Lean-to Shed Construction Progress

[captain14]

https://www.todayshomeowner.com/video/diy-outdoor-shed-addition/

Here's the link to my post #21 above. I finally found it after some Google fu.

 

[naf305]

I think I need to quote myself here:

So when making a design decision, in lack of experience or knowledge, I will always go with the more cautious options. Plus time here is not really a factor. I want to build it well and be proud of what I did.

And I had a choice between pressure treated plywood or OSB and I now second guess my choice....

 

[captain14]

Like you when you had the third piece of pie at the holiday event until....

 

[DGersic]

I think I need to quote myself here:







And I had a choice between pressure treated plywood or OSB and I now second guess my choice....

I'd have gone with the treated plywood. Shed floors get moisture from below, and sometimes wet from above. Not sure that OSB will work there. Check before continuing to putting your walls on top of it.



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[naf305]

I read that Advantech is a really good product for subfloors. I like the water resistance and stiffness of it.

Maybe using that along with a vapor barrier (6 or 9mil) sitting on the top of my joist foundation would create a solid and life-long floor?

Or should I go with with pressure treated plywood. My problem with is that I saw the product and it is not a not a nice quality product with lots of knots (at least at my home depot). I'll try to shop around at the lumber yard and commercial building supply stores in the area.

Thoughts?

Also any tips on removing a fresh OSB floor glued with liquid nail and 3in framing nails?

 

[DGersic]

I read that Advantech is a really good product for subfloors. I like the water resistance and stiffness of it.

Maybe using that along with a vapor barrier (6 or 9mil) sitting on the top of my joist foundation would create a solid and life-long floor?

Or should I go with with pressure treated plywood. My problem with is that I saw the product and it is not a not a nice quality product with lots of knots (at least at my home depot). I'll try to shop around at the lumber yard and commercial building supply stores in the area.

Thoughts?

Also any tips on removing a fresh OSB floor glued with liquid nail and 3in framing nails?

https://www.buildgp.com/dryguard-enhanced-osb

The way I read it, this is intended for use as an interior sub floor. It can take some moisture, like you might get while building a house, without swelling. It's not weather proof, and I'd be hesitant to use it in an unprotected or semi protected outdoor application, like a shed floor.

We don't have a Home Depot around here. My choices are Lowe's and Menards. I find the wood quality and selection is better at Menards. If you have one available, try there. If you want the best looking pieces, be prepared to un-stack the whole pile until you find the ones you want. Sometimes the top few are in the worst shape, because somebody like me pulls the best ones out and restacks the pile.

I built my shed with a 2x8 frame on 16" centers, topped with 3/4". The 2x8s and the plywood are all treated. There is gravel underneath to provide drainage. It's similar to what you're building. Mine has been there five or six years now, and is holding up well.

Removing? A cats paw and hammer will deal with the nails. Adhesive can be broken loose, or chipped off with a scraper. OSB probably won't come off clean no matter what's holding it down. It doesn't have to look perfect, once the floor I down, you'll never see it again.

I don't want to rain on your parade, but I'd pull the OSB and put down treated plywood for your floor. I'd rather have a few knots in the floor than a problem later. If you like the OSB, put a layer of that over the plywood, but inside the walls, so you can remove it later if it doesn't hold up. At least that way you won't have it exposed to ground moisture from below. A vapor barrier could help there too.




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[naf305]

I'm not happy with myself for not thinking of this before doing all this work... But this is how you learn right?

I don't have a Menards by me. Only Lowe's or HD. There are some lumber yards too. I'll have to call to see what they have.

About the vapor barrier:

Should I just put a layer of plastic sheeting over the entire joist assembly? This will prevent me from using construction adhesive when putting back the new plywood.

What about filling the gap between the joists with 3/4in foam boards?

I just want this floor to last. I'd rather do the work now than taring everything apart years down the road.

 

[gunguy]

Unless you have gutters draining under the shed or other water draining/flowing,it should be plenty dry. You're installing metal mesh around the perimeter to keep critters out so you should have plenty of ventilation. Will it be popcorn-fart dry? Probably not but dry enough that I bet what you have down now will last many years. But if you want to pull it off an lay pressure treated plywood, now's the time to do it.

Using construction adhesive when laying subflooring is mainly to prevent squeaking which is important when doing residential interiors. In a shed it's probably not necessary. If you want, staple the poly sheeting down then screw your plywood floor over top and don't even worry about the construction adhesive in this case.

If I'm wrong, I'm sure someone will point it out in short order.

You're doing fine. The way I see it you are not just building a shed, but using it as an exercise to learn and enhance your building skills.

Looking forward to your next post.

Jim

 

[brent769]

naf305, I like what you're doing. Just a question though, are you planning on two doors like the initial drawing? Would it not be better to have 1 door (largest you can go) so you don't lose storage space? Just a thought. Please keep us updated.

 

[JRC3]

My thought: If the doors open out, they don't waste floor space. Also you don't necessarily have to walk through the door, just reach in and pull out what you want. On such a narrow design an extra door/doors could give you more storage because you won't give up so much space for a full length walking area.

 

[brent769]

You do raise some good points. I just see it as lost shelf space, haha.

 

[naf305]

@jrc3 and @brent769,

I thought about the door situation for a while debating on storage vs accessibility. I choose in the end the later.

I have a lawnmower and a 16ft ladder for which the front entry (on the short side) door is simply a must. But then I figured having only this door would make it difficult to get to the tools, garbage cans, wheelbarrow all the way in the back. I'd have to take the lawnmower out and so on...

This is where the side entry door come in. I'm still debating on a double vs single wide door. In the end both doors will be outswing (a must) so not loose any precious floor space inside and so I can pack it to the rim .

 

[Pointbock]

I think two doors are a good idea - stuff always gets stacked/tossed in one door and you lose your access.

I'd go with the treated plywood. Everything else on this build has been on the "safe vs sorry side" - I wouldn't choose a "probably ok" option at this point. Especially one that will be hard to fix later.

 

[naf305]

Unless you have gutters draining under the shed or other water draining/flowing,it should be plenty dry. You're installing metal mesh around the perimeter to keep critters out so you should have plenty of ventilation. Will it be popcorn-fart dry? Probably not but dry enough that I bet what you have down now will last many years. But if you want to pull it off an lay pressure treated plywood, now's the time to do it.

Using construction adhesive when laying subflooring is mainly to prevent squeaking which is important when doing residential interiors. In a shed it's probably not necessary. If you want, staple the poly sheeting down then screw your plywood floor over top and don't even worry about the construction adhesive in this case.

If I'm wrong, I'm sure someone will point it out in short order.

You're doing fine. The way I see it you are not just building a shed, but using it as an exercise to learn and enhance your building skills.

Looking forward to your next post.

Jim

Hey Jim, thanks for the comforting thoughts. I've been scratching my head over this the past couple days.

The problem is that "if" there a chance that the floor rots 4-5 years from now I will forever hate myself for it. And while I hate myself now for not thinking this through better I'll sleep better at night knowing I redid the work the proper way.

Now is PT plywood enough? What else can I do to seal this ^%@$# floor?

Would adding a plastic sheet layer cause any issue with trapping moisture in the plywood (though I really won't have much moisture coming from the inside the shed).

I want to put all the chances on my side for this shed to last 50 years. So any suggestions are welcome.

Also, I read somewhere that one should not build the wall on top of the subfloor because the floor will fail and that it is not a matter of if but a matter of when. Therefore he suggested to build the subfloor after the wall are put it and do it in a way that can be easily replaced down the road (no adhesive, screws instead of nails....). No really sure how this would work in reality and how the walls would be properly supported since your sitting a 2x4 bottom plate on the edge of a 2x6 joist. No sure if you ever heard of something like this.

 

[Finallygotit]

Subscribed

Great thread!

OK, here's my $0.02. I would definitely replace the OSB with pressure treated plywood and not use a vapor barrier as I think it would trap moisture especially if a liquid is spilled from above. Definitely use screws instead of nails both for the ease of future maintenance and they don't squeak. You should have enough ventilation with what you have already put in place to not worry about rot for quite some time.

HTH

 

[naf305]

I think two doors are a good idea - stuff always gets stacked/tossed in one door and you lose your access.

I'd go with the treated plywood. Everything else on this build has been on the "safe vs sorry side" - I wouldn't choose a "probably ok" option at this point. Especially one that will be hard to fix later.

This is my ultimate plan, build something that I feel will last my lifetime in this house.

And like you said, I didn't go cheap on the rest of the foundation so I feel terrible already that I may have choose a sub-optimal for my floor.

I'm getting myself mentally prepared to the unavoidable fact that I will need to rip off what I did last weekend, spend a day doing the demo and another day reinstalling the new floor.

 

[Locker537]

PT plywood should be enough.

 

[forAK]

I'd just get some good oil based primer and prime the heck out the osb. With all the work you just did on putting it down, multiply that by 10 and that's how much more work you'll have to rip it up. The moisture from under won't be an issue as you have tons of ventilation around it. It's not just going to wick it up and keep it.

 

[naf305]

I'd just get some good oil based primer and prime the heck out the osb. With all the work you just did on putting it down, multiply that by 10 and that's how much more work you'll have to rip it up. The moisture from under won't be an issue as you have tons of ventilation around it. It's not just going to wick it up and keep it.

So about ventilation. The stone almost everywhere go up to the bottom of the joist assembly whether inside or on the perimeter so I don't think there will be much airflow.

The question is during big downpours how much water will sip in under the shed and drawn up and absorbed by the OSB. I really don't have a good answer for that. Only time will tell.

I think in the end I would rather regret extra work put in than turning in my sleep for the foreseeable future wondering if I made the right choice. As I understand it now the right choice is put in PT plywood.

If this was an issue that could be easily repaired down the road I might leave it as is. Given that the walls are resting on that floor it would be a major pain to fix down the road. I'll take the pain to redo now than down the road.

Trust me, I'm reluctantly making this choice but I'll think I'll be happier in the end knowing it was done the best I could do it.

 

[Blackhawks63]

I would put down a high quality oil base primer on that floor and move on. Button that structure up nice and tight and make sure roof rain is properly channeled away and you will be fine. So is your car never going in garage?

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[naf305]

So is your car never going in garage?

No my cars are never going in my garage. Eventually once it is cleared from all the gardening tools and other junks that will be going in this shed, I will be renovating it into a woodworking workshop (my next build thread). There won't be place for cars.

It took some convincing with the wife but she is on board now.

 

[naf305]

Subscribed

Great thread!

OK, here's my $0.02. I would definitely replace the OSB with pressure treated plywood and not use a vapor barrier as I think it would trap moisture especially if a liquid is spilled from above. Definitely use screws instead of nails both for the ease of future maintenance and they don't squeak. You should have enough ventilation with what you have already put in place to not worry about rot for quite some time.

HTH

So here are my thoughts at this point:

- Remove OSB plywood
- Clean joists from leftover construction adhesive
- Lay a 9mil plastic vapor barrier
- Put 3/4in pressure treated plywood using galvanized screws made for PT wood
- Smooth surface/knots with waterproof filler
- Coat the upper plywood face with some waterproofing paint (epoxy paint) that will give me a surface easy to sweep yet be non slippery

This is based on the idea that either you leave both side clear hoping for enough ventilation to dry any occasional water/condensation or in lack on ventilation seal the heck out of both side.

I have a feeling ventilation won't be my friend. The foundation assembly if 4in from the ground and drainage rocks almost goes all the way up to the bottom of the joist.

So I opting for sealing it. Any thought on a good top coat?

I also read somewhere that I should ideally use pressure treated 2x4 as bottom plates as extra insurance against water spill inside the shed. This I feel is overkill but want to hear your thoughts on it.

 

[toolfanatic]

I'dlike to chime in here, I don't know what your ground conditions or ventilation are like but it seems to me that ripping up that OSB would be a nightmare. You'll have chips of OSB and adhesive residue sticking to the treated joists which will need to be scraped off- there's a few hours work there I'm sure. You will need some minimal ventilation to the underfloor void anyway to prevent even the treated wood rotting, make that ventilation as good as you can. The worst that can happen is that the OSB will wick in some moisture and probably sag between the joists over time. Why not remove the existing screw fixings and seal the top of the OSB with a good primer and then overlay with ply which will give a much better wearing surface and will resist any water spillages. Once screwed through the ply and OSB directly into joists, what can happen? The most vulnarable parts of the OSB sheeting are the sections that span between joists, the strips sandwiched between joist and ply shouldn't take up any significant amount of moisture and as long as the sheeting is glued and screwed through I think the risk is minimal. Just my thoughts....

 

[gunguy]

This is what I used to paint the pressure treated plywood deck of a home built motorcycle trailer. Worked out pretty well. Might be a little difficult to sweep though. Never tried it.

https://www.lowes.com/pd/Valspar-Da...r-Paint-Actual-Net-Contents-128-fl-oz/3086157

With a vapor barrier on the bottom and paint on the top, is there any concern about sealing in any moisture? As any moisture tries to escape, it may cause the floor paint to bubble. I don't know.

Unless you're hosing stuff off in the shed (which I'm pretty sure you're not) or have concerns about run-off from a snow blower, I wouldn't worry about a LITTLE bit of water, especially since it's pressure treated lumber. If it's the melt-off from the snow blower, maybe park it on some sort of catch mat during snow season.

And yes, for the couple extra dollars, I'd opt for pressure treated lumber for the sole plates.

Wish I could be there for the ribbon cutting ceremony.

Jim

 

[naf305]

This is what I used to paint the pressure treated plywood deck of a home built motorcycle trailer. Worked out pretty well. Might be a little difficult to sweep though. Never tried it.

https://www.lowes.com/pd/Valspar-Da...r-Paint-Actual-Net-Contents-128-fl-oz/3086157

Thanks for the reference, I'll check it out. Sweeping is not my main concern. I can use the shopvac to clear things up if needed.

With a vapor barrier on the bottom and paint on the top, is there any concern about sealing in any moisture? As any moisture tries to escape, it may cause the floor paint to bubble. I don't know.

So I agree that trapping moisture is bad but if I seal it (bottom: vapor barrier and top: waterproofing paint) then moisture should never be trapped in the first place. The only moisture that will exist is the one from pressure treatment, right?

And yes, for the couple extra dollars, I'd opt for pressure treated lumber for the sole plates.

I'll see what I can find around here. It may not be a whole lot more expensive to do that and (while probably overkill) may give me the piece of mine.

Wish I could be there for the ribbon cutting ceremony.

This my friend may take a while. I'm not the fastest worker, I got a busy job and a little newborn fresh out the oven so time to work outside is limited. Hopefully I'll be done before Thanksgiving

 

[naf305]

I'dlike to chime in here, I don't know what your ground conditions or ventilation are like but it seems to me that ripping up that OSB would be a nightmare. You'll have chips of OSB and adhesive residue sticking to the treated joists which will need to be scraped off- there's a few hours work there I'm sure. You will need some minimal ventilation to the underfloor void anyway to prevent even the treated wood rotting, make that ventilation as good as you can. The worst that can happen is that the OSB will wick in some moisture and probably sag between the joists over time. Why not remove the existing screw fixings and seal the top of the OSB with a good primer and then overlay with ply which will give a much better wearing surface and will resist any water spillages. Once screwed through the ply and OSB directly into joists, what can happen? The most vulnarable parts of the OSB sheeting are the sections that span between joists, the strips sandwiched between joist and ply shouldn't take up any significant amount of moisture and as long as the sheeting is glued and screwed through I think the risk is minimal. Just my thoughts....

You bring a good point about maximizing the ventilation even just for the joist/beam assembly. After I remove the OSB I might remove some of the stones to leave some space and airflow everywhere.

As for "The worst that can happen is that the OSB will wick in some moisture and probably sag between the joists over time". This is going to haunt me forever.

I know I'll get a lot of comments about all the unnecessary work I'm going to be doing. I'll take those over years of mild anxiety.

Oh and did I mention I nailed the **** out of that OSB? Framing nailer with pressure triggers are so much fun. Getting all those nails out won't be as much. I started removing some on a small section. It's doable, it is just going to take me a while.

As for the adhesive/OSB residue, I'm hoping I can use my power planner on the lowest setting to help with the tough spots. I don't really use for anything else so I might as well put it to good use.

 

[toolfanatic]

Good luck with whatever solution you go with, I love these build threads! I finished my own small woodwork shop build two years ago and like you I had many doubts about construction methods etc. I'm fairly particular myself and I never regretted any additional work or spend afterwards, go with what's going to work for you!

 

[gunguy]

Just for comparison, a common 2x4x8 is $3.18 vs 4.77 for PT at my local Lowes. Well worth the $10 it may add to your project in my opinion.

I used an angle grinder with an old flap wheel to remove old mastic from some patio stones I had to reset. Worked pretty well. Hitting a broken off nail with a planer can't be fun and certainly doesn't do the blade any good. Be careful.

Yes, pressure treated lumber tends to be a little wet, even at the store. You may have to let it dry awhile before painting. One idea might be to paint the floor as one of the last steps of the project. This should give it plenty of time to dry. You won't be able to paint the area under the sole plate but you'll have the vapor barrier underneath. If you're concerned about mucking the floor up before you get a chance to paint it, lay down some rosin paper or flattened cardboard boxes if you can find enough. That will protect the floor and still allow it to dry albeit a little more slowly. I really don't think it will be an issue.

Ah newborns. Among other things they really teach you the meaning of 24/7.

Good luck,

Jim

 

[naf305]

I used an angle grinder with an old flap wheel to remove old mastic from some patio stones I had to reset. Worked pretty well. Hitting a broken off nail with a planer can't be fun and certainly doesn't do the blade any good. Be careful.

Love that idea. It give me a reason to buy an angle grinder though I could probably use the good old drill on this one.

Yes, pressure treated lumber tends to be a little wet, even at the store. You may have to let it dry awhile before painting. One idea might be to paint the floor as one of the last steps of the project. This should give it plenty of time to dry. You won't be able to paint the area under the sole plate but you'll have the vapor barrier underneath. If you're concerned about mucking the floor up before you get a chance to paint it, lay down some rosin paper or flattened cardboard boxes if you can find enough. That will protect the floor and still allow it to dry albeit a little more slowly. I really don't think it will be an issue.

I agree, I won't plan on painting or sealing the top until the project is in its final stage. I might even cover the top with some underlayment or something to prettify the floor once the walls and roof are up. That should give it plenty of time (specially at my pace) to dry.

 

[naf305]

Let the "Fun" begin

Ok so first of all I would like to thank everyone who chipped in the discussion.

After my last update, I received the following comment that turned my world up side down:

Is that flooring plywood or particle board? I'm not a builder, but I would have used pressure treated plywood because of ground moisture.

I started to question everything I had done so far.

Bottom line, this is what I learned:

OSB is not designed for ground contact (duh) not suited for a shed floor sitting above grade. Moisture from the ground will eventually damage and rot the OSB. And while the speed at which it brake down will vary widely depending on your situation (how much water you get underneath your shed) I decided not to take the chance.

Pressure Treated plywood should be used instead.

Now comes the (not so) "fun" part. I need to remove the 5 sheets of OSB I nailed and glued. I did a little experiment yesterday on a half sheet. Here is the result:

Removing the nails wasn't so bad. I had a small cat claw (nail puller) from a previous project but that turned out to be slightly too small. It would keep slipping out of the nail head and take 2-3 tries to get it out. I'd then finish with my regular hammer to get the whole nail out.

I quickly realized this wasn't working for me so I went to HD and got a large cat claw. I picked one that would grab easily the whole nail head but also one as pointy as possible, essentially one that will dig into the wood the quickest.

This worked out way better. One hammer blow on the new cat claw gets it deep into the wood and the long arm of the claw now let's me pull the whole nail in one pull. Much better.

Then came the part of trying to remove the sheet glued to joist. Not so much fun and as you see in the picture a lot of the OSB particules are left stuck on the joist (which we expected). It took a lot of effort pulling that sheet up slowly braking that glue bond.

I think I'm going to try a different method next. I'll still get the nails out. That part I got down. But I'm thinking about using my sawzall to cut out as much as I can first. Leaving just the strips of OSB glued to the joist. Then I'll either chisel/pry those strips. I think that will be easier as it will give me more room to get to those glued strips.

Anyway thanks for watching. I'm hoping I can get this demo job done in a single day this weekend. I'll keep you guys posted.

 

[bj383ss]

Interesting build you have going on. I was cruising through it really enjoying your overbuilding(I am the same way) and then came the floor debacle. But you made the right choice I think.

I built a shed last year for the exact same reason as you. I have a woodshop setup in my garage although it does house 2 cars as well. I was able to build a 12'x18' shed to house all the garden tools and storage and build an auxiliary workshop as well.

I used exterior grade plywood for my floor but the one thing I regret is not blocking between the joists. So as such my floor squeaks when you step on the joints.

I look forward to your shed progress but more importantly the new woodshop setup!

If you want to have a look at my shed build it starts on page 17 of my build thread.

Bret

 

[naf305]

Interesting build you have going on. I was cruising through it really enjoying your overbuilding(I am the same way) and then came the floor debacle. But you made the right choice I think.

I built a shed last year for the exact same reason as you. I have a woodshop setup in my garage although it does house 2 cars as well. I was able to build a 12'x18' shed to house all the garden tools and storage and build an auxiliary workshop as well.

I used exterior grade plywood for my floor but the one thing I regret is not blocking between the joists. So as such my floor squeaks when you step on the joints.

I look forward to your shed progress but more importantly the new woodshop setup!

If you want to have a look at my shed build it starts on page 17 of my build thread.

Bret

Wow I landed on the page where you were setting the dust collection. I cannot wait to get to that stage. Those are the kind of problems I want to be dealing right now, not removing glued OSB floor. But I know that day will eventually come. I just need to be patient and stay focused on each tasks.

I started to look at the shed build. It looks awesome. I'll have to pick your brain about raising the long walls. I noticed you had on some sections 3 top plates. If I understand this is where 2 sections of the wall meet, right? With the last stud of section 1 landing at 8in from the end of the bottom plate and the first stud of section 2 starting at 8in from the beginning of the bottom plate. Then you but the 2 sections together and use a 14 1/2in piece of 2x4 on top and bottom to join the 2 together. Did i get that right?

I saw somewhere that I could also leave my studs 16in from the end/beginning of the bottom/top plates and once the 2 sections in place install the missing stud sitting over the split between the 2 sections. Any pros/cons on the 2 methods?

I kind of like your way though, it might be easier. Let me know!

 

[Growlertdi]

I would not recommend putting the vapor barrier under the new plywood flooring. just pull some of the stones away from the bottom of the floor joists around the perimeter to allow for ventilation (you mentioned that there is 1/4" mesh to keep critters out so you should be good there.) with this area ventilated well, you will not have a wicking problem as the moisture would have to wick up through wood grain that looks like = to get up to the plywood.

All of your floor joists and support beams are laid on their sides so wicking wont be a problem. you are going to put siding on the shed which should prevent any water from getting on the end grain of your plywood from splashback etc. If you wanted to put a seailng coat of paint on the top of the flooring thats not a bad idea.

 

[bj383ss]

Wow I landed on the page where you were setting the dust collection. I cannot wait to get to that stage. Those are the kind of problems I want to be dealing right now, not removing glued OSB floor. But I know that day will eventually come. I just need to be patient and stay focused on each tasks.

I started to look at the shed build. It looks awesome. I'll have to pick your brain about raising the long walls. I noticed you had on some sections 3 top plates. If I understand this is where 2 sections of the wall meet, right? With the last stud of section 1 landing at 8in from the end of the bottom plate and the first stud of section 2 starting at 8in from the beginning of the bottom plate. Then you but the 2 sections together and use a 14 1/2in piece of 2x4 on top and bottom to join the 2 together. Did i get that right?

Yes you are correct. Since my long walls were 18' I used a 2x4x12 plus an 2x4x8 to make the bottoms and cap. .

I saw somewhere that I could also leave my studs 16in from the end/beginning of the bottom/top plates and once the 2 sections in place install the missing stud sitting over the split between the 2 sections. Any pros/cons on the 2 methods?

I kind of like your way though, it might be easier. Let me know!

Honestly I just built the corners like you do a house with the blocked end. Which is a 2 studs with spacers between them. Once you put the corner together you still have 1/2" to nail your inside sheetrock or osb whatever you use.

I took a lot of pictures of the build if you happen to have any specific questions.

Bret

 

[madoc1]

i really think you are over thinking this. osb has been used for years in most conditions with no probs. i know jersey is humid but i think you will be fine for a long time..you can always lay another layer of treated ply on top of what you have now or later if you find a prob. the part under the plates will not be a prob since they are sandwiched between wood and not exposed. just my opinion.
i grew up for a while in lincoln park and my sister lives in east winsor. near you? what ever, good luck. i know it will turn out fantastic.
p.s. i understand about the wife having less than solid backing on your project. been there.

jim

 

[tjpavlov]

For your wall bottom plates, I have heard of people using a layer of composite decking and then regular lumber above that. Might be easier than dealing with lower quality pressure treated lumber and continues the theme of over engineering things.

 

[naf305]

I would not recommend putting the vapor barrier under the new plywood flooring. just pull some of the stones away from the bottom of the floor joists around the perimeter to allow for ventilation (you mentioned that there is 1/4" mesh to keep critters out so you should be good there.) with this area ventilated well, you will not have a wicking problem as the moisture would have to wick up through wood grain that looks like = to get up to the plywood.

All of your floor joists and support beams are laid on their sides so wicking wont be a problem. you are going to put siding on the shed which should prevent any water from getting on the end grain of your plywood from splashback etc. If you wanted to put a seailng coat of paint on the top of the flooring thats not a bad idea.

Thanks for the explanation. This definitely helps. I will definitely check my ventilation again now that I'm opening my floor again.

About the vapor barrier. I guess my understanding is that either you seal everything (to guarantee no moisture will be trapped inside the wood) or you don't seal anything letting the wood breath so that moisture can escape.

I guess my initial intuition was that a vapor barrier would be the safe choice but I've seen a lot of conflicting thoughts and idea on the topics and I'm definitely not so confident about it anymore. No one seems to have a definitive answer probably because there are many factors that cause a floor to rot and that each scenario is somewhat unique (ventilation, slop, water drainage, height from ground....).

I guess my best bet for a long lasting floor will be to keep water away from the shed. Proper drainage, rain water collection and siding will have more of an impact that a vapor barrier alone.

 

[naf305]

For your wall bottom plates, I have heard of people using a layer of composite decking and then regular lumber above that. Might be easier than dealing with lower quality pressure treated lumber and continues the theme of over engineering things.

I had never heard of that one yet. No sure I'm ready to venture this way. I checked the stack of PT 2x4 the other day, and while most are not perfect, I can pick and choose the best looking ones. I think I'll stick with PT on this one.

 

[naf305]

Step 9: Rip out the OSB floor and put PT plywood instead

So you all know the recent debacle and what turned out to be a mistake on my part. I had installed 3/4in OSB and while this may have lasted a couple years with no problems (who knows maybe a decade?) I was taking a chance that it would rot sooner than needed.

I made the decision to rip out the OSB plywood to put 3/4in pressure treated plywood instead.

It was a significant undertaking given that I had fastened that OSB so well (nails + construction adhesive). I had posted a attempt at a small portion of the floor earlier which gave a taste for what was coming.

First I spent a couple hours removing nails. A nice 2lbs mallet with a properly sized cat claw did the job. I only broke 2-3 nails overall. Not bad. You can also see that after a week the OSB was already soaking water in. I'm glad I'm ripping it off.

Here is the box of removed nails. I didn't count but it's got to be a couple hundred at least. I was a little trigger happy with my new framing nailer. Regret it now.

Next I decided to cut out all the hollow sections of the floor not glued to the joists. This way I have a bit more space to work to lift and chisel out the strips glued. I set my circular saw (with an old blade) to shy of 3/4in. Turns out I had forgotten a few nails. The blade will have to be tossed after this job.

In the second picture above you see the cutout portions removed. Then came the tough part. Using a masonry chisel and pry bar I hammered, hammered and hammered the glued strips. Fast forward couple hours, and I am finally standing in front of my floor assembly. At this point all nails were removed.

Problem is that there was still a lot of leftover OSB particles and glue. Enough to mess up my level if I put down plywood over it right away.

I took my Bosh power planer which made a nice job at getting all that leftover junk off my joist. The only side I couldn't really use it on was the side where the garage wall is. There I just used a little more elbow grease to chisel the rest out. Not perfect but at this point good enough.

I decided not to put any vapor barrier. I was really on the fence on this one but the only consistent info I was given here or found online about shed floor is to not put any and make sure the joist assembly is properly ventilated. I removed a bunch of stone now the floor was open again to make sure I had a much air space as I could provide to the joists.

I then finally went to get my new pressure treated plywood. So happy to get this part (a second time).

This time I did a little less measuring. Simply put down the first sheet square with the floor assembly, marked the joists, screw it down then but the next sheet. You'll see there is a little plywood hanging my side joist. I used the circular saw to cut a nice straight line out of the 4 sheets installed.

You'll notice I didn't finish the last portion of the floor in the back. This is because I have to remove the fence panel to give me space to install another 4x6 on the end to sit flush with the garage wall. Once installed I'll cover up that end.

Removing that vinyl fence panel meat that I had to create on the other a temporary fence so that the dog won't escape when I remove it.

I'm back where I was last weekend but feeling better already. Thanks for watching!

 

[Growlertdi]

Looks like you did a good job fixing that up.

now you can sleep well at night.. Congrats.