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Earthquake Retrofit Inspection Finds Roof Condensation Damage

Earthquake Retrofit Inspection Finds Roof Condensation Damage

Experienced investors often know what problems to look for before they purchase an industrial building, warehouse, or manufacturing facility.  There are quite a few new faces in the commercial real estate market today; due to the current economy and the great prices that are available, it is a good time to buy commercial properties.  New investors, however, who are trying to quickly get into a seemingly good deal often miss the problems that experienced investors have learned to avoid.  There is little return on investment (ROI) on a building that is found to be rotting from the inside out. Roof condensation, which causes the deterioration of a building’s roof system, is one of the more common issues found in a commercial building.

Like a slow-growing disease, roof condensation damage accumulates over the course of many years, eventually destroying the buildings’ entire roof system one element at a time.  Every part of the roof system is impacted, including framing, hangers, and even the nails. Often, damage from roof condensation is uncovered when the building is going through the process of an earthquake retrofit.  The foil layer is pulled back revealing years of preventable damage.  The best way to prevent roof condensation damage is to know what it is, inspect for it regularly and then treat it correctly right away.

Roof condensation is moisture that develops in the roof ceiling area and is trapped there by foil insulation or other types of radiant barriers; it is a condition that easily occurs in concrete tilt-up buildings with a panelized roof system.  If this situation is left untreated, there is no doubt that it will slowly destroy the entire property.  Some property owners procrastinate in taking care of this issue, failing to realize is that this problem can be a 25-cent or a 10-dollar per square foot problem, depending on how quickly the condensation issue is addressed and rectified.

Usually, a roof structure contains a vapor retardant.  This retardant, a foil radiant barrier, is basically R-11-faced fiberglass batting that is connected to the sub-purlins or wrapped around the purlin beams on the underside of the roof structure.  One of the worst scenarios for creating damaging roof condensation is when the batting insulation is covered with foil insulation.

Buildings heat up during the day and as the roofing material directly absorbs the hot rays of the sun, heat is created in the air cavity between the insulation and the roof.  Amazingly, this area can reach a temperature that is at least 50 degrees warmer than the rest of the building. Hot air increases the evaporation of the ambient water molecules, pulling moisture into the air cavity.  Because of the insulation, the individual roof cells are not able to vent and dry out.  When the building cools off, the air cavity cools, causing the trapped water to condense and seep into the wood roofing materials.  Until the issue is corrected, the building goes through this condensation process day in and day out, causing more and more structural damage.

Roof condensation damage is typically seen in several ways.  Buildings that have the foil barrier attached or wrapped may have black lines streaming down the purlin hangers.  Rust is often found; the rust typically weakens the integrity of the purlins, and therefore the entire structural support of the roof.  When roof condensation occurs, it is much more than an investment hazard; it is also a safety hazard that increases the chances of significant damage during an earthquake.

To begin the repairs necessary for this condition, the building must dry out and “breathe”.  Typically, the first step is to peel back the foil barrier and cut air vents where it joins the purlins.  Depending on the results of a complete property inspection, there are several other steps that may be necessary to completely resolve the condensation issue, such as hurricane clips, wood ledgers, GLB connections, and finally, re-nailing the roof.  While the most critical finding from the inspection is the condition of the roof nails, be aware that this is something frequently missed by many different types of inspection contractors, including roofing, HVAC, insulation and general contractors

An earthquake retrofit provides existing structures with more resistance to seismic activity due to earthquakes. In commercial buildings, this process typically includes strengthening weak connections found in roof to wall connections, shear walls, continuity ties, and the roof diaphragm.  Because the initial earthquake retrofit inspection process is so thorough, many issues with roof condensation are discovered. Saunders Commercial Seismic Retrofit can provide a complete, multi-faceted inspection of any commercial building; their earthquake retrofit inspection process is based on years of experience in commercial building safety and security.  Saunders Commercial Seismic Retrofit provides a retrofit insurance quote based on present and after-retrofitting values so you can quickly calculate your Return on Investment.  If you’re considering a property investment and would like to have full understanding of any potential roof condensation concerns, call Saunders Commercial Seismic Retrofit today.

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(408) 267-3876


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