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-   -   Double subfloor in new home? (http://www.diychatroom.com/f19/double-subfloor-new-home-164263/)

ironman612 11-21-2012 01:23 AM

Double subfloor in new home?
 
Hello -

We're in the process of having a house built. The house is framed with 14" engineered joists, mostly 16 and 19.2 OC. with 3/4" osb t&g subfloor.

Of course, if tile is put down, additional underlayment will be used.

We've been told (not by the builder) that adding another layer of 3/4" subfloor (staggering the seams) throughout the home will make for a rock solid floor.

The builder says they will do it, but it is expensive (> $10K). They also said that using their standard system, along with screwing and gluing, they have very few complaints or callbacks.

Does anyone have an opinion as to if this is worth it? Or, is it totally overkill and a waste?

Thanks!

md2lgyk 11-21-2012 06:00 AM

Unnecessary, in my opinion. In our house, the floor joists (2x12s) are sistered in certain areas, primarily where there's high traffic. This wasn't my idea; it's what the plans called for (built the house ourselves). The subfloor is glued and screwed Advantech, which is stiffer than other types of subflooring. Our floor is very solid.

$10K sounds awfully high for what would be involved if you chose to do it.

jrepp44 11-21-2012 08:52 AM

Consider upgrading to a thicker subfloor:
http://shop.mccoys.com/building-mate...nderlay/p.2074

ddawg16 11-21-2012 09:36 AM

That price is high....

If the 1st subfloor is not down...then upgrade to 1 1/8" T&G plywood. I personally would not use OSB as a sub floor. I did in my garage and I know what issues I had. I just don't see it as a good floor material (long term) as compared to plywood.

I did my upstairs with 1 1/8" plywood on top of 2x12 joists 12"OC. It's almost as hard as a concrete slab.....I balked with the architect at first when I saw it....he said "Do it, trust me, you will be glad". Well....I'm glad.

At most, I think those sheets cost $15 more.

One other thing....for it to really be right....you need that plywood down before the walls go up. (assuming your going with the 2 layers.)

lylsutherland 11-21-2012 05:50 PM

no need for a thicker subfloor, if you want to stiffen the floor so it don't bounce or vibrate and crack the grout in your tile take a look at the IBS2000. We can design a floor to higher criteria for alot less money.If you can supply the clear span of the I-Joists and the series you are going to use,we will design it for you so your china don't rattle www.luxorcorp.com

woodworkbykirk 11-21-2012 06:47 PM

do you mean sublfoor as in underlay or floor sheathing first off and was the double floor spec'd on teh drawings

advantech is a much superior floor sheathing by far. much better glues in it and better deflection ratings


3/4 sheathing is industry standard but its also the minimum, if your going to have a tile floor in any areas you will need a minimum of 1 1/8" to ensure that you wont have tiles popping or grout cracking. most tile manufacturers wont even warrenty their product unless its on a 1 1/8 floor. for hardwood all thats needed is 3/4". regarding the double layer ive build custom homes that had a double layer of 3/4" specd because certain areas of the house were going to have very heavy live loads in conjunction with having 1 1 /2" of concrete poured for in floor heat.

anyhow by the sounds of the builder it seems like you hired a custom builder who goes above industry standard. this is a good thing you will have far less issues with your home in the long run. i know contractors whose bread and butter is going into 1 year old homes that have all sorts of issues and then fixing them.. ( fixing mass produced homes that are built fast not well)

ironman612 11-22-2012 12:18 AM

Thanks for all the replies. The 1 1/8 subfloor is a good suggestion -- I am going to get a price on that.

Whatever we decide to to, we'll be doing it before any walls go up.

I will also check on Advantech.

This question is regarding the base subfloor, and not any underlayments. If tile is put down, additional underlayment will be added on top of the subfloor.

Aside from the price, my main concern with the double 3/4" subfloor was causing any additional issues. For instance, should the second layer be glued to the first? I've heard that can leave voids, and cause floor noise.

Thanks again!

md2lgyk 11-22-2012 06:24 AM

You won't go wrong with Advantech. Besides being a generally superior product, it has a 50-year water damage warranty.

Gary in WA 11-22-2012 05:00 PM

Have you discussed this with your designer/architect? The floor rating is variable, depends on the intended use/deflection; http://www.woodbywy.com/literature/TB-104.pdf Adding underlayment will give a stiffer floor (not stronger); http://books.google.com/books?id=1uY...lywood&f=false

http://www.apawood.org/apacad/images...specs/Y310.pdf

I wouldn't use Huber's AdvanTech on walls in a heating climate...https://docs.google.com/viewer?a=v&q...ZoxkKEMlmyCNhg
Their flooring is fine.

Some design numbers; http://www.tecotested.com/techtips/p...signcapacities

Underlayment/adhesives; http://www.apa-europe.org/Languages/.../PDF/R340G.pdf

Gary

woodworkbykirk 11-22-2012 08:04 PM

if you want to know about advantech, hear it from loneframer.. he did a 5000 sq ft house that was framed with steel, the floors and walls were both sheathed with adventech.. the walls got it before drywall

md2lgyk 11-23-2012 06:14 AM

Quote:

Originally Posted by woodworkbykirk (Post 1058448)
if you want to know about advantech, hear it from loneframer.. he did a 5000 sq ft house that was framed with steel, the floors and walls were both sheathed with adventech.. the walls got it before drywall

Why would a house be built that way??

woodworkbykirk 11-23-2012 01:34 PM

home owner requested it.... ive heard countless stories about that house from lone and would boggle your mind.. such as no visable fasteners in paint grade trim which meant either blind nailing all trim or using a 23 gauge micropinner

md2lgyk 11-24-2012 06:59 AM

Quote:

Originally Posted by woodworkbykirk (Post 1058713)
home owner requested it.... ive heard countless stories about that house from lone and would boggle your mind.. such as no visable fasteners in paint grade trim which meant either blind nailing all trim or using a 23 gauge micropinner

Well, the customer IS always right. I can only imagine what that house cost to build.

woodworkbykirk 11-24-2012 08:00 AM

multi million

md2lgyk 11-24-2012 10:41 AM

Quote:

Originally Posted by woodworkbykirk (Post 1059072)
multi million

Yeah, and with all that AdvanTech, that's probably what it weighs too.


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