[GSBN] re: Straw and insects

[Robert Tom]

Derek wrote:

> Since this has been going on in this Pennsylvania building for several
> months, I would be worried that there may be an undiscovered source of
> moisture and a significant gap in the air barrier/plaster.

> It may be that the problem is not in the bale wall,
> but that some other places in the structure are the source of the
> problem.

> Laura Bartels wrote:

>> industrial manufacturing facility(grain moth infestation)seems to be  
>> worsening

>> We also just got a huge crop of nats that he says
>> is tied to the straw."

I agree with the Derelict.

Not knowing the nature of the manufacturing operation (ie whether it is a  
space cooling or heating situation) it's difficult to pinpoint whether  
it's infiltration or exfiltration that is the cause of moisture transport  
into the straw but I would get two doughnuts and a bagful of cookies that  
air leakage does play a big role in the presence of the moths and gnats.

But since this message comes in early Spring, my guess would be that it is  
bulk moisture transport piggy-baked on heat-driven exfiltration leakage  
over the winter and with the advent of warm temperatures, the winter  
accumulations of moisture started brewing up in the wall creating the  
ideal conditions for life, of the pestiferous variety.

Chemical treatments and sexual trickery are I think, likely to be  
ineffective since they are only a reactive measure against the symptoms  
rather than pro-actively eliminating the cause.

In any instances of bug infestations due to wet conditions, reducing  
humidity levels is usually effective since it removes the amenable living  
conditions. This may be as simple as mechanical dehumidification of the  
space. But if exterior RH is high and the upper portion of the thermal  
envelope is air-leaky, one does run the risk of exacerbating the problem  
since one would be drawing warm, moist air through air leaks  where it may  
condense in the upper portions of the wall just behind the cool(er than  
outdoors) plaster.

Placing desiccants in the wall might be another option. (ie drill holes at  
regular intervals, insert perforated tubes in which desiccant-filled  
tampons are inserted, cap the tubes, replace desiccant as requ'd.

Mechanical drying by blowing _dry_ heated air into the wall via those same  
perforated tubes would probably do the trick as well but would be  
energy-intensive.

While the latter do attack the problem at the source (removing moisture)  
they are only temporary fixes for this season.  The bugs would likely  
return next year and the year after. The permanent fix would of course be  
to identify the leakage points and seal them.


-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
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