Rigid Foam Insulation on Home Exterior

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Old 05-22-20, 09:25 PM
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Rigid Foam Insulation on Home Exterior

- 1975 built 30' x 30' bungalow.
- 2 x 4 wall construction.
- Saskatchewan, Canada climate to contend with (+40 deg C summer extremes to -40 deg C winter extremes).
- we have some mold issues due to our 2 x 4 walls (winter time brings cool walls where moisture brings a mold issue in our closets).
- white original pebble-style stucco on the exterior.

For years, we've talked about removing the stucco (big job) and applying 2"-4" of rigid foam & building wrap then covering with vinyl siding or that nice modern tinted stucco you see these days. I would like to do all the work myself (with help) besides maybe the stucco finishing. I would have to trim out/build out the windows and doors to compensate for the extra 2" - 4" from the foam thickness. I would also like to do the eaves, facia and soffit as well.

Advice/suggestions/comments anyone? What the best way to do this? What specific foam product would you recommend? I want to reduce my costs where I can help it (though I know you get what you paid for). Sweat equity at it finest...
 
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Old 05-23-20, 06:01 AM
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I'm not an expert on EIFS by any means, but I have both seen a lot of it done and torn off a lot of it on a variety of projects. (It doesn't stand up to hail very well).

IMO you would probably choose the thickest XPS foam insulation you reasonably can since its R-value is better. (Such as Foamular) EIFS is most often applied over EPS foam, which cheaper and has lower R-values.

Thinking about your soffit, I cant see your house or how the soffit was built but It would be quite likely that you would want to demo your soffit before you Install your foam, so that the foam can extend all the way to the top plate. This is also a good idea so as to help prevent leaks. You would then fasten a 2x4 horizontally over the foam with long screws for your new soffit (or soffit j channel) to fasten to.

Dryvit is one very popular brand of EIFS but there are others too. I dont think it's that hard to do, just takes practice. The main thing would be familiarizing yourself with their best practices... how to detail around doors and windows, how often to create expansion joints, how to apply and bed the fiberglass mesh, reinforce outside corners and edges, how far to keep it above concrete or roofs, etc.

Also, you could consider leaving your existing stucco, and just have all your walls spray foamed. Tear off all exterior drywall and insulation and fill the cavity with spray foam. Then apply maybe another 1" of foam to the interior to act as a thermal break over the studs. Then re-drywall, add extensions to windows, doors outlets. Retrim. Too bad they used 2x4 walls.
 
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Old 05-23-20, 09:20 AM
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Thanks for responding XSleeper. I have a lot of comments and questions below, sorry in advance.

I'm not an expert on EIFS by any means, but I have both seen a lot of it done and torn off a lot of it on a variety of projects. (It doesn't stand up to hail very well).
I wonder who I can talk to who is an "expert"? We do have a local "Roofmart" I've dealt with before, they seem to know what they are talking about. I know this project will take me weeks to finish... the house might be exposed to the rain, hail and wind in the meantime (this worries me). I might get a professional to apply the stucco over the foam, my concern is I book a date for them to stucco and... 1. I'm not done applying the foam (I'm not sure how long it will take me) or 2. I'm done and they are delayed and the foam gets rain/hail/ and/or wind damaged.

IMO you would probably choose the thickest XPS foam insulation you reasonably can since its R-value is better. (Such as Foamular) EIFS is most often applied over EPS foam, which cheaper and has lower R-values.
Formular eh? I will Google it to see how they recommend one secure/apply the product. I know that the local Home Depot carries the product. Know anything about the foil-faced products? I will see what Lowes offers. Roofmart too...

Thinking about your soffit, I cant see your house or how the soffit was built but It would be quite likely that you would want to demo your soffit before you Install your foam, so that the foam can extend all the way to the top plate. This is also a good idea so as to help prevent leaks. You would then fasten a 2x4 horizontally over the foam with long screws for your new soffit (or soffit j channel) to fasten to.
I agree, I plan on removing my soffits and extending the foam into the soffit area. I will notch the foam so I can slide it up and around the 2x4 horizontal soffit boarding. Our interior drywall in our living room has a few mold spots at the ceiling line so I'm thinking the soffit area on the exterior has no insulation and the interior top wall plate has some type of thermal heat bridging going on. Some exterior rigid foam in that area should fix that problem.

What about our triangular gable ends? Seems like a waste to apply rigid foam all the way to the peak when the unheated attic is on the other side of the wall. Could one just install rigid foam to just above the interior ceiling line maybe 12" above? Then just have a filler space to keep it even all the way up the gable end? How would this triangular area be stuccoed if there's no foam underneath it? It would reduce the amount if rigid foam I would need. I hope it's clear what I'm saying.

Dryvit is one very popular brand of EIFS but there are others too. I dont think it's that hard to do, just takes practice. The main thing would be familiarizing yourself with their best practices... how to detail around doors and windows, how often to create expansion joints, how to apply and bed the fiberglass mesh, reinforce outside corners and edges, how far to keep it above concrete or roofs, etc.
Dryvit? I will see if it is available locally. Maybe a stucco or insulation contractor could advise me on this. I didn't know that expansion joints are needed, I will have to research this more. Window and door extensions - I will have to see what is out there locally. Maybe Roofmart can advise me on this.

Right now our stucco and concrete foundation parging is flush with each other. When I rip the old pebble-style stucco off some of the concrete parging is bound to come with it. Any advice on this? When I apply the foam the stucco will then protrude out beyond the concrete foundation below it. Will this look OK?

Also, you could consider leaving your existing stucco, and just have all your walls spray foamed. Tear off all exterior drywall and insulation and fill the cavity with spray foam. Then apply maybe another 1" of foam to the interior to act as a thermal break over the studs. Then re-drywall, add extensions to windows, doors outlets. Retrim. Too bad they used 2x4 walls.
I've thought about ripping off all our interior drywall and apply spray foam, then re-drywall. This would be a huge, expensive job. As opposed to doing the job from the interior - our exterior could use a facelift (nice new tinted stucco or vinyl siding would improve our house's appearance considerably). I recognize that either way, interior or exterior, its going to take a lot of work, time and money. I'm cussing about our 2x4 exterior walls... darn!

Thanks for the advice, keep it coming!
 

Last edited by Howitzer; 05-23-20 at 09:37 AM.
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Old 05-23-20, 10:05 AM
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EIFS is a specialized trade. I think the only person who would be really knowledgeable about it is someone who actually does it for a living. So if you were going to ask Roofmart anything, it would be for a referral to someone who does stucco and EIFS for a living. In our area, there are many Hispanics who are proficient in this trade since it's far more common in the south.

Foam faced products are usually ISO foam. There are basically 3 types of foam. XPS, ISO, EPS. I don't think ISO has much advantage over XPS. It initially has better r value but that is said to dissipate over time due to off gassing.

I would not notch the foam, I would cut out any lookouts and replace them after the sheet of foam is up and a horizontal 2x4 ledger is installed.

On your gable end you would use the same thickness of foam. You could switch to EPS above the top plate since it's cheaper. Or frame it out and add a minimum thickness of foam, such as 1" which I believe is the minimum thickness you can use.

Will it look ok? How should I know, I can't see your house! You can stop the insulation at the bottom of your existing stucco, have it protrude, and the bottom will have to be finished with EIFS just like the front is. You dont have a choice anyway. You shouldnt install EIFS below grade so it has to terminate somewhere above grade.

As for vinyl siding over insulation, yeah you can do that too. But vinyl siding is, well... vinyl. You would also be limited on the thickness of foam you use since roofing nails don't come in 4 or 5" long lengths. LOL It's drafty so you would be relying on your foam being tight and sealed up or you will still have drafty cold walls. At least with EIFS all those seams are covered with the acrylic stucco. Your biggest problem with EIFS will be the edges of windows, doors and other details where water can leak in. Most the the EIFS I have torn off has been because of mold behind it.

So I'm in no way advocating EIFS as very much of how well it performs is related to the details in how well its done. You could be creating a moisture problem for all I know. And it makes future work of installing windows and doors pretty difficult.
 

Last edited by XSleeper; 05-23-20 at 10:20 AM.
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Old 05-23-20, 11:32 AM
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Thanks again for all the help XSleeper. Is EIFS used in our cold climate? You might not know the answer to this but I thought I'd ask. I've watched a couple YouTube videos about it, since I've not familiar with it. I do see houses with that same type of stucco so likely it is used here. I need to contact a local contractor like you suggested.

I watched this video: How to Install the Ultimate Acrylic Stucco System: EIFS
 
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Old 05-23-20, 12:13 PM
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It is occasionally used here (mainly commercially but some residential) although it's not quite as extreme of a climate as yours. (Ours is 40C to -20C)
 
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Old 05-23-20, 01:00 PM
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Eifs

Is EIFS pricey? It looks like it is. Can I do any of the EIFS process myself?
 
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Old 05-23-20, 01:04 PM
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I think you are grossly under estimating the time it will take. Instead of weeks think months.

I did something similar but my place had chip board panels on the exterior so I did not have to remove stucco, Just had to fix areas where the chipboard was skunky/warped.
I also replaced all the windows, reusing and modifying the windows will take you more time since you have to be careful and I just ripped the old ones out.
I did the soffits, facia, new windows, 1 inch of added foam insulation, house wrap and vinyl siding.
Wife helped with a couple windows and wrapping the place. Friends helped get the picture window up as it is a bi-level. Also had new gutters installed. Otherwise I did it all myself.
Started in early May and finished mid October.
 
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Old 05-23-20, 01:23 PM
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Everything is pricey. And I do most everything myself, I'm self employed. What I cant do, I hire others to do. Yes, I'm sure it will take longer than you imagine. But you can also work in sections, one side at a time. Start on the back first and learn as you go. Save the front for last.
 
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Old 05-23-20, 01:29 PM
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I think you are grossly under estimating the time it will take. Instead of weeks think months.

I did something similar but my place had chip board panels on the exterior so I did not have to remove stucco, Just had to fix areas where the chipboard was skunky/warped.
I also replaced all the windows, reusing and modifying the windows will take you more time since you have to be careful and I just ripped the old ones out.
I did the soffits, facia, new windows, 1 inch of added foam insulation, house wrap and vinyl siding.
Wife helped with a couple windows and wrapping the place. Friends helped get the picture window up as it is a bi-level. Also had new gutters installed. Otherwise I did it all myself.
Started in early May and finished mid October.
Manden - thanks for responding.

You might be right about me underestimating the time it will take. I don't need to remove any windows or doors. I need to get it done by September 1st if possible.
 
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Old 05-26-20, 10:14 AM
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I have been in consultation with a experienced local stucco contractor that tells me that I might be able to secure/adhere the foam directly over top of the present house stucco, as long as the present stucco is securely fastened and solid. I could then get new stucco applied overtop. Comments? Would this produce a double vapour barrier?
 
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Old 05-26-20, 10:19 AM
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Nothing wrong with that IMO, assuming you have decent sheathing behind the stucco to screw your foam washers to.
 
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