I was just thinking of a low expansion 1/2" or 1" bead of foam to seal the gap, like caulk, but foam instead.

I think that a modern home with sprayed-in closed cell foam is probably super efficient, but for me to use it, I'd have to have a home that was designed from the ground up for closed cell foam. The enormous downside to me is that it makes the wall interiors an enormous nightmare for any changes, repairs, etc.... I can't even imagine having to run new plumbing, new wiring, etc.... I'd want something with huge conduit that could have stuff run through it, and might want some sort of sheathing, like a 6mil plastic to cover everything so the foam wasn't forever bonded to everything inside the walls.

As stated, there's no way in hell I'd use that on a house like this.

Good call! I'm using 5/8" firerated drywall for almost everything instead of 1/2" lightweight sheetrock too (for the sound deadening properties). 1/2" lightweight =35-40# per sheet. 5/8" fire rated =70-75# per sheet.

I've put a wall back in that has been taken out sometime in the past 30 years. It's 6" wide instead of 4" with alternating 4" studs, and then I'm going to put the sound deadening insulation in the wall.

I think I see where the problem is, I wasn't clear in my thought.

Yeah, I was thinking this (to seal the gap)
https://s3.amazonaws.com/badgerlands...ksfoam__1_.jpg

NOT this
https://cdn.hpm.io/wp-content/upload...39dba029_o.jpg

I happened upon this article while looking for a pic of someone installing spray foam. I thought it was interesting (and presumably it would apply to BR as well.

https://www.houstonpublicmedia.org/articles/news/2017/12/22/258534/fema-required-insulation-might-not-be-great-for-houstons-climate/

It's interesting that they are saying the closed cell will trap moisture but the open cell won't. But then if it floods, then the open cell will hold the moisture in for a long time like a sponge, and I wouldn't think that much moisture would get in at all with the closed cell. I'm sure the wood could absorb moisture that would then be sealed into the wood by the foam, but if the moisture could get in, then presumably, it could also get out. And I would think that the amount that would get in would be VERY small.

That is the ony POSSIBLE downside to any Iceane foam spray. However back in 97l I purchased a home that was built in the mid 80" built on piers, it had the pink insulation under it, after initial inspection the sellers had to replace 1800 sq ft of pine due to rot from moisture. This is not a job that you want to do your self. You don't have the equipment and access to enough raw materials to do a really good job/ One other benefit is when you do spray foam you will be surprised at how much more "solid" floors and walls become. As for as running electrical and plumbing...been down that road also, but guess what, your house is off the ground and you also have an attic. If you inspect most older houses off the ground that have been rewired, the majority of the receptacles and a foot or two off the floor. Rewired from under side.
Welcome to the joys/headach4s of an old home. You have to make compromises but there also benefits that new construction may not offer. Regardless of how much you insulate, with what ever method. Old houses are gonna leak air, and need to instantly be dusted, and more of then than not you will always need a dehumidifier for every 1200 sq f for best comfort. With regards to cost, on an old house, your major cost is the last 10% of your restoration, and you can put money on this, one job often tuns into 3 or 4 other task and will increase the cost by about 50%.

Get a piece of wood, preferably something rot resitnat and close the gap, then caulk around that.

Previous I suggested blown in insulation but since this has some exposer to the elements you may be better with plastic encapsulated batt insulation?

I used this stuff when I reworked the inside of one of my barns to make a workshop with heat and a/c:

https://www.ecofoil.com/products/double-bubble-foil-insulation-foil-both-sides-4-x-125-500-sq-ft?msclkid=9d860ae340b9141423136b70eb7712e3&utm_so urce=bing&utm_medium=cpc&utm_campaign=~%20Shopping %20-%20Bubble%20-Double%20Bubble&utm_term=1101104157562&utm_content =Double%20Bubble

It was very easy to cut and attach and in a high rodent area, barns next to fields, it was recommended to me. Has worked great...odorless, dry and does not hold moisture.

I can't tell if it will work for your specific needs, but I was able to effectively install the insulation with no special clothing or tools.

Good luck!

Ouch! Yeah, not good.

I've been surprised and pleased because our HVAC keeps the house really dry. Yes, there's always something.

I've looked for that for the attic. I've used it before on our previous house. It's so much better to work with. I'll look again, but just a month or two ago, no one had it and I couldn't even order it.

Thanks! If nothing else, I'll keep that in mind for when it's time to start on the garage.

Batt fiberglass insulation is designed to work in conjunction with an air-infiltration barrier (house wrap - Tyvek) on the outside, and a vapor barrier (Visqueen) on the inside. Without both of these materials/products used in conjunction at the same time you are looking a poor performance and future problems in my opinion.

The three products typically favored and used in retrofits are:

1. Blown-in foam (open or closed depending on which side of wall moisture migrates).

2. Blown-in Cellulose

3. Mineral Wool

The 3 above insulation types do not need and in fact perform better without vapor barriers.

A wall/roof should be permitted to allow excess moisture to migrate either to the inside or to the outside.

A vapor barrier on the inside of the wall dictates migration to the outside which is why house-wraps allow moisture through.

One method gaining popularity in both new and retro fit is a 1/8" layer spray-on foam (inside of wall sheathing face) with mineral wool in the stud cavities. This seals off leaks and allows moisture to breath to the inside where the HVAC system can remove it. This two step procedure is more expensive but very effective.

SIDE NOTE: Two coats of oil based paint on the interior walls is about 99% there in perm count as a vapor barrier (100%). Meaning you almost have a vapor barrier with many coats of old lead oil/paint and putting vinyl siding on the outside might start to trap moisture in the walls. Think sun comes out when wearing a raincoat as a kid, you start to swelter because vinyl does not breathe. Lots of vinyl sided houses have mold issues, and it's not a mystery, just physics.

FYI: The forum below is excellent when researching these issues.

http://www.greenbuildingtalk.com/

Good info thanks.

You'd think the blown in cellulose would be a termite problem, but I understand that it's treated to prevent that.

It looks like Lowes has mineral wool insulation. There's no Lowes close enough to deliver, Yay!

Fortunately, we don't have any concern about lead paint inside the house, and there's no vinyl siding. It's all wood or in a few spots cementboard. And if we're talking about air permeability, I'd squarely rate this house as "sieve" level. It breaths in spades.

Use Great Stuff if you do. DO NOT USE DAP.
No stick. No rise with warm shaken cans. After 10 seconds I was holding a couple empty cans thinking "are they serious?"

As a note: For the multi-story rental, for kitchen wall pipe penetrations local code wanted rockwool with red 3M fire-rated foam and caulk to seal it.
A little more expensive but perhaps worth it in residential as well.

The rockwool is supposed to be the best if you can find it.

Any sort of blown in insulation will settle and IF it gets wet it will really settle and can become nesting ground for mice. Also. if you use batt insulation under the house you must cover that with a s screen type [product. Critters like getting in the insulation and the wire mesh will, or at least attempt to stop that.

Our old home had blown insulation in the attic. I was NOT a fan, and can't see myself ever using that unless I absolutely had no other choice. I know it's easier and cheaper, but there are too many downsides to me.

^All excellent points Instrument 41.

Steve, if you DIY spray foam the underside of the house, it needs to be above 50deg minimum or the chemicals won't mix and fully stick. It might even retract at the edges or crack later on. Even a single inch would be a huge improvement though. Insulating the vents and water pipes is also a necessity.

It's probably too late this year and it's going to be a cold winter. You could put plastic around the perimeter and run a torpedo heater underneath to warm up the surfaces but that is a hack. Check the surface temps with an infrared thermometer. You'll have to open up, use fans, and spray very fast on a warm day. Put the tanks in a hot bathtub of water for an hour. I'd suggest a full body suit, new chem mask, gloves, the works. The Isocyanenes are very toxic. The closed cell will provide stiffness and a vapor barrier if all surfaces are continuously wrapped. Plastic on the ground will also prevent water vapors from rising.

This is my bathroom wall which might have the plant-based foam. I'm not sure.. Either installed in the mid-1950s or early 1990. Whatever it is has failed. The stuff crumbles into dust when touched.
http://forums.pelicanparts.com/uploa...1637076909.jpg

Yeah, I need to get under the house and put down a vapor barrier on the ground.

Last year we had a crazy cold winter (snowmaggedon) here. Hopefully, this year is not like that again. Last year I put 2 cheap halogen work lights under the house and sealed with plastic and then stacked some hay outside the plastic during our big freeze. I also kept the heat on in the house. We didn't have anything freeze. We have had some plumbing done and the guys insulated all of the supply lines in the crawl space in the process which made me happy.

Wow, that foam is NASTY!

Spray foam is NOT a DIY project. Pay to have it done professionally.

Yep, I've got no plans to do spray foam in this house.

You need to close up those gaps where you can see daylight with a solid material, like wood or metal, not foam or pink fiberglass. Think water or moisture intrusion.

The house walls should be fully insulated, top to bottom, with fiberglass or sprayed cellulose.

Any pipes you can get to should be insulated. Never hurts.

I had a cottage that had spray foam insulation throughout the structure. Excellent insulation. Also makes the perfect home for ants and termites if there's any moisture.

Attention to detail is the key here. You don't want to be opening those walls again.