Assume I am considering buying a lot and building a house in it. Is it possible and how would I project what the humidity level will be in its basement? Say the basement is built using concrete blocks. Some factors that come to mind are the precipitation table, gradient of the lot, position relative to nearby streams etc.

But are there well established heuristics for gauging the level of moisture penetration I can expect?

2 Answers 2


If you have to account for water penetrating the basement, then you likely don't want to be building a basement there.

If you're building from scratch, you'll ideally build a basement that is properly waterproofed and insulated from the outside and is set up to handle any drainage issues.

At that point, the humidity you have to deal with will be airborne. That humidity comes from the air...so for instance, if you live in MN in the summer, you'll note that it's incredibly humid. The basement tends to be cooler, allowing some of that humidity to condense, and basements tend to not have much air flow, so it can build up.

The solution to that problem is to include the basement as part of your conditioned space. Ideally it would have AC and Heat, but, barring that, you'll want to have a dehumidifier running.


If you want to know what the humiditiy level of your house will be then you need to find a house in the area that has similar traits and construction as yours and ask. You might also want to talk to a local building inspector. Not sure I totally agree with DA01 on this one but he has a point if the levels are extreme.

The fact is you won't know until everything is done unless you find a decent clone. You have cement thickness, type of cement, insulation, install variables, windows... tons of variables that you can't exactly measure.

I will note too that airflow is a big deal. I just finished my basement and I created a circular air flow between the sides of the basement. Even with just a couple small windows it gets fresh after 20 mins of a few open windows.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.