We have owned our house for almost 3 years. I have a temperature/humidity reader in the house that is fairly accurate and it usually resides in the master b/r. Up until now the humidity has ranged between 40 - 55% give or take during non-winter months. Recently, since summer started to wind down, it has been around 60% to 63% in the bedroom and elsewhere in the house. The master b/r is on the second floor of a two story wood frame house. We bought a dehumidifier over the weekend and plan on running it until the winter months make it drier in the house.

My question is why all of the sudden does the humidity start to spike. I realize that the a/c isn't running now due to outside temps but I have not noticed this before.

My concern is that something has done awry with the moisture in the house. There are two issues that I think could be causing this but don't know enough about building and science to be certain:

1) Our crawlspace is a constant job when it comes to moisture. We installed two sump pumps and need to replace our tattered vapor barrier but we get very little airflow in the crawl due to our location and therefore, the humidity in there stays high until winter months.

2) We have Masonite siding and I worry that somehow moisture has infiltrated it and is stuck between the siding and the wall and is seeping into the house air. This is a conspiracy theory but we have been told that Masonite was in a class action suit and needs to be replaced because it wicks moisture.

Any insight into this issue would be much appreciated. I just want to make my home as livable and safe for my family as possible.