How to joint compound over a wood surface to make flat with adjacent drywall?

There is 1/2 inch chip board adjacent [flush surface] to drywall and need to blend between the two with a flat surface.

*IF* instead of wood the surface were drywall; I would just tape and apply joint compound and skim coat until flat. But, this is between drywall and 1/2 inch thick wood. So, the question is "What is the BEST way to do this?" Should the wood be sealed [painted], or is it alright to simply 'use' the bare wood as if it were drywall?
Reply to
RobertMacy
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No idea which is best - I've done it both ways - but I'd probably put on a coat of primer.

Reply to
dadiOH

to blend between the two with a flat surface. *IF* instead of wood the sur face were drywall; I would just tape and apply joint compound and skim coat until flat. But, this is between drywall and 1/2 inch thick wood. So, the question is "What is the BEST way to do this?" Should the wood be sealed [p ainted], or is it alright to simply 'use' the bare wood as if it were drywa ll?

I would add sojme wood glue to the joint compound to help it adhere to the wood. But, I would bet my pension that over time there will be a crack som ewhere in the vicinity of the junction unless you use something flexible so mewhere at the joint. Wood just expands and contracts too much to avoid so me evidence of the dissimilarity of the two materials.

Reply to
hrhofmann

Robert:

Is it feasible to replace that chip board with 1/2 inch drywall?

Because of the swelling and shrinking of the wood with changes in it's moisture content, you're always going to get a hairline crack opening up over the joint between the two materials.

However, if I were to do this, I'd:

  1. Apply self adhesive fiberglass mesh drywall joint tape to the joint between the drywall and the chip board.

  1. Dilute some white wood glue to a paintable consistancy and paint the chipboard with that diluted glue. Also paint the fiberglass mesh tape on both sides of the joint. As the glue dries, it'll help bond the fiberglass mesh tape to both the chip board and the drywall. There's no problem letting the glue dry because white wood glue re-emulsifies when it gets wet, so the wet drywall joint compound you put on the dried glue will reactivate the glue and it'll help bond the joint compound to the chipboard.

  2. I would use a "curved trowel" to apply joint compound over the tape. A curved trowel looks like an ordinary plastering trowel until you set it down on a flat surface or sight along it's edge and notice that it arches upward in the middle about 1/8 of an inch.

':: WALLBOARD Trim & Tool :: Curved Blade Drywall Trowel'

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Because you hold the trowel at a confortable angle to the wall when using it, a curved trowel allows you to spread a perfectly symmetric "mound" of drywall joint compound over the fiberglass mesh tape that's only about 5/64ths inches thick in the middle. That's too thin to show as a "bump" on the wall, but it's plenty thick enough to cover fiberglass mesh tape.

The curved trowel will make it easier to deal with the chipboard and drywall not being perfectly flush at the joint as well. That's because it's only the corners of the curved trowel that contact the wall, so things don't have to be flush in between. If the chipboard is wider than a few inches, I'd just use a regular trowel everywhere except over the joint.

  1. Sand smooth while holding a bright light close to the wall. The sharp angle at which the light hits the wall exagerates the roughness of the joint compound making it easy to see bumps that need to be sanded down and dips that need to be filled in with more joint compound.

  1. Prime and paint.

Reply to
nestork

What Nestork says sounds great!

Reply to
hrhofmann

I tore out a remodeling job from the '80s and found exactly that - drywall taped to plywood and skimmed - never would have guessed it wasn't continuous drywall.

Reply to
Bob(but not THAT Bob)

Not feasible. The chip board 'fills' in a triangular area about 1 ft by 4 ft long which has almost NO support behind it. Luckily the skim coat over the adjacent drywall is over 1/16 thick. Too late to put in 1/4 inch board with 1/4 drywall [if exist] on top.

Any suggestion as to which glue?

Reply to
RobertMacy

Corner, or flat wall?

Since the chipboard is nailed adjacent to the drywall AND the minimally attached further in, I assmed the shrinkage will be held a bit at the stud and there won't be much possibility of cracking.

Reply to
RobertMacy

Chip board is very vulnerable to moisture, so I'd be sure to seal it thoroughly. I'd put some fine-weave canvas on it, sealed with same (spray?) sealer....then glue up the canvas with thinned Elmer's Glue. Never done it to a wall, but have put canvas and linen on plywood for oil painting. I'd have a roller handy to smoothe the fabric, and be careful not to let it soak long or stretch it while applying it. All kinds of primer coats have been used on linen/canvas, including hide glue or gesso (plaster base). Let us know :o)

Reply to
Norminn

Since you wrote earlier that the chipboard is only about a 1-foot by 4-foot triangular piece, with minimal support behind it, I think you could still remove the chipboard and replace it with a piece of drywall. When you put the replacement drywall piece in, you should be able to secure it to the one existing stud where the chipboard is now attached; and also attach it around the perimeter of the triangle by screwing in some would strips or braces behind the existing drywall and behind the new piece. The point is that there is always a way to secure the new piece of drywall in place for a section that is that small of an area.

Then use some patching plaster or a hard "setting-type" joint compound similar to this

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to fill in the perimeter gaps. Then finish like any other drywall by taping etc.

I think that, in general, leaving the chipboard there is only going to cause a problem down the road as the chipboard expands and contracts and/or absorbs moisture.

Also, a couple of photos might help. You could use

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to do the photo upload.

Reply to
TomR

Any white wood glue will work for you. They can all be thinned to a paintable consistancy if you mix water into them.

Personally, I normally buy Weldbond, but that's not because I think it's better than other white wood glues. I've just never been sufficiently disappointed with Weldbond to have shopped around for a better white wood glue.

Reply to
nestork

Thanksto all who responded and this idea I really like with the canvas.

I put up plywood on one side and chip on the other.

Then two very thick coats of our interior/exterior house paint [had it lying around] to seal.

The plywood gave NO problems whatsoever. Skim coated, flat perfect.

However,...the chip board has little lcations here and there [in spite of thick sealing coat] that raise up from the joint compound. Between the two, I'd rate plywood ok and chip board close to disaster. I'm going to have to do a lot in that area to fix.

Reply to
RobertMacy

Sadly, I agree with your dire predictions of future problems, sigh.

Didn't know about 'hard setting' plaster. just seems fraught with peril, so to speak.

Have not been able to use any method so far of uploading pics to those websites. I go there and the website does nothing, just sits, saying finished and there's no way to upload, no way to register, nothing. Often I can't even get people's posted pics downloaded either. I go to the posted URL and the website sits there with NO indication of any 'next step'. Sometimes works, sometimes doesn't, but usually hangs this system. and I have to reboot - if I'm lucky, sometimes the hang is so bad I have to power off. Then it's a bit of a wait to be back up again. And I've lost things in 'process'

To envision, this is a rework of a fireplace. Ceilings 10 ft mantle 6 ft. From mantle up used to go straight to ceiling, Now matches the Tuscany style of the home with sloping top. The front is around 10 degrees sides a bit more. So the repair work on the wall is over the small triangles on each side of the 'stack' Luckily these are interior walls with NO insulation or filling, but surprised me, never noticed, One wall is stud thickness, the other wall is two stud thicknesses! A lot of wasted space as the wall runs about 10 feet to the bathroom doorway.

Just got done last night. Very happy about using an ABS plastic drain pipe buried in the stack and down to the electronic shelf. Cabling just inserts and self guides down and completely out of sight with the TV mounted up there. Like floating.

Reply to
RobertMacy

Noooooooooo.....by sealer on the chipboard, I meant non-water based. Water base paint, I expect, would raise grain and/or loosen the glue. Chipboard+water=sawdust.....moisture softens the glue too much.

Are your results the final product or test pieces?

Reply to
Norminn

Like your advice but not sure glue is needed. I like to use mesh tape where stresses and continued cracking might develop like in the corner of a door frame.

Reply to
Frank

ARRRGGG! I have a can of Zinsser(sp?) forgot I had it.

This is the final. Where a patch has come up [about 1 inch diameter] 3 times now, I finally dug down, rounded the 'hole' and put Tub 'n' Tile over the spot. That'll work.

Reply to
RobertMacy

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