Condensation on basement ceiling

[jsfinn]

Tonight I noticed some water spots on the ceiling in our basement. I knew right away it was from condensation because there were several little spots all kind of grouped up.

The basement is about 80% finished with an unfinished utility room running just about the entire length of the front of the house. The ceiling in the unfinished part is open to the rest of the basement finished ceiling space (does that make sense?). The furnace is in the utility room and keeps the utility room pretty warm but the rest of the basement is definitely cool.

The spots are on a "bump-down" area of the ceiling - I cut a hole so I could see what's going on.

The "bump-down" is there because there is a metal I-beam running the entire length of the house and it looks like water is condensing on that I-beam. When I touched the I-beam it didn't feel particularly cold but certainly not warm. There are a ton of warm uninsulated heating ducts running near the I-beam too.

It's been between 5 and 30 degrees here for the past week or so. There is a faint cool air draft coming from the hole I made so I guess I need to add insulation somewhere but I guess I'm not sure how this I-beam ties in to the outside walls of the house and how exactly to insulate it. Do I need to cut holes in the outside walls on both sides and stuff insulation in? Could I just spray insulation from the hole I already made to avoid a bunch of patch work? I can post pictures if it would help. I guess I'm just not exactly sure how to fix my condensation problem.

Thanks!

 

[Xcusme]

Re: Condensation on basement ceiling

Beams are typically supported at the ends in 'beam pockets' in the foundation walls. Poured concrete walls or block walls will be constructed with the pockets, the beam will have support posts spaced down the length of the beam. The posts stand on their own footings placed before the basement floor concrete is placed. The beam pockets don't go all the way through the wall.

 

[chiefalen]

Re: Condensation on basement ceiling

A de-humidifier might be the ticket for you. And to avoid emptying the tray all the time just have it drain into the sump pump hole if you have one.

The sump pump will pump the water out, if it gets to high but most likely will just leach into the soil.

One thing i would like to point out for you to check, if your sure it's condensation, and not a pipe leak, are the walls also wet, maybe behind the finished part of the basement ??

Just my 2 cents

 

[jsfinn]

Re: Condensation on basement ceiling

Beams are typically supported at the ends in 'beam pockets' in the foundation walls. Poured concrete walls or block walls will be constructed with the pockets, the beam will have support posts spaced down the length of the beam. The posts stand on their own footings placed before the basement floor concrete is placed. The beam pockets don't go all the way through the wall.

Thanks for this information. I must have some sort of wood beam pocket because my poured concrete only goes up maybe 4 feet and the rest is wood. The basement is really only maybe 2 or 3 feet under ground.

I guess this means that the ends of the I-beam could be left uninsulated and they radiate cool air in to the void space in the ceiling along the metal I-beam? ...this is starting to sound like an unpleasant fix.

 

[jsfinn]

Re: Condensation on basement ceiling

A de-humidifier might be the ticket for you. And to avoid emptying the tray all the time just have it drain into the sump pump hole if you have one.

The sump pump will pump the water out, if it gets to high but most likely will just leach into the soil.

One thing i would like to point out for you to check, if your sure it's condensation, and not a pipe leak, are the walls also wet, maybe behind the finished part of the basement ??

Just my 2 cents

Thanks, Chiefalan -

The basement humidity is about 30-31% most of the time so I don't think that's a big issue.

I'm going to take down some more of the ceiling this weekend to be sure it's not a leak - it just happens to be below the kitchen sink. I cut a hole last night in the ceiling that's about a square foot. I was thinking that if it was condensation, it would probably dry up overnight. This morning, part if it was dryer but I could still see a drip of water forming on the top of the i-beam. I still mostly think it's condensation (it was COOOOOLD last night) but you're right, it could be a pipe leak.

 

[Tim Frank]

Re: Condensation on basement ceiling

If your RH is ~ 30%, a dehumidifier would be a waste of money and time.
In fact if your humidity is in that range, the beam would have to be getting really cold to cause condensation to the degree that you are noticing.
As a "dart in the board" let's say that your basement ambient is 65 F. and RH is 35%....dew point chart will tell you that the beam would have to be at a temp of 35 F. to cause condensation.

Here is a dew point table

http://www.lamtec.com/dew-point-calculator.htm

I would look for a leak.

 

[jsfinn]

Re: Condensation on basement ceiling

If your RH is ~ 30%, a dehumidifier would be a waste of money and time.
In fact if your humidity is in that range, the beam would have to be getting really cold to cause condensation to the degree that you are noticing.
As a "dart in the board" let's say that your basement ambient is 65 F. and RH is 35%....dew point chart will tell you that the beam would have to be at a temp of 35 F. to cause condensation.

Here is a dew point table

http://www.lamtec.com/dew-point-calculator.htm

I would look for a leak.

I can't wait to get home from work and rip that ceiling out now..

It's possible that the end of the beam against the wall is 35 F or lower. It was about 7 degrees out last night. Condensation COULD be running down the beam from the ends but I guess I won't know until I get in there.

Thanks for the post and link though - that's good thinking.

 

[jsfinn]

Re: Condensation on basement ceiling

If your RH is ~ 30%, a dehumidifier would be a waste of money and time.
In fact if your humidity is in that range, the beam would have to be getting really cold to cause condensation to the degree that you are noticing.
As a "dart in the board" let's say that your basement ambient is 65 F. and RH is 35%....dew point chart will tell you that the beam would have to be at a temp of 35 F. to cause condensation.

Here is a dew point table

http://www.lamtec.com/dew-point-calculator.htm

I would look for a leak.

Tim, I feel like I owe you something.

It was a leak after all and in the worst possible spot.

There was a jumble of tees and elbows running every which way right smack dab on top of the I-beam. You couldn't even see it without holding a mirror up there.

Man, I was *sure* it was condensation because it was wet in two spots and one of the spots had little tiny spots around it but I guess water does funny things.

Thanks for helping me troubleshoot this mess!

 

[gonefishie]

Re: Condensation on basement ceiling

That's why I think this board is so awesome. It's like having a bunch of friends/brothers/advisors with all different level of knowledge, skills, and wisdom. If you ask a question, somebody will give the right answer.

 

[jsfinn]

Re: Condensation on basement ceiling

That's why I think this board is so awesome. It's like having a bunch of friends/brothers/advisors with all different level of knowledge, skills, and wisdom. If you ask a question, somebody will give the right answer.

I 100% agree. Man, I was a million percent sure it was condensation but I got good guidance here that proved otherwise. I still don't know how the pipe joint just started leaking after 10 years but it did. For what it's worth, it was CPVC.

 

[Tim Frank]

Re: Condensation on basement ceiling

Glad to help, thrilled you got it solved.
Good luck with the repair.