Replacing plaster crown molding will cost you
Q: Our plumber has had to cut two holes in our dining room ceiling and remove a section of original cast-plaster crown molding to assess, access and repair the second-floor bathroom plumbing above. Although I’m thankful we won’t have to pull up any of the near-perfect 1913 hexagonal bathroom floor tile, I have no idea where to go for replacement molding. Will we need to have a mold and molding custom-made, or is this something we could do ourselves? Would it make sense to repair other areas of water damage in the room at the same time?
A: The molding in your dining room wasn’t cast separately and put up in sections. The pictures show that it was run in place, meaning a plasterer pushed in the shape by running a template with the opposite shape against wet plaster.
The molding and ceiling can be patched in an authentic way to look good as new, but it isn’t cheap. One reason is that even a small repair is time-consuming. Another is that there aren’t many people who still know how to do it. One who does is Reggie Bullard, who has nearly a half-century of experience as a plasterer and does interior and exterior work throughout the Washington, D.C., area through his company, R.T. Bullard in Woodbridge, Virginia.
Bullard said he would first assess the situation. Then he could answer your question about whether it would make sense to repair other areas of water damage at the same time. Plaster lasts essentially forever if it stays dry, but water can make it crumbly and loose. He would need to figure out whether the other areas are just stained or are disintegrating.
To replicate the missing sections of molding, he would need to copy the shape, then cut a mating profile in stiff metal. After filing the edge for a perfect fit, he’d outfit the blade with wooden stiffeners and a bottom piece, called a sled, that he could slide against a straight guide screwed to the wall, underneath the existing molding.
He’d patch the ceiling first, aiming to create a perfectly level surface. “You need a true plane,” he said. He often has to enlarge ceiling holes by another foot or so to get a big enough area for a smooth, level patch. A difference of more than one-sixteenth of an inch from the surrounding ceiling would be noticeable.
Although older plaster was typically backed up by thin wooden slats called laths, Bullard often fills in behind with metal laths. Then he spreads on layers of molding plaster. It stiffens quickly – often in 10 or 15 minutes - so he can do mul- tiple coats. But there’s little opportunity to go back and fix details if they don’t turn out right the first time. The plaster dries hard; any unevenness can’t be sanded smooth afterward, unlike drywall mud.
Bullard estimated that it would cost about $4,000 to repair each of the holes shown in the pictures you sent. D.L. Boyd in Hyattsville, Marylandd, which also does plaster repairs, offered an estimate that was only slightly lower: $1,568 for one ceiling hole and $1,962 for the adjoining crown mold- ing. For estimates from either company, of course, you would need to arrange for someone to visit your house.
Given the cost of doing the repairs in an authentic way, you might be tempted to do the work yourself or search for other patching options. There are YouTube videos on how to patch plaster crown, but unless you are especially talented, it might not turn out well. Bullard said the do-it-yourself patches he’s seen look “like you let kids come in and do it with PlayDoh.”