My attic has 5/8" OSB around the heater/AC/water heater. As I walk on it, I can feel flexing of the board. I searched this forum and learned 3/4" is recommended for 24" OC. Honestly, I am afraid of the board breaking under my foot. The board must have been there since the house was built in 1990's. Live with it? Add 3/8" plywood over it? Thank you.
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5/8" OSB 24" OC in the attic
- Thread starter paker
- Start date
matt_i
Well-known member
I have one better. My attic in my shop was sheeted with 1/2" ply @ 24" centers when I bought the house/shop. Superflex.
So I realized I had a couple of choices, rip it all out and add 3/4" or better, or add another thickness. I went for the doubler, I bought a fair number of tubes of construction adhesive which were put down in X/Z shape patterns, in order to build shear between the layers.
Its very acceptable now.
So I realized I had a couple of choices, rip it all out and add 3/4" or better, or add another thickness. I went for the doubler, I bought a fair number of tubes of construction adhesive which were put down in X/Z shape patterns, in order to build shear between the layers.
Its very acceptable now.
Kaizen
Well-known member
Just add 3/4 on it if it makes you feel better. No sense ripping it out
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finn
Well-known member
Is this a floor you walk on every day or for storage in a typical attic, where you access it every few months?
5/8” is used on roofs with 100-120 lb/sf snow load rating with 24” truss spacing every day.
In fact, they used to specify 1/2” for roofs.
7/16” might even work for a rarely accessed storage attic, although it would be a little bouncy.
5/8” is used on roofs with 100-120 lb/sf snow load rating with 24” truss spacing every day.
In fact, they used to specify 1/2” for roofs.
7/16” might even work for a rarely accessed storage attic, although it would be a little bouncy.
red94chev
Well-known member
Have the same think at my mom's garage but I only use it for light storage and don't get up there much. When I do, I try to walk on the rafters. With your situation, I think I would add something over it.
rburke65
Well-known member
You would probably realize a noticeable difference if you even glued and screwed 1/2 plywood over the existing floor.
pattenp
Well-known member
You would probably realize a noticeable difference if you even glued and screwed 1/2 plywood over the existing floor.
Agree, this is all you need to do.
Is this a floor you walk on every day or for storage in a typical attic, where you access it every few months?
5/8” is used on roofs with 100-120 lb/sf snow load rating with 24” truss spacing every day.
In fact, they used to specify 1/2” for roofs.
7/16” might even work for a rarely accessed storage attic, although it would be a little bouncy.
I went up there only to replace the air filter. It's going to happen twice a year.
May I interpret your post as "though bouncy, it will hold distributed load"? I will then leave it as is and avoid stepping in the middle. If I lose sleep because of this, I will add (glue and nail) 1/2" board as suggested by many.
Thank you.
Mick56
Well-known member
If you only walk on it twice a year, I would mark where the rafters are and only step on them.
b-boy
Well-known member
I'd double up the plywood.
I had the same situation in my living room. I tore up my carpet to install hardwood on my subfloor. The builder used rally crappy materials. I think some of the plywood may have even been 'used' when it was installed. They also used small scraps to patch the floors rather than using larger pieces. I found several 16" x 12" pieces of plywood on the floors in my bedroom. It barely spanned 1 set of joists. When you stepped in that area, you felt the board flexing.
The floors bounced and squeaked like crazy. I bought 3/4" plywood, glued and screwed it over the old flooring. I made sure to hit the joists with 3" deck screws, and made sure that my seams didn't line up with the old seams.
When I was done, that floor was incredibly solid, and no more squeaks.
I had the same situation in my living room. I tore up my carpet to install hardwood on my subfloor. The builder used rally crappy materials. I think some of the plywood may have even been 'used' when it was installed. They also used small scraps to patch the floors rather than using larger pieces. I found several 16" x 12" pieces of plywood on the floors in my bedroom. It barely spanned 1 set of joists. When you stepped in that area, you felt the board flexing.
The floors bounced and squeaked like crazy. I bought 3/4" plywood, glued and screwed it over the old flooring. I made sure to hit the joists with 3" deck screws, and made sure that my seams didn't line up with the old seams.
When I was done, that floor was incredibly solid, and no more squeaks.
Paco Pena
Well-known member
You could add a layer on the area you have to walk on and forget the rest.
paco
paco
Flargen
Active member
I did 1/2" ply and learned that you want to orient the grain perpendicular to the studs... When parallel, there is absolutely noticeable flex, but no problems have resulted. The perpendicular pieces I laid later are way, way more solid.
Innovate1
Well-known member
I put 7/16 OSB in my attic with 24" spacing on the trusses and it's fine but I only use if for light storage and occasional access. Yes, it flexes a little but in my case the sheets are full 48" width. Less width will flex more - a lot more if it is a lot narrower. And as others have noted plywood and osb is stronger in one direction than the other. Sounds like you may have some narrow and/or short pieces or run in the weak direction. Also depends on how heavy you are but I am 190 lbs. Thickness and support spacing isn't all that affects flex. You can put another layer over if the flex bothers you but I would still recommend you pay attention to the other details to get the least flex.
Skiff Builder
Well-known member
An easy solution for your situation could be to tack down some 1x10 utility board in the service area.
Skiff Builder
Skiff Builder
Depending on the size of it, I think my biggest concern would be the area where the water heater sits. 40-50 gallon W/H that could be 350-400 lbs sitting in one spot. How does the floor look under it ? I wonder if it's sitting atop a truss bottom chord ?