Plywood Type Recommendation

[Tom McDonald]

Hi Everyone,

I am a newbie woodworker and a this is my first post. I will be purchasing some plywood soon to make window boxes.

My question -- may I use birch plywood since I plan on finishing with primer and two coats of paint or should I use exterior grade plywood? If I need exterior plywood what types should I purchase? Thanks.

Tom

P.S. To all members. I have learned much by reading all your posts. Thanks for yout efforts!

[Kelly C. Hanna]

Hi Tom and welcome to the Creek!

If they are going to be sheltered by the roof or an overhang, you can get away with Birch. That said you will need to paint it well.

Otherwise, go with the PT plywood.

[Tom McDonald]

Kelly,

Thans for the info. What is PT plywood?

[Greg Hines, MD]

For a planter box that is going to be in contact with dirt, you need to use pressure treated (PT) plywood. Even if you paint it well, ordinary plywood is going to rot in a short time.

Doc

[Brad Sperr]

Depending upon the size of your planters, you could also consider pvc trim or miratec or something similar.

[Von Bickley]

For a planter box that is going to be in contact with dirt, you need to use pressure treated (PT) plywood. Even if you paint it well, ordinary plywood is going to rot in a short time.

Doc

I agree with Greg. The birch won't last......

[Kelly C. Hanna]

Pressure treated plywood for outdoor use. It kinda goes without saying that any plywood in contact with dirt will rot in a relatively short time. PT plywood isn't rated for direct contact with dirt like posts and landscape timbers and will only last a bit longer than Birch ply.

It also is a good thing to line the boxes unless you are using solid wood. This will prevent rot from being a huge issue. If you want the longest lasting boxes without a lining do not use plywood at all. Use Cedar, Cypress, Douglas Fir.

[Rick Fisher]

Red Cedar is the best choice. Treated wood will still rot if in contact with dirt.

There is a treated wood called PWF which is meant for direct dirt contact but... its disgusting.. saturated in chemicals.. etc..

Cedar will still rot evenually, but up on Rainy Vancouver Island, it lasts for years.

If you go with Cedar, wear a mask. It really bothers some people.. if your one of them, you become hypersensitive to it after its aggrivated you a few times.

[Joe Scharle]

Look into this or similiar products.

http://www.azek.com/

[abram godshall]

i made numerous window boxes using pvc trim; as long as you support well with cross braces it works fine (unsupported it is like limp spaghetti). i used stainless pins and glue to hold them together. best part, no maintenance.

[Roger Jensen]

You may already know this, but if you go with PT plywood be sure to do your cuts in a well ventilated area and wear a good mask. That is nasty stuff, and if it is imported from China you may be working with some unknown chemicals.

[Tom McDonald]

Hi everyone,

I been away from the computer for a few days. Thanks for all the advice. I will price the options and make a choice. I am leaning toward pressure treated plywood. The window boxes be off the ground, and plastic containers will hold the dirt inside the windowboxes. I think pressure treated with several coats of paint should last a few years in the Chicago area. Thanks again for all the replys.

Tom