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How can I float new drywall that was top coated prematurely?

woodskill's picture

Came onto a job where the previous guys skimmed with topping before floating the walls. Since topping compound is extremely soft, has no glue and bad bonding properties and I need to float these walls, should I a) coat all the areas with that pink plaster bonding adhesive and continue with floating process , b) fiberglass mesh the whole wall and continue on c) sand the heck out of the whole thing down to the all purpose compound and continue, d) simply dust off the walls with a wet towel, prime and continue or e) ??  

My concern is that in areas that require a heavy float (over 1/4"), there will be problems much sooner than later in terms of cracking, flaking, or detatching compound from the top coat.

I am allergic to doing more work than I have to but am compelled to do the right thing. . .

Help me out here. (post #206963, reply #1 of 5)

You say floating the walls, what is that exactly?

Had they built up/finished the beveled joints and butts?  Then roll coated/skimmed?


A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Floating defined (post #206963, reply #2 of 5)

Floating a wall is more often associated with plastering than drywall,  as framing preparations tend to be controlled with shimming, etc.   In this case, it is done after taping, and secondary build up  when there are significant differences between the field areas on the wall and any metal work done at the base or around windows/doors.  It is also handy if there are tricky elements that need to be transitioned or cheated without being evident over a highly reflective painted surface or some other highly visible area.  One can determine if a float is necessary by holding a 6-8' straight edge on the wall in areas in question.  Usually, one would make a hot mix of part all purpose and some 20 minute, apply heavily, and screed with a straight edge (similar to stucco brown coat application).  It is left rough to take a skim coat later. 

ok (post #206963, reply #3 of 5)

As I imagined, no regional differences.

So the finish wasn't done to the level intended and then was "skimmed"-

that's a word that has two meanings here in my area.

Some drywall finishers will roll coat with thinned mud-then apply their trowell to "skim" the board.  The "skimcoat" is done to even the paper to mudded areas.

Skimming can also be done with "topping" and a knife.  This is usually more to even up, feather out while also blending the paper and mudded areas.


What is it about their skim coat which leads you to believe it will not hold?   Even topping has adhesive, admittedly not as much as all purpose and especially less than the real Durabonds.



EDIT:   I looked up your profile to see where you might be-LA via Cleve?   No kidding.

Maumee (outside Toledo), via BGSU in the late 60's after graduating Solon HS. 

Small world.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Topping (post #206963, reply #4 of 5)

It is the poor bonding properties of topping compound that concern me.  Sure it bonds to what was underneath, but I have seen tape release and feather edges come off in sheets as well as crumpleing when bumped.  The topping is so soft that compound that cures harder (especially 20 min!) on top doesn't seem to have a solid substrate.  Topping holds primer well and when bumped will dent or come off in that immediate area;  not a whole area of whatever is on top getting dislodged because there is nothing solid underneath.


Floating provides a rough solid substrate for the topping compound skim to provide a paint ready surface.




Small world indeed.  Bedford HS.  Best friends from OSU went to Maumee and Wauseon.  In the LA big leagues now more than ready go get back to the small town. . .

wood (post #206963, reply #5 of 5)

I agree that tape should never be bedded in topping and most buildup should be done with at least all purpose.

I have had good luck with Plus3, the USG product.  While I always bed tape (mesh or paper) and hit corners and first coat L-bead type trims with Durabond, I sometimes do take it the rest of the way with Plus3.  Most of the time I'll use Easysand (timed) after bedding/first coating with Durabond.  Never have problems with either method.

There's the resultant bubbles when feathering into a painted surface, but no adhesion problems.

If you're concerned, I sure can't say Plasterweld will help.  I use that on old plaster walls as a bonding agent, but it goes on first, b/4 any other product is applied to the wall.


So, back to your friends, at 63-I may have known their parents-we've lived here now about 23 yrs.  My daughter spent some time at OSU-she's 29.  If you haven't updated your profile, this information may be meaningless.

Best of luck out there.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.