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.

 

[woody]

Just my two cents, if I were in your situation as in owning the mill and the trees I would use some white oak and enjoy a solid deck for years.

 

[Doughknob]

You "can" use pine, or anything else --- if you properly treat and care for it. Stain itself will not work. You'd have to use a good outdoor varnish or paint. And you'd have to re-apply every few years. The idea is to keep rain and, more importantly sun, from direct contact. The topcoats like varnish or paint will do this if maintained.

So, to clarify - paint does work, assuming the top surface is painted. As the poster below said, the wood can still breathe if the bottom surface is unpainted. Or like on old houses or barns with wood siding, the 'inner' surface is not painted.

 

[Egon]

Coat with a preservative first. Then a stain. No paint. The coatings applied should be able to breath and not restrict the passage of moisture.

Both products are readily available at regular stores.

 

[RalphVa]

Whatever you do, do not use a stain that is more like a paint. It holds moisture in and causes the wood, even treated wood, to decay.

We're replacing our boards and rail tops with PVC called Azek. Had a stain on the treated wood, and it just went to pot. Had to replace most of the screws with stainless because they were corroding.

Red cedar would be my first choice.

 

[skipmarcy]

I would tend to agree that the white oak would be better, red oak rots more easily and bugs go for it more too. If I were going to do this project I would use a couple of coats of oil based stain or preservative and let it dry well. Then I would use spar varnish on the top surfaces with some sort of traction material added. You may not want this type of finish for your surface though.

The red cedar would certainly hold up but it's going to go gray without the spar varnish or some sort of good UV protection. I've been considering cutting my 7 very large red cedar trees for years now to make lumber but I hate to see them go and am getting too old & tired to be messing with sawmill lumber anymore. My trees are approx. 20"+ in diameter and quite tall - could get 2 or maybe 3 decent 8' or 10' logs out of each one.

 

[ponytug]

@N80 How big is this deck? If it isn't that big, I would go with your downed oak.

Slashleaf pine (one of four species called southern yellow pine) is a wonderful wood, and quite strong, and would also make a great deck.

I love cedar for paneling, fence posts, and trunks. For weight bearing use on a deck, I am much less excited, as it has a tendency to fracture. If you have ever seen someone step through a deck, it is ugly, as the knee jerk response is to jerk the leg up, thereby driving the wood splinters into the leg. You would need to oversize the cedar dimension by about two fold to get to the strength of pine, and even then it tends to fail completely, rather than cracking.

Copper sulfate will stain your wood, and won't do much for preservation, as you can't get very much into the wood. Copper naphthalenate is available, but it will stain everything dark green, including you, and stinks to high heaven.

One comment on oil vs varnish; you do need to re-treat the deck with linseed oil (or whatever clear stain you decide to use) every couple of years depending on sun exposure. With a sprayer, or a roller, it goes really quickly. Varnish is, in my experience, much higher maintenance and can need sanding and varnishing annually in high exposure areas. Don't get me wrong, I love the look of varnish, but it isn't do it once and forget it. If you change your mind after varnishing, it would mean sanding the whole deck down.

On the subject of stains; don't waste your money on a water based stain for a deck, that really won't last, contrary to what the can says. It has no penetration, and so no endurance. I think they are marginal for fences, and that is about their only use. (Who me, opinionated?)

Good luck!

All the best,

Peter

 

[EddieWalker]

Here in East Texas, pressure treated deck boards are lucky to last a decade. Everything else usually rots away even faster. But something that I've noticed is that when I've made some emergancy, temporary fencing repairs with regular 2x4s and 2x6s is that after years out in the weather, they are still solid. None touch the ground. All are almost totally surrounded by air and they are installed on the edge so water never sits on them. I plan to replace them, but I'm also curious to see how long they last. The oldest one has been there since 2013.

 

[BigBlue1]

Well, Rust-Oleum makes a product called Creo-Coat that is great for preserving and protecting untreated wood, above or below ground. But it is black and likely not something you'd want on a deck.

 

[Captain Dirty]

Yankee redneck solution (likely not EPA approved). Dig a shallow trench or build a wooden frame, line same with 6-mill poly, place board(s) in trench or frame and cover with used crankcase oil. Will also have to cobble together a rack or pan with grating to let the treated boards drain/dry. Painting or further treatment not practicable.

 

[Captain Dirty]

Do not underestimate the durability of "natural" or "older" growth wood when compared to the "forced" growth of plantation-grown trees. A friend trimmed his house with eastern white pine milled from "natural" trees on his property. Others told him it would last 3-5 years, max. Forty years later it is still fine. He did prime 6 sides and painted the exposed sides.