Q-I plan to do some tuckpointing in the brickwork on the outside of my chimney because some of the mortar joints are crumbling and cracked.
I want to repoint all the joints, but I’ve been told that I have to scrape out the old mortar to a depth of about half an inch before applying new mortar.
I’m using the edge of a stiff putty knife and a beverage-can opener with a hooked point to scrape out the old mortar, but some of it is too hard to scrape out. Is there a better tool to use for this job?
A-For most such jobs, a masonry chisel with a wide blade, or a heavy, cold chisel with a blunt edge work well.
Hold the chisel at an angle to the length of the mortar joint and use the corner of the blade to chisel away the mortar while tapping lightly with a hammer.
Don’t hammer harder than necessary to chip away the mortar, and never drive the blade straight in at right angles to the face of the mortar joint. Use a hose to wash away all chips and dust before troweling on the new mortar.
Hot water backflow
Q-Can you tell me how to hook up hot-water pipes so as to prevent heated water-from the tank-from going back into the inlet and outlet pipes while the heater is not in use?
A-Two methods are commonly used to prevent backflow or siphoning of heated water back into the water line. You could either install a back-flow preventer right after the gate valve in the cold water inlet line (this is something like a check valve and is often required by local codes) or install a vacuum breaker in the hot water outlet line.
I suggest you check with your building department or plumbing supply house for details.
Stucco paint flaking
Q-My old stucco house was painted about three years ago. Even though we used a top quality brand of masonry paint, the paint is now lifting off in big flakes. Can you tell me what caused this?
A-One frequent cause is that the paint has been applied over a very dusty or dirty surface. Another possibility is that a primer or sealer was required but was not applied before the finish coat was applied.
Also, there are some forms of stucco-such as magnesite stucco-that cannot be painted successfully. I suggest you call the manufacturer and ask for help. Some companies will send someone out to examine the paint job, and some will ask you to send them the flaking chips of paint for analysis.
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Write to Bernard Gladstone in care of Your Place, Chicago Tribune, 435 N. Michigan Ave., Chicago, Ill. 60611.
