I’m recommending we NOT INSULATE This Old House

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[aarontpassmore]

You’re missing the most relevant factor as to why those walls are dry on the inside: lime mortar. The bricks are laid with lime mortar, which is less dense than the bricks and breaths/allows the moisture to wick out on a grand scale and evaporate.

[ronnie-being-ronnie]

I lived in an old home in Spain. No insulation, concrete and stucco build, plaster walls.
It got cold and I turned on my kerosene space heater, closed the door to that part of the house and started fixing dinner. You cannot imagine my shock when I went back into the living room to discover I couldn’t see farther than my arm! The extreme moisture held in the walls formed a thick fog cloud inside the house with the introduction of the heater. ☁️☁️☁️☁️☁️
I opened the windows as the air outside was drier than inside.

[castleclark]

Thank you for this video! Perfect timing. We're renovating a 100 year old victorian wood frame house in Cocoa FL, and we just had water seep into the walls after the hurricane. The house has no rot at all and all the wood behind the plaster has been in perfect condition. You helped us understand that these old houses can dry out. We still need to seal up a few places where water was getting in, but now we know that it has been self-drying for the past 100 years and will continue to do so.

[dee]

I think what everybody missed on this home is that it is balloon framed the wall studs go all the way to the foundation it's constantly circulating air all the way around the outer shell from the crawl space I think this house could be insulated within baffles in the wall to keep the air flow circulating it'd be perfectly fine for another hundred years

[dragoneyeshatesggle]

1) The particle board has a air gap between it and the brick (That is 1 reason why it's survived so well as others pointed out old brick work sheds humidity better than modern mortar) 2) if you want to give the particle board air you can use Sofit spacers used for insulating rafters to keep the insulation 1.5" from the sheeting. you'd be able to insulate while maintaining the original air gap on the inside of the sheeting. 3) Now that the Original particle board has Numerous holes you've punched into it you'll have to change the approach to keeping it dry by increasing the volume of airflow so the interior of the board doesn't retain humidity (Which is what you saw at the base with discolored particle board. Not enough air) 4) A completely closed pocket must stay closed and have some through absorbent surface to shed any moisture (Which the original plaster was) since you plan to go with drywall and you perforated the outer board you definitely want insulation to mitigate rapid moisture changes in outer walls.

[mattv]

If you add air conditioning you're changing the way the house works regardless of insulation. On a hot humid day, warm air is going to flow through the wall cavity (through the giant holes in the sheathing you showed) and condense on the back of the cold sheetrock.

[nholt]

Our 1948 ballon frame house had no insulation, tar paper, and 105 wood siding nailed to the studs. The upper part had tar paper, 1x4s spaced out with double course cedar shakes attached to those. And we still had rotten siding on a few spots! We recently stripped the exterior walls, added Rockwool insulation, plywood not osb, 30# tar paper, and double course cedar shakes. Above that hardie board. I’m loving it so far.

[jmpersic]

One of the biggest takeaways I've gotten from watching this channel is the importance of things drying out. Getting wet or exposed to moisture is not always a problem if things dry out. It's made me look at my old house differently.

[DiaEule]

This was great because you are back to reality, advising on problems most of us will face rather than new ideal builds

[donheggenstaller]

Matt, I lived a old 1800's brick mill and had a Mason repoint the bricks. When they were finished, they sprayed the entire structure with a silicone sealant. Rain would bead up and run off the outside. But it was breathable so any moisture on the inside could escape.

[alafrosty]

One time, I added exterior underground insulation to a basement. It did nothing after adding on the long sides. One side was above ground due to terrain slope. But when I added the final 25" of rigid insulation, suddenly the basement was a LOT warmer! While you might want to add insulation on the spots without that particle board, based on my experience, it'll be a waste of money because the heat loss from the uninsulated area will dominate the heat demand.

[ardenthebibliophile]

As someone who lives in a 120 year old house with plaster walls, this was much appreciated. I like your style on new construction and am appreciative that the principles you speak of, properly applied, still work with old construction.

[hbb]

Not a contractor, and really a only small project DIY guy, but I never miss one of your vids. Thanks dude!

[markpashia]

Good gracious you are a young man. That product was sold well into the 1970s and was very common. It is a use of cane fiber. Mostly on the exterior it was sprayed with asphalt as a vapor barrier.The reason that corner had one by wood sheathing was for wind bracing. All corners were diagonally braced with that non structural sheathing in between. If you are going to plaster again don't insulate, but if you are going to use drywall, use a non vapor barrier insulation like unfaced fiberglass and then use a vapor barrier floor to ceiling and corner to corner over the studs. Then drywall. With modern AC I do believe you will want to insulate. That non insulated with double hung windows was very common in the south for the walls to breath. But a cold surface from AC will give you grief without vapor barrier and insulation. Better bone up on old methods!!!

[mattv]

I have the same particle board sheathing on my brick house from the 60's. The walls have fiberglass insulation and two layers of sheetrock, and as far as I can tell that's how it was built. There are no moisture issues that I know of. It has stood this way for 60 years, so I guess it must be fine.

[TheHudakattack]

my professional opinion is pack those stud bays with moist soil from the lawn, set up a sprinkler to keep them wet for 48 hours, staple some poly over it, and drywall it in, but then again my profession has nothing to do with home construction

[KevinCGleason]

I did some work on a house built in 1928 in South Florida, had the same type of particle board walls with no rot. Had the material tested for asbestos, came back clean.

[WoodchuckNorris.o]

You should look into how straw light clay insulation works with lime plaster. It's a different approach to moisture movement through walls than what you normally talk about. That system allows moisture movement and it works because the straw and clay diffuses moisture rather than allowing "hot spots". Then lime plaster wicks the moisture out of the wall

[DoItYourselfDIYAtHome]

Thank you, Matt. Along with your video about how vapor barrier and vapor retarder should not be installed on most houses, this appears to be the last piece of the puzzle for me to maintain my exterior walls on my 1960s stucco home. Now, my tentative plans are: 1. No vapor barrier or retarder, 2. No insulation, 3. Possibly replace the drywall that has paper backing with either plaster or cement backerboard, and 4. Seal large cracks and openings in the walls.

[petrirantavalli]

I have an old log farm house here in Finland that serves as my summer cabin, disassembled moved to it's place in 1920's. Just by keeping the doors shut it stays "cold" in 20C no matter how hard the sun bathes the walls in the summer, kids call it the "ice room" because the temperature difference to some times over 40c outside is so big on summers. Other end of the house that sees more traffic doesn't do the same as the door there is most of the times open and people go in and about as it has the kitchen and the living room.
On winters though the house is cold as heck but still keeps naturally relatively warm in -10C and the old masonry heaters take ages to warm up. original double windows help to keep it warm though as do the floor that sits 1meter above ground with 1/2 meter of saw dust for insulation, the mid roof (the house has an attic accessed from outside) is similarily insulated albeit with clay and straw.
Only issue the house has is that frost has moved the stone foudation over the years so the house has started to drop from one side and also dry rot that eats timber over time.
There are techniques to make foundation to not move (staves under stones in foundation similar to today) but those are only found in mansions of the nobles not in farms of the common folk.