How to water proof wooden outdoor enclosure

[Hbomb]

So i built a tort box out of plywood so my greek can have some outside time (its hot here in california!). My question is what is safe use to make the wood water proof so it can last a while and not rot?

 

[ZEROPILOT]

My outdoors enclosure is made out of 1" x 6" x 72" pressure treated fence pickets.
The pressure treated lumber doesn't contain arsenic like the old stuff did. And my enclosure has been in use every day for the better part of the last 8 or 9 years

 

[Hbomb]

I have already built this one. What can i use to seal it. Not interested in purchasing more wood to build a whole new enclosure.

 

[queen koopa]

I have already built this one. What can i use to seal it. Not interested in purchasing more wood to build a whole new enclosure.

Hmm... look at the hardware store for a pet friendly sealant. Built a lil wood house for the lawn and we used a sealant. Can’t remember the brand....

 

[Len B]

Boiled linseed oil will work and is safe to use. Raw linseed oil will work also but takes forever to dry.