Context:
78 YO house, 2 ft thick uninsulated masonry walls, full daylight basement with walkin on north side (bummer), massive concrete foundation with basement stairs, laundry room floor, and two porches all poured along with the foundation. The front of the house faces south, but the south side is bermed and the north side is exposed, exactly backwards from what we want. They don’t build ‘em like this any more… for good reason.

One of the worst thermal weak spots is the massive concrete pouring on the north side which forms the basement stairs, laundry room floor, adjoining porch, and north side basement wall. 4 or 5 feet high by 20+ feet of this mass is directly exposed to the outside, and in the winter, it is a huge thermal sink. It’s the coldest part of the house by far.

The correct thing to do would be to foam insulate the exterior of the whole north side and get that whole mass inside the heated envelope. But it may be a few years before we can budget that in - first priority is some passive solar treatment on the south side. So until then, I’m looking for an inexpensive way to insulate this mass from direct exposure to the cold air.

That’s where the straw bales come in. Very cost-effective insulation. But it has to be kept dry. I’m envisioning the bales in some sort of bag or covering (say, polypropylene or similar) that will hold up for a few years. Stack them up to cover this mass. Looks aren’t important - this is the back of the house and it can’t be seen from any adjacent properties.

Anyone ever seen anything like this? Is this idea crazy? Your thoughts are welcome and appreciated.

Insulboard and glue for a 5x20 area would cost less than $70 and alot easier to install than straw. The straw will attract rodents and be a mess to clean up when your ready to do something different.Straw here is $3 bale and it will take 25-30 to cover that area.I think insulboard is the better and cheaper route.

Yes, that would be easier. But you’re talking, what, R8 vs. R50? Not really comparable. And rodents aren’t as much of an issue here in NM as they are out east.

Isn’t NM Hanta virus territory? The last thing I would do is create a habitat for deer mice around my house. They may not be an issue now, but make a nice safe home for them and they will come.

From 1993 through 2007, there were 69 reported cases of hantavirus in New Mexico. Even with our small population, that’s statistically buried in the noise floor, and nothing worth worrying about.

Besides - there haven’t been any mice around here (or pidgeons, either) since Pico the mouser arrived on the scene She’s an amazing hunter.

About 15 years ago I did some work (soffit and and facia) on a new house constructed with straw bales. Post and beam structure with bales filling the spaces between beams. It is still standing today and the last I talked with owners (years ago) they claim it heats very easily and have no rodent problems. It was one of the strangest building sites I had been on. After stacking bales they used a weed-eater to smooth surface a little ,then installed chicken wire and applied stucco.

I lived in a straw bale home for 2 years.  Best house I ever owned.  Warm in the winter and cool in the summer.  Super quiet.
Moisture is the killer of straw.  Get yourself a moisture meter and take readings every season.

Straw bales can work for you with some attention to a few key details. As mentioned moisture is what to avoid. Make sure that you provide a good drainage layer of gravel beneath and set them on two 2x4 sleepers. Pay attention to all sources of moisture (roofs, vents, etc.). You won’t get r50 out of them without plastering to seal the outside up as wind can blow right through straw bales. I recommend plain old mud clay straw plaster as it is breathable and will be easy to break up when you re-do.

Thanks for the great input, guys. If I end up going this direction I’ll follow up with a report.

Call me geographically challenged, but . . . what’s the insulation for in New Mexico?

keeps the heat in or keeps the heat out
its like waxing on or waxing off

It’s to keep the heat out

Here at 7000 ft altitude in the foothills of the mountains, we have real winters…

Precaud, I have been looking into straw houses very effective in our climate (I live by Kingman AZ). Just do the wall......will turn out to be the warmest wall in the house.

Doug

Doug, tomorrow I’m going to take a pic of the wall in question and post it… I think that will make things clearer. But now - it’s off to the mountains, and to do my patriotic duty by burning some Memorial Day weekend gasoline (well, not that much… the Honda is a sipper

OK, here’s a pic of the north side of the house. I’ve edited the photo to bring detail out of the shadows, and traced the approximate upper surface of the concrete with the yellow line.

From left to right, you see a screened-in porch, laundry room, then the house, with the electrical service entrance to the right of one of the house windows. In the horizontal, the pouring runs from this service entrance to the porch, and in the vertical, from about 2.5 ft. under the windows down to the basement floor, which is a full 8 feet high floor-to-joists. And, it extends a full 8 feet into the house. If you were to look into the window next to the electrical box, you’d see the concrete stairs into the basement.

Not including the porch, I calculate there is over 1300 cubic feet of concrete in this massive pouring. Once this thing starts getting cold in November, there’s no way to keep the north side of the house warm. This thing sucks the btus out bigtime.

Any input/ideas are welcomed.