EIFS over open framing

[Sean Thornton]

This house had what looked like (PI) EIFS over open framing. There was no plywood or OSB sheathing under the EIFS in the attic, but I'm not sure about the rest of the house. Is it likely that the rest of the house has no sheathing? The client wants siding installed and my gut feeling is that to install new siding the EIFS will need to be removed and sheathing installed which would be expensive. Am I right about this? Opinions?

[Sean Thornton]

For clarification, the substrate you see in the attic photos was similar to a fiberglass panel or insulation board. I could actually see daylignt shining thru the substrate in the areas where the EIFS surface coat was damaged.

[Scott Patterson]

This house had what looked like (PI) EIFS over open framing. There was no plywood or OSB sheathing under the EIFS in the attic, but I'm not sure about the rest of the house. Is it likely that the rest of the house has no sheathing? The client wants siding installed and my gut feeling is that to install new siding the EIFS will need to be removed and sheathing installed which would be expensive. Am I right about this? Opinions?

Hi Sean, the substrate is the board that you are seeing from the attic. It is a poly-iso (polyisocyanate) board. It is basically closed cell foam that is encased between two layers of a fiberglass fabric. It is very common in your neck of the woods. It was a type of EIFS system (DEFS direct applied) that was used for only a few years by a few manufacturers. Dryvit called theirs "The Sprint System" because it went up so fast! The big advantage of it is that you do not have OSB that will rot in the walls, but that is the only advantage!

Most of the time you will find spider web like cracks throughout the walls, it is kind of like an egg shell. You will usually have a base coat and then just the finish coat and many times you will find just the finish coat. It is a crap system that sold well because it was lower in cost.

If your client wants to install a new cladding they will need to remove the existing mess and add a proper sheathing and then the new cladding. Cost will depend on what they put back up. If they put up a Hardiplank type cladding I would say that the tear-off and replacement would be in the $25-$30 per square foot range. So yes, it could be very costly....

[Sean Thornton]

Thanks for the reply. That's good information.

[Jerry Peck]

The big advantage of it is that you do not have OSB that will rot in the walls, ...

I guess they used either let-in wood diagonal braces or metal diagonal braces?

No sheathing makes a structure much weaker, even if the above braces are installed.

No sheathing also makes the structure susceptible to wind-borne debris going right through the walls (anyone in high wind event -hurricane - areas, typically wind zones of 120 mph and greater, knows what wind-borne debris is ;) ).

[Sean Thornton]

There were wood diagonal braces. Wouldn't want to be in this house in a windstorm

[Scott Patterson]

There were wood diagonal braces. Wouldn't want to be in this house in a windstorm

Keep in mind that home went through Katrina back in 2005! In Brandon the winds were around 110 to 120 mph for about 3-4 hours! That poly-iso board is pretty strong stuff when used as sheathing.

[Jerry Peck]

Keep in mind that home went through Katrina back in 2005! In Brandon the winds were around 110 to 120 mph for about 3-4 hours!

That is why I stated "typically wind zones of 120 mph and greater, knows what wind-borne debris is", less than 120 mph is not a dangerous regarding structural loads and especially flying (wind-borne) debris.

When they did the testing, speeds equivalent to 140 mph (as I recall) resulted in the 9 pound 2x4 going through the concrete block walls if the 2x4 did not hit a cell web in the block. It's been quite a while since seeing those test results, i.e., 1992-1994, but the tests were impressive.

Added with edit: scroll down to page 8 for frame walls - http://www.depts.ttu.edu/weweb/Research/DebrisImpact/Reports/DIF_reports.pdf

[Benjamin Thompson]

I guess they used either let-in wood diagonal braces or metal diagonal braces?

No sheathing makes a structure much weaker, even if the above braces are installed.

No sheathing also makes the structure susceptible to wind-borne debris going right through the walls (anyone in high wind event -hurricane - areas, typically wind zones of 120 mph and greater, knows what wind-borne debris is ;) ).
Add to that minimal wall framing, looks like 2x4 studs on 24 inch centers.

[cuba_pete]

Keep in mind that home went through Katrina back in 2005! In Brandon the winds were around 110 to 120 mph for about 3-4 hours! That poly-iso board is pretty strong stuff when used as sheathing.
Kind of like a tree bending in the wind. My home (and thousands of others) in Virginia use cellulose sheathing and that's all...the siding goes right over that. It doesn't prevent racking at all. In any storm over 40 mph winds the creaking walls would keep us up at night. Hurricanes? Forget about it...

[Steve Duchene]

I lived in Ridgeland MS back in the early 90's and saw the homes at Northbay with golf ball holes all the way through the EIFS for the very lack of a solid backer. What an asinine way to save a few dollars on materials. I can't imagine what damage wind borne debris would do.

[cuba_pete]

I lived in Ridgeland MS back in the early 90's and saw the homes at Northbay with golf ball holes all the way through the EIFS for the very lack of a solid backer. What an asinine way to save a few dollars on materials. I can't imagine what damage wind borne debris would do.
Just as you would think. Small branches less than 3/8" diameter penetrated the siding and the backing during Isabel in 2003. A direct strike on the roof by a large branch was more desirable due to the lesser damage (or none!).