Replies

1. 
   user-2310254 | Apr 20, 2021 03:03pm | #1

   This article is quite old, but it way provide some guidance on how best to approach monitoring.

   https://www.aivc.org/sites/default/files/airbase_10393.pdf

1. 
   SierraWayfarer | Apr 20, 2021 05:29pm | #3

   Thanks Steve,
   There apparently was quite a bit of early research done in Canada on straw-bale houses. I ran across a number of references to it. I only did a quick scan of the pdf but it looked like they were doing research to confirm that it was easily possible to determine bale moisture levels. The wood block method they developed was interesting but am looking for something cheap and convienent for a whole house, 30 or more sensors.

   There are number of good portable straw-bale humidity probes for measuring individual bales. I may end up using one of those if I don't find a convienent inexpensive ready made sensor system.

   At the base of the bale wall, under window ledges, and low down on door frames, I could insert some sort of hollow capped tube into and protruding from the bales before I plaster and then plaster them permanently into the wall. Then periodically I could go around the house and pull caps off the tubes and insert the probe to check bale moisture. It would be cumbersome. I might just do it at windows and doors where the greatest risk is or I might try to build a messy/ugly Raspberry PI system...

1. 
   user-2310254 | Apr 20, 2021 06:29pm | #5

   I get what you are saying but would worry about things ground faults, limited sensor life, and high install and lifetime costs. A solution based on blocks of wood accessible from the interior space and a replaceable moisture meter has its attractions. I'd put the blocks near window and door openings and other penetrations.

   Or I might drill holes in these areas and insert a probe once a year just to be safe. The hole could be plugged when not in use. I had an EIFS house inspected several times using this approach. (It was always dry, BTW.)

1. 
   SierraWayfarer | Apr 20, 2021 06:39pm | #6

   Steve,
   These sensors run on almost nothing, microwatts. Sensor life is an issue but some of them are so small that they could probably be inserted into the bail thru a whole drilled in the plaster the size of a quarter. You would have a little patch mark in the plaster until the next time you skim coated it but I think the some of the sensors are fairly reliable. Many of these sensors were developed for industrial uses, harsher environments than a straw-bale or blow in insulation wall.

2. GBA Editor
   Kiley Jacques | Apr 20, 2021 03:19pm | #2

   Though not specific to straw-bale walls, this article might be of interest: Measuring Moisture in a Double-Stud Wall. Also, keep an eye out for an upcoming article on data loggers from residential building scientist Doug Horgan. Among other things, he will explain where to place them and how to work with the data they supply.

1. 
   SierraWayfarer | Apr 20, 2021 06:16pm | #4

   Hi Kiley,
   Looked at the HOBO data logger he used. Looks like that is a self contained unit with only one sensor. I want to put a wire chase at the bottom of walls and have bunch of sensors. Its a shame nobody is selling this yet. The technology is there with individual temperature and humidity sensors selling retail for $3.

   Heck, there are passive RFID temperature and moisture transponders (no battery or wiring required) but the price is still way too high. When they become affordable you will just stick them all thru the walls and your computer will query them and notify you if something is nees looked at. The IoT....

   Till then I guess I will settle for periodically manually probing thru portals into areas of highest risk, like below windows. I don't want to mess with all the wires, probable programming, and learning curve needed for a Raspberry PI system.