? The Number 1 rule is to make sure all gutters are clear, and all downspouts route rain water away from the building's foundation.
? For best results you typically don't want the humidity getting above 55%. If your basement (or other gun area) humidity level can spike during downpours, then adding a heater stick inside your gun safe is all you need. Warming tends to ward away minor humidity.
? If your basement regularly stays higher than 65% humidity, then that part of your house was probably not originally built as a "living space", and could therefore benefit from introducing some of the home's furnace air. Moist air is typically stationary air, and it simply needs some circulation. In those cases you can buy a 3" hole saw and introduce new openings in the duct work. 1 or 2 holes in the supply lines is enough to circulate air, and change the temp by 2? and lower the humidity 10-15%.
? Homes in the Southeastern US have a particular issue with humidity build up in basements and crawl spaces. Most homes in this area are equipped with small, metal foundation "vents". In theory you open the vents in summer and close them in winter, but there is always more rain than wind, and this design is an absolute failure. The only cure is to seal up all basement doors and vents, then lay thick plastic sheeting atop all exposed dirt, and install a dehumidifier that is permanently plumbed to empty outside.
Also be aware that modern furnace/AC units create condensate all year round. This also needs to be removed from the home.
Hope this helps.
