New Roof & New Condensation Problem


#1

Warning, this posting got to be a little long… sorry! :wink: ]

In May we had a new roof put on our 1923 colonial house in CT. I like the contractor and think he did a nice job.

BUT come winter, I’ve just discovered a new problem: water is dripping from the shingle nails onto the attic floor and more importantly onto all our stuff up there that could get damaged.

I discovered the dripping in early December and have seen it happen 2-3 times so far. It seems to be from condensation on the cold nails. It happens most/worst when the temps go below freezing at night but go up into 40’s in the day.

The OLD roof was 3 layers (1 cedar shake + 2 asphalt) and lacked a ridge vent. It NEVER HAD CONDENSATION dripping problem. In fact, attic always seemed like the driest part of house.

The NEW roof has all new plywood deck, plus 1 layer of Timberline architectural shingles, and a ridge vent. So the theory is that the condensation is due to the NEW THINNER ROOF and possibly NEW RIDGE VENT.

With fewer layers, the roof itself provides less insulation by itself. And the nails may stick through more than before (not sure about that, but it’s possible). Also, attic seems maybe colder than past years, perhaps due to the new ridge vent.

THEORY: Colder nails, sticking through further, leads to dripping.

(NOTE: Only the nails that come through the shingles are wet. There are many other old nails that they banged down before the new roof was installed and those are all dry!)

Q: Does this sound like good theory?

Q: If so, how should we address the problem?

My contractor is against getting rid of the ridge vent and I understand his reasoning. I suggested blocking the ridge vent from inside during the winter months and he didn’t seem to like that.

But his suggested solution is really a band-aid. He wants to nail FIBERBOARD to the underside of the rafters, but leaving openings at top (near ridge) and bottom (near eaves) for air flow. The fiberboard would catch the drips before they fell to the floor.

But I have some concerns with this idea. The fiberboard seems like it’ll absorb the water from the drips which doesn’t seem so good, possibly harboring moisture or mold. And I wonder if adding this layer under the rafters will be good thing to keep my roof healthy and to keep the attic cooler in summer & warmer in winter.

Another thought I had was if the ventilation could possibly be worse now, even with the new ridge vent. I’m thinking the new roof is tighter & more sealed (weather watch?) at the gutters/soffits than it used to be. We never had or needed soffit vents before, but maybe we need them now.

Any advice would be greatly appreciated!

-Rich


#2

Ok, Ridge vent WILL NOT WORK without soffit vents period. Fiberboard is not the answer.

Insulation is also one of the problems but not the major one. Without soffit vents the ridge vent can not work.

email me and i will help you understand this better. ALot to type on this site. I deal with this atleast once a week in the winter months.


#3

[quote=“gtp1003”]Ok, Ridge vent WILL NOT WORK without soffit vents period. Fiberboard is not the answer.

Insulation is also one of the problems but not the major one. Without soffit vents the ridge vent can not work.[/quote]

I think I understand how ridge & soffit vents work in tandem. But what is puzzling is that the prior roof, which was 80+ yrs old, never had a ridge vent and NEVER had this condensation problem. Do you have a theory on that? What did you think of my wondering about the roof being tighter, more sealed at the gutters/soffits… could that be the major factor?

Also, the insulation is no worse than it was before. In fact, it should be a little better since I filled in some missing spots after the roof job.

Thanks for the responsiveness.


#4

Hi,

The whole cedar roof was a vent. Air escaped all over.

GAF makes and intake fan.

See if the nails are rusting on the outside.

The old nails are sheilded from the cold more then the new ones. This may be the cause of the difference. The colder the nail the moisture will go those nails.


#5

Ok heres the run down:

Ventilation During Cold Weather
Dealing with the effects of moisture buildup. When
winter arrives and temperatures plunge, you might think
the movement of heated air would no longer cause problems
in attics. But that’s not true. With seasonal changes,
the conditions just reverse. Heat doesn’t travel from an attic
into the living quarters. Instead, heated indoor air travels
from the home into the attic – along with moisture.
Furnace-warmed air circulates through the
house, picking up water vapor generated by activities such
as cooking, bathing, and the washing of clothes and dishes.
The use of humidifiers, common in many homes, provides
an abundant and continual source of moisture. Keep in
mind also that the warmer the air is, the greater its
capacity to hold moisture.
The problem is especially acute in homes with electric
heating. Most of these homes were built since the mid-
1970s, using advanced insulation materials and methods.
As a result, most are “tight,â€


#6

Hi,

He stated that the old nails did not have condensation on them.

You do not like brainstorming do you???

I am in no way trying to brusie your ego. I am just throw things out there to find a solution.


#7

So is there a consensus that my new roof is likely more tightly sealed than the old one, especially at the eaves?

(Note: I have not yet confirmed yet whether plastic or weatherguard was folded over the edge and slipped behind the gutter, but I do know that both were used on my new roof where none was used on my old roof)

You mean look at the heads under the shingles? And what can I conclude if they are rusted or not?

That’s what I was thinking. Otherwise I wouldn’t know how to explain why the old nails are dry while the new nails (whose heads are closer to the cold weather) are wet.


#8

ok the nails are wet from condinsation. They are the first to attract the water that you can see. And they rust. You need to have soffit vents that is what is causing the problem. Im sorry lefty i did not read the post all the way.


#9

The old roof did not have ridge vent and had cans i can assume. The cans do not need soffit vents. The man problem is you have half a ventilation system and a good roofing professional should have known that. AS far as checking the new nail heads that might void your warranty since you have to unseal the shingle to find out. Email me your phone number so i can better explain what it is that is going on in your attic. I will be away for dinner back back in an hour or so. Then i can call you about this.


#10

I’m obviously thinking more and more about ventilation in my attic and how it might be less than it was.

Soffit vents were discussed w/ my roofer before the job, but since that would’ve added considerable cost to my job, and since the contractor didn’t insist on them, we decided not to do soffit vents. Perhaps that was a mistake by all.

I gather that people don’t think much of the 2" round vents. But they’d be the easiest/safest to install. My soffits are 83 years old and they may have some water damage from past ice-dam-ing, etc. So I’m a little concerned that they might break if we saw big long vent holes in them.

Q: Does anyone know if it’s common for old soffits to break and then have to be rebuilt because of damage during vent cutting?

Q: Also, does anyone want to recommend a good soffit vent system?

Finally, it’s winter and although it’s been mild so far, I’m not sure it’s possible or likely that we’d be able to do soffit work before spring. So I’m wondering if I should do something temporary like open my gable end windows a crack, although that might just defeat all the energy conservation we’ve been doing this year because our oil price is 15% higher than last year.

Q: Or is it safe just to have a higher-than-ideal humidity in my attic over just one winter and then deal w/ the problem in the spring?


#11

I don’t know what cans are but I don’t think we had any.

But the old roof had it’s own way of breathing it seems. Plus there are quarter-round gable windows at one end. And a 3’x3’ louvered exhaust fan at the other end.


#12

Hi,

There is nothing wrong with drilling a hole and installing 3" round vents. That will be the easiest and most econimical way to go.


#13

Hi,

**You mean look at the heads under the shingles? And what can I conclude if they are rusted or not? **

There is not always a definte answer. Just gathering information to come to a conclusion.


#14

Hi,

Open your windows a little. It will let the ridge vent draw better.


#15

Well thats the major problem. Your contractor should have known better to install a ridge vent system without soffit vents. I know i would never sell that system to a home owner without it. That is your problem without a doubt. I hope you went to the air vent web site to even further give you information about it. If you plan on putting new windows in your home anytime soon you will really have troubles if you have not already. Rasing the R value on the homes windows will only make the heat rise more and with the lack of insulation (if it is wet it needs to be replaced because it is useless now) you will be back in the same boat.

There is alot to properly ventilating a home and insulation is a large part of making the home more efficent.

Please send me your outside measurements so i can let you know how many soffit vents you will need to balance the airflow.

Gable vents are a no no also with ridge vents. It will cut the roofs ability to flow in an upward motion off causing a twister effect taking the effectiveness away from the ridge vent. Ridge vent works like a airplanes wing. It is called the Bernoulli Effect. It equalizes pressure on both side forcing air out the vent just like a planes wing get lift. And if you disrupt the upward flow of air you will reduce the ridge vents ability to work. Refer to airvent.com for more on this. Some people agree with me on this some will not but if you think about it, air follows the path of least resistance and anything in the way will slow or impeed the progress of the movement. Hope this helps


#16

If you email me your number or pm me it i can help you better understand the problem and help you solve it.


#17

ridge (exhaust) vent wont work without soffitt (intake), as i am just agreeing witheveryone else. was your roofer a “ROOFER” or just a construction company that does windows and doors and builds additions? if he was a “constuction co.” not a roofing company that is why he doesnt understand the full effect of ventilation. the length of your nail has nothing to do with it. dont look under the shingles because you will break the seal (which will not reseal on its own) and void any manufacture warranty. i think i read that you noted that the attic was cooler now than before. it should be a s close to the outside temp. as possible (while still maintaining proper ventilation). if you add 3" soffitt vents make sure you have a clear airflow from soffitt to ridge with no insulation blocking it. if need be get some styrofoam insulation baffles and stick them in there to keep an open space for air to flow. you also asked about weatherwatch. its main purpose is to protect your plywood from ice backing up under the shingles and rotting it. it is also required by code in the northern half of the united states.


#18

I like how you said that. You know what im taking about M.


#19

Thanks again to everyone for all the advice.

One OTHER thing I’ve noticed this winter is that the 2nd floor windows have much more condensation than I remember.

We always had a fair amount of this in the past… we have old/leaky windows & storms. But this year it’s gone to another level and it’s been almost constant, whereas in years past it was more sporadic.

So this seems to support one of the main theories that I have, which is that my new roof forms a much tighter seal on the top of my house than my old roof did.

The old one had a cedar shingle base, with 2 layers of asphalt shingles on top of that. And there was no felt, no plastic, no weather watch. So I think it breathed a lot more, and thus let the moisture from my living space (and attic) escape.

So I think my biggest problem is that the mosture is not escaping when the house is closed up for the winter.

Does all this sound logical?

I’ll leave the discussion about soffit venting, etc to my next reply. :wink: ]


#20

A series of 3" vents would certainly be easier/cheaper than continuous venting or near-continuous venting. Are you talking about the 3" round type? Have you found them to work well enough? One vent per bay?

(Note: My roof is standard colonial… ridge 31’… attic footprint 24’ x 31’)

Are the styrofoam baffles pre-fab? Do you have any links to some?

-Rich

p.s. I would still like to get your feeback on my prior reply and my theory about the tighter roof trapping moisture. Thanks!