Launch Slideshow

Playlist For JLC Extra Slideshow Test

Play Slideshow >>

Playlist For JLC Extra Slideshow Test

  • http://www.builderonline.com/Images/160653751_1_tcm10-1560809.jpg

    385

    Assess the Crack

    Often you can't tell how bad a crack is until you cut it open. I use a couple of tools for this process, starting with a standard utility knife to separate the paint and the top layer of plaster

  • http://www.builderonline.com/Images/2125385307_2_tcm10-1560810.jpg

    385

    Plaster is brutal on sharp edges, so I keep a pocket-sized whetstone handy to restore the knife's edge.

  • http://www.builderonline.com/Images/1795118102_3_tcm10-1560811.jpg

    385

    Crack Opener

    After the first incision, I reach for a small hand tool called a crack opener, manufactured by Hyde Tools. A painter's 5-in-1 tool can work, but since the crack opener is made from high-carbon steel, it stays sharp much longer. When it does get dull, I have a Dremel nearby, set up with a minigrinding wheel, to restore the edge

    www.hydetools.com 

  • http://www.builderonline.com/Images/1591093212_4_tcm10-1560812.jpg

    385

    Widen the Crack

    To fashion a strong bond between patch and plaster, it's important to widen each crack and undercut the edges to form a key. I use the crack opener to scrape out loose plaster and undercut the edges of the crack.

    Note: Power tools like a RotoZip or minigrinder are also effective for excavating plaster cracks, but they must be used with care, because they're very messy. Also, they carve through sound plaster almost as fast as through the damaged stuff, so it can be hard to know when to stop. With a hand scraper, I know instantly when I meet up with sound plaster.

  • http://www.builderonline.com/Images/47802312_5_tcm10-1560813.jpg

    385

    Install Plaster Washers

    Before breaking out the mud, I verify that the plaster is firmly attached to the lath; otherwise, future cracking is inevitable. I apply pressure with my hands along either side of the crack. If the wall feels spongy, I'll use plaster washers (available from Charles Street Supply) and screws to secure the lath and plaster tightly to the framing.

    www.charlesstsupply.com

  • http://www.builderonline.com/Images/1984338249_6_tcm10-1560814.jpg

    385

    First, Countersink

    I locate the wall framing and drill 3/32-inch pilot holes a couple inches from each side of the crack. To make finishing easier, I slightly countersink the plaster washers so they're flush with the wall surface. I use a 1 1/8-inch spade bit, stopping the drill as soon as it makes a circle in the plaster.

    Note: If you drill too deeply, the plaster will be too weak to withstand the pressure from the washer and you will not be able to secure the lath and plaster tightly to the framing.

  • http://www.builderonline.com/Images/1698515460_7_tcm10-1560815.jpg

    385

    Rust-Proof Screws

    I install the washers with 2-inch exterior-grade screws driven firmly into the studs. The galvanized screws will prevent rust bleed-through during my mud work

  • http://www.builderonline.com/Images/1494826796_8_tcm10-1560816.jpg

    385

    Check for Loose Plaste

    After fastening the plaster to the studs, I check the spaces in between for movement. If further reinforcement is needed, I'll fasten plaster washers to the lath alone. This time I use 1 1/8-inch Type S drywall screws, which are made for steel studs; they have narrower threads, so they're less likely to split old wood lath. Even so, this operation requires a light touch with the screw gun.

    Note: Countersinking becomes more challenging when there's no framing support, because the sharp tip of a spade bit will bore through the lath. So I use a 1 1/4-inch carbide hole saw (one made for tile cutting) instead.

  • http://www.builderonline.com/Images/1157468658_9_tcm10-1560817.jpg

    385

    Mist the Area

    When all of the washers have been fastened and the wall feels solid, I brush or vacuum all loose debris out of the crack. I then lightly mist the crack with water to prevent the dry plaster and lath from drawing the moisture out of the joint compound while it's curing.

  • http://www.builderonline.com/Images/1028655073_10_tcm10-1560818.jpg

    385

    Apply Mud

    I use a setting-type joint compound like Durabond 90 to fill the gaps, mixing up only as much as I can apply in about an hour. By working the setting compound from both sides, I completely fill the cracks.

  • http://www.builderonline.com/Images/428981989_11_tcm10-1560819.jpg

    385

    Mesh Tape

    After wiping away the excess compound, I cover the seams with fiberglass mesh tape

    Note: The advantage of using Durabond is that it sets up as hard as plaster and dries quickly, so if I'm in a hurry I can second-coat it the same day. But I've also found Durabond to be almost unsandable, so I make sure to wipe the edges and overlaps clean.

  • http://www.builderonline.com/Images/1714645719_12_tcm10-1560820.jpg

    385

    Finish With Ready-Mix

    I follow up with a second coat of Durabond. After it dries, I use an all-purpose ready-mix joint compound for the succeeding coats, applying it exactly as I would for a drywall job.

Cracked plaster always presents a dilemma:

Should you drywall over it or hire a specialty sub to repair it? Or do you contend with the messy consequences of removing it?

Before you reach for your demo tools,  take a look at this slide show, in which restoration contractor Tom O'Brien demonstrates his technique for making seamless patches in cracked plaster using a few hand tools, plaster washers, and drywall mud.

To read the entire article as it appeared in JLC, click here.