Green Tractor Talk banner

1 - 19 of 19 Posts

·
Premium Member
Joined
·
1,706 Posts
Discussion Starter #1
Has anyone ever seen plywood shrink this much?
The plywood 7/8" thick & is the sub floor in a house that was converted from a garage. There are some sheets where the plywood has split in the middle of the sheets The conversion was done in 1992.
I have been in construction for over 40 years & I have never seen anything like this before.
 

Attachments

·
Super Moderator
Joined
·
5,097 Posts
Huh. That's extremely unusual. I've never seen it shrink that much either.
 

·
Administrator
Joined
·
20,671 Posts
Wow. Must've been really high moisture content when it was installed.
 

·
Premium Member
Joined
·
14,712 Posts
Very unusual guessing same as others of moisture. My first look at the picture with tape showing size of gap ,,looks to me IMO that someone had taken a circular saw and opened a gap to maybe let water run off the subfloor during building .. :dunno::dunno:
 

·
Premium Member
Joined
·
1,706 Posts
Discussion Starter #6
Very unusual guessing same as others of moisture. My first look at the picture with tape showing size of gap ,,looks to me IMO that someone had taken a circular saw and opened a gap to maybe let water run off the subfloor during building .. :dunno::dunno:
The floor has always had a roof over it. There has never been standing water in the building. This building is next door to me. I saw the construction progress when the work was done. The joints were tight when the floor was put down & has been covered with the original carpet since 1992. As Jason said, the moisture content of the plywood must have been very high when it was put down.
 

·
Premium Member
Joined
·
14,712 Posts
The floor has always had a roof over it. There has never been standing water in the building. This building is next door to me. I saw the construction progress when the work was done. The joints were tight when the floor was put down & has been covered with the original carpet since 1992. As Jason said, the moisture content of the plywood must have been very high when it was put down.
Ok if no water was on floor doing construction , plywood must have had a lot of moisture.. Sure don't see that normally with plywood.
 

·
Registered
Joined
·
2,207 Posts
Was it treated plywood or standard. The only reason I ask was because it was supposed to be a garage floor. When they pressure treat they force the moisture of the preservative back in, essentially in an autoclave.

Pressure treated plywood does shrink allot.
 

·
Premium Member
Joined
·
1,706 Posts
Discussion Starter #9
Was it treated plywood or standard. The only reason I ask was because it was supposed to be a garage floor. When they pressure treat they force the moisture of the preservative back in, essentially in an autoclave.

Pressure treated plywood does shrink allot.
It was not pressure treated plywood. It looks like poplar. It may be imported plywood. The original concrete garage floor is 40" below the plywood. The plywood is attached to 2 x 10 floor joists.
 

·
Registered
Joined
·
1,072 Posts
That is a new one on me, I was thinking the same thing meager was about it being treated.
 

·
Premium Member
Joined
·
4,387 Posts
Has anyone ever seen plywood shrink this much?
The plywood 7/8" thick & is the sub floor in a house that was converted from a garage. There are some sheets where the plywood has split in the middle of the sheets The conversion was done in 1992.
I have been in construction for over 40 years & I have never seen anything like this before.
A couple observations; If the floor is over a garage floor or cement, is there any ventilation underneath? That could keep moisture where it doesn't belong.. I have never seen this much shrinkage ever. The plywood looks like it was cheaply made, never witnessed this type of plywood not pine or fir, and lastly,, also don't know anyone that wouldn't stagger the joints on a floor.. I would guess a pretty good bounce happening..
 

·
Senior GTT Super Slacker
Joined
·
37,404 Posts
My first thought was saturation, but how would it swell that much with respect to the cross grained layers?

Strange situation for sure! Interesting how it's held at width with the nails.
Pretty much my thoughts also. :dunno:
 

·
Premium Member
Joined
·
4,387 Posts

·
Registered
Joined
·
5,936 Posts
Has anyone ever seen plywood shrink this much?
The plywood 7/8" thick & is the sub floor in a house that was converted from a garage. There are some sheets where the plywood has split in the middle of the sheets The conversion was done in 1992.
I have been in construction for over 40 years & I have never seen anything like this before.
Joints should definitely have been staggered, probably had a high moisture content when installed, underneath area have proper ventilation?, What is the grade, span rating and glue type? There should be a mill stamp with all this information on each sheet or it is probably reject seconds.Is it t&g plywood. Haven't seen 7/8" plywood around here before. At this point I would just overlay with 1/2" structural plywood with staggered joints, glued and screwed to prevent squeaking or tear off and do over, or forget about it and have a beer!:laugh:
 

·
Registered
Joined
·
990 Posts
Looks like Luan to me. Nothing says the layers run perpendicular to one another either. Sometimes wood is installed dry and swells,the edge grain gets crushed and when it drys out the cracks are much bigger. The wood may also be a species that has a very high expansion and contraction rate and the combination of moisture content @ installation vs later vs. today all got you here. The plywood may also be material that was never intended for exterior use which is essentially what you have and it's content moved a lot due to this. I also have never seen that much movement in plywood but would venture to say that it is not cdx rated nor from a north american mill. Is it spongy to walk on?
 

·
Premium Member
Joined
·
1,706 Posts
Discussion Starter #18
The person that did the conversion was not the sharpest knife in the drawer. He worked for a contractor that did commercial work. They mostly remodeled & built hospitals.

I have repaired a lot of stupid & shoddy work that he did. I could write a book & provide pictures on the wrong way to do construction. Insulation was a very week point. I do not understand him not doing a better job of insulating the place, because he lived in it several years after the conversion. There were 2 families that lived in the house after the builder did. Both said they spent a lot for gas & were still cold.

The joints should have been staggered, but the floors have a solid feel, they do not bounce.
 

·
Registered
Joined
·
1,051 Posts
Has anyone ever seen plywood shrink this much?
The plywood 7/8" thick & is the sub floor in a house that was converted from a garage. There are some sheets where the plywood has split in the middle of the sheets The conversion was done in 1992.
I have been in construction for over 40 years & I have never seen anything like this before.
I took a good look at that pic. First thing I noticed is that four corners should never meet when sheathing a floor. I also believe that he left a space between the boards prior to nailing them off. He didn't toe them in snug to begin with. Floor sheathing should be done tight. Exterior wall sheathing should be done with a slight gap between boards to allow for expansion and contraction. We use to take nails and put them between the boards while nailing them off than pull those nails out. If you don't do this, siding will buckle. One generally doesn't have the temperature swings and moisture issues on interior sheathing so boards should be snug with seams staggered.
 
1 - 19 of 19 Posts
Top