Additional Sealant for Pressure Treated Lumber?

[Thomas McCurnin]

I've got a well head cabinet/enclosure to make which is in a remote location, about a 2 mile hike through the mountains without any trails. I've spent a few hours making measurements, and we will likely make this in sections, and strap them to our backs and assemble it in the field. There is no electricity there and it is very rough terrain, making footings or site building is not an option, we just have to put this thing on the dirt and its back side against the mountain. It will rot, I get that. Our existing one was heavily painted and has lasted since 1980, but it is rotted.

The plan is to use PT lumber, prime it at least twice, and a color coat with about 3 coats, and I will use an expensive paint like Sherman Williams or Dunn Edwards.

But the bottom and back will soon be buried in muck.

Is there an additional sealant to the bottom and back I should consider? I'm thinking multiple coats of Flex Seal or a similar product. I assume I place this over the primed and painted cabinet at the bottom and back.

Any other suggestions?

[Doug Garson]

Have you considered making it from PVC or some other plastic that won't rot?

[Bill Dufour]

Maybe use plastic shutter panels as walls.
Bill D

[Bill Dufour]

I would suggest rock and mortar.
Bill D

[Thomas McCurnin]

To build the entire structure which is 4x3x3 with a lid out of stone and mortar would take 15+ bags of mortar, each weighing 60 lbs, and you guys would hike 2 miles carrying a mortar hoe, mortar box and a dozen bags of mortar? OK, you are in better shape than I am. And just building a footing doesn't help much as the well head comes out of the mountain horizontally, so any structure has to sit flush with the side of the mountain, up against it, covered in debris and when wet, muck.

Nah, I'm building this out of wood. The other one lasted forty years. My question is sealing pressure treated lumber to enhance its protection against rot where it is direct contact with soil.

[Rich Engelhardt]

I've always used Black Jack - either straight or cut with mineral spirits.

Flex Seal should work - but - the cost of it is up there.

[Brian Runau]

Would coating the surfaces exposed to dirt with black tar or tar paper (sealed) make any difference?

[Alex Zeller]

If you use PT make sure it's the better ground contact rated version. I would also try to find some that's had time to dry. There's a lot of weight difference between wet stuff and dry.

[Lee Schierer]

The plan is to use PT lumber, prime it at least twice, and a color coat with about 3 coats, and I will use an expensive paint like Sherman Williams or Dunn Edwards.

But the bottom and back will soon be buried in muck.

Is there an additional sealant to the bottom and back I should consider? I'm thinking multiple coats of Flex Seal or a similar product. I assume I place this over the primed and painted cabinet at the bottom and back.

Any other suggestions?

I agree with the others that you should let the lumber dry before you attempt to put any type of protective coating on it.

You need to avoid the "buried in muck" part of your plan. Instead you need to provide as much drainage as possible around the base. The lumber will last longer if it is allowed to dry out.

I built this barn over 40 years ago using untreated Hemlock boards for the siding. The siding is still going strong and will likely last another 20-30 years, barn.jpg

Perhaps use a combination of materials. Use materials that don't rot for ground contact and treated lumber for the above grade portions. Metal roofs are known to last over 50 years.

[Tom M King]

Treated lumber today is different than the treated from 40 years ago. Putting any coating on the part below ground is just like putting it in a bag, so it will probably last less time than if it was bare. Drainage would help, but I have no idea what the ground is like there. I've found out the new treated process ground contact posts last less than half as long in concrete as they do bare, so wouldn't expect much difference with any kind of coating.

I have found out that Sherwin-Williams Rain Refresh is great stuff.

[roger wiegand]

Find UC4B rated treated lumber for at least the in-ground portions of the structure. It has half again more preservative than the more common UC4A "ground contact" treated lumber and it suggested for "critical components or difficult replacement". I think your situation qualifies. At least it will last long enough that someone else will probably have to do it the next time!

[Jim Becker]

Choose your PT wood carefully. There's "ground contact" and "in ground" ratings. Using the latter for what actually touches the ground, even if it's not "in" the ground (at least initially) might be a good way to help preserve it longer. You may also want to investigate some of the newer preparations available to coat posts that help with additional preservation.

[Maurice Mcmurry]

Get the highest retention rating you can find. Some stores call it "Critical Structure Ground Contact". I would not use paint. You can treat your end cuts, and the whole structure for that mater, with copper green wood preservative. If you do not paint it you can re-apply coper green in the future. Copper green is nasty and leaches. I would want to know for sure that it would not contaminate the well. Pine tar, linseed oil and turpentine is a good exterior coating that can be easily renewed.
+1 for the idea of using a plastic material like Azek.
https://azekexteriors.com/products/sheets

I am intrigued by the logistics of your project!

[Bill Dufour]

See my recent thread about ground contact treated 4x4 fence posts rotting off after ten year or less. This is the new improved brown stuff. The 15 year old ones, green, are fine. Get your treated wood and air dry it for a month or two. Then stand the posts upright in a barall full of the preservative or oil. Let soak for several months. Then stand on the the rend and repeat.
What does the local law say about treated wood near water?
Bill D

[Bill George]

My mom when she was alive had a Neighbour with a treated wood basement. I have not seen that house for 30 years so I have no idea if its still standing.


When I was growing up on the farm in the early 1950s there was a spring coming out of a fairly steep hill someone had put a box around it so the cows could drink but it had something like a 2 inch steel pipe driven back into that hill that kept the water clean and headed into that wooden box. You could also build your well head from native store gathered up and held together with mortar with the suggested PVC shutter to keep it dry enough to set up.

Buy, rent or borrow a 4wd ATV to haul your stuff up the mountain. My dad used a two wheel walk behind garden tractor with chains.