condensation?

[woodturner9]

I built an attached garage with a flat EPDM roof in Western Pennsylvania. The attachement to the house is a 2x12 ledger bolted to the house. Bolts are epoxied into the edge of the concrete floor of a covered porch.

I am getting water dripping off the exposed ends of the threaded rod. At first I though it must be a leak, but I am now suspicious it's condensation.

Any suggestions on what to do to stop it?

Thanks.

 

[Vicious_Cycle]

If it's condensation, maybe coating them with something like Plasti Dip would help? I haven't tried it because I never needed to, but that's the first thing that came to mind.

http://www.plastidip.com/consumer/index.html

 

[russlaferrera]

I am sorry. I do not understand your post. Are the bolts the same as the threaded rod? What is a EPDM roof?

As you know condensation occurs when hot meets cold. That being the case . What part can you insulate to keep this from occurring?

 

[Lu47Dan]

Make some caps out of 2" foam insulation . bore a hole to fit the nut and then cover the hole . Use screws to fasten it over the nut . Dan

 

[woodturner9]

I am sorry. I do not understand your post. Are the bolts the same as the threaded rod? What is a EPDM roof?

As you know condensation occurs when hot meets cold. That being the case . What part can you insulate to keep this from occurring?

EPDM is black rubber roofing. The bolts and the threaded rod are the same - the threaded rod is epoxied into the wall, the ledger is drillled and installed on the threaded rod, with a washer and nut on the face of it (i.e. on the inside of the garage).

 

[kbs2244]

You don't get condensation unless you have 3 things. High humidity, no air movment, and a metal surface cooler than the room.
So you attack it in that sequance.
Why is the garage damp? What can I do to dry it out? Don't rule out a dehumiderfier, but check your gutter and downspout design first.
Can we get a fan to move the air around a bit? It dosn't take much. A drug store oslating fan will do wounders. In combo with a dehumiderfier it will fix most problems.
Why are the bolts cold? Is the concrete wall an outside one, exposed to low outside temps? But insulating the bolts is fixing the symptom, not the problem. You shouldn't have that much moisture in the firs place.
If it is a leak, then I am sure you know you have a sealing problem where the roof meets the wall.

 

[bgarrett]

http://mb-soft.com/solar/saving.html

read about humidity control

 

[hog1340]

Hey KBS
What does the gutters and downspouts have to do with condensation?
Is it just to draw away from the building, and what type of design should we look to acheive?

Thanks Ed

 

[kbs2244]

Hey KBS
What does the gutters and downspouts have to do with condensation?
Is it just to draw away from the building, and what type of design should we look to acheive?

The idea is to get as much water away as fast as possible. Any water that soaks into the dirt around the garage will find its way up through the slab and just into the air in the area. You end up with a damp garage. Put up gutters at the roof with downspouts tied into sloping downhill ground level pipes running off as far as legal or pratical. I have run downspout pipe along fences all the way to the sidewalk sometimes. 3 or 4 inch PVC works great also. If it is attached, or even just close to, to the house, look for a way to tie in the house downspouts also. Keeps the sump pump from working so hard. And even of the power goes out, gravity will still be working.
Biggest project I ever did was on a house the used to get 2 and 3 inchs over the basement floor all the time. You could actualy see little fountians of water coming up through the cracks. After gutters all around that were tied into a 4 inch by 100 foot underground pipe going off to a lake channel, the basement stayed bone dry. It was a big house and it was amazing how much water a roof collects. That pipe would run half full at the outlet in a good rain.

 

[Morrisman]

You don't need high humidity to get condensation. ALL air contains moisture, if it didn't you wouldn't be able to breathe properly, so you only need a colder surface introduced into a warmer room and condensation will appear on the cold item.

If ever you walk from a cold room into a warm room with spectacles on they will mist up, until they get to the temperature of the warmer room.

You need to cover these bolts with insulation so there is not such a temperature differential between them and the room temperature, as the cold is feeding in from the other end of the bolt.

 

[1320stang]

You say the porch is covered, but is it protected from the weather? I'm assuming the common wall side is a retaining wall to the house or a basement wall, correct? Is the roof flat and covered with EPDM because it has a deck over it? I'm wondering if the porch isn't protected and it's not sealed, the concrete could be absorbing the moisture and it's weeping out at the rods.

 

[woodturner9]

You say the porch is covered, but is it protected from the weather? I'm assuming the common wall side is a retaining wall to the house or a basement wall, correct? Is the roof flat and covered with EPDM because it has a deck over it? I'm wondering if the porch isn't protected and it's not sealed, the concrete could be absorbing the moisture and it's weeping out at the rods.

Thanks, everyone, for the thoughts and comments.

The house is basically a rectangle. Attached to the back of the house is a second rectangle, a one car garage. Above this garage is a "porch", which is really a garage sized room. Brick walls, no insulation, lots of glass, and a shed roof.

The new garage is attached to the (formerly) outside wall of the one car garage and doglegs around the back of it.

The new garage roof is a flat roof because if a peaked roof were used it would cover the windows in the porch. In addition, the plan is to eventually put a deck on the flat roof.

The flat roof is black EPDM, so in the summer the roof heats up during the day due to the sun. The new garage also heats up some inside, but the covered porch/old garage stay relatively cool. The ceiling of the old garage is the floor of the porch and is concrete - that's the concrete the threaded rods in the new garage are epoxied into.

So it seems to be that the cooler concrete may be cooling the rods, resulting in condensation at night when the garage starts to cool off.

It's possible that moisture in the construction lumber is providing the moisture for the condensation, but it has been up a year now so I would have thought it would have dried out by now.

Thanks.

 

[woodturner9]

A bit of an update.

The weather broke late last week - had been cold, warmed up, rained most of the week.

Rain cleared Saturday, went out to the garage. Noticed the brick wall was sweating, and noticed the garage was cold, outside is warm.

I think the brick and block are holding the temperature, so the humid air is condensing on the colder block and brick, and the threaded rod embedded in it.

I got some PVC pipe caps and foam insulation, am going to try capping and foaming one to see if that solved the problem. If it does, I'll do the rest.

Thanks.

 

[kbs2244]

You are going to need a dehumidifier if you keep any kind of tools or machinery out there.

 

[1320stang]

I think I'd get some Snow Coat and coat the black EPDM with it and make it white. That would reflect a lot of the heat, but it may cause an unwanted glare when on the porch. Once you deck it though, it would be gone. I think putting on the deck, and coating the concrete porch would help a bunch. A close look of the connection from above between the porch and the roof should be looked at. There might be water infiltration at this connection.

 

[snorvet]

I agree with kbs2244. Get a dehumidifier. Last saturday it got to 80 degrees and humid here after several cool days. It was several degrees cooler in the detached garage in the morning when I opened the door for the first time in a couple weeks. I left the door open all day and the epoxy floor was sweating by noon. I installed a cheap thermometer with a humidity gauge and the humidity was reading 65-70%. After a few hours with the door closed and dehumidifier on, the humidity dropped to 50% and the condensation on the floor disappeared.

 

[Vicegrip]

He has a dehumidifier now. The cold wall in the warm space. I would insulate the wall and use a vapor barrier. There is a silver tape with a foam layer that is used to cover HVAC pipes that works well for stopping sweating. That might be an easy fix on the exposed metal fastners. I don't know the lay out but you might be able to get away with rigid foam board insulation if it is air tight sealed. Look for any places water is getting into the space and then being warmed by the solar input.