BEFORE THE ARCHITECT – HOME DESIGNING BACKGROUND – UNIQUE HOME DESIGNING ARTICLES

 HOME BUILDING PROBLEMS - SPECIAL CEILING HOME AIR QUALITY CONSIDERATIONS
By Before The Architect  Copyright 2003-2009 Before The Architect

If you're interested in interactive home planning wherein your own thoughts, questions, and decisions are not only welcomed but expected, then you're where you ought to be.  If not, not.  Before The Architect

hOME BUILDING PROBLEMS - special CONSIDERATIONS IN CEILING VENTING AIR QUALITY

	Special consideration shall be made for raised and cathedral ceilings and otherwise to ceiling ventilation air quality, where wallboard is fastened tight to the interior faces of rafters or bottom chords
	Ceiling area along rafter lines Shall substitute for ventilated surface area for air quality calculation and Each plane of ceiling along rafter lines shall constitute an area to be distinctly ventilated (most critical in hip roof applications, notably involving skylights, stacks, and similar intrusions within rafter bays) for both calculation and application and For free and completely unobstructed space for air flow shall not be less than 2 linear inches from roofing sheathing toward interior along entire width and length of each rafter bay
	Aside from simply deepening dimensioned lumber to accommodate both the 2 linear inches continuous and unobstructed air space and the flushed roofing sheathing supports, one may consider alternatives, among them  Furring to the interior faces of rafters in marginal remediations Heavier sheathing (say, 3/4 linear inch in lieu of more common 1/2 linear inch) Let-in steel strapping on not greater than 4 linear feet centers in lieu of the flushed 2 linear inches x 4 linear inches
	A practiced option to venting for air quality in such conditions as cathedral ceilings and the like (and others, particularly in environments subject to excessively cold weather) is to apply a so-called “cold roof” as described in For Pros/By Pros: Framing Roofs (The Best of Fine Homebuilding), “Framing a Cold Roof: Preventing roof leaks caused by ice damming” by Steve Kearns, The Taunton Press, Inc., 1998, ISBN 1-56158-328-6