I built a garage that attaches to the house. The garage is wood frame and Hardiplank, the house is double wythe brick at the point where the ledger attaches.
More details are below, but I have confirmed there are no leaks after rainstorms, etc. However, it appears that moisture is condensing on the threaded rods and I am getting some drips inside the garage. In addition, the ends of the rods are rusting.
Any thoughts what is causing this and what to do about it?
Details:
I attached a double 2×12 ledger to the house to support that side of the flat roof. That is the uphill side, and the slope is 1/4″ per foot.
I drilled through the two wythes of brick into the edge of the concrete floor of the house, a depth of about 12″. I then epoxied 1/2″ threaded rod into the holes. The rods are 12″ O.C. in two staggered rows, so there is a rod every 6″.
I installed the double 2×12 ledger over the rods and secured it with 1/2″ nuts and washers.
The roof is a “flat” EPDM roof, glued to the plywood decking with the proper contact cement. I lapped the roofing up the house wall 12″, applied the compressible sealer behind it, installed a termination strip, and sealed the termination strip edge with the specified sealer.
I have checked the roof thoroughly before, during, and after light rain, heavy rain, blowing rain, etc. but have found no leaks.
If I go out to the garage on a colder but not raining morning, I see drips of water under the threaded rods. The exposed part of the threaded rod and the nuts are rusting, but the back of the washer and the threaded rod in the hole is not rusting.
It appears that moisture is condensing on the threaded rod, then dripping down. I’m not sure why, and why no condensation on other metal parts of the building.
Any suggestion on how to stop it?
Thanks.
Replies
the temp of the threaded rod is below the dew point of the air in the space where you are getting the condensation.
i would try insulating the end of the rods somehow. simple solution and should solve the problem
I believe you have a water leak in the brick wall and not condensation.
A brick wall is not waterproof. It will let water penetrate it. The holes for the dowels are a path for the water to weep out. I realize some of the symptoms are confusing, but this is the most likely answer. To confirm you would need to shield the wall from any wind driven water for a couple of weeks
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>I believe you have a water leak in the brick wall and not condensation.
Thanks for the comments. The thing that makes me suspicious is that I don't get drips when it rains, or even for several days after - I only seem to get the drips when the weather has turned cold overnight.
It also seems that the water would not come out through the holes, given that they are filled with epoxy and the threaded rod. Would the water pass through the epoxy?
If it is leaks through the brick, what would I do to fix it?
Those are good points, especially if no sign of water right during and after a rain. I'm re-reading and thinking this...
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Maybe the fact the rods are inserted in the brick mass acts as a reverse heat sink, keeping the rods cooler than most other metal in the shop. an insulative abrrier would eliminate condensation. Something as simple as a styrafoam cup for trial experiment
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There seems to be an abundance of moisture in the air. New concrete floor ? Evidently not much circulation up there either. Wonder what the heat source is?
An insulated cap sealed to the 2x's would keep the moist air from the metal. Perhaps something as simple as a coating of that Dip-it tool handle rubber coating would work.A great place for Information, Comraderie, and a sucker punch.
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I was thinking of that as a next step, but from my POV wanted to be sure this IS indeed condensation. Glue a styrafoam cup over a couple of these for a couple of weeks and if there is no drips to the floor under them when there is under others, AND if there is no water trapped inside the cups, then it is condensation, and so a thermal break like dip-it might do-it
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Thanks again for all the thoughts and comments.
I'll try the styrofoam cup idea and let you know.
There really is not an unusual source of moisture - the floor was poured about a year ago, the framing has been up for 9 months, anyway. The bottom plates are still shrinking, though - I recently retightened the holddown nuts.
Could there still be enough moisture in the framing lumber to be providing the moisture source.
One other interesting point I forgot to mention - not all of the rods are "sweating". For example, the ones above the garage door are not - that is, the rods that are above the garage door when it is open (about 8' back from the door opening). I don't understand why that would make a difference, with the garage door closed, but they aren't getting wet.
The roof is a flat EPDM roof, and there is no insulation, so the sun heats the roof pretty well. Guess I have a solar heated garage - great in the winter, not so good in the summer.
Thanks.
I agree w/ the advise given so far. Condensation does seem the most likely culprit.
You mentioned that this occurs mostly in the morning. Bear in mind that the masonry (the rods, and the air) have had 10 or so hours to cool down.
The next morning, the masonry and rods will undoubtly take longer than the air in the garage to warm up. The temp differential will cause condensation.