Problem condo - floor prep for LVP

Discussion in 'Floor Preparation' started by Scott Horton, Sep 18, 2019.

  1. Scott Horton

    Scott Horton Soundproofing Pro

    I meant clamp alongside, then screw it to the old/existing 2x10 joist. The only concern I see with that is some potential tortional load on the joist. But once screwed to the subfloor that should go away; locking the position and preventing any twisting.

    For a shim, I like your idea of scribing. Still, will take a very accurate cut and it's not necessarily a straight line.. I could get 2 out of a 2x6 no problem. Maybe more. Save a little $. But more room for some error/thick/thin in places. If I'm going to all this trouble, might as well be dead flat. Still, may be worth a try to see how that goes.

    But your input gave me an idea... If I use a board to clamp to the side as the guide, it would be a pretty good reference to then add shims. Make shimming easier anyway. Fine tune with thin material as necessary. But shim would need to be something that would not blow up when a screw hit it.

    Still, just adding the boards is the easy button, I think.
    Last edited: Sep 20, 2019
  2. Mike Antonetti

    Mike Antonetti Senior Member

    I was looking for pre made shims in varying thicknesses of 1/4,1/8”,1/16” out of 2” wide wood but all I found were wedges. The window industry makes nice horseshoe plastic wedges but they would not be feasible.

    I use the rotary laser to give me a topography indication of what needs to be done on a slab though, way different ballgame.
    • Like Like x 1
  3. Mike Antonetti

    Mike Antonetti Senior Member

    Think I’d still use maybe trim pieces down the molding aisle of Home Depot or Lowe’s. The 2” wide strips I know are in 1/4” thickness. When it’s 1/2” add two. I’d use a bit of adhesive as to allow each piece to bottom out, not let the adhesive cause a gap because compression will cause movement. Maybe 1/8” shims? I’ve heard but never seen drywall shims I think they’re 1/8” thick. Use a finish nailer to hold in place as to not cause obstruction of subfloor fasteners. So those thicknesses will allow for the specs of subfloor flatness.

    I’d also use screws that do not snap to avoid the vertical friction squeaks.

    No sistering required, the joists still carry the designed engineered load.

    After looking at the prices of trim pieces I’d just buy some sheets of underlayment that could be easily planed and cut them 1&3/4” wide, glue and temporary nail, let dry then plane or sand. Not exactly sure what best sheeting material to use, ply probably won’t plane easily but sanding would.

    Attached Files:

    Last edited: Sep 21, 2019
    • Like Like x 1
  4. Scott Horton

    Scott Horton Soundproofing Pro

    Guys, after studying this for a while, I've decided to move forward with the sistering the joists plan. Friend is a structural civil engineer came and had a look, said I didn't need to reinforce the existing joists and no more that I was "shimming" I could even use 2x4 instead of 2x6 if I chose to. Screw or ring-shank nail gun and glue.

    Next issue is the living room part of this floor has a small balcony outside the sliding glass door. That balcony is supported with joists that are already sistered to the LR joists and cantilevered out. They are fine right now, but one day, being outdoor, they could need replacing. If that day comes, the subfloor will have to come up again. That will be someone else's problem I hope.

    I own a Quick-Drive screw gun for subflooring. It drives flat head torx subfloor screws. That's what I'll be screwing new Advantec to the newly shimmed joists.

    My floor person will have to use Ardex featheredge to do some final prep around the perimeter of this subfloor where is it higher than the old floor, and does not go all the way to the wall.

    So here's the pro floor Q where experience I don't have counts: I don't want the subfloor screws to telegraph through the LVP. I'm planning on using one of the thicker LVP's with the built in pad so maybe not a issue anyway? But if it is, what can I skim those screw heads with that would stay put and serve this purpose while being able to be picked out for potential future screw removal? I figure Ardex would be a bitch to get out of those screw heads, or maybe not? What would be best to skim them with that could be dealt with reasonably should that subfloor ever need to be unscrewed? Latex Caulk? Drywall mud, etc?
  5. Chris 45

    Chris 45 Director of P.R. on some deserted island. I Support TFP

    Leave em be, you’ll never see them.
    • Like Like x 1
    • Agree Agree x 1
  6. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    What you wanna do.. Go buy a dowel the size of the screw heads right, then fit them all in at the depth the screws are driven...

    Oh wait, i mean, what Chris Said
    • Like Like x 1
  7. Mike Antonetti

    Mike Antonetti Senior Member

    C178629D-7CB5-4FFF-9980-EC518A42980D.jpeg 90725E0A-6B97-4677-90F1-65D31FC128EA.jpeg For a few(less than 100) a utility blade dogs out the slots ok. If the Ardex covers the whole surface the new cats paws are narrow by estwing but some rare earth round magnets will find the screw heads and the cats paw I found another one with wider prongs that is grabbing screws in a 3/4” 2nd layer of plywood we are removing.

    HART brand, good leverage made for larger nails or screws. sent two wives for the estwing with a picture, came back with anything but. Did they stop making them? Uh 40 nail pullers to choose from I can see why it’s a bit confusing.

    I looked for every size pry bar, got a Marshalltown coming tomorrow probably by the time the job is done. Any and every way possible to pull nails the fastest. Not much available for such a primitive fastener.

    Example of hidden nails and screws. The magnets Elmer recommended. Lost a few as they attached to hammer head on downstrike. Hard to put them out of the way, they even stuck to my proknee. Started with 20, may have 12.

    The prybar arrived after the job, it’s a beast for next time.

    HART 180 Degree 10 in. Nail Puller-HNP1801 - The Home Depot

    Attached Files:

    Last edited: Oct 7, 2019
  8. Scott Horton

    Scott Horton Soundproofing Pro

    Thanks guys.
  9. Scott Horton

    Scott Horton Soundproofing Pro

    Finally got a baby start on this. As luck would have it, it keeps getting worse LOL. Had my man remove what was on the kitchen subfloor. Kitchen is going to have to be dealt with too, due to an huge difference and the door between kitchen and dining room. Step one was to pull the vinyl sheet that was there. Found that had square "tiles" under it. I don't know if that's linoleum or what. They were brittle. Worrying about asbestos it wasn't disturbed any more than necessary.

    The black stuff left behind is tacky, tar like, sticks to your shoes, nasty.

    The majority of this section will be replaced with new subfloor. What's left including about 10" x 8 feet along the wall to the 1st joist, and a 2'x2' section around the corner I really need to have finished with feather-edge or similar.

    What is the easiest way to deal with this glue? Hoping I can covered it with a primer of some sort? It will be a bear to get up/off.


    Closeup IMG_2513.JPG
  10. Chris 45

    Chris 45 Director of P.R. on some deserted island. I Support TFP

    :eek: ........
  11. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    Don't ya love flooring :)
  12. Mike Antonetti

    Mike Antonetti Senior Member

    Either skimcoat it or if it’s not asbestos grind it off but equipment availability is usually scarce.

    Attached Files:

  13. Scott Horton

    Scott Horton Soundproofing Pro

    Suck! It's getting harder and harder to get this floor prepped right.

    I'd cut out all the subfloor with adhesive but one section is under a wall that's running parallel to the joists so a problem. I'll have to open some inspection holes, I *think* the wall is sitting on the next joist and the offending subfloor with the goop goes under that wall. If the wall is over the joist I can probably get away with cutting the subfloor at the wall (see pic, "new" cut). Then add a new joist, PITA.

    Meanwhile, Ardex said they don't have anything when this adhesive is on/over wood:

    "ARDEX does not have any material that can be recommended for use over a combination of wood and adhesive substrates. If there is clearance available, the most cost effective method for providing a new, clean subfloor would be installing new wood underlayment over the existing. There is no cleaning product that would remove the adhesive without contaminating the wood subfloor below."

    I think it will be harder to get that crap off the floor than to cut it out and add a joist. And, short of the expense and delays of testing, I don't know if it's got asbestos in it or not.

    Anyone else make a product that can go down on top of this? Or, something you guys use in spite of mfgr spec that you know works? If I cover it, I have to be able to level it a little, 0" to about 1/4" over 14"

    Attached Files:

  14. Scott Horton

    Scott Horton Soundproofing Pro

    Mike: It's on wood, no grinding. Skimcoat with what? Since it's on wood, Ardex says no for featheredge.
  15. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    Skim it off with a coat of ardex feather finish mixed a little light because that coat is going to be terrible and get all kinds of little chunkies stuck in it, scrape it and repeat. Specs be damned I do it all the time. It's not realistic to presume that people have endless budgets and time to deal with that sort of thing :)
    • Like Like x 1
  16. Scott Horton

    Scott Horton Soundproofing Pro

    Thanks Mark. Mapei reluctantly said I could use the Planiprep SC which I assume is the competitor to Featheredge. I say reluctantly because it says not to put over asbestos. I am guessing that is there for liability reasons not some technical issue where potential asbestos causes no-bond.
    • Agree Agree x 1
  17. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    100% liability, planipatch was my go to for years mixed with 100% of the acrylic milk jazz over blackout
    • Winner Winner x 1
  18. Scott Horton

    Scott Horton Soundproofing Pro

    Product name ? :)
  19. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    You know what's sad, I don't even know what it is called. Just plani patch additive is all I have called it... and this is over an 18 year career lol
  20. Scott Horton

    Scott Horton Soundproofing Pro


Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.