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reaconserv
Drywall over painted block

Can someone tell me if it acceptable to install drywall directly over painted masonry block with adhesive in lieu of firring strips?

HoustonRemodeler
Re: Drywall over painted block

You can IF

1- This is a dry location and there is NO risk of water getting to the back side of the drywall

2- You have no desire to remove the drywall in the future. Whomever gets to remove this drywall will curse the day you were born. Furring strips help solve this problem

3- The block is plumb and straight enough to get nice drywall joints. Furring strips help solve this problem

4- You have no desire to attach baseboards, crown moulding, or trim. Furring strips help solve this problem

5- You have no desire to have electrical, plumbing, audio / video. Furring strips help solve this problem

6- You have some way to get the drywall panels to stay where you want them while the glue sets. Furring strips help solve this problem

Why do you want to do this?

A. Spruce
Re: Drywall over painted block
HoustonRemodeler wrote:

3- The block is plumb and straight enough to get nice drywall joints. Furring strips help solve this problem

Now wait a minute, are you saying that furring strips will F-up a plumb and straight wall?

I know what you meant, but it bears fixing for clarity. :cool:

HoustonRemodeler
Re: Drywall over painted block

I am thinking about leaving it, just to see if anyone else is paying attention. :rolleyes:

reaconserv
Re: Drywall over painted block

This is an existing finished area being used as a church nursery. Existing walls are painted block (many coats). The existing doors are trimmed with 3/4"material and all electrical is existing and fine where it is. The purpose of the drywall is to update the look of the block. This area also has a drop ceiling. If I use firring strips I will have to re-trim the doors and extend the jambs. If I apply the drywall directly, I will save the cost of this as well as the cost of applying the firring strips.

A. Spruce
Re: Drywall over painted block

Rather than overlay the walls, I think I'd be inclined to skim coat them with either plaster or drywall compound to smooth the surface and mimic drywall. It would be a whole lot easier, cheaper, and cleaner to do.

Nestor
Re: Drywall over painted block

Two easy ways that any newbie can skim coat any wall:

1. Use a "V" notched adhesive trowel to spread joint compound on the wall, and allow to dry. Then, holding that same trowel upside down, fill in the trowel ridges with the un-notched side of the trowel. The result will be a uniformly thick layer of joint compound on the wall.

2. Use a "V" notched adhesive trowel to spread joint compound on the wall. While the compound is still wet, mist it with water using a spray bottle, and trowel it flat using the un-notched side of the trowel.

In either case, it's best to first paint the wall with white wood glue diluted in enough water to make it into a paintable consistancy. Allow that dilute glue to dry on the wall. The moisture from the joint compound will re-activate the glue, causing it to bond the joint compound to the wall. For a Cadillac job, one could use concrete bonding agent instead of white wood glue. Concrete bonding agent has a "window of opportunity" during which wet material will re-activate it's adhesive properties. Once that time window has closed, concrete bonding agent becomes unaffected by moisture. I'm thinking that if moisture coming through the block wall was a problem, it would mucked up the multiple coats of paint on that wall by now. If moisture migration through the wall isn't a concern, then white wood glue won't re-emulsify and drop the skim coat of joint compound onto the floor.

Hank Bauer
Re: Drywall over painted block

I would agree that skim coating is acceptalable I would stay away from the dry wall product and use an Acrylic Plaster applied to the block.
Check on One of these products.
Variance Acrylic Finishes.Located in Albuquerque,NM

Litex Incorported, Fort Lauderdale, FL

SAFRA veneer plaster products

Master of Plaster

All the above can be textured or applied smooth with color no painting required.
Can be applied over a painted surface some require a bonding agent that will come with the product that you select.
I say no Joint Compound based on my experence as a plaster.
75 % of my work comes from the use of Drywall product applied over substrates that will last from 5 to 20 years than I get to due high dollar repairs.Been doing these repairs for the last 35 Yrs.

reaconserv
Re: Drywall over painted block

Great ideas! Thanks!

jkirk
Re: Drywall over painted block

im with sprucey on this one, definitely just get the wall parged

Mastercarpentry
Re: Drywall over painted block
Hank Bauer wrote:

I would agree that skim coating is acceptalable I would stay away from the dry wall product and use an Acrylic Plaster applied to the block
Yrs.

I agree. These days there aren't many left who understand plaster finishes- it's different than drywall but is still very viable for purposes like this. Plaster will stand up much better and much longer here than a drywall mud skim. If it were possible I would scarify or sandblast the paint to get a direct bond with the block underneath- that way even if the paint underneath were to fail later on it wouldn't matter-the plaster would still be well bonded.

Positively avoid any drywall installed directly over masonry- I've never seen it last as it should. The temperature differential with masonry always carries condensation with it; the question isn't "If" but "How much" and plaster, being closer to masonry's make-up than sheetrock mud, will keep the issue at the surface where it can evaporate instead of under the sheetrock mud where it will loosen the bond. While gluing helps hold drywall, if the paper backing on the drywall sheet comes loose from dampness it all falls down. Drywall needs to be fastened through the face as it was designed to be done; that way the entire thickness has to fail before it falls down.

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