Tile Roof Erosion

Dave Hardcastle · 08-19-2010, 06:46 AM

I have never seen this kind of erosion on concrete tile before. It is caused by the exhaust vent of the furnace but I don’t know why. Looks like the tile has been sand blasted. 11 year old house with original high efficiency furnaces installed

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**Ken Rowe** · 08-19-2010, 07:46 AM

The exhaust from a natural gas burning appliance is corrosive to clay tile. That's why your not supposed to vent them through a chimney without a metal or pvc liner. The vents pictured should be raised up, especially the ones in direct contact with the roof.

**H.G. Watson, Sr.** · 08-19-2010, 07:56 AM

Kidding, right? You don't know why?

Neither vent is correct, the installations are WRONG. Doubtful all depicted is AS ORIGINAL.

Acidic corrosion & errosion!

Negligable free air for dillution at terminus. The second one mutiply depicted is effectively, and nearly completely obstructed as it is run into the tiles themselves! Expect now compromised HEs/appliances.

**H.G. Watson, Sr.** · 08-19-2010, 08:13 AM

BTW wrong direction - Sh*t isn't the only thing that "flows downhill" - pipe was rotated 180 degrees, probably when some idiot last spray painted the flashing and the vent pipe made up of wrong direction fittings. The tiles were additionally not likely protected from the spray paint or primer either, thus contributing to the etching, corrosion, errosion process.

Expect the fasteners for the tiles above are all but gone.

Whether the roofing tiles were glazed terra cotta or cementious, the damage has been done and will continue even when you have the venting corrected, the damaged tiles will need to be replaced. Surface "neutralization" won't work.

This isn't a DIY forum. Recommend you consider the services of a professional home inspector to help you identify ALL of the issues, not just those of your roof and vent terminations.

**Jerry Peck** · 08-19-2010, 02:14 PM

Incorrect venting termination.

Wrong flashings too (I can't imagine that nothing other than 'caulking' is supposed to be around the top of that flashing, likely needs something like a storm collar on it).

The ridge tiles need to be anchored down properly, the top course of tiles do not have the required headlap, etc.

Elliot Franson · 08-19-2010, 03:04 PM

http://www.britishprecast.org/associ...esandpipes.pdf

**Jerry Peck** · 08-19-2010, 05:30 PM

Originally Posted by Elliot Franson

http://www.britishprecast.org/associ...esandpipes.pdf

http://mlt.boralna.com/technicaltool...de-2010Web.pdf

Scroll down to page 18 (page 22 of 92).

Elliot Franson · 08-19-2010, 09:04 PM

Originally Posted by Jerry Peck

http://mlt.boralna.com/technicaltool...de-2010Web.pdf

Scroll down to page 18 (page 22 of 92).

JP, er uh, Mr. Peck: I was aware of that, but didn't think much of the graphic. Though correct, it lacks necessary detail.

**Jerry Peck** · 08-20-2010, 02:42 PM

Originally Posted by Elliot Franson

JP, er uh, Mr. Peck: I was aware of that, but didn't think much of the graphic. Though correct, it lacks necessary detail.

Uhhh ... Aaron ... that graphic lacks detail?

Which part, the part where it specifically states and shows "STORM COLLAR"?

Yes, it also says "or sealant on cone style flashing(s)", but it also shows the two step process and that the FLASHING IS ON TOP OF THE TILE and not under the tile as shown in the original posters photo. And, yes, the drawing you linked too also shows a two step flashing with the flashing on top of the tile.