Need help with pole barn overhead detail - Concrete next week!

[Dstyduhar]

We plan to pour concrete late next week and a thought just occurred to me about the overhead door openings. As thing sit, the plan is to put a form board on the outside of the door jamb trim and pour the concrete right up to the tin in the door openings. I didnt think/realize that concrete against tin is not ok so I need to figure out what to do asap.

I have attached a pic showing one side of the opening. Note the non PT 2x4 attached to inside of post and left long so the door wont fall out of the track before concrete is poured. This will get cut off flush before pour but thats what is behind the tin if its cut away. Sort of tough to tell but the building has two rows of skirting so there is a row of tin below the rat guard that turns into the door openings. If you cut the door jam trim, this second tin layer is underneath. Cut that away and its the non PT 2x4. Remove the 2x4 and you are looking at the post.


Orange line is grade of concrete inside building
Red line shows 1/2" drop from door track to outside to help shed water.
Blue line is just a rough guess of where I would cut the trim to keep it above the concrete.

Here are some ideas

1. Leave as is but put tarpaper or foam on the tin so it doesnt rust
2. Snip the jamb trim 3/8" above the red line and cover the remaining exposed tin/wood with tarpaper

thank for any ideas or advice.

PS - dont mind the foam in the pic, its used to keep critters out of the barn.

thanks,

Drew

 

[Leaflessshadetree]

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[Zeke]

I'd definitely cut the tin to above finish concrete. Below finish concrete wrap any exposed wood with bituthene. Tuck it up under if you can. Foam is a no go — holds water. Copper will work too.

 

[Dstyduhar]

I'd definitely cut the tin to above finish concrete. Below finish concrete wrap any exposed wood with bituthene. Tuck it up under if you can. Foam is a no go — holds water. Copper will work too.

Problem is that 2x4 is not PT. If I cant tuck the ice and water up under the snipped piece then it will be exposed.

 

[Zeke]

Part of the problem is that the intended remaining part of the 2 x 4 is not PT. PT was not made so sit below finished concrete as is the case with any wood. You need to isolate it from the concrete. You can coat it with waterproofing material designed to be below earth grade. A little bit of copper will slip under the jamb metal. All bituthene is consists of a butyl rubber with a hardy self sticking backing. It's sold under different brands. Before bituthene they used copper or lead. All you need to do is try and keep any wood below the finished concrete dry.

It shouldn't be there in the first place, but now that you've created that situation, just fix it best you can. Many times concrete porches were put level with the interior finish floor or within inches. On raised floor houses this puts the concrete well above the floor framing and mud sill. What I told you would work is what they do in these circumstances. Sure, the backside of the floor framing is open which makes this work for years after years. You do what you can.

 

[Dstyduhar]

I guess what I'm stumbling on is why to cut the tin at all and instead just isolate the tin from the concrete? The tin appears to protect the wood right now so is the only issue here just getting the door jamb trim above the concrete? What if it stays below the concrete but is protected? Is this an aesthetic issue? I would think if someone ever needed to remove the jamb trim, they could still use a multitool flush with concrete, remove, hand cut a cleaner line slightly above this cut, flash and reinstall. Im prob missing something.

Another issue is we are still getting a bunch of rain due to Ian so really dont want to open up the tin if I dont have to.

Appreciate the advice.

Drew

 

[Firebrick43]

I guess what I'm stumbling on is why to cut the tin at all and instead just isolate the tin from the concrete? The tin appears to protect the wood right now so is the only issue here just getting the door jamb trim above the concrete? What if it stays below the concrete but is protected? Is this an aesthetic issue? I would think if someone ever needed to remove the jamb trim, they could still use a multitool flush with concrete, remove, hand cut a cleaner line slightly above this cut, flash and reinstall. Im prob missing something.

Another issue is we are still getting a bunch of rain due to Ian so really dont want to open up the tin if I dont have to.

Appreciate the advice.

Drew

Eventually that door piece is likely to get beat up and you will want to replace it. Second it will corrode if touching the concrete and gets water(which it defiantly will there)

As other said, cut it back, and cut out the 2x4 and put some composite lumber.

Also the foam there across the threshhold appears to be higher than the plastic inside. The top of the foam should be the same height. If you vary the thickness of concrete it will crack there. Or at least remember to put a joint across there.

 

[Wolley]

I think some how you need to pour concrete up against the post. Cut slightly above the red line and cut everything back to the post.

Or unscrew the trim and remove and cut it correctly later.

Or you could do nothing and pour as is and let future you deal with it.

 

[Zeke]

If rust starts below grade it will crawl up. You could coat the metal below the finish grade of the concrete, but it will show because it needs to be slightly above. I think it's cleaner to end the metal where it should end.