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Old 12-08-2018, 12:39 PM   #1
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attic insulation and moisture problems


I just had a new roof put on a house i bought. The house is 60 years old and the insulation in the attic is covering the soffits. I want to do blown in insulation so i tried to put as many vents in as i could. I also have a ridge vent on the top. It is about 1300 sq ft. and i was able to get 18 vents in. it is very tough because the house is a ranch and i cannot get into a lot of the eaves. I am also noticing some of the insulation is damp and the plywood on the roof is damp as well. My questions are

1. Is 18 vents enough? its better than nothing and i don't want to have to take the soffit out from the outside.

2. Is the moisture due to all the heat from the house escaping through the ceiling and making the attic warmer?

3. would it be ok to blow insulation over the insulation that is already moist?

any information would be helpful. i want to get the insulation done due to a baby coming in February and it is beginning to get very cold out.

Thanks in advance!
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Old 12-08-2018, 12:58 PM   #2
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Re: attic insulation and moisture problems


Mold need food and water and old insulation will have lots of dust on it so leaving it damp is a guarantee for mold. Moist air leaking from the house is often the big problem.
You would like to have more intake air at the soffits than exit air at the peak so it would pull less from the house. So now what you want to look at is wires, pipes ceiling lights and anything else that comes into the attic as well as the attic access door. You need to dry it out before adding more. And in some cases the old should be removed.
Bud is good at this stuff and he will be along hopefully sooner better than later.
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Old 12-08-2018, 01:47 PM   #3
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Re: attic insulation and moisture problems


What size vents (NFA)? There are guidelines for how much vent area is good and we can review that with you. Describe your vents.

Do any kitchen or bath fan vent into the attic or are they maybe disconnected?

House humidity?

During the winter cold air tends to be drier, but may be location specific. Add your nearest big city to your profile to help us.

Unless the roof is leaking that moisture is coming from inside the house. A small amount passes through the drywall (diffusion) but the majority of it is carried by the air (humidity).

Wet insulation says enough moisture has collected to drip onto it, not good. Is it just one area? Any recessed lights, exhaust fans in that area?

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Old 12-08-2018, 04:01 PM   #4
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Re: attic insulation and moisture problems


The vents are 14" wide total, and the actual space where the air flows through is 10". i bought them at lowes. They are the black plastic ones. The only vent i have going to the attic is from the bathroom and that is connected. The humidity in the house is 41% per my nest thermostat. (not sure how accurate that is) I don't see any water dripping from the roof or rafters. The roof just seems to be damp on the north side of the house. The insulation doesn't seem to be wet all the way through, almost seems like condensation on the top. I just put the vents in a week ago and only noticed the moisture when i was doing the vents. seems to also be over the kitchen where we have vents in the floor pumping out heat which is more than other rooms and no recessed lighting. Now when i bought the house the inspection came back with mold in the attic on the plywood. I had a company come in and remove it. Not sure if that mold was caused by this problem over the years.
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Old 12-08-2018, 04:45 PM   #5
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Re: attic insulation and moisture problems


"The vents are 14" wide total, and the actual space where the air flows through is 10".
Sounds like you are describing rafter vents which are actually baffles to keep the insulation away from the roof. They are necessary but the NFA (net free vent area) is determined by the soffit vents.

As for the baffles you have, they are supposed to be in every rafter channel (I heard you moan). That allows the incoming air to remove the moist air directly below the cold roof deck. But still sounds like there is a moisture source we haven't identified.

You said "The only vent i have going to the attic is from the bathroom and that is connected." Does that vent continue and exit the roof or gable end of the attic. They are not supposed to exhaust INTO the attic.

70 air at 41% RH forms condensation at 45 which would be common in any cold attic.

Note, the mold issue you had was definitely caused by the same problem you are trying to resolve now. They only treated the symptom and did not solve the problem.

You put the baffles in a week ago, was there room for air to flow from the soffits into the attic area?

I'm concerned that your ventilation is not and has not been working.
1. Look at the underside of the soffits and describe the openings. A picture would be great. I would expect something like one of these.

Bud
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Old 12-09-2018, 03:40 PM   #6
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Re: attic insulation and moisture problems


Before you had the new roof installed were there no soffit vents or ridge vent installed ? With the mold issue you had resolved it sounds like the moisture problem has been there a while and may still be there now . Is there a vapor barrier under the current attic insulation and the ceiling ? And I agree with what has already been stated , you need to make sure all bathroom and kitchen vents go to the outside of the structure and not into the attic .
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Old 12-09-2018, 07:20 PM   #7
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Re: attic insulation and moisture problems


The insulation in the attic goes over the soffit vents. So i was able to clear 18 of them after the new roof was installed. There is a vapor barrier under the insulation and all vents are connected and venting out of the attic. The mold issue that was resolved was just a company coming in and scrubbing the plywood and cleaning out the mold. They told me they were not able to get the soffit vents cleared of the insulation.
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Old 12-09-2018, 07:27 PM   #8
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Re: attic insulation and moisture problems


Quote:
Originally Posted by scotty22 View Post
The insulation in the attic goes over the soffit vents. So i was able to clear 18 of them after the new roof was installed. There is a vapor barrier under the insulation and all vents are connected and venting out of the attic. The mold issue that was resolved was just a company coming in and scrubbing the plywood and cleaning out the mold. They told me they were not able to get the soffit vents cleared of the insulation.
So you have vented soffit but the insulation has fallen out into the soffit area? Have you thought about a shop vac with a long pipe so you can reach it from a distance?
Have you installed air chutes in the ones that are clear.
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Old 12-09-2018, 07:46 PM   #9
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Re: attic insulation and moisture problems


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So you have vented soffit but the insulation has fallen out into the soffit area? Have you thought about a shop vac with a long pipe so you can reach it from a distance?
Have you installed air chutes in the ones that are clear.
the insulation is jammed in there that i have tried everything but the shop vac. The way the roof is sloped, I have a real hard time getting in there. I have installed air chutes in the ones that are clear. I was able to do a total of 18.
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Old 12-09-2018, 07:52 PM   #10
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Re: attic insulation and moisture problems


Quote:
Originally Posted by scotty22 View Post
the insulation is jammed in there that i have tried everything but the shop vac. The way the roof is sloped, I have a real hard time getting in there. I have installed air chutes in the ones that are clear. I was able to do a total of 18.
I would try the shop vac.
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Old 12-10-2018, 07:38 PM   #11
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Re: attic insulation and moisture problems


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I would try the shop vac.
I tried the shop vac today and it was a no go. Who ever installed the insulation really jammed it in there. I think the only way to get it is to remove the soffit on the outside which is going to be a total pain.
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Old 12-10-2018, 07:40 PM   #12
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Re: attic insulation and moisture problems


Quote:
Originally Posted by scotty22 View Post
I tried the shop vac today and it was a no go. Who ever installed the insulation really jammed it in there. I think the only way to get it is to remove the soffit on the outside which is going to be a total pain.
What kind of soffit material do you have? That could get real messy.
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Old 12-10-2018, 08:15 PM   #13
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Re: attic insulation and moisture problems


Are you using some pieces of plywood to get around on? I hate trying to crawl on top of floor joists. When done leave them up there for the next emergency.

The baffles or chutes are there to provide air flow to each rafter bay, not just an air path to get the air up to the upper attic. Where you are seeing the moisture, is it in areas that do not have chutes?

Just covering all bases but you said new roof and a ridge vent. There have been instances where the ridge vent was installed but the opening was not cut or the underlayment was left covering the opening. Do a visual or test the air flow. I always hesitate to suggest a smoke test but maybe baby powder and a bright light. Incense sticks work but not everyone has them around.

To dry out the moisture that is there set up a fan to circulate the air.

Bud

PS if soffits are vinyl that may need to wait until warm weather.
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Old 12-11-2018, 05:36 AM   #14
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Re: attic insulation and moisture problems


Quote:
Originally Posted by scotty22 View Post
I tried the shop vac today and it was a no go. Who ever installed the insulation really jammed it in there. I think the only way to get it is to remove the soffit on the outside which is going to be a total pain.
cut teeth in the end of the pipe so you can dig into the insulation.
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Old 12-11-2018, 07:52 AM   #15
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Re: attic insulation and moisture problems


Scotty, can you post a picture of what you are looking at?

In my younger days I've crawled so far into tight spots that I almost had to be pulled out by my feet. I've learned not to do that, but with planning I still get close.

Bud
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