# Rigid Foam Insulation on Home Exterior



## Howitzer (Sep 12, 2008)

- 1975 built 30' x 30' bungalow, gable roof.
- 2 x 4 exterior 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 re-do the eaves, facia and soffit as well.

Advice/suggestions/comments anyone? What the best way to do this? What specific rigid 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...


----------



## Windows on Wash (Aug 30, 2011)

Jump on the green building websites and there are plenty of project photos. What kind of shape are the windows in? 

How are your carpentry skills? Be sure to air seal the shell prior to the foam as well as seal the foam.


----------



## Howitzer (Sep 12, 2008)

Windows on Wash said:


> Jump on the green building websites and there are plenty of project photos. What kind of shape are the windows in?
> 
> How are your carpentry skills? Be sure to air seal the shell prior to the foam as well as seal the foam.


Thanks for responding! 

1. Green building websites... I need more details on what you are referring to.

2. Our windows are in good shape (we replaced them about 10 years ago, along with our exterior doors).

3. Carpentry skills - I think I'm sufficient in that department. When I don't know how to do something DIY, off to Google and YouTube I go. I've renovated most of our house myself inside and out over the 22 years we've owned the house. Lots of sweat equity here.

4. "Be sure to air seal the shell prior to the foam as well as seal the foam." How would you recommend I do so?

5. On another forum, I was suggested using EIFS (Exterior Insulation and Finish System), good idea for our cold Canadian climate?


----------



## Bud9051 (Nov 11, 2015)

When the foam gets extra thick it becomes an issue with hanging the new siding. I opted to add another layer of 1/2" sheathing over 3.5" of foam. Or I could have used strapping and left an air gap which is now being recommended.

With thick exterior insulation you have a choice of where the windows will set, innies, or outies. I chose outies as I was also replacing all windows. You could remove your newish windows and reinstall. My net increase in wall thickness would have reduced my soffit overhang from 12" to 8". I preferred the 12" or greater so extended my rafters, a lot of extra work.

Note, mold in closets is to be expected when that space is closed off from the heat.

Lots of details to your project but now many articles about people doing it. Sounds like your climate will be a good fit.

Bud


----------



## Nealtw (Jun 22, 2017)

Bud9051 said:


> When the foam gets extra thick it becomes an issue with hanging the new siding. I opted to add another layer of 1/2" sheathing over 3.5" of foam. Or I could have used strapping and left an air gap which is now being recommended.
> 
> With thick exterior insulation you have a choice of where the windows will set, innies, or outies. I chose outies as I was also replacing all windows. You could remove your newish windows and reinstall. My net increase in wall thickness would have reduced my soffit overhang from 12" to 8". I preferred the 12" or greater so extended my rafters, a lot of extra work.
> 
> ...


I think your sheeting was a good idea, the gap is not called for with vinyl siding and it likely does better with a smooth surface backing it.


----------



## rjniles (Feb 5, 2007)

Look at ZIP-R sheathing with foam attached. Also look at YouTube videos by Matt Risinger.

Sent from my Moto E (4) Plus using Tapatalk


----------



## Howitzer (Sep 12, 2008)

I am starting to lean towards stucco being applied over the foam, like EIFS... how pricey is EFIS and can I DIY some of the job myself?


----------



## Bud9051 (Nov 11, 2015)

@Howitzer, I'm a retired energy auditor and besides the wonderful reduction in energy costs I wanted some first hand experience with a deep energy retrofit. Although I love the results, not fully completed as yet, I would not recommend doing this without a huge amount of that sweat equity. Even with a huge amount of DIY one needs to evaluate the benefits vs investment. To that end, you or anyone can run some calculations on heat loss for different levels of r-value. It requires some guessing as your end product will improve more than just the cavity r-value, there is air sealing and thermal bridging.

Here is a link with lots of reading on deep energy retrofits.
https://www.greenbuildingadvisor.com/collection/deep-energy-retrofits

Bud


----------



## Howitzer (Sep 12, 2008)

Bud9051 said:


> @Howitzer, I'm a retired energy auditor and besides the wonderful reduction in energy costs I wanted some first hand experience with a deep energy retrofit. Although I love the results, not fully completed as yet, I would not recommend doing this without a huge amount of that sweat equity. Even with a huge amount of DIY one needs to evaluate the benefits vs investment. To that end, you or anyone can run some calculations on heat loss for different levels of r-value. It requires some guessing as your end product will improve more than just the cavity r-value, there is air sealing and thermal bridging.
> 
> Here is a link with lots of reading on deep energy retrofits.
> https://www.greenbuildingadvisor.com/collection/deep-energy-retrofits
> ...


Thanks for the great advice Bud. I'm trying to make sure I get what you are saying... are you saying that sometimes the work, time, effort (and money) isn't worth it? I will have to read the link you shared with me.


----------



## SPS-1 (Oct 21, 2008)

What do you have now ? My guess would be that you have R13 fiberglass batts with a 6mil poly vapour barrier on the inside. Is that right ?

The potential issue with putting several inches of foam on the outside is that that is likely to be a vapour barrier also. There are ways to have the vapour barrier on the inside or the outside, but you don't want to have two vapour barriers. Any moisture that gets into the wall should be able to dry either to the inside or the outside - one or the other, but not neither.


----------



## Bud9051 (Nov 11, 2015)

Here's an article to help explain what SPS mentioned about interion VB with a lot of exterior foam.
https://www.greenbuildingadvisor.co...m-insulation-cause-mold-and-moisture-problems

Bud


----------



## SPS-1 (Oct 21, 2008)

Confused yet ? It is a complicated subject. I don't pretend to have all the answers.

But if conclude you are best with a vapour permeable insulation board, you may want to look at Rockwool board.


----------



## Howitzer (Sep 12, 2008)

SPS-1 said:


> What do you have now ? My guess would be that you have R13 fiberglass batts with a 6mil poly vapour barrier on the inside. Is that right ?
> 
> The potential issue with putting several inches of foam on the outside is that that is likely to be a vapour barrier also. There are ways to have the vapour barrier on the inside or the outside, but you don't want to have two vapour barriers. Any moisture that gets into the wall should be able to dry either to the inside or the outside - one or the other, but not neither.


SPS-1 - thanks for responding. We have 2x4 walls (with pink fibreglass insulation and poly vapor barrier) so its likely R13 as you said. I hear you about the double vapor barrier issue...


----------



## Howitzer (Sep 12, 2008)

Bud9051 said:


> Here's an article to help explain what SPS mentioned about interion VB with a lot of exterior foam.
> https://www.greenbuildingadvisor.co...m-insulation-cause-mold-and-moisture-problems
> 
> Bud


Thanks Bud!

Like you said, there is a lot of literature on the subject. The link you posted earlier has a huge number of articles to read through, which is the most relevant?


----------



## Bud9051 (Nov 11, 2015)

Greenbuildingadvisor.com and buildingscience.com are two excellent sources of energy information. As for which article is best, I'd have to do a lot of reading (again) to answer that. 

Since you are in Canada we assume you have an interior vapor barrier, code required up there, but you should confirm your house has one. Looking to the side of electrical boxes you might be able to see. Here is a link on vapor barriers that talks about Canada and the origin of VBs.
https://www.buildingscience.com/documents/insights/bsi-073-macbeth-does-vapor-barriers

To increase your reading list consider Roxul Comfort board, it come as a 110 or 80 formulation. The 110 formulation apparently has a higher density.
https://www.finehomebuilding.com/2018/10/10/installing-rockwool-for-continuous-exterior-insulation

Now, I have never used the comfort board but have used the Roxul batt insulation and like it.

On the walls we used the ComfortBoard 110 formulation–which is a bit more dense than the ComfortBoard 80 and should be much more vapor open. Here's a link which I've only skimmed through but should discuss air and vapor permeability.
https://www.rockwool.com/siteassets...nagement-Technical-Guide.pdf?f=20180430144415

I'm reading also, but since you are probably stuck with a plastic vapor barrier on the inside the Roxul comfort board option for the exterior may be a perfect fit and it has been well tested.

Bud


----------



## Howitzer (Sep 12, 2008)

Great stuff, thanks Bud!


----------



## Howitzer (Sep 12, 2008)

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 like SPS-1 was warning me about?


----------



## ClarenceBauer (Mar 4, 2005)

Your Stucco is correct you can adhere foam board to the existing, but i don't think you can use the XPS ridge type board, you would need to use the EPS board.
Your best bet is to have the wall assemble analyzed with the materials as built.
Than add the new materials & have that analyzed this should give you the info of were the dew point will mostly occur.
If you are sticking with Stucco the new Stucco will have to be the Synthetic Stucco System.
If you can get all the materials description that are in the existing wall system & send it to STO CORP. they can do the analyzing & tell you the STO products that can be used.


----------



## Biscuits (May 11, 2020)

Howitzer said:


> Thanks for responding!
> 
> 
> 
> 5. On another forum, I was suggested using EIFS (Exterior Insulation and Finish System), good idea for our cold Canadian climate?


EIFS is not a good idea anywhere.


----------



## Howitzer (Sep 12, 2008)

Biscuits said:


> Howitzer said:
> 
> 
> > Thanks for responding!
> ...


Hi Biscuits, thanks for responding... what is the problem with EIFS?


----------



## Nealtw (Jun 22, 2017)

In Vancouver BC we had a big deal here with leaky condos (Apartment buildings) I think most were a problem with stucco. We don't see new anything with stucco anymore.


----------



## ClarenceBauer (Mar 4, 2005)

Yes you will have problems with most anything if you don't follow the written installation instructions.


----------



## Howitzer (Sep 12, 2008)

ClarenceBauer said:


> Your Stucco is correct you can adhere foam board to the existing, but i don't think you can use the XPS ridge type board, you would need to use the EPS board.
> Your best bet is to have the wall assemble analyzed with the materials as built.
> Than add the new materials & have that analyzed this should give you the info of were the dew point will mostly occur.
> If you are sticking with Stucco the new Stucco will have to be the Synthetic Stucco System.
> If you can get all the materials description that are in the existing wall system & send it to STO CORP. they can do the analyzing & tell you the STO products that can be used.


Hi Clarence, thanks for responding. I believe our materials are as follows from inside to outside:

1. 1/2" drywall.
2. Poly vapour barrier, thickness TBA.
3. 3 1/2" wall cavity insulated with fiberglass batting.
4. 1/2" plywood sheeting.
5. Tar/felt building paper.
6. Stucco wire mesh with white old 70's style pebble stucco.


----------



## ClarenceBauer (Mar 4, 2005)

Howitzer said:


> Hi Clarence, thanks for responding. I believe our materials are as follows from inside to outside:
> 
> 1. 1/2" drywall.
> 2. Poly vapour barrier, thickness TBA.
> ...


You will also need the interior paint thickness.
Exterior paint thickness.
Thickness of the existing Stucco.
Also anything else that was applied to the wall.


----------



## Biscuits (May 11, 2020)

Nealtw said:


> In Vancouver BC we had a big deal here with leaky condos (Apartment buildings) I think most were a problem with stucco. We don't see new anything with stucco anymore.


Same in Seattle. What we heard is the insurance companies would not insure new buildings built with EIFS is because the buildings were leaking like sieves. 

I'm sure EIFS is marginally acceptable in the southwest US for commercial construction, such as Targets and WalMarts where those corporations have a 30 year remodel cycle.


----------



## Nealtw (Jun 22, 2017)

Biscuits said:


> Same in Seattle. What we heard is the insurance companies would not insure new buildings built with EIFS is because the buildings were leaking like sieves.
> 
> I'm sure EIFS is marginally acceptable in the southwest US for commercial construction, such as Targets and WalMarts where those corporations have a 30 year remodel cycle.


All the home warranty companies went broke and left homeowners on the hook, some for more than the home was worth. The gov. had to lend them no interest loans just to get them all fixed. But they weren't all stucco either.


----------



## Biscuits (May 11, 2020)

Where I work now, the municipality has banned EIFS for any new construction. There is still some older junk out there, but nothing in the past ten or 12 years has been constructed.


----------



## ClarenceBauer (Mar 4, 2005)

Did anybody find the reason for all the water leaks in the EIFS?


----------



## Biscuits (May 11, 2020)

Lots of speculation. Everything ultimately pointed towards a combination of a material not suited for the climate, and install error.


----------



## ClarenceBauer (Mar 4, 2005)

Biscuits said:


> Lots of speculation. Everything ultimately pointed towards a combination of a material not suited for the climate, and install error.


I will agree with not installed as per manufacture written installation instructions & furnished details.
As for speculation no it was known that there were many details that were not followed.
Improper Caulk & No backer rod , No caulking around windows or a three sided caulk, NO sill Pan installed under windows , NO head flashings installed , System applied over an improper substrate , Control joints not installed properly or just not installed , improper butting dissimilar materials , NO flashing - improper flashing & NO kick out flashing , Back wrapping of system edges not complied with , NO drip edges installed & NO drainage provisions.
This is just a few details that were left out of the application.
As for getting insurance to apply the EIFS not a problem if you have not had claims filed you can get a certificate of insurance had one since 1978 & the company has insurance as of this date not a problem (cost is high for it ).

Reference Building Science Corp. BSD -146.
" EIFS can be used in almost all climate zone & exposure.)
" EIFS are among the most robust & advanced moisture control assemblies available"
You just have to follow the rules & guidelines.


----------



## Biscuits (May 11, 2020)

ClarenceBauer said:


> you just have to follow the rules & guidelines.


Well, yeah that applies to everything. 

The general consensus here between Olympia, WA and Vancouver BC is the rules and guidelines are too numerous to follow for EFIS to work. 

So either the system is flawed, it's not suited for this climate, or?


----------



## Nealtw (Jun 22, 2017)

Biscuits said:


> Well, yeah that applies to everything.
> 
> The general consensus here between Olympia, WA and Vancouver BC is the rules and guidelines are too numerous to follow for EFIS to work.
> 
> So either the system is flawed, it's not suited for this climate, or?


I have to agree with @ ClarenceBauer if rainscreening is followed any siding will work


----------



## ClarenceBauer (Mar 4, 2005)

I went back & dug up some paper work related to the EIFS.
I worked with the Oak Ridge National Laboratory in January 1, 2005 thru March 30, 2006.
This was for research on the EIFS, The Hygrothermal Performance of Exterior Wall Systems: 
A building was constructed which consisted of test panels being installed on the North & South Elevations on the East & West ends we kind of had the freedom to use the Synthetic Stucco system as we selected.
The test panels consisted of various configurations of exterior cladding systems ( EISF , Brick , Stucco Concrete block & cementitious fiber board siding. All of the claddings had finishes applied as per manufacture spec.
Each of the wall panels contained a variety of sensors that recored a full profile of temperature, heat flux, relative humidity, & moisture content. These sensors collected data 24 hours a day 7 days a week & transmitted the data to the O.R.N.L.
Study approach: in keeping with the DOE's strategy of promoting a whole building approach to building design, operation and maintenance, the research project considered the building envelope in its entirety, rather than studying isolated materials or component systems. This building was fully insulated with drywall finished & painted. was fully conditioned with its own weather station contained on the interior.
Quote from the report: The best performing wall system was the EIFS consisting of four inches of expanded polystyrene insulation board. This wall out preformed all other walls in terms of moisture while maintaining superior thermal performance.
We did do a test panel of Vinyl siding it did not make it past the 3 MO. period.
We even directed some rain water behind one of the rain screen test panels that had a liquid waterproofing applied no water got past the water proofing the rain screen worked as design.
There was also a test building like this one in the state of Washington along the coast.
If EIFS & Stucco are done as per spec. you won't have a water or moisture.


----------



## Biscuits (May 11, 2020)

That's probably correct. And why the big contractors here can't do it right I don't know.


----------



## Bud9051 (Nov 11, 2015)

@ClarenceBauer a tip of the hat to O.R.N.L. 
One of the problems from where I sit is introducing any new product to an old established workforce. Once the building industry gets comfortable with their old school methods it takes an act of God and decades to retrain them and all of the inspectors watching the process. Heck how many posters here totally ignore our simple building codes. And building codes are often at the discretion of each building department.

Commercial, maybe, but for residential KISS is a necessary part of building practices. 

Bud


----------



## ClarenceBauer (Mar 4, 2005)

Biscuits said:


> Well, yeah that applies to everything.
> 
> The general consensus here between Olympia, WA and Vancouver BC is the rules and guidelines are too numerous to follow for EFIS to work.
> 
> So either the system is flawed, it's not suited for this climate, or?


If the guidelines for EIFS are too numerous lets compare them to the guidelines for an electrician.
Look @ how many different layouts you can have with the electric system & it seams to work very well until a person NOT trained in it, tries to install it.
Would this make the electrical system flawed? It all has to do with training.
Take the Plaster trade A helper / apprentice before he can become an Journeyman must undergo on the job training for NO less than 5 years at the craft plus supplement his experience with 144 hours of classroom instruction.
Now how many workers doing Plaster / Stucco had anywhere near this amount of training after the year 1975.
If a person has to be certified to do electrical work WHY not require a person be certified to follow those EIFS guidelines.


----------



## Biscuits (May 11, 2020)

ClarenceBauer said:


> If a person has to be certified to do electrical work WHY not require a person be certified to follow those EIFS guidelines.



Is this about EFIS or the building industry as a whole? 

IMO, there is a cultural shift that is required. There are few entities who (can afford to) construct buildings to last. A lot of the industry is built on the theme of get in, get it done, get out, move on to the next job. Time is money. 

By the time the walls are filled with water and anyone notices, the LLC that slapped the condo together has been dissolved. 

And this hardly entirely the builders fault. The lenders want their money back. So the builder is under the gun to produce. 

And the municipalities want their cut. There are some jurisdictions where I live who are adding north of $30K onto the price a new SFH. You gotta have this permit, you need that permit, plus those permits, and let's not forget the regular permits...

The purchaser can only cover so much of that, so some of that cost is recuperated by quick and dirty construction. 

Plus of course a lot of hands on work has been demonized by the public school system in this country. So some of those, who would be ideally suited for the trades are funneled off into accounting business, for example.


----------



## Bud9051 (Nov 11, 2015)

Another issue with required certification is it often only involves one member of the crew and the rest are supposed to follow his/her direction regardless of their training. I had some electrical work in progress and spotted the helper not doing something correctly. Talked to the one holding the license and that work had to be removed and done over. Only happened because I was there. PS, never saw the electrical inspector on the job site. 

Bud


----------



## ClarenceBauer (Mar 4, 2005)

Biscuits said:


> Is this about EFIS or the building industry as a whole?
> 
> IMO, there is a cultural shift that is required. There are few entities who (can afford to) construct buildings to last. A lot of the industry is built on the theme of get in, get it done, get out, move on to the next job. Time is money.
> 
> ...


So based on all the above. 
Does that make the EIFS a bad product as you stated.
Or does it relate to the builder / home owner hiring unqualified contractors?
It cost more to have the properly qualified workers install all building materials.
The purchaser can only cover so much , but i can get paid twice as much to correct the bad installation?
There is an OLD FRAM OIL FILTER ADD: ( you can pay me now or pay later )


----------



## SPS-1 (Oct 21, 2008)

ClarenceBauer said:


> We did do a test panel of Vinyl siding it did not make it past the 3 MO. period.


I don't get it. What exactly failed/how? The vinyl failed ???


----------



## ClarenceBauer (Mar 4, 2005)

SPS-1 said:


> I don't get it. What exactly failed/how? The vinyl failed ???


Water leaking behind the Vinyl siding, wind blown rain.
Installed as per written instructions furnished with the siding.


----------



## Biscuits (May 11, 2020)

ClarenceBauer said:


> So based on all the above.
> Does that make the EIFS a bad product as you stated.


EFIS could be the next best thing next to sliced bread. 

But given the choice, I would never choose it. 

What works perfect under laboratory conditions is not real life.


----------

