspot.com/_vDMlZQUYRTI/SGegiiYswcI/AAAAAAAAARs/TVFD9-0tALw/s1600-h/deck_table.jpg

I am excited to build it… My big concern is using pressure treated wood on the top… I plan to use pocket holes for all the joinery, with a skirt and 4×4 as the legs.

If I use pocket hole joinery to face joint the top pieces…. With the treated wood as it dries out have room to move? In other words will it crack if met flush together?

any advice on how you would tackle building it would be greatly appreciated. It will all be with treated pine.

Thanks!

Brandon


24 replies so far

View mnguy's profile

mnguy

159 posts in 1997 days


#1 posted 484 days ago

First, let your lumber air dry for several days – week before you begin milling. Treated wood is sooo wet, it will really move if you mill it wet. It will even tend to rust your tools. I would also rough mill and then let it dry again for a few days before final milling.

Your example photo appears to show boards that a) have a relief or small gap between them, and b) are breadboarded. I would not firmly lock the boards together with pocket screws or other firm fastening methods, but leave a small gap between the boards for drainage. Bread boarding the ends will help keep cupping under control. Glue / screw the boards on the two edges to the breadboard ends, and then put one screw / a spot of glue in the middle of the end each field board to hold it to the breadboard ends but still let it expand and contract. I’m not sure how much of a gap you should leave between the boards, but if you measure one of the boards for the top before you let it air dry and then measure it after, you’ll get some idea of the max width it will have in the assembled table.

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1757 days


#2 posted 484 days ago

Why are you using pressure treated wood?

-- jay, www.allaboutastro.com

View Don W's profile

Don W

14635 posts in 1166 days


#3 posted 484 days ago

I’s use cedar. You’re going to have a tough time keeping PT from moving, and do you really want to eat off PT?

-- Master hand plane hoarder. - http://timetestedtools.com

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Cosmicsniper

2199 posts in 1757 days


#4 posted 484 days ago

Pressure treated wood is best used where you might get insect decay due to excess moisture, meaning its typically used where there is contact with the ground. I see no virtue in using it for the top of a picnic table, particularly since I wouldn’t want to be eating off it. I know PT wood is cheap, but there are good woods for outdoor use that will withstand the test of time. Don mentioned Cedar. I like white oak. Others like teak. But even if you use good ol’ fashioned pine or fir, you can give it a good finish to help it last longer.

-- jay, www.allaboutastro.com

View Charlie's profile

Charlie

1001 posts in 885 days


#5 posted 484 days ago

Pressure treated wood is safe for a picnic table as long as food is never prepared on it. HOWEVER….. and it’s a BIG “however”... pressure treated wood is invariably VERY wet when you get it and it takes a long time to dry through. If you get it and and build with it when it’s not dry, it WILL crack and split and move like crazy.

Do NOT use pocket hole screws to securely face join the top pieces. My opinion is that you’re asking for trouble. The suggestions for cedar and teak are nice, but if you’re in an area like mine, .... it’s actually cheaper for me to go to Canada and buy cedar and bring it back than it is to buy it locally… and that’s if I can find it anywhere at anything resembling a reasonable price. And teak…. well… forget it.

Over the years I’ve had better luck using ANY decent wood I can find…. kiln dried or very well air dried… applying a penetrating oil and a marine type finish. Those items seem to outlast pressure treated, not because the pressure treated stuff rots, but that it basically tears itself apart.

Just my 2 cents…. probably worth every penny. :)

View BrandonR's profile

BrandonR

56 posts in 892 days


#6 posted 484 days ago

Thanks for all the great advice. I planned on using pressure treated because it is an outdoor project. I know cedar is ideal but in my area is 3 x as much…. Not an option for this piece and budget…

My options are basically pine or treated pine…. I guess it sounds like I should make it out of pine and then have my client seal or stain it right away….

I would love to use teak as well, but can’t imagine the price…

It looks like I will just use pine, and have my client apply a finish to it right away.

View chrisstef's profile (online now)

chrisstef

10403 posts in 1605 days


#7 posted 484 days ago

Could you possibly use cypress instead of pine? It works about the same and should be relatively close in cost if you can get it in your area.

-- "there aren’t many hand tools as awe-inspiring as the #8 jointer. I mean, it just reeks of cast iron heft and hubris" - Smitty

View bbc557ci's profile

bbc557ci

541 posts in 672 days


#8 posted 484 days ago

If you call around to lumber yards (not the Home Depot and Lowe’s types) you might be able to locate some kiln dried PT.

-- Bill, central NY...no where near the "big apple"

View Bill White's profile

Bill White

3343 posts in 2559 days


#9 posted 484 days ago

Kiln dried PT lumber is an unknown entity in my area.
I wouldn’t touch that job without soooooo many caveats that the potential customer might wanna rethink the material of choice.
Just my opin .unless they are just finiky
Sealing “right away” is an effort in futility. That stuff is soooo wet with chems and other crap that the project will fail.
Not “if”, it is ” when” it will fail.
Might wanna consider an exterior grade of mdf such as EXTERA unless they are just set on a wood specie.
Don’t get yourself in a “you built it and it fell apart” situation.
My dad built a picnic table from a Masonite product called “die stock”. This was many years ago, so the names might have changed, but it sure looked like today’s exterior grade mdf.
The table was solid after many years in the South Mississippi sun and humidity.
Bill

Bill

-- bill@magraphics.us

View Don W's profile

Don W

14635 posts in 1166 days


#10 posted 484 days ago

Isn’t kiln dries PT dried before treating, so its still wet when you get it?

-- Master hand plane hoarder. - http://timetestedtools.com

View Hammerthumb's profile

Hammerthumb

1121 posts in 574 days


#11 posted 484 days ago

I believe Don is correct. The kiln dried PT lumber is treated after drying. It would still be wet. I would not use PT lumber for this project. Too many toxins and chemicals that are hazardous to the end users health. You might also think about using one of the simulated wood products produced for wood decks. Would last forever. Don’t know about the price though.

-- Paul, Las Vegas

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treaterryan

109 posts in 885 days


#12 posted 483 days ago

Lumber is kiln dried and then treated as Don said. The treatment process adds a small amount of water as, depending on the preservative, water is generally the carrier for the active ingredient. Usually, PT lumber comes in around 18% after treatment. So you coukd dry it for a few weeks in your shop before cutting. All PT consumer grade lumber is kiln dried.

Pressure treated is NOT okay to eat off of. I know, you eat off of plates, but what keeps a kid from eating his gummy bears off of the table top?

Generally you have to use special grade fasteners for PT as the preservative is highly corrosive.

Stick with pine or doug fir to match their deck.

-- Ryan - Bethel Park, PA

View BrandonR's profile

BrandonR

56 posts in 892 days


#13 posted 477 days ago

Thanks for all the posts.

My client is deciding with going with regular pine and staining and sealing it right away, or splurging on the cedar…

If I am going to use a stable wood, would it be ok to screw the top together using pocket holes? Or would you still recommend not going with this method?

Furniture construction is very new to me. So trying to figure the best way to tackle this!

View redSLED's profile (online now)

redSLED

687 posts in 491 days


#14 posted 476 days ago

Outdoor table = big temperature and moisture ranges! No matter what your do with your pine, it will move, expand, contract and knots will pop. Unless you have barn-stored straight 100-yr old heart pine or something similar. Cedar is highly recommended or hardwoods mentioned by others above. And yes, you can pocket hole the boards, or biscuit them together and pocket hole them – BUT THEN YOUR TABLE TOP MUST BE A “FLOATING” HELD-DOWN TABLE TOP – not screwed down/fixed to an apron/skirt or cross members underneath because if so your boards may incur grain cracks (across-the-grain shrinkage) and/or buckling/cupping (across-the-grain expansion) within 6 months easily.

-- Perfection is the difference between too much and not enough.

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BrandonR

56 posts in 892 days


#15 posted 476 days ago

redSled- Thanks for the information. I am defiantly doing the build with cedar now, just got confirmation from client. Do I still need to be worried about how I attach the top to the skirt and base? Or was this just for pine or treated?

Thanks!

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