Replies

1. 
   Luka_ | Dec 24, 2001 09:25am | #1

   *
   You have warm, moist air entering the attic from the house, venting into that soffit over the porch. Where the water in the air condenses and drips on you, or forms the icicles.

   Find the air leaks into the attic from the house, and stop them up.

   You don't have any plumbing up above that porch cieling do you ?

1. 
   Don_King | Dec 24, 2001 10:13am | #2

   *Thanks Luka, no plumbing there. Sounds like I have a problem because the air leaks from the house are the whole rafter cavities that are open to the soffit over the porch. I thought it was desirable to vent the attic or ceiling right into the porch soffit. guess I blew it. everything is finished and would be very difficult to get to the attic space now. any othe solutions?

1. 
   Don_King | Dec 24, 2001 10:21am | #3

   *Come to think of it, my whole house is vented this way. The ceilings over the living spaces are open into the soffit and the soffit is either perforated aluminum or the pine with vent strips. Why wouldn't I have this problem everywhere?

1. 
   Luka_ | Dec 24, 2001 10:39am | #4

   *You could pull the porch cieling and seal up the wall from there. But that would just move your problem from the porch to the attic. You probably are having a problem in the attic, it just isn't as acute, or noticeable because there is so much positive air flow out of the attic, to the space over the porch. Block off that airflow, and the water will start to condense in the attic, instead of getting swept, (while still moist air), out over the porch.There are a lot of people here who will have a better idea of the whole situation than I. There will undoubtedly be good solutions put forth that I can't/haven't thought of. But since I am the one writing right now, I'll give you my opinion. (Again)I never suggested that you block the venting from the attic into the porch roof. You have to find the places where the warm moist air is leaking into the attic from your house, and stop them up. The air in the attic isn't that warm and moist just because it is sitting over the living space. You obviously have a lot of warm moist air getting into the attic from somewhere, and the only somewhere that it can be coming from is your living space. Plug those leaks. Leave the porch soffit alone.You will probably find yourself with a lower heating bill as a bonus.

1. 
   iron_helix | Dec 24, 2001 03:25pm | #5

   *Don,Another point of view....................Built-up roof sequences lend themselves to "splitting" of seams when snow/ice and cold cause the roof/tar membrane to shrink.Please don't rule out a leaking roof, considering the nature of your roof. Go looking for a hair line split, opened pockets or a protruding set of nails.Look first at the intersection of the house and porch roof where the attic temperature is warmer than the porch roof temp.---makes for a nice shear zone.....................Iron Helix

2. 
   Terry_Smiley | Dec 24, 2001 08:05pm | #6

   *DonI have a couple of questions.1.Is this porch roof on the north side?2.Does the roof pitch change from the house to the porch?3.Are there currently ice dams on the roof?4.How cold is it at night, what is the relative humidity?5.Is the whole roof tar & gravel on a 4/12 pitch?6.Is it dripping the whole length of the porch or just one spot?7. Can you remove some soffit to see if there is hoar frost on the bottom of the roof sheathing.Without these answers I can't diagnose your problem, but the first thing I would do is install a heat tape at the eave weaving it 3 feet up the roof to try and warm the eave line and remove possible ice dams.Terry

3. 
   Rein_Taul | Dec 25, 2001 12:14am | #7

   *Don,Make sure you don't have a bathroom vent or kitchen fan emptying into the attic. They need to vent clear to the outdoors. It is surprising how often you see these or a broken/leaking stack in the attic. There is a big source of moisture.

4. 
   Boss_Hog | Dec 25, 2001 12:35am | #8

   *Any chance of getting a picture ?That would go a long way towards helping us figure out what's happening.

5. 
   Don_King | Dec 25, 2001 01:03am | #9

   *It's on the south side,The roof peaks between the porch and the house 4/12 on both sides. There are no ice dams to speak of and it is in the high twenties at night. It is dripping troughout the lenghth of the porch ceiling in many different spots. It only seems to drip in the late evening. It would be very difficult to remove any soffit at this point. I am almost convinced there are no leaks in the roof other wise I would have dripping during the day when things warm up. The snow on the roof is almost gone. The only way for moisture to be getting from living space to attic would be through any flaws in the vapor barrier which includes plastic seals over the pot lights.(that I can think Of) There is no plumbing or mecanical venting in this part of the house. Sorry I don't have the ability to post a photo. Thanks guys

6. 
   Terry_Smiley | Dec 25, 2001 02:17am | #10

   *DonAre you sure there is air flowing from your soffit vents to your attic vents? I've never seen this much hoar frost with good air flow.You didn't describe your ridge vent, do you have one?Keep giving us info, now you have me curious. I can solve this riddle you joker.Terry

7. 
   Don_King | Dec 25, 2001 02:55am | #11

   *Terry, In the soffit I have a 1 1/2 inch strip vent at the top and bottom of the soffit, or, one at the facia end and one where the soffit meets the wall at the top of the pitch, they both run the width of the ceiling. No ridge vents. The ceiling cavities from the interior of the house are wide open to the soffit. Before I put the soffit pine on you could see right down the between joists. The insulation had about an inch and a half of space above it with those styrofoam spacers above the insulation. The peak of the roof is where the porch meets the house. All the ceilings are also vented on gable ends through perforated aluminum soffit. It is 4pm here in Kelowna, B.C. and the temp is about 32, I have not seen any moisture or drips yet today but I expect it to start in a few hours like it has been doing for the last few nights. Temp in the house has remained about 70 until 8pm or so the we let it get down to about 62. Humidity is presently at 80% outside. Merry Xmas

8. 
   Terry_Smiley | Dec 25, 2001 03:12am | #12

   *DonIMHO you're not getting unrestricted airflow through your attic. You're trying to force the warm moist air thats entering your eaves back down and out of the gable soffits. You need either a continuous ridge vent or multiple attic vents. I really beleive this is the problem. Your attic is air tight. Get that air moving. Please keep me informed and feel free to email me with any other questions, information or ideas you have.Happy HolidaysTerry

9. 
   Luka_ | Dec 25, 2001 03:50am | #13

   *i Before I put the soffit pine on you could see right down the between joists.You do mean joists and not studs, right ?What kind of insulation do you have in the attic ? In the walls ? If you meant studs, and not joists, you could have living space air escaping into the attic through the walls, as well as the cieling.Thinking about this, and sleeping on it, it occurs to me that if the problem is as severe as you seem to alluding to, it would take a huge amount of heated air escaping into the attic to do this. At one point you said the snow is almost gone. And now you say the dripping hasn't started yet, but you expect it to at any time. Don't be too quick to rule out a roof leak.All that said, I grew up in Indiana. I do understand a bit of what goes on with leaky houses in very cold weather. It is still possible that it is simply a warm, moist air problem. If that is the problem, then what Smiley says makes a lot of sense. Howsomever... If you open up the attic, and vent it well through the gable ends, etc... The water problem may go away in the porch and attic both, but you will still be pumping a lot of your costly heated living space air into the outdoors.Look for leaky vent stacks, leaky bathroom vents, etc, as some others have said. Then look for all the insidious little leaks from the living space into the attic. Venting may take care of the symptom, but taking care of the problem itself will keep from venting your wallet any more than necessary from now on.

10. 
    Don_King | Dec 25, 2001 08:14am | #14

    *I meant joists, rafters, whatever, not studs. Half of the house has been here for thirty or forty years, same basic layout, 4/12 tar roof vented from the soffits, no ridge vents, no problem. Can I be venting too much? Maybe I have a leak in the roof. I have not seen any dripping tonight. I used to be a roofer and have pretty good grasp on the eccentricities of H2O. I'll have to have a good look in the spring to be sure I guess. I think I need a better grasp on venting and condensation and possibly one more eggnog before I lay out the cookies. Good night to all and to all a good night. Thanks so much for your opinions.

11. 
    Johnnie_Browne | Dec 25, 2001 06:18pm | #15

    *Why not get up in the attic with a flashlight and look for moisture?

12. 
    Terry_Smiley | Dec 25, 2001 08:23pm | #16

    *DonMore questions:1. Describe your "tar and gravel roof". Is it a hot mop or torchdown system?. Did you install it?2. How long (approx) are your rafters (north side over living and south side over porch)3. You say that the original house was exactly this same configuration, describe what you added on.4. Is it a simple gable roof, with only 2 pitched roofs meeting at a central ridgeline?5. What venting have you added from the original construction.6. The is no access to your attic is there? It's all vaulted ceiling right? Is the ceiling joist the roof rafter?To help you understand condensation here's my simple understanding of what happens. Warm, moist air comes in contact with a cold surface (ie outside of a glass of icewater). In my mind, based on the information you've given so far here's whats happening. Just like in the formation of a cloud, the warm, moist air (80% relative humidity) from under your soffit is rising (due to natural convection currents). It enters your attic space and continues to rise to the highest point of your roof, taking the moisture with it. As the temperature of your roof cools it reach the dew point. This is when condensation begins, it's the same temperature where dew forms on the ground or that it begins to rain if there's enough moisture in the air. This warm moist air will not travel down unless forced, you must allow it unrestricted upward flow. You don't need to be losing moisture from your house for this to happen, as I stated earlier, there's enough moisture in the air. You're building clouds. I hope my explanation doesn't offend you I just wanted to be sure you understand what's happening. I've seen it in the most expensive homes when the conditions are just right, your only going to see it get worse as the temperature drops. Please give me more info, I'm a pit bull when I get my teeth into a problem. We can fix this.Terry

13. 
    Don_King | Dec 25, 2001 11:35pm | #17

    *Terry, It's a hot mop and I didn't do it myself but watched pretty closely. North slope is about 40 ft and slopes back down on the south over the porch about 18ft. I added the area in question which houses the kitchen mostly. I kept the same roofline and instead of having a 2nd storey just made real high vaulted ceiling, a simple gable with only 2 pitches, 2x10 rafters with 10 inches of batt insulation strapped with 2x4 and sheeted with 3/4 t&g osb. 6ml vapor barrier between the rafters and the t&g pine 1x6 ceiling. The ridgeline is above the door leading to the patio which also has t&g pine ceiling but no vapor barrier. There is no venting between the new construction and the old. On the old end of the house I covered the original plywood soffit with perforated aluminum, not really changing the venting at all. Yes, the ceiling joists are the roof rafters (2x10s). I tend to agree with the building clouds theory, so, With a good vapor barrier over the kitchen it is the moist cold air outside that coming into contact with the warm air rising up through the rafters? If this is the case, does that mean I need some ridge venting? Makes sense. And of course it's not hapening on the old part of the house because the roof over there is all over living space. The key to the equation must be the cold slope of the covered porch. Sounds like the way convection or upslope fog is made. Am I on the right track? Thanks, DK

14. 
    Terry_Smiley | Dec 25, 2001 11:58pm | #18

    *DonI really beleive this is the case. You said earlier that you had used styrofoam channel forms as vent space in each rafter bay on top of the insulation. If this is the case, yes the easiest solution I see is opening up the ridge. Without attic space this will require the whole length of ridge to be opened and a "Coravent ridge vent" or similar product be installed. As I said before I really beleive this is your solution.Good luck and Merry ChristmasTerry

2. 
   Don_King | Dec 25, 2001 11:58pm | #19

   *
   I finished building my house in the fall. It has a 4/12 pitch with tar and gravel and vaulted ceilings. On one side of the house is a covered porch also with a vaulted cieling that I covered with T&G pine. The soffit, or ceiling of the porch is leaking water between the pine in many places and toward the facia forming icicles. I am presuming for the moment the roof is not leaking and I am having some kind of condesation problem. The soffit is vented at the facia end and where the soffit meets the wall of the house, the roof of the house is open into the soffit thus venting a majority of the roof into the soffit over the porch. I used a 6ml vapor barrier over living space but not over the porch area. It is below freezing out and there is old snow on the roof. I hope someone has an clue to the mystery. Thanks