Umm, the trouble with spray foam is it seals too well. Water comes in through the walls or around the windows, runs down inside the walls, then can't get out at the bottom leading to the growth of black mould.

A great deal of the issues with water is actually condensation, but your sentiments about once moisture finds it's way in, then it needs a way out is 100% correct. Which is why I was advocating non-vapor barrier construction so the wall can dry to the inside.

Apparently the thin coat of spray-on foam insulation I mentioned earlier has recently been dubbed a "hybrid wall" and the latest considerations about dew point allow use of batt and not just moisture resistant mineral wool or cellulose that can get wet because they also dry out (fiberglass has issues drying out).

The Flash-and-Batt Method
https://www.greenbuildingadvisor.com/article/the-flash-and-batt-method
http://forums.pelicanparts.com/uploa...1637100257.jpg

I've lived in an old house that had been retrofitted with cellulose. On damp cold rainy days, or shall I say an endless week of cold rain the comfort level drops. I just needs time to dry back out to be really effective.


http://www.sprayfoamgreenland.ca/batt_insulation_en_7542cms.htm
http://forums.pelicanparts.com/uploa...1637100705.jpg

Five Rules for Wall Design
https://www.finehomebuilding.com/project-guides/insulation/five-rules-for-wall-design

Kach- the problem with that diagram is he does not have exterior sheathing. His siding is fastened directly to the framing. I would be very leery of any expanding foam that would adhear to the siding and seal any air gaps. This house is still standing 100 years after construction because it can breath.

Sealed batt insulation will give some R not be fastened so air will still circulate and have a barrier to protect the insulation from the elements. He could fill the cavities with foam board but that seems like a lot of work for little if any improvement over sealed batts?

I was not designing a system for the house in question, just attempting to describe some old house standards such as cellulose and mineral wool that accept being a bit damp at times. Second post on hybrid systems shows items that may not apply to this house but illustrate critical dew point.

Something that might work here is a system some people have used on old basements. They offset rigid insulation as not to touch the exterior wall and foam in place in between the studs. No wicking, no conduction and an air seal. If room in the stud allows; batt or mineral wool panels can be placed over the rigid insulation and drywalled over.

Such an application here would maintain the original siding ability to breath, and have the siding act as a rain-screen wall. And as someone mentioned earlier, patch up any gaping holes letting light in from the backside first. The problem then becomes flashing (and venting) the wall like a true rain screen wall, and that could get ugly.

I do not understand the term "Sealed batt insulation" you (drcoastline) are using. Like I said, even fiberglass batt needs at least one direction in which moisture can escape to.

One thing to remember is that needs will be very different between MI with it's cold winters and the Gulf (of Mexico) coast or South East US where the weather is warm and humid most of the year and rarely cold.

My understanding is that some folks will have a vapor barrier either on the interior or exterior of the walls depending upon the climate.

This guy seems to think that most folks don't need a vapor barrier at all, but some areas do.

<iframe width="560" height="315" src="https://www.youtube.com/embed/q8fOMBlfh3A" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Sorry dude but those boards are rotted.
Replace them and at least install some sort of flashing,
from the pictures it looks like they went bad from the inside out.
If you don't want to keep the hardwoods;) have you considered heated floors, they are the bomb in bathrooms.

In this shot?
http://forums.pelicanparts.com/uploa...1637032822.jpg

Yes, I know. I took photos of all of the boards around the house that I need to fix (there are a bunch of spots around the house), and this was one of them. I'm not at home and this was the best pic that I had that showed what the exterior of the bathroom would look like without having a pic of that exact spot.

Open cell foam after Houston flooded. Yeah, seems like a bad idea.

The video will start at 5:34, which is right at the spot where he shows a short video with flooded open cell spray foam.
<iframe width="720" height="480" src="https://www.youtube.com/embed/a1jPx9xQeXk?start=334" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Iv done a bunch of houses with blown in insulation. It works great. we always did it from the outside rent the machine its like a reverse vacuum throw the bales in its kinda fun and it doesnt even make you itch

Thank you for posting this, I've always heard/read the same but didn't realize it was such a small affected area map wise.

Rented a U-haul trailer today to go get some mineral wool insulation. Then just happened across this.

<iframe width="720" height="480" src="https://www.youtube.com/embed/jhoQ_f9ZnzQ?start=6" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

That’s incredibly awesome. It’s like they’re doing science.

I can’t imagine what that amount of competence would cost here in seattle. Terrific install quality. Those vent pipes?!!

Thanks for sharing the video, I’m going to call dorkin like they suggest.