1/4 inch plywood

[martymcfly]

BB from HD 4x8 sheet 1/4 is not even close to 1/4 inch thick. So I went to a real lumber yard and got some that was real 1/4. That stuff is heavy, and not cheap either, but is sure is pretty. Is it worth it? I am going woody.

[Sparksalot]

Go for the quality. You want to build this once and do it right. Measure 4 times , cut once!!

Mine is a woody also. in 2008, I spent $130/sheet for two 4x10x3/4 red oak veneer sheets. I haven't regretted it.

BTW, if you're going for marine grade, expect $$$$. I'm building a kayak, and spent $67/sheet of 4x8x3mm. Ouch.

[friz]

Mine is mostly 4mm Okoume marine ply. The stuff is great to work with.

[swoody126]

1/4" plywood is often sold as 6mm in better quality

it can be 3ply 4ply & 5ply

the 3ply can have a core of a lesser grade of wood as well as have substantial internal voids

4ply is rare and i haven't cut any recently to comment on the internal components

5ply(usually found in exotic/tropical marine ply) commonly is all veneer ply inside & out w/minimal voids if any

some soft wood marine ply(usually fir) can be found w/ only 3plies of the same material and minimal voids

softwood marine ply will have what was knots filled in w/ football shaped plugs which can be wood or putty therefore claiming minimal voids(i have experienced as many as 11 footballs in a area smaller than 16" x 36")

all that being said the real issue IMHO is the glue

is it stamped on the surface EXTERIOR GLUE or WATERPROOF GLUE?

if not it aint and will eventually fail as moisture eeks it's way into the fibers

the actually measurable thickness isn't as important as the nature of the plies and the glues

again IMHO it would be a shame to invest an huge amount of time when you can reasonably expect issues within less than 5 years when saving a couple more months would allow you to purchase better materials w/ a much longer life expectancy and a reasonable resale value if you decide to move on (up/down or out)

BTW, i have recently been & am currently involved in boat builds involving big box exterior, marine fir and okoume/miranti marine plywood along with a variety of glues/bonding agents along with several finishing methods and that is where my comments come from

¿ have i muddied the waters sufficiently ?

sw

[KTM_Guy]

I have been in a lot of Home Depots and have never seen real Baltic Birch in one. BB will come in metric sizes and until recent sheet sizes were around 60"X60". the place I buy from is starting to carry 4'X8''s in some sizes. I like the 5'X5' and that is what I get most of the time.

This is what 6mm BB looks like, it's five ply and is real close to 1/4"




I like Baltic Birch and I think it is a bargain compared to the crap they sell at the big box stores. I pay around $16 per sheet of 1/4". The down side is it is heavier than normal plywood and it is tough on cutters and blades.

Try to find a wholesale hardwood dealer in your area and see if you can buy from them. Let them know you;ll be buying 20+ sheets.

Good luck

Todd

[working on it]

...5ply(usually found in exotic/tropical marine ply) commonly is all veneer ply inside & out w/minimal voids if any

some soft wood marine ply(usually fir) can be found w/ only 3plies of the same material and minimal voids

softwood marine ply will have what was knots filled in w/ football shaped plugs which can be wood or putty therefore claiming minimal voids(i have experienced as many as 11 footballs in a area smaller than 16" x 36")

all that being said the real issue IMHO is the glue

is it stamped on the surface EXTERIOR GLUE or WATERPROOF GLUE?

if not it aint and will eventually fail as moisture eeks it's way into the fibers

the actually measurable thickness isn't as important as the nature of the plies and the glues...sw

from another thread concerning plywood usage I happened upon a killer deal for pre-sanded, phenolic resin-glued plys, 3/4" plywood (for $25 a sheet)

• I started my build with a great quality sheet of 1/2" birch plywood, that had been leftover from a flooring project we had done many years before, using it for several rooms in our old (now demolished) home. We had bought a lot of it at a now gone Payless Cashways store, that had a complete lumberyard type operation , unlike the Home Depot or Lowes stores, so it was pretty good stuff. I only got to use the one sheet, because my wife was keeping 4 sheets in our shed, to use later, but I had purloined the one before she knew it. After being stored for a decade, it was still perfect, but I had to cover it up with a 1/4" Luan sheet, which was needed to bury the carriage bolt heads that secured the deck to the frame. So, I needed more plywood to build the upper structure, which I obtained from a Home Depot, that I had gone to, originally seeking hardware for my trailer.
• I (and my friend, at whose shop I was building the TTT, 50 miles away from my home), were looking over the plywood there, with birch being very expensive, and oak slightly less, as my original preferences (we didn't know of any lumber yards nearby, so HD was our alternative). I demurred at buying 6 sheets at those prices, as I was on a no-budget build, hidden from the CFO wife. But, as we were leaving the store, we saw a stack of plywood sheets not in the normal place, but with a handwritten sign pricing them at $25 each. I looked them over, counting the plys and checking their quality, as best I could. They had a branding sticker on them, Arauco, so I used my web-browser on my flip-phone, to look up their website and check them out. It took quite a bit of time, as my phone was maddening-ly slow...an AT&T feature phone with an abysmal browser installed.

• 

  Samsung Rugby 2 flip-phone (used from 2010 to Sept.2012).JPG (121.76 KiB) Viewed 2530 times

  not really good for internet use, but a tough reliable phone

• 

  Araucoply sanded plywood, .703 thickness, with phenolic resin bonded core.JPG (81.08 KiB) Viewed 2530 times

  not marine Baltic Birch, but a darned good plywood, afterall
• My research on the website showed me what I was wanting to see: that the plywood had phenolic resin, and was pre-sanded on both sides. And with minimal patching, and no apparent gaps between the 5 or 7? plys, I decided to purchase 6 sheets, quickly, because there were only 8 sheets left (half the stack had gone, while I spent 30 minutes on my slow phone).
• Since I was going to use a good coating (to be determined. later), I was wiling to get the softwood ply, instead of the hardwood birch, I originally sought, because the good coating would protect it, just as well (I hoped). It turned out to be a good choice, because it turned out to be easy to work with, and readily accepted my choices of polyurethane, "the mix", and outdoor-Acrylic enamel paint (without any sanding, on my part). After a 2-yer build, and 4.5 years of limited use (it's stored in a garage between trips), I have seen no faults with the Arauco plywood...still straight and flawless. Sometimes I wish I hadn't completely covered-up the plywood with my paint scheme, because it looked so good with the clear polyurethane base covering.

• 

  which looks better.png (734.66 KiB) Viewed 2530 times

  sometimes I wish I had left it as a "woody"

[doris s.]

My hubby and I went to hoe depot and lowes today looking for plywood for the floor of our build, it was a total waste of time. They didn't have any exterior grade plywood that was not treated. Ugh! We are looking for some plywood for the floor 3/4" I guess we will have to order it.

Doris

[Sparksalot]

Find a local woodworking supply. Even if they don't have it in there stock, they may be able to get it for your in a few days.

Ordering online will kill you with shipping costs.

[tony.latham]

We are looking for some plywood for the floor 3/4" I guess we will have to order it.

Doris:

Go to a real lumber yard--not a box store. They'll have pallets of 3/4" ACX and CDX.

Tony

[Sam I am]

Use good grade plywood in a tear. I used Baltic birch in mine, built in 2006. It has held up through rain with no warps, delamination, or leaks!