[Howitzer]

- 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]

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]

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]

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]

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

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]

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]

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]

@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]

@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

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]

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]

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]

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]

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]

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]

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]

Great stuff, thanks Bud!

 

[Howitzer]

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]

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]

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]

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.

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