Sub Floor

Weekend_Sawyer · June 14, 2019, 07:38:10 AM

The Deck on my timber frame is going to be 40x40.
For the sub floor my builder wants to use Advan tech, It's a type of OSB that is waterproof. You probably knew that.

I plan on spending a LOT of time in the downstairs workshop and I just don't want to look up and see OSB. So my plan is to use 3/4 random width boards as the sub floor with the Advan Tech on top of that. I'll have a good looking ceiling in the basement/workshop and a nice smooth nailer for the flooring.

Here's my question, I only have about 1000 bd ft of White pine milled for the floor. I also have at least 1000 bdft of yellow poplar. Other than the way it will look, which I think it will look pretty good. Is there any reason why I can't use poplar and white pine mixed for a sub floor? Especially since it will have the layer of OSB on top of that.

An by the way, If you have read this far. I have decided on a timber frame for my retirement home. I have contracted a timber framer and we are moving forward with the build. I hope to be under roof in September.

Jon

Raider Bill · June 14, 2019, 07:52:27 AM

What will you use for joists?

Weekend_Sawyer · June 14, 2019, 08:01:29 AM

True 2x12 white pine joists on 16" centers.

Raider Bill · June 14, 2019, 09:17:31 AM

Will you be finishing the underside of the joists?

I used Advantec sheathing on my floors. Very happy with it. It got rain and snowed on most of the winter while I built the second story walls and roof with no ill effect.

Jim_Rogers · June 14, 2019, 09:42:51 AM

Shrinkage rates maybe different. you may want to put down some black paper between the boards and the plywood so when you look up between the gaps you see black instead of the green underside of the plywood.
Jim Rogers

Weekend_Sawyer · June 14, 2019, 10:00:03 AM

Bill, I hadn't thought to do it, probably not.

Jim, great idea. Would you use roofing felt or is there something different you would recommend.

Raider Bill · June 14, 2019, 10:06:29 AM

I didn't either. Considered sheet rocking it or something else but decided I liked being able to have full access to the plumbing and electrical.

Weekend_Sawyer · June 14, 2019, 12:05:54 PM

Some counties have a requirement for drywall as a fire stop.
Not mine. I like it open same reasons easy to get to the services.

Jim_Rogers · June 14, 2019, 12:26:10 PM

black paper should work, no need for anything special unless you want to make it a vapor barrier.
Jim Rogers

Don P · June 14, 2019, 05:11:39 PM

Is there a reason for a 2 layer subfloor. I'm sawing framing and sheathing for a small house that will have diagonal board sheathing on the floors and walls. The finish floor will simply go over the diagonal boards. If you do go with an underlayment layer of osb I would wait to install it until after dry in. Water will get trapped between layers and this time of year it'll grow mold in that hard to dry in between area. If it goes in after dry in it doesn't need to be Advantech.

Rob in NC · June 20, 2019, 09:05:14 PM

We use advantech everyday and I think it's a good product but if your going to run 3/4" boards on the entire floor I don't think you need it on top. Just scrap the advantech and use the boards in its place. The reason we don't use individual boards in the industry is time to install is slower and material is more expensive not because the product is necessarily inferior. The advantech does have a wax like coating but it's still particle board and less desirable to a solid 1x in my opinion given time and material costs are not factored in.

scsmith42 · June 20, 2019, 10:42:03 PM

When I remodeled my old Sears Kit House I installed Georgia Pacific Plytanium over the 1x2 T&G original subfloor. The floor is very rigid and has no air leaks up from the crawl space.

I considered Advantek, but thought that the plywood would be slightly better.

Since the house was already dried in no issues with wet flooring or mold.

Weekend_Sawyer · June 24, 2019, 08:45:39 AM

Very good advice all. Thank you.
I will definitely let it dry in before installing the Advantec.

My General contractor is one of the best builders in the area and a good friend of mine so if he wants to use it I'm going to go with his way of doing it.

Other than cost, there is no penalty for overdoing it. ;D

Don P · June 25, 2019, 04:42:31 AM

None at all, it makes a stiffer floor. Do make sure everyone is on the same page elevation wise, accounting for that future layer while framing rough opening heights.

Weekend_Sawyer · June 25, 2019, 08:41:33 AM

Will do Don.

Thanks again everyone for your insightful replies. I am taking forward some good information.

My idea is after the boards are down I'll build a 4' knee wall right down the center and hang a 50x50 tarp over it to tent the tarp up and allow air flow for a couple of months, then put the black paper and advanteck down just before we stand up the frame.

Jon

GRANITEstateMP · June 30, 2019, 08:52:08 PM

Not an expert, but just a question. When we put down the Advantec at my house when we built it in 09, my builder used a glue between the manufactured wood joists and the Advantec. I asked why, he said to help keep it quiet. That being said, is there any chance the Advantec over the pine & poplar will result in any squeaks or noises when walking over it? Just something to chew on

Weekend_Sawyer · July 01, 2019, 05:13:21 AM

Good question, but the paper between the layers should take care of that.
I worked on a house that was built in the 20's they had put newspaper on top of the joists I suspect to keep it quiet.

Bruno of NH · July 01, 2019, 05:22:44 PM

If you put 2 layers of 30lb roofing felt between the plywood and boards it won't squeak.

Don P · July 03, 2019, 07:23:43 AM

We used to use deadening felt under hardwood floors, basically tarpaper without the tar. It was a bit softer than roofing felt and did a better job at reducing squeaks but I haven't seen it in years, not sure if it is still available.