Weird moisture/humidity problem
I have a customer that manages an asssisted living “village”. Each building contains (4) 1 bedroom/1 bath units, slab on grade construction with electric heat.
In one of the buildings in the middle unit they are having a really high humidity (60-80%) whenever the a/c isn’t running. There are no issues in any of the other units in the building. But you can smell a distinct musty smell when you walk in the door. The furnace has been checked, the ducts have been cleaned, paper towels left on the floor retain no moisture, the bath and range vent fans seem to be in proper working order and directed to the exterior. There also doesn’t seem to be any mold growth that I can find.
So short of an exorcism, what else should I be looking at ?
The resident is allergic to a bunch of plastics so most de-humidifiers are out of the question. Plus, I would really like to figure out where the moisture is coming from.
Naive but refreshing !
Replies
Woody
Try a needle type moisture meter (potentiometer) in the drywall to determine is there is an unusual amount of water trapped. Located the areas of higher readings and investigate for a very slow pumbing leak----domestic water or sewage. Check water meter readings for an ever incrreasing consumption rate...at all four units over the last year.
Make sure the A/C condensate drains are really taking the water AWAY.
Are the slabs finished with vinyl sheet goods and rubber backed carpet. If so the only place "extra moisture" could escape would be through the bottom plate of the walls.
No exorcism....Just deeper investigation..........................Iron Helix
I look into that, thanks.
As far as the a/c condensate drains are you are saying the a/c could be building up moisture in the air handler ? The humidity levels come down to normal when the a/c is running, but when the a/c is off the humidity comes way up. Naive but refreshing !
Woody,
Check out where the condensate actually goes, if it goes at all.
A plugged condensate drain can leave a whole lot of water in the A-coil cabinet and lining and when the unit shuts off there is still the mass of water in the unit. Hence the instand High Humidity in a small apartment.
If the condensate is draining well from the unit then be sure the drain is actually removing condensate totally from the building. Confirm where the condensate exits the building...TOTALLY!
From your description there is obviously water being trapped into the unit/apt. ...sleuth it out! It maybe weird when you find it...but it is still happening.
Anything is possible...even if unreasonable as you know it now!
.............Iron Helix
Water pipe leaking in the slab.
I've done a fair amount of moisture sleuthing in my day. Many of it mysterious and seemingly nonsensical.
fans "seem" to be in good working order. A sleuth has looked at a rock and said there is nothing underneath. No offense intended.
In addition to the other posters suggestions, I'd double check the exhaust duct work. While all the units were likely constructed identically, someone may have screwed up something with the exhaust ducts ... pinched a flex duct, painted over a louver, bound a backdraft damper, etc.
When were the units built? Any cooking going on? Maybe that unit has a fish tank or lots of plants? How about the frequency of showers/bathing? Are all exhaust fans on manual switch? If so, maybe the occupant doesn't use it or leave it on long enough.
I'm guessing no individual water meters ... so the one poster's idea won't hold water (nyuk); but it's a good idea.
Where is the air handling unit? in the attic? in a closet?
Like energy, moisture doesn't just appear w/out explanation. It's science ... simple science ... and complex at the same time. Shouldn't be 'rocket science', though.
FLIR
Water pipe leaking in the slab.
Tape a piece of plastic sheeting down on the slab in several areas, or use a moisture meter. A paper towel would only indicate standing water, or nearly that level of saturation.
Yeah, that's what I said post #4. Seems to have been ignored.
Corporation: n. An ingenious device for obtaining individual profit without individual responsibility. --Ambrose Bierce
Thanks to everbody for the pointers. Gonna start looking on Monday, see what I find.........Naive but refreshing !
Woody
paper towel on floor? I have always used plastic on the floor and see if it condensates under it.
Depenting on temperature and relative humitity of the space, you wont get condensation on the towel, just moisture passing thru the towel into the space.
Lots of good ideas from the posters on what to check.
Re. the exhaust fans, make sure they vent to exterior also. (might have been mentioined so sorry for repeat)
Lots and lots of bath exhaust fans in my area have been vented into attic areas for lots of years or into the soffits. (doesnt meet IRC)
I often check that when I am doing other projects in a home.
Easy sell to a client to pipe to exterior as they should be.
I though it warranted repeating.
If it's relatively new construction I'd bet it's either a missing barrier under the slab or the guy takes a lot of showers without venting the bath and boils a lot of foods without using the range hood vent.
The amount of moisture from these sources is quite significant. If it was a problem before the current tenant it's probably the slab barrier, if not it's probably the tenant.
Maybe a water leak above the slab barrier, but I'd be surprised.
Beer was created so carpenters wouldn't rule the world.
My bet is that it is a roof leak somewhere and it becomes less noticeable when the A/C is running because of air circulation.
Jeff
Well, there doesn't seem to be any evidence of that in the ceiling anywhere.
I taped a piece of plastic down yesterday, so well see what that says this afternoon. A/c guy gonna check the condensate drain today........ Somebody suggested a FLIR which is a tool I don't have..............yet =)Naive but refreshing !