This arch cracked years ago and was patched, but the rebar inside has continued to rust and expand, breaking the patch. (Reader photo)

Q: I have two cast-concrete arches across the front of my townhouse, as do my neighbors. My pair cracked some years ago, and I had them patched. But the rebar inside the concrete continues to rust and expand, breaking the patch even more. How can I replace the arch?

Washington

A: You probably have issues beyond just replacing the arches, said Roger Becker, the vice president for technical services at the P recast/Prestressed Concrete Institute , after taking a look at the photos you sent.

Becker, who has credentials as a professional engineer and a structural engineer, worries that there is inadequate or perhaps nonexistent waterproofing on the balconies above the arches. “On the brick, I see all kinds of white mineral deposits,” he said. “And underneath the balcony slab, there are a lot of mineral deposits.” Mineral deposits point to underlying moisture because they form as moisture moves through the masonry. At the surface, the water evaporates, and a mineral crust is left behind.

Adding to Becker’s concern is the amount of rust visible in the rebar in one of the photos. The rust may be compromising the structural strength of the arches, he said. But, he added, it’s possible that the arches are purely decorative features and that the weight of the balconies is borne by the walls behind the arches.

A reader has heard a dripping sound coming from this fireplace. The chase cover has been replaced twice, but the problem persists. (Reader photo)

Becker suggested that you work with your condominium association to hire an engineer, preferably a structural engineer, to assess not only the arches but also the balcony slabs and waterproofing. “It doesn’t pay to ask how to replace the arches until you deal with the waterproofing,” he said.

A structural engineer can also offer advice about whether the arches can be salvaged or must be replaced. If they need to be replaced, Becker suggested getting several bids from companies that specialize in forming precast-concrete features. It would probably be a custom job, he said.

Q: I live in a 1994 single-family house that has a prefab fireplace. About two years ago, I started hearing a dripping sound in the fireplace when it rained. Despite two new chase covers and inspections from three companies, the drip evolved into water actually coming into the firebox. I hired a company to check the chimney again, and it decided that the new chase cover and work by the previous company was all wrong. The new company ordered another cover, added a storm collar and changed the cap. I continue, however, to hear this dripping sound when it rains. Recently, when I thought I heard water hitting metal, I placed a paper towel in the fireplace and left it there for several days when it rained. The paper towel came out stained. The last company refuses to even come back to see whether it missed anything because it contends that it covered everything. What else can I do? Oh, I didn’t mention that in addition to paying lots of money for the work done so far, I have also had the roof and siding checked and contacted the manufacturer of the fireplace, but it offered nothing of substance. There are no visible signs of water damage inside the house.

Hyattsville

A: If it’s just a little water and it happens only in a big storm, perhaps wind is the culprit. “It could be raining sideways,” said Mike Taylor, one of the owners of Acme Stove, a fireplace shop in Rockville (301-309-1998; acmestove.com). Chimney caps are, by necessity, not closed at the top, just covered with a “roof.” So there is plenty of room for windblown droplets to get inside the chimney during a strong storm. A little moisture that gets in this way isn’t necessarily a problem, Taylor said.

But the fact that the last company won’t come back for a recheck raises a concern that perhaps it didn’t do the work correctly. For peace of mind, you might want to invest in one more inspection. Taylor said his company refers calls about chimney problems to American Professional Chimney in Hyattsville (301-453-7496; americanprofessionalchimney. com). Office manager Catherine Wilson said the company charges $75 for an inspection but waives that fee if it winds up doing a repair.

Inspectors look for places where leaks usually start: an ill-fitting cap or a hole in the siding or in the chase cover on top. Chase covers are typically aluminum or steel, both of which can corrode enough to create pinholes, Wilson said, which is why American Professional Chimney installs only stainless-steel chase covers. But sometimes, she said, everything checks out okay and a little water still gets in. “It could just happen,” Wilson said.