Re: Re: How to predict if mold will grow inside of gypsum wallboard-faced walls.. measure the humidity inside of the wall cavity..

[Guest guest]

Pros use inexpensive data loggers that you place inside of the wall

cavities, and leave there for a few days (at least, the longer the better)

so you can get a realistic picture of the temp vs. RH during a range of

weather and humidity conditions during that time of the year. Ideally, you

would want to know what it was like the year round.

Any instrument that measures temperature and relative humidity will do,

however, it should be able to be sealed in there (having a hole to run a

wire would change the behavior)

It has to be measured inside of the wall cavity, the RH inside of wall

cavities is often very different from the RH outside of it, and the

temperature and RH can often vary widely depending on a multitude of

factors.

There is a software program called WUFI that I have heard about that can be

used to simulate the behavior of a wall system, but its very technical and

not something most people on would be able to use.

I don't know what an infrared moisture tester is. . There are FLIR imagers,

(i.e. " thermography " whch is probably what you are thinking of???) and

there are meters that measure the high levels of resistance in a fixed

distance of a building material and exterpolate moisture from that.. (at

least that is how I think they do it..)

Neither would do what I am talking about. the amount of moisture at the

surface of a piece of gypsum wallboard I would suspect would be lower than

the amount of moisture trapped within it (assuming that it was in the

process of drying out and that there wasn't a hidden source of water that

was entering or wicking into the wall, like a plumbing or roof leak, or

condensation)

Also the tendancy of a piece of damp material to cool slightly from

evaporation (what a thermal imager would see) would be dependent on the RH

of the air around it and its own temperature and that of the air..

Walls are dynamic systems that have a lot going on in and on them!

All told, IMO, the best way to get an idea of what's happening inside of a

wall is to stick a probe in there and log it.

The situation would also change A LOT from season to season.. things are

VERY different from, say, summer to winter!

The inside of a building's 'envelope' (the part you live in) may be warmer

or cooler than the outside, the humidity can be higher or lower..

On Sun, Aug 10, 2008 at 2:31 PM, jill1313 <jenbooks13@...> wrote:

> That's very cool but how do you determine it and what exactly are the

> cutoff points?

> Do you use an infrared moisture tester, or a regular one, or what?

> Thanks.

>

>

>

> >

> > Barb,

> >

> > This is an interesting paper that does the work of predicting whether

> > stachybotrys mold will grow in a wall or produce mycotoxins inside

> the wall

> > that accumulate there.

> >

> > If the RH inside of the wall can be kept down, then mold can't/won't

> grow!

> >

>

>