Cathedral Ceiling Attic Ventilation

You ll want a tight ceiling air barrier with no air leakage into the cathedral ceiling a critical detail for all cathedral ceiling designs.

Cathedral ceiling attic ventilation.

Bliss points out in the original q a on cathedral ceiling ventilation the risk of forming a vapor barrier sandwich around fiberglass ceiling insulation foil faced insulation above and poly vapor barrier below is that any moisture entering the insulation will be trapped risking future mold or rot problems. Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. If your cathedral ceiling ventilation ports space between the decking and the top surface of insulation resting on the ceiling drywall is visible from an accessible attic and there are no obstructions any type of properly installed attic vent will do as long as it provides adequate output. Even with the attic bypasses sealed and effective vapor retarders installed proper ventilation is essential to prevent moisture problems in cathedral ceilings.

Although there is no separate attic to vent air circulation is still necessary to. A vaulted roof offers open living space directly below the rafters because there are no horizontal ceiling joists. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. With v baffe s design you can quickly and easily retrofit cathedral and vaulted ceilings that would otherwise have been next to impossible.

The cathedral ceilings of the 1970s and 1980s were thermal disasters. Proper ventilation is necessary in order to address water vapor that cannot be blocked to allow it to escape rather than allowing it to accumulate until it causes problems. Attic ventilation for cathedral and vaulted ceilings require attic baffle vents. Research has shown that the amount of airflow in the vent channels of low slope roofs is very limited for roofs with less than a 3 12 pitch.

Cathedral ceilings on the other hand traditionally feature straight sides that slope upward at the same angle as the exterior roof line. Sometimes they included flimsy proper vents between the fiberglass and the roof sheathing but often they just specified thin batts to ensure that there would be an air space above the batts for ventilation.