Podcast Episode 671: Stucco Problems, Peeling Plaster, and Basement Finishing
Listeners write in about insulating behind stucco and ask questions about basement finishing and a “leaky” chimney
Welcome to the Fine Homebuilding podcast, our weekly discussion of building, remodeling, and design topics aimed at anybody who cares deeply about the craft and science of working on houses. This is senior editor Patrick McCombe. I’m joined by Fine Homebuilding editorial director Brian Pontolilo, Fine Homebuilding associate editor Grant Baver, and producer Andres Samaniego. Please email us your questions to [email protected].
You can find previous podcasts and check out the show notes at finehomebuilding.com/podcast.
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Check in:
Brian: Window repair feature article
Listener Feedback 1:
Kerry from Westminster, Mass., writes:
FHB folks,
The question about blowing cellulose into a stucco wall struck a chord with me, and I had to write this comment. First, I’ve been involved with a home that experienced paint failure on one wall after cellulose was blown in. There was water in paint bubbles on the cedar! You could poke them and they would weep water! It definitely happened after cellulose and after a new paint job, not before, but just on one wall. This was years ago when I worked for Paul Eldrenkamp, and he spared no expense in trying to learn why it was happening. I’m not positive what the conclusion was, if there was one at all. I think the combination of high humidity indoors, cellulose, and a new paint that had less permeability outside was the cause—on one wall only!
Next, stucco. Is all stucco permeable? Was the EIFS (exterior insulation and finish system) issue too little insulation and that the insulation was the impermeable material that rotted framing, or did the stucco itself have any role? That is a side note question for a fascinating rot repair I did in 2017. The house was built in the 1990s and had a stucco exterior on 2×6 studs with plastic for vapor control on the interior side. It faces south side, has full sun exposure, and is lakefront property. The windows leaked for a long period of time into three floors of wall cavity. I was asked to inspect and repair a presumed leak when the plaster around the windows started staining. Well, the wall cavities became a steam room that resulted in three floors of 2×6 turned to dust except for about 1.5 in. of the inner faces on most. Some were totally decayed. These walls supported long-span I-joists! Luckily the floor-cavity areas had no plastic inside and could dry, so the I-joists themselves were not affected other than a little mold. If this were built with 2×4 walls there would have been a full-on collapse before anyone knew there was a serious problem. I understand there was a bulk water leak, with plastic trapping the moisture, and high vapor content due to the full sun exposure. I had assumed the stucco played a role in that it trapped water too. If the stucco was permeable, as are masonry products, then it was getting soaked and then driven inward by sun. Anyway, I’d be nervous about retrofitting cellulose into wall cavities with masonry on the outside—not so much for the integrity of the masonry finish, but for the structural wood itself.
Please enjoy a couple of photos! Honestly, it is fun to see and repair such devastation when nobody was harmed, right?
Kerry
Retrofuture Remodeling
PS The situation was likely more about plastic vapor barriers and poor craftsmanship, which worry me more than stucco.
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Listener Feedback 2:
Patrick comments:
My electrician friend David Shapiro (featured in FHB #329) emailed me a while back about tamper-resistant receptacles. Do you guys have these in your house? Brian, I’m guessing you do? Do they frustrate you? How about you Grant? Andres? They’ve been in the NEC since 2008.
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Question 1: What is causing my plaster to peel every few years?
Ryan writes:
FHB crew,
First, thanks so much for all of the work you put into the podcast. I look forward to Friday for many reasons, one of those being able to hear the new episode when it drops. Previously, I was able to listen to a couple each day, but now I’m all caught up!
We have a house in south central Wisconsin that was built around 1910. The exterior walls are all masonry with a plaster coating on the inside. We have a small amount of insulation in the attic floor and decided to apply closed-cell foam to the underside of the roof deck ( I know, I know) about four years ago to help with climate control and eliminate access for some bats that we were having trouble getting rid of.
Here is our problem: The plaster in our son’s bedroom on the second floor is peeling off of the chimney walls and a portion of the ceiling near the chimney. I have to re-plaster this area about every five years or so. It was even happening before we applied the spray foam to the roof decking. This chimney is currently being use to vent our natural gas fireplace in the living room directly below. During the winter, we run this fireplace about two to three hours each night. Our dogs love to lay near it. Nothing else vents into this chimney.
When I start to remove the loose plaster, the wall and ceiling feel damp, almost like the roof is leaking. This time, there were even a couple of streaks on the wall where something had run all the way down to the floor, making a small puddle. To verify this, I went to the attic only to find that the chimney, the framing around it, and the insulation are all dry. The roof is about 15 years old and seems to still be in good condition. I do plan to add a “cricket” on the back side of the chimney when we replace the roof again.
Our attic runs about 10 degrees cooler than the rest of the house (we only keep the house at 63˚F during the winter).
The only thing that I haven’t checked is the venting for the natural gas fireplace. When it is running, there seems to be an adequate amount of heat coming out of the chimney. Is there a chance that the temperature difference of the chimney in the attic vs. the bedroom is creating a point for condensation to form?
I’m really stumped here. Any help (or criticism) is appreciated.
Ryan
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Question 2: What’s the best approach to air-sealing and insulating a basement remodel?
Alex writes:
FHB team,
After years in an office job I have endeavored to try a new pursuit as a general contractor. To gain the technical experience, I’m leading projects for a local premium remodeling company. During a recent basement remodel, I encountered the double-stud assembly (in photos below) in a basement on a job I am not leading.
Due to my relative greenhorn status and being younger than the PM, I did not question the method, but it seems the insulation/air-sealing is lacking in this cavity. Can you please share your plan of attack if this was your remodel? A few elements I noticed are the foundation blocks probably need to be sealed off, the cavity needs loose fill (versus batted), and the rim joist cavity above needs some sort of insulation/air-sealing.
Thanks for your time,
Alex
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Unfortunately that is all the time we have for today. Thanks to Mike, Grant, and Andres for joining me and thanks to all of you for listening. Remember to send us your questions and suggestions to [email protected] and please like, comment, or review us no matter how you’re listening–it helps other folks find our podcast.
Happy Building!
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