What is the best wood and paint/varnish solution for outdoor woodworking projects?

[Dolmetscher007]

I am planning to build a sort of Japanese inspired wooden gate frame that will sit in basically direct sunlight, outdoors, in the rain... at all times. I am also going to be building craftsman style shutters for the front of my house, that will also be in the elements at all times. I have always assumed that "pressure-treated" lumber from the home store would be the wood I'd use, and I'd get around to finding out what is the best type of paint for outdoor wood projects. But now that I am getting closer to pulling the trigger, I wanted to ask you guys what you think. 

I definitely do not have the budget for any wood that is more expensive than pressure-treated lumber. In other words, I can't afford to build it out of Ipe from Brazil, or whatever. I have, however, never painted pressure treated wood... so I do not even know if that is a potential issue. What is the absolute most iron-clad wood and a wood-treatment option for outdoor projects that I hope to end up white?  I am absolutely open to using something like Thompson's Water Seel, or a Spar Urethane... and then painting over all that with another white paint. 

I am also open to scraping and repainting in a few years. What I am NOT looking for, is a solution that will warp to hell in the sun, and/or soak in water like a sponge and rot where it touches the ground. 

[riqmar]

Why do you plan to use PT for parts not in contact with the ground?

[Dolmetscher007]

11 minutes ago, riqmar said:

Why do you plan to use PT for parts not in contact with the ground?

What do you mean? Are pressure treated boards only good for wood that touches the ground? I always thought that one would use pressure treated wood for all outdoor stuff. Decks... Picnic Tables... etc...

[wtnhighlander]

If you plan to paint, you can use most any suitable lumber. The paint will protect the wood. PT stuff from home centers is awful stuff to work with, is usually far from dry, and doesn't hold paint well until it IS dry.

I'd suggest pine or poplar. Beware that pine knots hold a lot of pitch, and require extra care to paint well. Use a good quality outdoor primer and paint, take steps to form the parts so that water drains away, and that no unpainted wood is exposed. 

Consider that before the advent of aluminum and vinyl siding products, wooden siding for homes was quite common, and very often simply painted pine boards. Of course, if you can obtain a weather resistant species like cedar, cypress, or white oak, your pieces will last even longer.

Something I've heard, poplar sap wood is supposed to be more rot resistant than the heart, so it may be a good choice for painted projects. The main natural entrance to Mammoth Cave still contains water piping made from bored out poplar logs, used for a gunpowder producing operation during the civil war, if I recall correctly.

[Bankstick]

I found this interesting- I was in Lancaster, PA last summer. Amish crafters are now making outdoor furniture out of colored synthetic boards. Why?  They last forever and don't need painting. Cypress was big in Louisiana if you could find it. One guy cut some to allow better access to his boat dock. State fined him several thousand dollars...and kept the logs.

[Dolmetscher007]

1 hour ago, Bankstick said:

I found this interesting- I was in Lancaster, PA last summer. Amish crafters are now making outdoor furniture out of colored synthetic boards. Why?  They last forever and don't need painting. Cypress was big in Louisiana if you could find it. One guy cut some to allow better access to his boat dock. State fined him several thousand dollars...and kept the logs.

I'm all about recycled composites. Do you know where I can find fake timber for outside stuff?

[Tom King]

Pressure treated needs to dry, around here for at least a year, before it can be painted.   I have best luck with oil based primer, followed by Sherwin-Williams Emerald, which is guaranteed for the life of the structure.

I've seen Heart Pine, and Cypress that have lasted more than 200 years outside.  I don't expect anyone will ever see 200 year old composites.  On docks, and decks around here, it's not lasting any better than treated wood.  All I've seen looks pretty awful after about 15 years.

We have some composite steps on our dog porch, that are 14 years old, and still looking in good shape, but they're on a North side porch that never sees direct Sun, or freezing precipitation.

[drzaius]

The only composites that aren't really ugly are quite expensive, more than ipe, and they still aren't great. Composites just make no sense at all to me.

[curlyoak]

I like western red cedar for outdoors. Teak is the best but over the top on price. Next is Ipe. Also expensive. Cedar would be neat. Then cypress.  You are asking a lot. Wood in constant sun and rain will be future problems. I would leave the cedar unfinished. The wood will gray but it will hold up for years. 

[Bankstick]

Any big box store should have synthetic decking but colors would be limited.

[Bmac]

I'm not sure where you are located but you have a number of options, depending on where you are. Besides the ones mentioned (cypress, cedar), there may be local hardwood option you could procure for a decent price.

Best domestic hardwoods for rot/decay resistance are Black Locust, followed by Osage Orange and White Oak. Don't discount Sassafras, Walnut or Cherry, all of these are resistant, but not quite as much as the first three.

Rot/decay resistance comes with a big caveat that you understand we are talking about the heartwood, NOT sapwood. All the above species will have their sapwood rot quickly, but it's the heartwood that is the resistant part of the tree. Was interesting what @wtnhighlander said about poplar sapwood, but that is the exception not the rule.

Finally, you don't need to buy kiln dried wood, air dried is best since it may be found for a better price and it's going to be outside in the air anyway and will end up where air dried wood sits moisture wise, 12-15%.

You could probable get a good price on some of these woods from @Spanky, great to work with and he can ship it to you if you are willing to pay the freight. Of course you might have some local options that would work better.