Drying in time frame

[Rutnbuck]

I am building a 16 x 24 cabin in Alabama.  I already have my 6 x6 post set for the foundation and plan on drying it in during the fall when it is cooler.  I'm going to use ¾ OSB for my flooring.  I live in South Carolina and have limited vacation time as I just started a new job.  So I know it will have to be weekend work extended over a period of a month.  My concern is once I put down my flooring how much time do I have to get it dried in if it gets wet?  I was thinking of putting down Tar paper to help keep it Dry.  Does anyone have any other suggestions?

Thanks,

Mike

[OldDog]

I wouldn't use osb!

check on adventech of plywood.

we used adventech and kept it tarped until framing started

[peternap]

Welcome to the board!

I really hate people that say this so don't hate me. We have had several threads on this subject. Do a search nd you'll find all kinds of applications to keep the subfloor in good shape.

[glenn kangiser]

OSB will swell in rain - Tarpaper will likely keep the water in there longer - the Avantek is supposed to be a lot better.  Removing the water and drilling drainage holes can help -- I have seen the OSB nearly too bad to use in about 6 months with water removal and drain holes- So I would say not over one season.

[n74tg]

I have the same problem as you, can't get it dried in as quick as I'd like.  So, I just painted my OSB subfloor with exterior latex.  It will probably get two coats before I'm done.  I considered covering it with visqueen, but forum members shot that down.  I think even one or two shot down the exterior latex idea, but in the end...you gotta do somethin.

Let us know what you decide. 

[John_M]

This may sound a bit crazy, but why do you need all of the floor in before framing?   You could just lay some sheets down to carefully to stand on etc.  But most of your work would be from the outside and on the roof.  Once she was dried in, then you could put the rest of the interior subfloor in.  Obviously the framing has to rest on part of the subfloor, but maybe something can get worked out to just put enough on the perimeter?  Plywood could stay covered in one pile while you were not there!

As far as I know, the floor does not really do anything structually for the building.

Think outside the box....maybe tongue and groove deck boards for flooring?  Would look nice when your finished too!   

[mvk]

I always took great care to keep deck's dry when I worked for myself, I saw what happened when I did production framing for others.

I used saw horses and 2x to build a little roof and covered it with tarps. I would lay out the saw horse's then use my wall plate stock to make a ridge with plenty of overhang on the ends. I would then use more plate stock or joists rafters what ever to make rafters from the ridge and overhang the deck on the edges. I would lay these flat with 1 spike in the top (ridge) and one on the edge. I would use rope over the tarp to prevent it from blowing off, put nails in the deck frame or the under side of the pieces used for the rafters and cinch them down with a truckers knot with the rope in the middle of the rafters. This worked for me and I didn't have to strap and nail through the tarp.

I never used this to get through a long period of time just maybe a big snow storm, rainy week or a hold up of some kind. I don't know what your stock would look like under a tarp for a summer in your climate, don't think I would want to work with it though, so maybe this isn't much help to you. Is this a wooded site maybe some pecker poles?

I would definatly try to keep the deck dry and give this advice to others so maybe my Idea might help out folks who work weekends on their places and then leave.

Mike

[JRR]

I think sorta like "John_M".  Why put the sub-floor down until the roof and walls are in place? 

A few dollars spent on wooden decking boards will make you a safe working surface that has no/little weather concerns.  The decking boards can be installed with 1", or more, gaps; with just enough screws to keep them down in place .... and they can be recovered later for "another life" (perhaps as a real deck!).

[Rutnbuck]

Thanks for all of the good advice.  This is a great site to learn from.  I will post pictures as we build.

Mike

[glenn kangiser]

Looking forward to it, Mike.

We are just trying to use the internet the way it was supposed to be used for a while before gov. figures out a way to destroy it.

[n74tg]

John M. states above "Obviously the [exterior wall] framing has to rest on part of the subfloor".  That made me do some thnking and some questions came from that thinking.  I know it's a common practice, maybe even required by building codes, but the first question is "why" does the framing have to rest on the subfloor.  Why can't it rest directly on top of the floor joists?  It would then allow the subfloor (OSB) to be installed later after the building is dried in.

Is it, that the subfloor actually functions partly as a header, spreading out the loads from the wall studs into the floor joists (especially if wall stud spacing and floor joist spacing were different)?  I would think that the sole plate on the exterior wall would also perform that function. 

Or is it, that the subfloor being on top of the floor joists, helps stabilize the floor joists from rotating lengthwise and "laying down", such as might try to happen with sufficient racking forces from wind. 

Or is it, this is the way we have always done it, and people are resistant to change.

Or have I missed the purpose of the subfloor going under the exterior walls completely.

I thought about making this a separate thread, so as not to hijack this one.  But, then I thought it would take forever to set it up, so I left it here.

[Jackson Landers]

OSB takes a long time to get really wet, since it does not have a continuous grain with which to wick moisture deep into it. But once it does get wet, it's often useless. It will never return to it's proper dimensions. The same principle that slows down water intake in the first place prevents it from drying out quickly enough to get it's shape back.

Whereas most plywood gets wet very easily, what with the continuous grain. But plywood will also dry out quickly and return to something about 99% identical to it's pre-wetting dimensions.

If you know for sure that the platform is going to get rained on and it's going to be out in the weather for an extended period, then I think it's a no-brainer. Don't use OSB. Use plywood.

Others may have had better experiences, but my encounters with painting OSB have been exercises in frustration. It usually seems to soak up the paint unevenly and once it does, I get some of the wood chips nearest the surface cupping and pulling away as they get soaked.

Tar paper on a zero grade is not going to be helpful. Tar paper is only good when water is running down a slope.

I think you should use plywood subflooring and maybe paint it with exterior grade primer. If the exterior grade primer is too expensive, go to the mis-tint section of your local paint store or paint department of your local big box hardware store and buy whatever exterior grade paint is marked way down for having been accidentally mixed to the wrong color. You get some serious deals that way. Mix and match with a gallon of one color and a gallon of another, since you'll be covering it all up later on and it doesn't really matter what it looks like. Let the floor be a rainbow if it's going to save you some money.

[JRR]

N74tg, I wonder the same thought.  Why does subflooring extend under walls?  I think its just easy practice in platform framing.  If the flooring did not extend under the walls, there would have to be some additional support between joists, just inside the walls to support the edge of the subflooring, or the subflooring would flex downward against the wall.

I currently refurbishing an old house that I wish the subflooring DID NOT extend under the walls, but ya just have to deal with it.

[glenn kangiser]

You miss a lot of bracing if the subfloor doesn't go to the outside edge.  A whole lot weaker.

Studs are often supplied pre cut so with the single bottom and double top plates, they make the proper height wall on top the sub floor on platform or single story construction.  Set them to the joists and the wall height is too short.

PEG will probably come along with much better reasons -- that's the ones I know.