Attic Ventilation

July 2012

by Bryce Given

When it comes to ventilating your home's attic, the right amount of air flow and air volume can make a significant difference to the comfort and durability of your home.  There are four primary reasons to ventilate, two of which relate to the comfort of your home and all of which can affect its durability.  The four reasons for ventilating are:

1. Reduction of summer time heat in attics: Proper ventilation will improve flow of the sun-heated air and direct it out and away from the attic space, reducing heat that radiates into living areas.  For flat roof designs, it is critical to cross ventilate through perimeter vents and unobstructed air movement channels within the roof's joist cavity.  For steep sloped roofs, ventilation is typically achieved through eave and ridge vents with at least 50 percent of the ventilation capacity located high on the roof's ridge.  Your local Building Department and current Building Code will provide specifics regarding Code compliant installations.
2. Reduction of winter time moist air and condensation in attics:  Attic moisture as vapor can condense to water droplets when coming into contact with a cooler surface, and then can drip onto attic insulation, gypsum board ceilings and wood framing causing them to stain or deteriorate.  Proper attic ventilation can help to eliminate moisture and discharge stagnant attic air, reducing the potential for condensation.  
3. Ice Dams:  An ice dam is a buildup of ice at the edge of a roof, which prevents melting snow water from freely draining off the roof.  Roof temperature imbalances cause the dam to form as melting snow flows down the roof but freezes again at the point where the roof is below 32°F.  The ice builds up over time as more water collects at the roof edge and freezes again.  Then the water above that has not yet reached freezing backs up behind the ice dam.  Cracks in the exterior roof covering allow this water to flow under the roofing and protective felt layers and into the attic, potentially causing damage to roof sheathing, framing, ceilings, insulation, and other areas of the structure.  Natural roof ventilation along with increased ceiling/attic insulation can help maintain uniform roof temperatures in cold weather to minimize or prevent formation of ice dams.
4. Prolonged service life of building materials:   Wood sheathing, framing and roofing materials are moisture and heat sensitive.  Materials can break down more readily through heating, cooling and moisture cycles.  Proper attic ventilation can reduce the highs and lows of these cycles to create a more consistent environment, thus prolonging material durability. 

Currently, the 2009 International Residential Code (IRC) is the generally accepted minimum standard for roof ventilation in most local jurisdictions.  Incorrect air ventilation design, blocked vents and non-sealed ductwork are often observed as contributors to water problems in attics.  Before undertaking ventilation and roofing projects, contact your local Building Department or qualified Design Professional to verify the requirements for the work you intend to accomplish.  

Construction Inspections

April 2012

by Bill Christenson

Commercial contractors have long understood the need and requirement to accept responsibility for quality control of the construction work, both their own work as well as their subcontractors’ work.  This entails proper staffing and expertise to perform the necessary ongoing inspection of the work. Municipal inspectors, whether they are city, county or state, also play an important role in the inspection process, however their inspections are mandated by the building permit and are very limited in scope and nature.  It is not the role of the municipal inspector to oversee compliance with the contract terms, project plans or specifications.

There are contractors, and more commonly residential contractors, that rely completely on the municipal inspector for their project quality control.  Their adage is: as long as the project passes inspection it’s acceptable and meets the necessary standards.  This is a fallacy and completely disregards the contractor’s responsibility.  The municipal inspector may be on the site only a half dozen or more times over the course of the construction project to perform code mandated inspections.  Who is responsible to ensure the quality of the work during the other 99% of the project?  That’s the contractor team’s responsibility, inclusive of the general contractor, subcontractors, and sub-tier subcontractors. The contractors are also accountable for work inspected by municipal inspectors, hence they are responsible for all of the work.

Construction  inspections can be contracted to independent third parties although this is more common in commercial construction than residential construction. The project architect / engineer is often contracted to perform inspection services.  In these situations the inspection and quality control responsibilities must be carefully addressed in each contract between the owner, architect/engineer, and contractor.  Building permits often require independent special inspections for certain complex phases of the work such as soils preparation (geotechnical engineer) or structural concrete and structural steel framing (structural engineer).  When planning a construction project, make sure the parties understand and accept their roles for project quality control and that the necessary means and expertise are available for successful project completion.

Table Saw Initiative

October 2011

by Michael Showalter

After years of allowing the power tool industry to police itself through voluntary standards, the Consumer Product Safety Commission (CPSC) is calling on toolmakers to strengthen safety standards. These actions come as table saw manufacturers face an increasing number of product safety lawsuits throughout the country.  One of those lawsuits resulted in a jury awarding $1.5 million to a man who had sawed his fingers on a Ryobi brand table saw.  In that lawsuit the plaintiffs charged that the manufacturer had known about a safety technology called SawStop, but had not integrated it (or something similar) to its products.  No less than 50 similar lawsuits are pending nationwide, putting manufacturers on the defensive.  Every day 10 people lose fingers in table saw amputations and the chairman of the CPSC would like to know why more isn't being done to prevent such accidents.

Most table saw operators who injured themselves removed the blade guard for operational convenience, according to a CPSC study conducted from 2007 to 2008 that looked at 66,900 "blade contact injuries."  For that reason, CPSC is considering requiring that table saws come with a safety brake like the one offered on SawStop contractor and cabinet table saws, according to NPR.  Within three-thousands of a second of contacting human skin, the brake fires and the blade drops down into the table, preventing injury.

SawStop detects flesh and almost instantly stops the saw blade from spinning and drops it into the tool and away from fingers and hands. In demonstrations using hot dogs, the technology has been shown to leave nothing more serious than a small nick on the skin.  CPSC says it costs the United States $35,000 every time someone is injured on a table saw, accounting for medical treatment, lost time from work, product liability & litigation, and human pain and suffering, so the CPSC is working to implement tighter safety standards for the common contractor tool.

However, cost is the main sticking point for requiring a blade brake like SawStop on every table saw sold in the U.S.  Most manufacturers say it would add $100-$200 to the price of a new table saw.  For a small portable or jobsite unit, that could double the current sales price.  As a first step to making the law, CPSC recently recommended publishing an Advanced Notice of Proposed Rulemaking in the Federal Register.  After that, public comment is sought before crafting a final rule.

Contractors must be prepared to provide the correct power equipment on all sites if and when the new rules for table saws are adopted.  Otherwise they may face liability for providing an unsafe work place and endangering workers.  The Washington Administrative Code regarding equipment can be found at this website:

http://apps.leg.wa.gov/WAC/default.aspx?cite=296-155-009