drdiy

Questions & Answers

In Q&A on November 21, 2011 at 7:12 pm

Q: We recently sold a family members house that had an 80-percent efficiency furnace. The purchaser hired a home inspector and everything passed with no problems. I was told later that there was no flue liner in the chimney and that it was a new code to have one.

A: You need to check with the furnace manufacturer. Most require the chimney be relined. But there are caveats. If the chimney is in the middle of the house, it may not be as critical to reline. Chimneys on outside walls are colder and contribute to greater downdrafts. Another consideration is the local code enforcement officer. They have the final say on whether it is needed. To summarize, most need relining, which prevents downdrafts and condensation from accumulating in the colder chimney. Relining helps eliminate carbon monoxide problems. As you can see it is almost always required.

Q: In the past you have stated to install ice shields to eliminate ice dams. What did you mean by installing them minimally 6-feet past the exterior wall? What about 6-feet from the eave edges of the roof (with a 2-foot wide soffit) making it 4-feet past the exterior wall? What width do ice shields come in?

A: I always would want the ice shields all the way up any and all valleys. I know many people who installed 6-feet of ice shields past the exterior walls and still had ice damage to the interior. By the way, that included my house and for that reason I installed the ice shields back up 12 feet. I also ran them all the way up all valleys and around all skylights. Don’t take the chance and try to save a few bucks, it may be short sighted. Finally, ice shields come in 3-foot wide rolls.

Q: I want to install an exhaust fan in my bathroom. What brand do you suggest?

A: The brand is not as important as size. There are several criteria you should follow. You need to know about the amount of cubic feet in the area so you know how much volume of air to move around. To determine, measure height times the length times the width of the bathroom and it will equal cubic feet. You’ll want a fan that has a capacity to change the air a minimum of 8 times per hour. Multiply the cubic feet by 8, which gives you the cubic feet per hour. Divide that by 60 minutes to get your cubic feet per minute (CFM). All fans are stamped with that number. Also, get a fan with the lowest “sone”. The lower the sone number, the quieter the fan. Finally, vent the exhaust fan to the exterior and not into the attic.

Q: My Birmingham condo’s basement floor is covered with cement dust that seems impossible to clean up. The building supervisor said to clean it with muriatic acid. After reading the label it sounds like I should not be using this product in a basement with only one small window for ventilation. Should this be the builder’s responsibility to clean this up or mine?

A: I agree with you. It should be the builder’s responsibility. Dusting on the surface of concrete is called “laitance” and too much water in the concrete or premature finishing causes it. The water that rises to the surface in newly placed concrete should disappear prior to troweling. Whoever ends up doing it should know that the dust could be removed with a 5 percent solution of muriatic acid. Indoors, use Trisodium Phosphate (TSP). Wear gloves and goggles and thoroughly rinse with clean water. Let the floor dry and apply a concrete sealer. Make sure the sealer can be used indoors and is safe around the furnace and hot water tank.

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