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dripping walls

3K views 14 replies 7 participants last post by  daveb1 
#1 ·
We insulated our 2 car garage walls and ceiling with fiberglass over the past summer, sheet rocked the walls. The door is from 1961, old and drafty, so we thought this would not give any problems. Now we have brown drips running down the sheetrocked walls inside as well as the siding outside the garage...what to do?? Where we live, we have both extremes of temps. Thanks
 
#3 ·
It would help if you were more specific as to the details of the insulation process. Faced or unfaced? If unfaced, what vapor barrier did you use? How did you overlap this barrier? How did you seal the vapor barrier to the floor?
Where do you live?
Ron
 
#7 ·
Dripping walls

Thank you all for replying so quickly. I hate to confirm what may be the worst...there is no ventilation between the insulation and the roof. We put the insulation between the roof's rafters. The roof's insulation has open faced insulation with a vapor barrier covering it (on the bottom, visible from inside the garage side). The walls have open faced insulation with a vapor barrier in between insulation and the drywall.

If I had to guess from your reactions this is not a good setup. We live in North Dakota. This means an average of zero degrees (with extremes of -30) and 80s - 90s in the summer. We have about a foot of snow on the roof right now too. The garage is attached and has a heat source. We keep it in the 50s though.

Thank your for your advice. Please don't hold back on opinions. We're starting to think that this way of insulating the roof is not a long term solution, to say the least.
 
#8 · (Edited)
By open faced insulation do you mean un-faced?Is the insulation touching the roof sheeting of the garage?I'm thinking moisture has become frost between the drywall and the insulation.Warmer weather has melted the frost and the water is now dripping. I'd reccomend NOT walking through or parking in the garage until you can open an inspection hole in the drywalled ceiling and see if this is happening.The drywall may be saturated enough to fall down.

As an after thought, is the ceiling dripping or just water running down the walls? If the ceiling is not dripping then you may not have to open the drywall just yet. You may have an ice dam forming in the eaves area under the foot of snow on the roof.

Can you post some pictures of the roof and ceiling?
 
#10 ·
Loook at it this way: you have a high humidity area, partially heated (so even greater humidity levels), some insulation - you don't say how much - the level of which in North Dakota is quite important and the presence of a vapour barrier. I presume you have no horizontal ceiling over the cars, just rafters and then the roof sheathing, is that correct? So I presume therefore that the heating "envelope" is the entire area under the roof...am I right or is their a ceiling over your head and an attic space?

Well, either way, you are getting excess humidity condensing on the colder surfaces somewhere in the... drywall/vapour barrier/insulation/rafter/sheathing... space.

Now you can lower the humidity, and/or make sure the humidity doesn't get past your vapour barrier (whatever it is), and/or get a better vapour barrier seal, and/or add more insulation.

Similarly, you can put in a ceiling and lower the insulation to that and let the roof get cold and ventilated.
 
#12 · (Edited)
These guys are right.
Pull that insulation down and toss it. It's wet now and it's R value is very diminished. Vent the roof with chutes, then put up the insulation, then poly. Myself, I would just use craft faced and let it breathe, even though it's not correct....I wouldn't want to worry about dehumidifying my garage 24 hours a day.

On edit, you could do a floor drain for your cars melting off, and some fans to get it dry. This may help if you want to use the poly. Either way, you must vent from the soffits to the top of the roof in every bay.

The stains you see are probably just dust that has collected on the rafters and is now being brought down from the condensation dripping.

READ the buildingscience blogs. Everyone should read it and get a better understanding. It really opened my eyes.
 
#13 · (Edited)
What type of Heat source ??

If its a wall mount vent less (gas) they will put out a lot of humidity.

Snow laden cars coming into a 50f garage will give off alot of humidity also.

I've seen this situation and figured the roof was getting hot enough to melt

the tar and soaking through the ply ( the ins was holding on to the heat of the hot roof in the summer and just cooking ).

The humidity mixes in the winter and then it drips.

The garage is attached to the house.

You could with a little work put in a drop ceiling and lightly insulate above it.

Vent the peak and soffits.
 
#14 ·
Well, OK then, one way to fix it will depend on whether you can put up a ceiling or not; I imagine you have trusses running side to side onto which you could put a ceiling - in which case you'd be making yourself an attic. What you are doing is twofold: making the heating envelope smaller i.e heating only the area you need to heat and not heating the roof (which doesn't need heating) thereby lowering your heating costs - and cooling the roof and letting it breathe.

So put in a ceiling if you can and remember to cut yourself an access hatch; but if you don't want to put in a ceiling, then your "envelope" will have to be water vapour-tight; that means having an air barrier (the drywall), then having a plastic vapour barrier properly sealed to prevent any moisture from reaching the attic and then the proper amount of insulation, preferably blown-in. Seal all outlets like holes in the ceiling where the light fixtures go so as to ensure that excess humidty does not travel up to the attic and then condense on the cold roof surface.

Leave the underside of the roof clear of old insulation and any other covering; make sure it is ventilated at the roof-top (if you have a vent up there, good!) and make sure there is air getting in to balance the air getting out. This will ensure the attic dries out in winter and in summer.

So, in order: drywall, vapour barrier, insulation...all around the envelope. More insulation in the attic - like about 6" or so but a good vapour barrier too. Dehumidify the garage if it gets too wet and make sure the drains work. Cold garages are best for cars. Do you have salt on your roads?
 
#15 ·
This is probably how I would remedy this situation also.Being as it is attatched I wouldn't heat the garage either unless I had work to do in there.On real cold nights I'd plug in the block heater if your vehicle has one.This is all I do in my unattatched garage.Taking a heated car into cold weather is hard on them.Imagine the type of moisture problem of your garage now happening in your engine and fuel tank.
 
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