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Photograph of EIFS synthetic stucco building interior. Stucco Over High-R Foam Insulating Board

Stucco wall systems installed over insulating foam board:

This article discusses the installation of stucco exterior wall finishes over insulating foam board, including the choice of high-R value insulating board for use under stucco on building exteriors.

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Stuccoing over High-R Foam Board Insulation

Figure 1-30: EIFS Wall System Drainage (C) Wiley and Sons, S BlissDiscssed here: Exterior wall stucco application over Thermax™ foil faced insulating board: polyisocyanurate. Stucco and insulating board application over masonry building walls. Synthetic stucco application over high-R insulating board. Solar Age Magazine Articles on Renewable Energy, Energy Savings, Construction Practices.

The EIFS schematic above is provided courtesy of Steven Bliss & J Wiley & Sons [13] and illustrates the layers in a typical EIFS installation and is detailed further at STUCCO EIFS DRAINAGE SYSTEMS.

[Click this or any of our images to see an enlarged, detailed version.]

Accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

This question-and-answer article about the choices of insulating foam board for use under stucco exterior finish on buildings, appears in full-text just below and quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Question: "In-Town Solar Condos: One Developers's Plan Book" (Solar Age, 9/83) includes mention of an exterior insulation system for masonry walls using 2-inch urethane under stucco.

I have had little success locating such a system in Phoenix that uses polyurethane and not polystyrene foam insulating board on the building exterior.

Can you supply me with information on a polyurethane insulation system or any other exterior insulation that might give me a better R-value than 2-inch polystyrene foam insulating board? - James Hoffman, Tempe, AZ.

EIFS building exterior inspection (C) Daniel Friedman

Answer: First, a clarification - strictly speaking the rigid foam insulating board used in the La Vereda Compound (the subject of the article) was a foil-faced polyisocyanurate foam insulating board (Thermax™), not a polyurethane.

Ann MacKinnon, office manager of LaVereda developer Communico, said that The company often used Thermax™ over concrete block walls and under stucco on buildings, as do most builders in the Santa Fe area.

Wire stucco lath is placed over the foam insulating board and attached to the masonry below using concrete nails. MacKinnon said that "a builder Santa Fe who didn't know and use this technique would probably be out of business" because demand is high for adobe-like finishes. She added that lath and stucco can be used over sprayed-on urethane foam insulation as well.

Readers should also see SIDING EIFS & STUCCO and also may want to

review POLYISOCYANURATE FOAM and IAQ.

Original article:

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-03-29 - by (mod) -

John

Certainly there are quite a few stucco systems that are applied to foam board.

Take a look at EIFS schematic above is provided courtesy of Steven Bliss & J Wiley & Sons [13] and illustrates the layers in a typical EIFS installation and is detailed further at STUCCO EIFS DRAINAGE SYSTEMS.

On 2020-03-28 by John

I am planning to finish an interior space 12x14 in the basement. Three of the walls are concrete block the fourth wall is an interior wall. The space is intended as a wine cellar so the wall finish can be very rustic. Can I apply a stucco like product directly on the concrete block? If I apply a rigid foam board system over furring strips can I apply a stucco product directly onto the foam board? What is the best stucco product to use in either case?

On 2017-10-16 by Lennox Hyman

I live in PA and have polyisocyanurate insulating foam board with foil facing with stucco on top as the exterior. i would like to remove the stucco, but concern the polyisocyanurate insulating foam board with foil facing will be damage and would need to sheath the entire house.
Lennox Hyman
lrhyman@gmail.com

On 2017-09-30 by Anonymous

Ken,

Since the exact and correct procedures for any stucco system depend on Whose materials you are using, I'm reluctant to pretend that I can guess at what is just right for the actual stucco application. However it is pretty reliable that if the styrofoam base is properly secured to the wall the added weight of the stucco on the base will not be an issue. The number and spacing of Fasteners also will depend on Whose stucco system you are using.

On 2017-09-29 by Ken

What is the proper way to install a three coat plaster finish over a 1" rigid foam insulation board over wood framing? I am concerned about what fasteners can be used to hold the 3 coat system when the foam board holds the plaster's weight 1" away from the wood structure.
Thanks.

On 2016-10-12 by Anonymous

Does insulated stucco meet the WUI state fire ratings?

On 2016-07-15 by al

Where can I purchase finish coat stuck in Savannah, Ga. I just need to do a little patching, also does it come with paint ?

On 2016-06-09 - by (mod) -

Phillip: typically on newer construction the building is sheathed with plywood; on an older home the builder could have used cross bracing or other bracing at building corners and omitted plywood sheathing in other areas.

On 2016-06-09 by Phillip

Should there be plywood behind the foam board when applying stucco over it? I've had to patch several holes due to a wood pecker and it's always at the top of exterior wall where the wall meets the roof. There is nothing behind the styro foam board. I've installed a doggy door at my brother's home here in Arizona which had plywood behind the foam. Not having the plywood to me seems to make the structure weak. Also difficult to patch these holes.

Question:

(Apr 21, 2011) cathie said:
how do I put the mesh and j-joints on foam for stucco job

(June 1, 2011) Lsimpson@dc.rr.com said:
do you have information on how to detect roof leaks with a laser?

Reply:

I'm not familiar with any laser tools that are used for leak detection. If however you meant infrared or thermographic equipment used for leak detection, those devices use infrared (heat sensors) not lasers.

IR and thermography are great ways to find ACTIVE leaks, based on the premise that the temperature inside a building cavity (stuccoed wall or under a roof) will be different (normally cooler) where there is moisture.

But watch out: leak detection methods like IR or thermography won't detect areas of prior leaks if the leaked-into areas happen to be dry at the time you are looking. That's one reason (among many) why relying on these tools alone is a mistake.
Without an accompanying expert inspection for visual signs of leaks or building construction details that make leaks likely we can't be confident that we have an accurate picture of the building leak history nor an accurate idea of where else there is likely to be hidden rot, insect damage, or mold contamination due to leaks.


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