Flex Seal For Post Rot

[joey1320]

Buying materials for an 8' x 12' lean-to I'm adding to my shed tomorrow. The posts will be set 36" deep due to frost heaves and I will be adding a 60LBS bag of concrete to each.

I was in the garage yesterday and realized I had two brand new spray cans of Flex Seal I had gotten some time ago.

Would Flex Seal help wood rot if sprayed on the 36" of the post that will be in-ground?

I can buy a sealer but if I can use what I already have...

 

[kj_mustang]

Wood only rots quickly at the surface. It takes oxygen and water to make wood rot.

 

[joey1320]

Wood only rots quickly at the surface. It takes oxygen and water to make wood rot.

Hmmm... So why do people recommend adding a sealer to posts that are to be buried in dirt or concrete?

 

[kj_mustang]

Because there are lots of variables. Wood type, soil type, moisture content, temperatures all affect the growth of wood fungus which causes the rot. If you keep the rain water away from the post base and it was a chemically treated post, it will last a very long time. Plenty of 100+ year old barns around with wood post in the ground.

 

[joey1320]

Because there are lots of variables. Wood type, soil type, moisture content, temperatures all affect the growth of wood fungus which causes the rot. If you keep the rain water away from the post base and it was a chemically treated post, it will last a very long time. Plenty of 100+ year old barns around with wood post in the ground.

Gotcha!

 

[mike93lx]

Keep dirt off the posts and you will be much better off. Water needs to drain away.

Best is to not put wood in the ground at all

 

[joey1320]

Best is to not put wood in the ground at all

I have to go 36" due to frost and don't feel like mixing that much concrete by hand.

The post will go into dirt. I just trying to prevent rot any way possible.

 

[mike93lx]

I have to go 36" due to frost and don't feel like mixing that much concrete by hand.

The post will go into dirt. I just trying to prevent rot any way possible.

At least get some stone in the hole to promote drainage.

You can also buy sleeves that will keep the dirt from contacting the post

 

[CraigStu]

Talking to my garage addition contractor 6 yrs ago about how I would redo the portion of the fence we took apart, he said no concrete is the current thinking. Gravel in the bottom of the hole tamp it some by hand w/ the post, drop the post and put the dirt back in the hole and tamp it. He said they were finding that the water gets between the post and the concrete and it can't get away so it sits there and rots the post. He felt it would be better if the post sat on gravel so the concrete was more of a sleeve than an upside down cap but best is no concrete. Admittedly this was just discussing a fence post but it makes sense to me.

 

[Stuart in MN]

Someone posted a product here recently called a Post Saver. It's basically a big piece of heat shrink tube that covers that area right at and just below ground level, where a wood post is most likely to rot. It looked like an interesting solution to me.

https://www.homedepot.com/p/Post-Sa...rotection-Sleeve-10-Pack-SKU-4-5-10/310441308

 

[joey1320]

At least get some stone in the hole to promote drainage.

You can also buy sleeves that will keep the dirt from contacting the post

My apologies. I plan on adding 2-3 inches of gravel to the bottom of the hole to promote drainage. I think using the same dirt I took off will be good. I may just get the wood sealer and coat the post with 2-3 layers of it.


Thanks!

 

[strutaeng]

Buying materials for an 8' x 12' lean-to I'm adding to my shed tomorrow. The posts will be set 36" deep due to frost heaves and I will be adding a 60LBS bag of concrete to each.

I was in the garage yesterday and realized I had two brand new spray cans of Flex Seal I had gotten some time ago.

Would Flex Seal help wood rot if sprayed on the 36" of the post that will be in-ground?

I can buy a sealer but if I can use what I already have...

Weren't you asking about the Simpson-type post base plates on a recent thread? I was going reply but forgot, LOL.

I would not embed the posts in the concrete because they will rot. Use the Simpson base plates; they hold the post off the ground. Wood endgrain will wick moisture.

In fact, the standoff is a requirement on the building code (I think IRC and IBC, not sure?)

 

[joey1320]

Weren't you asking about the Simpson-type post base plates on a recent thread? I was going reply but forgot, LOL.

I would not embed the posts in the concrete because they will rot. Use the Simpson base plates; they hold the post off the ground. Wood endgrain will wick moisture.

In fact, the standoff is a requirement on the building code (I think IRC and IBC, not sure?)

No, not me. I replied to that thread informing the OP which one I had used.

I'll check the local code.

 

[dcg9381]

I don't see why it would make anything worse. Traditionally, I've coated wood in epoxy or polyester resin where I was concerned about water causing degradation. Neither are UV stable, so you have to address that.. No idea about how flex seal handles long term exposure, but it's advertised uses seem to be in line with UV exposure.

 

[rburke65]

I have used basement exterior water proof tar on many 4x4s

 

[Loose Ctrl]

I tamp my posts in with pea gravel. My ex grandfather in law taught this to me. We had to take down his carport to relocated it and all the 8x8 posts looked like new and they had been in the ground for close to 50 years. I'm doing an 8x16 lean to addition to my workshop. My posts will be done this way up to the point where the concrete floor will be. I don't have much of a frost line here nor do I have high wind loads. We do get a lot of rain, especially the past few years. I can't comment on flex seal.

 

[Ralf11]

pour concrete and stick some plastic tubes in

add the 4x4 posts and wedge them so they won't move

makes it easy to pull the posts out a few decades later when they rot - they WILL rot, just a matter of time

 

[plout99]

If the posts are from the big box stores yes they will rot. Try to source posts that are uc4b treatment level. They are cca treated to 0.60 level if I remember correctly and will probably out last you. I pulled fence posts last year that were cca treated to uc4b that my dad had installed 35 years ago and they all will be reusable. There was a little rot at ground level on some but not much overall.

 

[jdsac]

Coat the posts with HENRYS liquid roof cement to a distance of 6-8" above ground level , let it dry & put on a second coat. It will take some time to prep your posts- plan ahead.
If the post can't get wet it won't rot.. Coat them properly, let the HENRYS dry, then set them

 

[nadogail]

I have decided to use steel posts wherever possible, I fully expect anything that I have built with steel posts to outlast me.

 

[Dan in Pasadena]

IF you're going to totally bury the wood posts in concrete - I would NOT - never encapsulate the bottom of the post in the concrete. It's like leaving the wood in a tub of water. Leave the wood sticking out the bottom into several inches of gravel.

I'd use an embedded steel anchor and make sure water its directed to run away from the wood.

 

[LS6 Tommy]

You don't set wood posts in concrete at all. In some places it's not even allowed by code. Use a steel post anchor.

Tommy

 

[Joe Reed]

Dammit, I did my fence posts all wrong. I just dug the holes, dropped the Lowes posts in (no gravel), filled around them with concrete. It's only been 17 years but they're all still solid. I did the same thing at my previous house 30 years ago and they're still solid too. Not a single post has needed to be replaced. Should I dig 'em all up and start over?

 

[65ranchero]

There is always things like this:
https://www.amazon.com/dp/B07RTYYTQQ/?tag=atomicindus08-20

https://www.adirondackbasement.com/helical-deck-piers/videos.html

 

[joey1320]

Dammit, I did my fence posts all wrong. I just dug the holes, dropped the Lowes posts in (no gravel), filled around them with concrete. It's only been 17 years but they're all still solid. I did the same thing at my previous house 30 years ago and they're still solid too. Not a single post has needed to be replaced. Should I dig 'em all up and start over?

 

[danfromsyr]

Dammit, I did my fence posts all wrong. I just dug the holes, dropped the Lowes posts in (no gravel), filled around them with concrete. It's only been 17 years but they're all still solid. I did the same thing at my previous house 30 years ago and they're still solid too. Not a single post has needed to be replaced. Should I dig 'em all up and start over?

same here son, same here.

 

[LS6 Tommy]

Dammit, I did my fence posts all wrong. I just dug the holes, dropped the Lowes posts in (no gravel), filled around them with concrete. It's only been 17 years but they're all still solid. I did the same thing at my previous house 30 years ago and they're still solid too. Not a single post has needed to be replaced. Should I dig 'em all up and start over?

I wish I had you do my mailbox.
I did it the same way the first TWO times. I redid it at 8 years and again at 14, but put gravel at the bottom. It's loose again...

Next time I'm getting a post anchor.

 

[Todd.Brock]

17 years ago , CCA was used for pressure treating, but some kids had to go chewing on the posts and get arsenic poisoning and ruined it for all of us.


Sent from my iPhone using Tapatalk

 

[danfromsyr]

I had thought about using roofing ice/water shield to wrap the bottom of the posts..
a small square on the base and a wrap sealing that around the post.

 

[plout99]

I had thought about using roofing ice/water shield to wrap the bottom of the posts..
a small square on the base and a wrap sealing that around the post.

I did that to the laminated columns I used for my build in 2019. The columns were uc4b treated and I picked up a new box of grace ice water shield off craigslist for cheap so I figured I was only out my time and a few dollars. Will I know if it works or not

 

[slackdaddy1]

You have to know your soil type.
If it is a clay based soil, and you dig a 36" deep hole, put 8" concrete in the bottom and the post, then backfill the rest with dirt,, you just created a swimming pool for the post, and do not back fill with gravel,, that will realy invite standing water in clay soil.

I have to go 36" due to frost and don't feel like mixing that much concrete by hand.

The post will go into dirt. I just trying to prevent rot any way possible.

 

[slackdaddy1]

To bad we can't get ACC treated wood anymore,, unless you are Ag

Dammit, I did my fence posts all wrong. I just dug the holes, dropped the Lowes posts in (no gravel), filled around them with concrete. It's only been 17 years but they're all still solid. I did the same thing at my previous house 30 years ago and they're still solid too. Not a single post has needed to be replaced. Should I dig 'em all up and start over?

 

[Ralf11]

Dammit, I did my fence posts all wrong. I just dug the holes, dropped the Lowes posts in (no gravel), filled around them with concrete. It's only been 17 years but they're all still solid. I did the same thing at my previous house 30 years ago and they're still solid too. Not a single post has needed to be replaced. Should I dig 'em all up and start over?

it's real common - mine are all done that way

but his comment about using steel post anchors makes sense to me

maybe not worth it in the desert or in real sandy soil

 

[VinnieCap]

Use these...

https://www.postprotector.com/