LVT Floor Prep Continued

[FloorKiwi]

After finally removing all of the thick mud set tile I have a few more questions.

Background – installing TurCor 12x24 7mm thick floating LVT. Subfloor is ½” plywood in foyer, hall, ½ bath and dining room. Dining room has additional ½” plywood underlayment (dining room had carpet). Doing some dry fitting, it looks like adding 1” underlayment in foyer, hall and ½ bath with 7mm LVT will fit under nicely under door jams and door thresholds.

• Do I add two ½” sheets to foyer, hall and bath or one 1” sheet? I obviously have to add 1/2" sheet to dining room to make all floors the same. Installation directions say I can use plywood, OSB, particleboard or chipboard but must be A.P.A approved with minimum grade BB or CC (I am still researching info from Commercial Floor Rep and Tile Tom from previous post - thanks, but thought I would add these details from the manufacture).
• How do I install the subfloor around the toilet flange? Flange is 7" diameter and waist pipe is 3" diameter. The flange sat on top of the ceramic tile and was encased in the mud bed. The screws fastening the flange to the subfloor are corroded. The metal toilet flange (cast iron?) and waist pipe (copper?) both seem in good shape. I don’t really want to remove the flange, install the subfloor and then install a new flange if I don’t have to. I know the flange needs to sit on the new subfloor. Any suggestions (see pictures)?
• Can I set ½ bath vanity (free standing on 4 legs) on top of LVT? Also I have read that the toilet flange should be on top of finished floor. Is this true for floating LVT? Seems like you don’t want to fasten the flange down through the LVT.
• I will have one doorway transition from LVT to hardwood. The height difference is about 5/8”. The LVT reducer can only span ~ ¼“ height difference according to the manufacture. So I might need to find a hardwood reducer that can span a larger height difference. Any suggestions on where to look?

Thanks for your help

 

[JCobb]

After finally removing all of the thick mud set tile I have a few more questions.

Background – installing TurCor 12x24 7mm thick floating LVT. Subfloor is ½” plywood in foyer, hall, ½ bath and dining room. Dining room has additional ½” plywood underlayment (dining room had carpet). Doing some dry fitting, it looks like adding 1” underlayment in foyer, hall and ½ bath with 7mm LVT will fit under nicely under door jams and door thresholds.

• Do I add two ½” sheets to foyer, hall and bath or one 1” sheet? I obviously have to add 1/2" sheet to dining room to make all floors the same. Installation directions say I can use plywood, OSB, particleboard or chipboard but must be A.P.A approved with minimum grade BB or CC (I am still researching info from Commercial Floor Rep and Tile Tom from previous post - thanks, but thought I would add these details from the manufacture).
• How do I install the subfloor around the toilet flange? Flange is 7" diameter and waist pipe is 3" diameter. The flange sat on top of the ceramic tile and was encased in the mud bed. The screws fastening the flange to the subfloor are corroded. The metal toilet flange (cast iron?) and waist pipe (copper?) both seem in good shape. I don’t really want to remove the flange, install the subfloor and then install a new flange if I don’t have to. I know the flange needs to sit on the new subfloor. Any suggestions (see pictures)?
• Can I set ½ bath vanity (free standing on 4 legs) on top of LVT? Also I have read that the toilet flange should be on top of finished floor. Is this true for floating LVT? Seems like you don’t want to fasten the flange down through the LVT.
• I will have one doorway transition from LVT to hardwood. The height difference is about 5/8”. The LVT reducer can only span ~ ¼“ height difference according to the manufacture. So I might need to find a hardwood reducer that can span a larger height difference. Any suggestions on where to look?

Thanks for your help

View attachment 13917View attachment 13918

It’s your call on either 1” or 2sheets of 1/2”, as long as all the areas are the same height. By the book regarding plywood direction it should be run the alternating direction to the layer below but with a floating floor In my opinion it won’t matter one bit. Plywood is always better for me unless you step up to Advantech on similar.

Regarding the toilet flange, don’t try to do it with a large piece. Just cut the hole for the pipe, you say it’s 3” give yourself a good 1” all the way around for wiggle room and the flange taper. Then split the piece in half and wiggle it under. You can use pieces of the floating floor to shim up the flange to the height of the finished floor. I have seen plumbers use pieces copper pipe, cut to the finished height of the floor installed between the flange and primary floor. The screws for the flange I believe are supposed to be brass.

I understand the concern about the vanity, but if the installation instructions say it’s okay then go ahead. Just like a fridge/ stove.

Many supply shops will stock unstained hardwood reducers, well around where I live anyway.

Just remember with any floating floor, the flatter the better.

 

[C.J.]

Plywood should ALWAYS be run perpendicular to the joists. You’re not going to get any strength alternating directions like a sheet of plywood itself has because you aren’t glueing the layers together. Plywood has a strength axis and that is in its long direction, that’s why you run it perpendicular to the joists because the plywood is what controls deflection between the joists. Additional layers of underlayment (the first layer is subfloor, and should be T&G, each additional layer is underlayment) should also be installed perpendicular to the joists. Alternating directions will negate the natural strength that plywood has. When you alternate directions you’re just building a **** sandwich instead of taking advantage of the natural strength plywood offers. This is really important especially since your first layer is only 1/2”. 1/2” really isn’t that strong and will allow deflection between the joists. I’m sure you’ve noticed this as you walk around on the 1/2”. If you 1/4 turn your second layer it will also deflect between the joists.

What I would do is to lay a layer of 3/4” plywood over the existing 1/2” plywood. You will gain more strength from one layer of 3/4” than you will from 1/2” even though you would be installing an additional layer of 1/2” on top of that. Install it perpendicular to the joists. Offset your side seams by at least 1’ and try to get your butt seams to land on the joists, preferably not the same one as the original layer of 1/2” below is on. You will gain strength from the 3/4” plywood as well as you can sand any proud joints before you bring things up to the required height with a final layer of 1/4”.

 

[FloorKiwi]

Plywood should ALWAYS be run perpendicular to the joists. You’re not going to get any strength alternating directions like a sheet of plywood itself has because you aren’t glueing the layers together. Plywood has a strength axis and that is in its long direction, that’s why you run it perpendicular to the joists because the plywood is what controls deflection between the joists. Additional layers of underlayment (the first layer is subfloor, and should be T&G, each additional layer is underlayment) should also be installed perpendicular to the joists. Alternating directions will negate the natural strength that plywood has. When you alternate directions you’re just building a **** sandwich instead of taking advantage of the natural strength plywood offers. This is really important especially since your first layer is only 1/2”. 1/2” really isn’t that strong and will allow deflection between the joists. I’m sure you’ve noticed this as you walk around on the 1/2”. If you 1/4 turn your second layer it will also deflect between the joists.

What I would do is to lay a layer of 3/4” plywood over the existing 1/2” plywood. You will gain more strength from one layer of 3/4” than you will from 1/2” even though you would be installing an additional layer of 1/2” on top of that. Install it perpendicular to the joists. Offset your side seams by at least 1’ and try to get your butt seams to land on the joists, preferably not the same one as the original layer of 1/2” below is on. You will gain strength from the 3/4” plywood as well as you can sand any proud joints before you bring things up to the required height with a final layer of 1/4”.

Thanks C.J. I am most likely going to use screws. Do I need to attach the plywood underlayment all the way through to the floor joists or is attaching to the existing subfloor ok? I will be running perpendicular to the joists and will try to offset the side seams and butt joints.

 

[C.J.]

Do I need to attach the plywood underlayment all the way through to the floor joists or is attaching to the existing subfloor ok?

There is a split opinion on that. Technically underlayment is to be fastened to the subfloor only. However whenever I installed underlayment in a situation such as yours I would use longer screws or nails to fasten the underlayment into the joists while using shorter fasteners in the field. So technically how I do it isn’t the right way, it does help to reduce and eliminate squeaks.

 

[FloorKiwi]

There is a split opinion on that. Technically underlayment is to be fastened to the subfloor only. However whenever I installed underlayment in a situation such as yours I would use longer screws or nails to fasten the underlayment into the joists while using shorter fasteners in the field. So technically how I do it isn’t the right way, it does help to reduce and eliminate squeaks.

Thanks. I did reach out to tech assistance for the plywood I am using and they just got back to me and said I do not need to attach to the floor joists.