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2nd Level Subfloor

2K views 6 replies 5 participants last post by  jagans 
#1 ·
We recently purchased an uncompleted 2 story cabin. Roof, framing, exterior siding all completed. We need to finish running electrical, plumbing, and then hang drywall and do flooring and cabinets.

The 2nd level subfloor that was installed is smooth edge 1/2' OSB. When We walk on it, it sags and moves a lot.

My question is, to beef up the strength of the floor, what would be the best thickness ( smooth edge or Tongue & Groove ? ) flooring we should install directly over the existing to have a solid and quiet floor?

We were thinking of using 1/2 OSB T&G glued and screwed through both layers into the joists.

Money is a factor and would like to go the route that would save the most money yet still gives me a strong floor that will last.

I need about 40 4x8 sheets.

thanks in advance.
 
#2 ·
1/2" was completly wrong material for the main subfloor.
Want a strong floor your going to have to go over that with at least 5/8, 3/4 would be better T & G subfloor. I prefure Advantec over plywood.
No glue is used.
There's marks on the panels for the nailing pattern.
 
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#3 ·
5/8 t&g is good for a subfloor initially over framing and for storage areas such as in 2nd floor "loft" areas where little foot traffic is expected. It could be doubled up -with glue and screws- to be used as a bare surface or under hardwood, tile, or carpeted floors. If it is used to 'double-up' the sheets should be turned 90 degrees to the run of the first layered sheets.
Always nail or screw only into the framing members below and don't trust the premarked lines on any sheeting.:thumbsup:
 
#4 ·
I do not always recommend this but you can find a cheaper alternative to advantech( the best subfloor on the market) that is 3/4" tongue and groove just like advantech but cheaper. I've found alternatives at lowes for $12 to 15$ a sheet depending on going market values... no one had mentioned this but how will the height of the new subflooring affect the space- can you just lay it over top the stuff that is there now? if so I recommend screwing down the stuff there now really good and when laying the new subfloor screw only into joists-not into the 1/2" only, you will want at least 3/4" penetration into joist framing member so at least a 2" screw -2 1/2" screw would be the best and recommended. make all breaks over top the joists also (split the center with the seams). you might get squeaks in between the two floors just because of how the 1/2" now floats over the joist spacing and it could buckle or warp over time and cause rubbing points, a layer of felt between the two floors helps somewhat but absolute squeak prevention would be to pull the 1/2" up before putting the 3/4" down.....
 
#5 ·
I do not see how anyone can answer this inquiry without knowing the spacing or type of supports the sub-floor is being placed on. The stiffness of the support members, their spacing, and the number of supports the sub-floor is on all make a difference.
 
#6 ·
Thank you all for the replies. I believe we would be able to overlay a new subfloor and our floor heights would not be an issue for doors to open.

I want to say that the floor joists are 2x10 at 16"OC. Held up with Simpson joist hangers.

I understand tearing up the old floor would be best but that would mean removing the already in place interior framed walls and door openings. Our plans were to sheet over the existing floor and nail extra blocking under the existing interior walls between the joists.

The cheapest I have seen 5/8 T&G at either Home Depot or Lowes was around $28-$29 per sheet. If I could find it for $10-$16 per sheet I'd buy what I need right now. 84 Lumber was $31 per sheet.
 
#7 ·
If I were you, I think I would bond the two layers together by applying a low rise urethane adhesive between the two layers, and screwing both layers down to the joists. I am talking about a roofing insulation adhesive. This should provide a very strong floor.
 
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