Mystery vents found during concrete tile roof inspection. Bathroom vents or roof vents or something else?

     Picture a hot, humid Saturday in July.  Who wants to inspect a roof, let alone a concrete tile roof? The risk of a fall or worse a wrong step and you may break a tile;  that is enough to turn off most home owners.   And yes, breaking a tile to most home inspectors is worse than a fall because cost of replacement of these tiles may be more painful.

Hard-working, dedicated and eager home inspectors, are expected to complete inspect a roof regardless of temperature or humidity in hot summer months.  These are the guys (and gals) who will risk life and limb just to get a peek at the condition of your chimney or roof. Keep and eye out for these people as this is a sign of a good home inspector.

The 2 story house is located in the posh neighborhood of Mississauga, Ontario.  One quick glance of the neighborhood and you can tell these houses belong on green properties of the Monopoly board game.  Well manicured green lawns and neat landscaping.  Clean walkways and drive ways.  Not a piece of trash in site.

Your average home owner may not even noticed the vents on a roof.  But, home inspectors are expected to know and inspect pretty much every aspect of a house.


Flat Interlocking cement roof tiles.  Ridge roof venting to cool roof.  Metal B vent to exhaust gas combustible appliances.

Concrete roof tile are made of cement and mostly aggregate in 1 to 3 ratio.  They come in several shapes including curved, spanish, flat shingles and flat interlocking such as the ones in the pictures.  Some manufactures provide a 50-year warranty on the tiles.   This type of roof is not typically found in the Mississauga area.

The most common conditions noted those tiles were cracks and broken tiles, most likely due to weathering, freeze/thaw damage.  Other conditions common with concrete tiles include missing or loose tiles due to wind uplift or ice dams.  Fastener failures are also common, mostly due to poor installation practice or rust and corrosion of the fastener.

Roof vents provide ventilation for attics.   The venting of warm moisture air out of the attic prevents condensation on structural framing.   In the summer, the warm air escapes and cools the attic, while during the winter, venting helps reduce ice damming by keeping the attic cold.  The venting system noted on our concrete tile roof included soffit vents and ridge vents.

As experienced and well-trained home inspectors, whenever we are on a roof, we make a note of all roof penetrations.  During the attic inspections we account for all the roof penetrations noted on the roof.  During the bathroom inspection of this house, it was noted that none of the bathrooms have bathroom vents installed.  Which then begs the question what are these vents found on one side of the concrete tile roof?


A vent exhaust to exterior found in the middle of the roof. A metal screen covers the vent hole.

This is a typical problem home inspections face on a regular basis.  What is this?  What is that?  Home buyer just want to know what they are buying.  And it’s what  they are paying good money for – to know.

If the attic is vented by ridge and soffit vents, and the bathrooms do not have vents installed and all the roof penetration were accounted for,  what are the two vents in question?

Turns out, they are indeed for bathroom vents, just not installed yet.  So they are considered rough-in for bathroom vents.  The roof manufactures know making penetration in concrete tiles is a big task so they install these rough-ins for future considerations.

T : 647-963-2424

C : 289-652-6351


Cuong Luu is a certified home inspector specializing in infrared thermography. This is a technology that detect defects around the house that are not visible to the naked eye. It is non intrusive which means no dry walls or ceilings have to be removed. Expect more from your home inspector. Get the whole picture on your house, get an infrared home inspection.

Posted in Home Inspection, Roofing

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