Advantech vs LP Legacy vs GP DryGuard vs... ?

[Mattilac]

Now that the shell of my garage is up and enclosed (except for doors and windows), I'm starting to look at subflooring options for the attic space. From what I understand, Advantech is the "best", but mostly due to its superior rain and weather resistance. In my case, the roof is on and the subflooring will see very little, if any, water. So the question is, are there any other options I should consider?

In other words, are there any benefits to Advantech beyond its great weather resistance? Is it stiffer than other subflooring? I see other products like LP Legacy Premium and GP DryGuard, both of which are less expensive than Advantech. But I don't know if I'm leaving anything on the table just to save a few bucks.

 

[Hank11]

Have not used the other products you mention, but lots of Advantech. Its fully proven and in my opinion worth the slight premium. Follow Huber’s directions when you install it and it’ll make a great floor.

 

[billconner]

I just put in a sub floor in a dry building. 3/4" CDX ply. Less expensive then OSB sub floor products at my local store, and I like working with ply better than OSB.

Definitely agree you don't need to pay for weather resistance.

 

[Mattilac]

I'm checking out CDX and finding it priced nearly the same as Advantech!

I also went and put hands on the LP Legacy and GP DryGuard panels and pretty much ruled out the GP DryGuard. It was noticeably lighter and flexed more than LP and Advantech, despite being the same thickness.

 

[Hank11]

Be sure you're pricing tongue and groove plywood. That's a big part about getting a flat smooth floor.

 

[mike93lx]

I love advantech, but it is a big premium over LP or regular osb.

My local HD has two grades of 25/32 osb plus the LP. I'd look at them in person and decide.

Either way, use glue

 

[Jeff C]

I’m a big fan of Advantech. Once you move around a couple sheets you’ll realize something has to be different about it. The stuff is ridiculously heavy and stiff.

But…… how much are you going to be using your attic and for what? If it’s the occasional random storage it may not be worth the premium. If you’re using it regularly (which looking at the size I’m guessing you will be) or for heavy storage I would lean towards the advantech.

Definitely need a tongue and groove product and something with a sanded face is much nicer.

 

[SKIPPINROCKS]

I used the dry gaurd (200 day no sand one). I think Advantech is much superior and wish I would have used it instead

 

[SKIPPINROCKS]

 

[Mainiac Mat]

Advantech is made with phenolic resin and is much more water resistant than CDX... which will delaminate if soaked long enough.

As noted, it is wicked heavy and seams more rigid than plywood. I also used it for the floor of my garage attic (also framed with room-in-roof trusses, spaced 24" o.c.) and it is plenty stiff.

 

[Mattilac]

23/32" seems to be all anyone keeps in stock. Is that what everyone uses for their 24" o.c. floors?

 

[ducatithunder]

Advantech all day long. Worth the premium over the rest. I've seen failures with the ZIP systems by huber so opted for the regular Advantech sheathing when building my garage due to wanting to do a rainscreen siding system. I had some pieces left outside over the winter sitting in slop and snow, in the spring they were still hard and the oem dimensions and no swelling. Typical OSB would have doubled in size and been soft as a wet sponge.

 

[Mattilac]

Well, the numbers don't lie: https://www.garagejournal.com/forum/threads/subfloor-options-my-findings.526603/

I'm leaning towards the Advantech, simply for the fact that it won my little deflection test.

 

[rlitman]

23/32" seems to be all anyone keeps in stock. Is that what everyone uses for their 24" o.c. floors?

I had no trouble getting 1-1/8" Advantech when I wanted two sheets for my bathroom project. Not that my weird use case has any relevance to you, but this stuff is crazy stiff and easily beats ply (the old-school best option) in both strength and water resistance. I have no regrets going with Advantech.

Anyway, I'm impressed with your deflection test. Project Farm quality work is what we expect here.

Next time though, you could probably set the whole test up in a store aisle (during some not so busy hours) with a few bags of concrete and some cement blocks, without having to buy anything. That was how I tested to see if Unistrut was sufficiently stiff when I used it as a chain hoist crane rail.

 

[Mattilac]

You ran TWO sheets of 1-1/8"? Holy cow!

I really wanted to like LP Legacy. It's significantly less expensive than Advantech while being the heaviest of the bunch. I thought for sure that would translate to stiffness.

 

[Jeff C]

23/32" seems to be all anyone keeps in stock. Is that what everyone uses for their 24" o.c. floors?

99.9% are 23/32”. You can get 7/8”, 1” or 1-1/8” but the price will keep going up and up.

 

[Hank11]

Look at the Advantech site for specs on spans. The 23/32 comes in a variety rated for 24” if I recall correctly. My latest is on 16” with 23/32 and its nice and stiff.

 

[rlitman]

You ran TWO sheets of 1-1/8"? Holy cow!

LOL, no, only one layer. The whole room took two sheets to cover everything, and right now it feels stiff enough to host a pogo-stick competition.

 

[mike93lx]

LOL, no, only one layer. The whole room took two sheets to cover everything, and right now it feels stiff enough to host a pogo-stick competition.

Wimp. Even my shed has double layer 1-1/8

 

[dogdog]

I used two layers (dryguard and regular plywood) for my subfloor. plus a layer of sound barrier 6mm in between. make sure you use PL400 or subfloor glue to joist on the dryguard layer.