Untreated lumber for uncovered deck?

[N80]

I am getting ready to order a portable saw mill. It will take several months before it gets here.

One of the first projects will be to build a deck extension off of the front porch of my cabin. This will be uncovered and fully exposed to sun and rain. It will be made of pine from off of my place....although oak is plentiful....but I've never seen an oak deck.

Anyway, my question is this: How do I prep untreated lumber for an uncovered deck? The only thing I can think of is a heavy application of an oil based stain on all surfaces of the lumber. Are there better ways? Better ideas?

By the way, none of the wood will be in ground contact.

Thanks for any input.

Brief rant: I could probably get as good a result with no treatment at all as I have from the treated lumber I used to build the front stairs of my cabin porch. It all came from a big box store of course.They are no more than three years old and the 2x6 treads have twisted, splintered, warped, cracked, broken deck screws and are generally falling apart. This is even after having been stained twice. I've never seen such useless garbage. And it was not cheap! This is part of what prompted me to buy a saw mill.

 

[/pine]

Using pine is not recommended (one exception is clear, dense heartwood yellow pine) ...every penetration (nails, screws etc...) will allow water to penetrate and the decking boards will start rotting where they bear on the framing...
White oak has been known to outlast most treated lumbers...
There are lots of trailers decked with white oak that are still solid after 40++ years...

 

[ponytug]

I hear you on pressure treated lumber. We had to replace a 6"x14"x20' beam supporting our deck supports after a year when it managed to warp despite being bolted down and nailed into. Not pretty.

Personally, I think that an oil based stain, or oil based clear coat is all you need. Even linseed oil will work. I like both Flood and Kilz. When I have used linseed oil, I dilute the first coat 50/50 with solvent to get better penetration, especially on the ends, and any screw holes, and then let it dry thoroughly before the second or third coats. Basically, I keep putting on oil as long as it gets absorbed. I recommend that you do the first coat on a warm day when you don't plan to be around for a day or two... For a deck, I would definitely also do the underside and sides with oil (but only three sides if you paint it). For the deck support beams, I covered the top surfaces of mine with a rubber seal tape that is supposed to keep water from wicking down the fasteners and rotting the support beams. Time will tell, but it was cheap in the grand scheme of things. Despite my poor opinion of pressure treated, I would use it for the beams under the deck, unless you can get some rot resistant wood locally.

You probably know this already; When you cut your lumber, seal the ends before drying them. It cuts down on cracking and checking. 2" boards are also the ones most prone to warping while drying. When you cut the lumber I would think about using use the quarters for your deck boards as the twist will be minimized and the shrinkage will be along the width dimension.

What kind of pine do you have? Shortleaf?

I happen to love oak, but I think it is a pain to work with in construction as you need to predrill all holes before screwing or nailing. I think that, and the cost, is the reason that you don't see a lot of it used for decks. It is also pretty heavy. Shortleaf pine is nearly as strong as red oak, though not quite as durable.

All the best,

Peter

 

[N80]

I think we have mostly short leaf pine, or some hybrid variation of it that volunteers from heavy planting in the region. People tend to call it yellow pine but not sure if that is accurate. I have tall, straight 40+ year old trees I can choose from. We also have loblolly. My loblolly trees are all old, very tall and waaay too big for me to handle on a portable mill. Wouldn't want to cut them down anyway.

We have lots of white oaks. In general I would prefer not to cut them down. However, we usually get a blow down or two every year.

 

[3Ts]

You may also want to look into using Copper Sulfate as a preservative. I've not used it but all the reports say that it helps. The current ACQ pressure treatment is a copper based preservative but a different form than the sulfate.

 

[CH4Ohio]

Paint has historically been used to protect untreated wood from weather. There are several deck finishes that are actually paint vs. stain. However, for long term maintenance and integrity, I think using untreated pine on a deck would be a mistake and require a lot of upkeep.

As Slash said, white oak is really strong. That's what ships were made from before steel. You've never seen an oak deck due to the cost, but if someone had a supply of free oak, that would be different.

Do you have building codes or inspections at this location? If so, that might limit the acceptable materials also.

 

[Rustyiron]

It's surprising how long "regular" lumber will last providing that it can dry to both sides. laying flat is a disadvantage but I made a picnic table with the flat boards (seat and top) made from common SPF lumberyard wood 10 years ago and the only rotting thats happening is where the P/T legs are in contact with the ground.
A sunny location will help.

 

[Tinhack]

I could probably get as good a result with no treatment at all as I have from the treated lumber I used to build the front stairs of my cabin porch. It all came from a big box store of course.They are no more than three years old and the 2x6 treads have twisted, splintered, warped, cracked, broken deck screws and are generally falling apart. This is even after having been stained twice. I've never seen such useless garbage. And it was not cheap! This is part of what prompted me to buy a saw mill.

That will happen to all lumber if not maintained. Even treated lumber dries out when exposed to sun. I've had to rebuild the front steps of my house about every 3-4 years. They are facing the South. The back steps and portch (facing North) are 20+ years old and still very nice. Although I have had to replace a few screws.

 

[Tinhack]

Loblolly (AKA- Yellow Pine) is trash trees down here. That stuff will bow, crack and split if you look at it twice. It's hard but doesn't even make good fire wood. I can't imagine using it for a deck or steps. The home stores here sell it but I don't know what for. It's cheap but can't even be used for concrete forms if exposed to sun.

 

[N80]

All of the pine here is primarily used for pulp wood and everyone calls all of it "yellow pine" including loblolly, short leaf and the various hybrids. You can sometimes sell large straight pines for telephone poles. My loblollys are in creek bottoms. That's why they are so big. The creek bottoms haven't been logged in decades. They are huge (takes two people to get arms around them). I would never cut them.

I have chainsaw milled some old loblolly. Hard as a rock. Very stable. Very tight grain. One of them fell in my creek bottom. Way too large to handle with a regular tractor or I would have gotten it out. It has been on the ground for over ten years and is still solid except for the bark and most external white wood.

Anyway, based on what you guys are saying I'm not sure what I'll make my deck with. If there are white oaks down I can use that. Otherwise I may try older pines, use primarily the heart wood and stain heavily with an opaque stain.

I can also get red cedar come to think of it. Plenty of that but the larger ones are harder and harder to find.