Water Content Balance

[C. Furtaw]

I have run an analysis on a wall section and the Total Water Content Graph' value (lb/ft^2) is less than the sum of the water content of the individual members. How do I reconcile this difference?
C. Furtaw

[Thomas]

I have run an analysis on a wall section and the Total Water Content Graph' value (lb/ft^2) is less than the sum of the water content of the individual members. How do I reconcile this difference?

By multiplying the water contents of the individual layers by the respective layer thickness before adding them up.

The water contents of the individual layers are given as the average water content per volume (cubic foot). The total water content is given as the water content per wall area (square foot) and is computed as described above.

Kind regards,
Thomas

[C. Furtaw]

Ouch, I should have looked at the ubits more carefully.
As a follow up, once the initial construction moisture is removed and the wall section goes through its normal yearly cycle of wetting and drying can an equilibrium point be determined?

[Thomas]

once the initial construction moisture is removed and the wall section goes through its normal yearly cycle of wetting and drying can an equilibrium point be determined?

Well, since the wall section is going through a cycle, there is no unique equilibrium point but an equilibrium cycle. To find this cycle, do a calculation over several years, always applying the same year of climate data until the wall has forgotten its initial state and reached the equilibrium cycle.

Then save the final temperature and water content profiles to ASCII files via the ASCII export, specify these profiles as new initial states for temperature and water content and do a calculation over one year. The result is one period of the equilibrium cycle.

Depending on what you are interested in, you may look at the water contents of the layers or at the total water content to see what the highest and lowest water contents during the equilibrium cycle are and when they are reached.

You can also run the calculation and then watch the film, with the "traces" of the profiles activated, so that at the end of the film the traces show the areas through which the profiles have swept. They show you the maximum and minimum water contents for each location in the wall. You can make a screenshot of this display or export it to a bitmap.

Regards,
Thomas