04:39PM | 12/09/05
Member Since: 12/05/05
3 lifetime posts
Hi all,

My basement is humid from spring to fall (I'm in Eastern Mass). There is no water to be seen, no obvious cracks or moist walls but all the boxes and books stored in the basement are growing mold. The basement smells musty and the humidity sensor hits 78% in the summer and only drops below 50% in winter.

It's a recent construction (2002) and the builder claims to have put in a high quality vapor barrier so he's perplexed about the problem. We have our water heater (which heats water for our baseboard heating system) and a 2nd fridge in the basement. A rep from the water heater company has looked at the heater installation and didn't see any problems.

This is a two unit condo and the other unit shares the same foundation (separated by a fire wall) and their basement has no humidity problems! (They are on the lower ground and the sump pump is on their side...)

We're stumped and stuck. If I can't find the source and eliminate it, I'll put in a dehumidifier but even then I'd be knowing the source of the problem, even if it can't be fixed.

Any suggestions on where to start?




04:49PM | 12/09/05
Member Since: 12/09/03
178 lifetime posts
I live in eastern Mass. also. Moisture in the earth rises out in the summer and sinks in during the winter. This is why basements get damp during the summer months. A dehumidifier will be a big help. People I know who have them their basements are drier. C.


05:33PM | 12/09/05
Member Since: 12/05/05
3 lifetime posts
Thanks cellarwater - I know a dehumidifier will ease the problem but I'm hoping to fix it at its source. The fact that my neighbors, who share the same foundation & vapor barrier etc, _don't_ have the humidity problem suggests that I might be able to solve it without the continual expense of running a dehumidifier...

Any thoughts?



05:41AM | 12/10/05
Member Since: 11/25/05
4 lifetime posts
First, let me say that a dehumidifier might actually create more of a problem - if your source of water is truly from outside, then a dehumidifier will only serve to "speed up" the process by drawing in more humidity.

2nd, check all sorts of odd things - I recently was asked to look at a wet basement problem. What I found was 2 problems: 1) the grading at the back of the house was graded so that a ton of water would rush off the backyard and dump right at the basement wall; 2) there was a pvc drip line for the a/c unit that terminated at the basement wall. You'd be surprised at how much water an a/c drip line can cause in the summer months.

My first suggestion was to extend the drip line out into the yard, away from the foundation. Secondly I suggested re-grading - the owners said they were going to install a concrete patio anyway, so it worked out.

Do some sleuthing - are the specific areas where it's worse than others? If so, then your problem is not just ground water.

It's also possible that the guys laying the vapor barrier pieced together 2 pieces and that there is a problem at the seem.

Get 2nd and 3rd opinions if you can't find the problem yourself.

And don't let your builder poo-poo the issue - no matter what your relationship is with him/her or how nice they are. If your home is under warranty, they have an obligation to fix this problem. I'm sure they're loosing sleep over it, because tearing up the slab to make sure the vapor barrier was installed correctly and re-pouring the concrete is costly. If your neighbors are not having this issue, then there is something unique about your house and/or the construction. It's possible that there was a different subcontractor layingthe barrier that day. Who knows?! But it's the builder's responsibility to figure out the problem and fix it.

Good luck. Remember water chooses the path of least resistance.


06:59AM | 12/10/05
Member Since: 04/25/05
1918 lifetime posts
While you might notice the problem more in the basement, it might be that you humidity levels are generally higher.

That can be from "lifestyle" - For example if you have lots of plants, 4 teenageers that are in the shower all the time, and you are constanting cooking soup you will give off much more humidity than the 30 YO single neighnbor that is only there to sleep and doesn't even cook.

Other things to look at is the use of vent fans and if they are working and installed properly.

Any unvented combustion appliances, ie - unmvented gas fireplace. Or a vented WH/furnacne that the venting is bad.

Then plumbing and roof leaks can also add humidity.

And you need to run some moisture test on the basemetn walls to see if moisture is mosing through the walls.

One test is cover a couple of sq ft of the wall with plastic vapor barrier and duct tape the walls.

Then remove it after a day.

If moisture is moving through the walls you will have a droplets of water or at least a darker gray spot.


11:22AM | 12/10/05
Member Since: 12/09/03
178 lifetime posts
Liked all the answers, Check them out. C.


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