Truss Rise / UF Insulation / Duct Cleaning / Ridding an Old Septic Tank

In Uncategorized on April 1, 2013 at 11:24 am


Have you ever heard of a house experiencing cracks in the winter between the ceiling and the walls or am I just cracking up?


You may be, but the other problem is called “truss rise”. In houses built with wood trusses, cold air in the attic in winter sometimes causes the trusses to expand and rise off the tops of the interior walls on which they are attached. Here’s what happens: Roof trusses are engineered structures, which function as a unit. When the exposed top chords expand or contract, the entire unit is lifted right off the walls. This problem is called truss rise.

The wallboards (i.e. drywall) that are nailed to the underside of this bottom chord are pulled up with it producing a gap. Rising roof trusses seem to occur more often in houses with heavily insulated attics, since the lower truss chord is well protected against moisture absorption by the insulation that covers it.

All this does not seriously affect the structural strength of the house; the problem is mainly the unsightly crack and its constant reappearance. Most, if not all, of this cracking can be eliminated by adding roof and soffit vents to keep the attic-moisture free in winter. Also make sure bathroom exhaust fans do not discharge into the attic.

Furthermore, minor cracks between the ceiling and wall can be covered with crown molding around the ceilings perimeter, but attached to the ceiling only. That way it will conceal the crack.


I have a question regarding home insulation. The walls in my house were insulated in 1977 with Urea Formaldehyde. I remember there were some health issue discussions as the time, but I never heard anything definite one way or the other. Was there ever an answer as to whether or not it was considered safe?


Urea Formaldehyde insulation was a good insulation with an excellent R-value. The problem was due to the installer. If they didn’t properly adjust the equipment, the insulation off-gassed high levels of Formaldehyde. The off-gassing caused irritations and respitory problems.

The same problems occurred in numerous FEMA trailers because formaldehyde is used in thousands of products including carpeting, furniture, paneling, cabinets, etc.

With time, the off-gassing dissipates and the product is safe unless you are extremely sensitive to volatile organic chemicals.


We are experiencing an odd smell in one room. It comes from the return air ducts. We had the furnace; AC, attic and room all tested, but cannot locate the odor. The odor does not occur every day and usually only when it is sunny. Any comments?


I know from your 2-page letter that you tore out walls and did mold testing, but why haven’t you had your ductwork cleaned and sanitized.

At the risk of sounding skeptical, be wary of duct cleaning companies that are too inexpensive. You really do get what you pay for.

There are many good companies, Safety King 800-AIR-DUCT and A-1 Duct-Cleaning 800-382-8256, among them.


My house had a septic tank. Many years ago when our sub converted to the city sewer, a sewer pipe was connected to the street side of the septic tank and joined the city sewer system. Lately, sewage is coming up through the floor drain. The plumber wants to drain the tank, crush and fill it and run a sewer pipe. I am worried about killing my 100-foot Blue Spruce that grows next to the tank.


Usually when one connects to the city sewers the septic tank needs to be drained, crushed and filled at that time. I’m surprised you got away without doing that.

Understand that the tree’s roots are probably in the tank and possibly in the drain leading up to the tank from the house.

Call a plumber that will run a camera in the sewer line and they should be able to pinpoint the exact problem.

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