Subfloor pet stains and then some

Can I cut the subfloor away and replace it?

I am finally at the point where I am ready to replace my upstairs carpet with the engineered flooring. When I pulled away the carpet it exposed the wood subfloor assuming ½” that is pretty flimsy and stained beyond recognition.
Looks like it’s build with 4X8 sheets of plywood (not T&G) extending from one room to another through the adjacent wall in the overlapping pattern.
Can I cut away this subfloor at let’s say 6-8” from the walls and replace it with the new sheeting, without jeopardizing the structural integrity?

Thanks a lot for all your help!

 

If you are about to float in an engineered floor, you can seal the subloor with a couple coats of polyurethane to elimnate pet odors. After doing so, purchase the best pad you can afford to buy. The better pad offers more sound deadening if using a floating wood engineered floor.

 

Thanks a lot!

When you mention the polyurethane, you mean like varnish? I assume… No KILZ and stuff? like other posts recommended...
Actually that what’s the problem – I’ve already purchased what is suppose to be the best sound deadening underpayment, cork. I am afraid if I don’t eliminate the smell
100% it will get into the cork, and then I am done for it….

 

If you use Kilz, don't use the water-based variety. If using a primer/sealer, apply two coats of one that is shellac based. My favorite is Zinsser. The reason I recommended polyurethane is that forum posts report success applying two coats to seal in urine odor in subfloors. If pet urine has contaminated along bottom of walls, then primer/sealer would be needed there. Some folks have reported having to remove baseboards to seal them and walls behind them because urine odor was so bad.

 

Thanks again Twelvepole!

I will do that for sure! Now the next question….
The subfloor I am cleaning is fairly even except one place where three sheets meat together in the middle of the room. In that spot, two of the sheets, who’s seam
(I assume comes over the joist) sagged about ¼ “ and if step on it, sagging even further.
I assume there is a reason for this sheets to be sagging, so if I just screw them down into joists and level it over with something like levolur, it’s going eventually pup back up.
What should I do?

Thanks,

 

Sagging subfloor indicates twisted or weak joists and will require structural repair from below. If subfloor has cupped at joints, sanding will be required. If you can not access joists from below, you may have to remove subfloor to assess the situation. Do your joists need additional support? Will shims resolve the situation?

After assessing and resolving any problems with joists, then screw down the plywood. Use screws, so they won't back out. Use lots of them.

What type of floor covering are you planning on installing? This will determine type of subfloor preparation or additional substrate.

 

Twelvepole,

I am not sure how to lift the subfloor. Should I just carefully pull all the nails out the sheet of the plywood (not even sure how to do that without damaging the plywood).
When I am done pulling the nails out, how do I lift the sheets, they all are extend under the adjacent walls?
Oh yea, I am installing a 1/2" engineered floor over the 5mil. cork underlayment.

Thanks,

 

If there is no way to access from below, you will have to go back to your original plan of cutting out the piece of subfloor.

 

Thanks again,

Again the question is: How far away from the baring and none baring wall is safe to cut the subfloor sheets?
As I understand the second floor studs are directly placed over my subfloor, so partial wait of the roof is applied to my floor.

mik_mik

 

CrzCntr,

How homes are constructed is usually first floor walls, second floor walls are placed over the subfloor. Those walls running parallel with the floor joists are placed directly on top of the floor joists (these are usually doubled floor joists). Those that are at right angles are done over the floor joists without the need to double the floor joists.

The first issue that we should know about is if you have roof trusses or is this stick built roof trusses? Normally second floor interior walls will not be load bearing if your have roof trusses and that the span of the roof trusses is not far.
The second issue is if the wall in question is located where in regards to your roof truss layout? Is this wall running parallel or at a right angle to the roof trusses. Where is this wall located in regards to distance from an outside wall?

This will assist in determining the possibility of any load on the wall in question.

Are we sure that the need to remove the subfloor under this wall is necessary? Was this stained also? The issue of a sagging subfloor, when stepped on, it sags further, may be that they didn't do a great job of placing the subfloor over the joist. This may just require a 2x4 to be nailed to the sides of the joist so that the subfloor sheets will be supported at the seam. Ensure that the joists are level and flush with the adjacent joists.

If removal of the subfloor at the wall is necessary, the issue of the need to lift this, however slight, will be needed to get the subfloor out. This may not be that easy and the length of this wall will be another issue. Two issues here are very important. The stud wall will be nailed down through your subfloor into a joist...you must remove the drywall and have access to these nails. A sawzall can be used to cut the nails (between the bottom plate and subfloor) which secure it to the subfloor but then you need to re-anchor the wall when done. Drywall will have to be removed to nail through the bottom plate. Some drywall cracking may/will occur at the wall/ceiling joint so be prepared to do some taping there.

Depending on the direction of the floor joists and the roof trusses, lifting will be done by placing at least a couple of 2x4's stacked with a small hydraulic jack,2 ton is fine. On top of the jack use 2-2x4's nailed very well together (this is the vertical) and a double 2x4 on top of this vertical (basically making a tee) - you want to make sure that you have the jack properly supported at the base and that the top 2x4's are running across the roof trusses. As mentioned before, not much is required to get load off the wall if there is any, so you only need to go up 1/4 inch or so. At that point, how you get the subfloor out from under the wall will be by using a flat bar, possibly a sawzall to cut any nails/adhesive. ***All this is fine but try and allow room to insert new pc or sheet - PLAN AHEAD WHEN PLACING JACK TO DO LIFT***

When you have this in place, remove jack and renail everything you have replaced.

Hope this helps!

 

Thanks a lot a very detailed answer Doug!

I was not planning on removing the subfloor from under the walls, unless it is necessary step to preserve structural integrity. In most cases stains did not extend beond 3-4 ” What I was thinking of doing is just setting my circular saw at little less \then ½” (in case the subflor is ½ “ instead of ¾ as I assumed).
Snapping a line alongside of all 4 walls at the distance about 6-8” and cut away the whole floor a piece at the time. Is that an acceptable approach?
Also, the new plywood I just bought at HD is T&G, do I need to leave like a 1/8 space between pieces left from the existing subflor and the new sheets?

Thanks,
mik_mik

 

CrzCntr,

You're very welcome, we all are trying to help you! I assume the answer was clear enough to understand.

I have to agree with all that you said. Nothing wrong with snapping the line and cutting it out. Good idea leaving a small space between old and new. Use construction adhesive and screws with your new subfloor install. It will be rock solid!

Good Luck!

 

Thanks again,

Follow up questions:

So how far away from the wall should I cut, or it doesn’t matter?
Does it make sense to replace current insulation that by the way looks like R3 (if one exists) or put a new one over the old one for less mess and may be better insulation?

Thanks,

CrzCntr

 

Thanks Doug for such a detailed and educating answer. mik_mik good luck with your project. Keep us posted on your progress.

 

CrzCntr.

The distance away from the walls can be whatever you think is necessary. You could go 6", 8" as long as it is accomplishing what you desire. Setting the saw blade to a 3/4" depth would be best as I doubt it wold be less, depending on age of home. If you have planking, diagonally placed it is 3/4, if it is plywood, it might be 1/2 but more likely 3/4".

The insulation has me wondering what you are referring to? Can you explain?

 

twelvepole,

Sorry, forgot to say you're very welcome! Anytime, you know how to reach me.

 

You guys are the greatest!

Thank you very, very much!

I will keep you posted on the project for sure…
Thanks for the reminder about the diagonal placing of the plywood.
About the insulation:
There is a thin layer ~ 3” of insulation between the joists, that’s why I said
something like R03, can’t imagine that been more then that…
So I was going to buy R15 or R19 insulation and place it over the old one,
just enough not to compress the insulation and to fill my 8” space between the downstairs ceiling and the upstairs subfloor.

Thanks mik_mik – now CrzCntr

 

CrzCntr,

Is there a reason to insulate the floor?

Doesn't help much with soundproofing if that is what you are considering.

What do you think?

 

Yes Doug,

The reason is actually two fold:

The biggest one is the temperature insulation. Because two of my bedrooms are partially above the garage, they are heated from above through the roof, from the garage below and from reflected heat of the garage roof.
The reduction of the noise is also a concern but not as big as the first one because
I am using the cork for the underlayment and it should do the trick.

Thanks again,
CrzCntr

 

CrzCntr,

OK, just don't expect too much from the soundproofing aspect.

Insulate with what you can, without squashing it. This may be the R19.

Good Luck!

 

Hey guys,

I just wanted to post a quick "Thank You" for posting the bit about the KILZ Oil-Based Paint to get rid of my subfloor pet stains/odors. I still can't believe how well it worked! It was a heavily soiled room, and it only took one coat to cover everything (I put on a second coat just in case, lol) and also rid the room of that horrid smell. Thanks again, I really appreciate it!

 

I've lost track of how many times we've had to paint a subfloor because the tenants didn't care what the cat did....