Attic Ventilation: Protecting Your Home from Moisture and Mold

Jamie: 00:00:00

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Today we're going to jump into a topic that you might not think about, something that you don't see until it's a problem, but something that's quite important. Something that is, as the summer heats up, as the temperatures stay warm morning, noon and night, you're going to really care about.

And that's attic ventilation. Why does attic ventilation even matter? Well, a couple of things. Number one, it prevents moisture buildup, avoids mold, mildew and rot.

The best kind of attic ventilation is the naturally occurring attic ventilation, meaning you have soffit venting down at the bottom of the eaves and you have ridge vent up at the top. So you get a natural circulation. As air enters your eaves, heat rises. Correct.

So as the air gets heated up, it rises, exits out the top and you get natural cooling that way. In the winter it works in reverse attic ventilation. Cold air drops because it's heavier, so it drops out the eaves.

So either way you get the natural ventilation. Not all houses have perfect attic ventilation, but they can still be effective in how they do it.

So number one, it prevents moisture buildup, which leads to mold, mildew and rotten things like that. It helps with temperature regulation.

Think about your attic, think about how much insulation you have up there and, well, how does that affect how your house feels? There's some rooms that have better, what shall we say, airflow out of your registers.

And so you might have that room, especially upstairs in a two story house where you have poor airflow, especially in the summer, the cooling doesn't get up there quite as easily, it doesn't flow as well. And so you're just generally not going to have the comfort that you'd like. And if you have a hot attic, it's going to be even worse.

And so adequately ventilated attic is going to help with that temperature regulation in those rooms, especially in the upstairs rooms if you have that.

And another thing that attic ventilation really helps is shingles, something you may not think about, but manufacturer warranties on shingles are difficult to collect on anyhow. But if you have a superheated attic, you're basically cooking your shingles and it may not.

You know, we found over the years that it's very different in how poor attic ventilation affects houses. You may not notice it other than you feel it and the difference inside.

But the shingles, they can cook and you don't even know it, that that can lead to premature curling and, and wear on the shingles. And they'll just be extra hot. So if they are walked on, you'll have more mechanical damage and things like that. So how does it work?

Well, it's about intake and exhaust. Cool air comes in through the soffit vents. Relatively cool air. Like this morning it was in the 40s. Right. And as that heats up, it's going to rise.

And as it rises, it goes up. Where's it going to go if it can't go anywhere? It's just kind of get trapped in there and that's going to lead to moisture issues, condensation.

And so you want some kind of balanced system. Ideally, your ventilation would be about 50% at the base or at the eaves and 50% at the ridge.

Now, we're not going to get too much into the technical part of how much you need per square footage of your home, but it's more important is it working, is it balanced? Because if you have too little up top, bunch at the bottom, air is going to tend to in the summer get trapped near the peak.

And we've seen that on homes where we go in the very peak of the house doesn't have good ventilation. And you may get some mold growth up there because that's where things end up in the condense and so forth.

And likewise in the winter months, if you have a lot at the top but not at the base, which that's not near as common, but we do see it, you can end up with some staining and moisture issues as well. So it's very important to not only have a balance of it, but that you have constant circulation going on throughout all that.

So here's some signs that you may not have enough attic ventilation. Number one, excessively hot in the summer. What do we mean by that?

Well, anything over 120 degrees when we do a home inspection, one way that we we judge on if you have good ventilation, one is just feel it, look for it. But if it's, let's say 80 degrees outside and your attic is over 120, that's way too hot for what the temperature is outside.

80 is hot, but it's not super hot. It's not, you know, the desert in Arizona hot of 110 or whatnot. So really, if you have Adequate ventilation for the most part.

There are general rules, but for the most part, your attic should not be more than 10 degrees warmer than the outside temperature. Now, I understand there's some variances to that depending on the time of day and when the sun's beating on what side of the roof and whatnot.

But in general, we go up there in the morning.

If it's hot yesterday and it heated your attic up to, let's say, 110 degrees, we come back the next morning, that should be back down because you should have had adequate cooling overnight. Good airflow to get that heat out of there. It won't be immediate, of course. Your attic is going to be hot when the sun's beating on the roof.

But you want some kind of process and some kind of ventilation that's going to cool that down at night. So, number one, excessively hot. Number two, condensation, frost or rust on the nails. And this will come in the winter.

Okay, you look up in your attic and you see one of two things. Let's say we're in the winter. One, you see the bottoms of the nails protruding through that the shingles are held on by. Look, white. That's frost.

Frost comes from condensation. That means you're not getting good ventilation. And so you want to improve the ventilation. So that doesn't occur. Now, if it's.

If you don't have certain conditions that are creating frost, right, then you might see black staining around the nails. So you poke up, you poke your head up in the attic and you see black staining around all the nails.

Well, that's from moisture, that's from condensation happening. And it's an indicator that you don't have proper ventilation up there. And then just general. The third sign of a not ventilation is mold or mildew.

Now, it's primarily mold. Mildew grows on living things like plants. Mold grows everywhere else.

And so any smells or visible staining, that's a sure sign that you got something going on up there that shouldn't be. That is lack of ventilation. So number four, we've just talked about this. Curling shingles, ice dams, or high energy bills.

If you have poor ventilation, especially in the winter. Well, only in the winter, it's going to lead to ice damming. And ice dams are.

When the snow melts a lot of times because you get too much heat loss coming from the attic, it melts, it runs down to the eavesdrop. And where the eaves are, it's not heated, right. There's no heat below the eaves. And so it refreezes and becomes ice.

And then as more snow melts and comes down, it can't get off the roof, backs up under the shingles and enters the attic. Now it's not uncommon for this to happen in small quantities. And if you have good ventilation, it's going to naturally dry that out.

But if you don't have proper ventilation, any type of ice daming at all is going to create a problem in there, damaging the wood.

Sometimes we'll see homes where the wood, the plywood under the, or the decking under the shingles has been replaced along the entire eaves on both sides and nowhere else. And that's from ice damming over the years and damage to it. So yet another good reason for ventilation. And then insulation that's damp or compressed.

This is where insulation is damp just because it's so moisture laden up there. Or you're getting dripping, literal dripping off the nails that are dripping onto the insulation and compressing it.

Sometimes you'll have ductwork up there that has drip marks all over it. And that's what that's from. It's just from condensation. You don't have a roof leak, you just have condensation.

So the math, how much ventilation do you need? So a General rule is 1 square foot of ventilation per 300 square foot of attic space with a vapor barrier. And without a vapor barrier it's 1 to 150.

example, let's say you have a: 1200

That means you need 4 square feet of ventilation and you want that split between the eaves and the peak. So two square foot up, two square foot down. Now how do you measure square feet in ventilation? Well, a ridge vent is going to be about 2 inches wide.

And so if you calculate that out, 2 by 6 inches is about 1 square foot, right? 2 by 612 inches. 12 square inches. And so calculate that out. You don't need a whole lot, but it needs to be balanced.

And the bigger the attic you have, the more that you need. So divide evenly between the intake and exhaust.

Don't add more exhaust with an out, ensuring proper intake so that can, that can backdraft moisture from the home into the attic. Let's talk a little bit about the types of venting you may have. Soffit venting soffits are on the underside of the eaves.

You'll see soffits with little small holes in them. And that's where the air goes into. So you don't make sure you don't block those.

Many times flippers will come in and spray paint everything and they'll clog up those holes. And that's certainly something to look for. Ridge vent, that's going to be in the peak of the roof. Number three, gable vents.

Gable vents are going to be on the end. So if you have a straight gable roof with the normal peak, then you have a gable vent on each end. That can be effective on smaller footprint houses.

It doesn't work real well for a house that's a little longer just because the air doesn't get through it. Unless you have just a baseline super, you know, straight line wind, it's hardly going to get from one side to the other, at least not effectively.

And even then it really doesn't get down into the eaves of the attic. It tends to stay higher in the attic and the center of the attic more than the eaves. And then you have roof turbines or box vents.

Box vents were very popular in the 80s and 90s. These basically just look like a square up on your roof. You'll see them many times. They're about two feet apart.

You'll have four or six of them on an attic. And that can be effective. It does provide more avenues for moisture entry, we have found. And they're not as effective as a ridge vent.

A ridge vent is the most effective. And then roof turbines. And this is kind of a circular type device that comes out of your roof and as the heat rises, it will spin the heat.

The heat rising causes it to spin and that draws airs out of your. Draws air out of your attic. This is sometimes done in attics that are very difficult to ventilate. They have a lot of twists and turns.

Maybe a ridge vent is not practical for what we need and so that can help. And then finally you have powered attic fans. Powered attic fans are connected to a.

Either a switch or a thermostat that controls the switch or controls the humidity and the heat. So when the, the heat gets too hot or the humidity gets too high, it will kick on and draw air out. These are debatable in their effectiveness.

It puts the home under negative pressure, so it's sucking more air through from the interior living surfaces. So air conditioning and things is going to be drawn up into the attic. And so that's not as efficient as what you would like.

So some deep, some inspection tips. If you're looking for your attic, look for daylight through soffits from inside the attic. You don't want daylight, but you do want to feel airflow.

Feel for it. On a breezy day, if it's stagnant air, you're not going to feel it anyhow.

But go up there on a breezy day, check for insulation blocking the soffit vents. Or remember that's under the eaves.

And so if insulation is crammed on into the eaves, unless you got the baffles in place that have channels for airflow, you're not going to be able to get that proper airflow. And they may need to be cleaned out.

And you use a hygrometer to monitor your attic humidity, they should stay under 50 to 60%, which is going to be difficult when you got a 90% humidity, 90% humidity out there during the day. So when to call a pro? Well, when you see signs of mold staining or insulation issues, I would suggest calling a pro.

Unless you have skills in that field. If you have the ability to make improvements on your own or you and your friends do, that'd be great. Otherwise, call a professional.

At least get an assessment on it. And that could even be like a home inspector. Call us. You need an assessment on your attic to determine if you if increased ventilation can help.

So if you're unsure how to balance your intaking exhaust, that's a good thing to do. We have found our experience with roofing companies is they don't have a lot of experience in ventilation.

They should, it's part of installing a roof. But they don't think about the balance.

They don't think about certain things related to attic ventilation improvements, even if they put on a brand new roof. So here's a couple of bonus tips in closing. Never mix ventilation types. Ventilation types that is ridge and gable.

If you have soffit venting and you have ridge venting and then you have gable vents on the end, close off the gable vents. That airflow is the pattern is going to be disrupted if you have those gables. So block those off. Insulation and air sealing matter too.

We had a podcast coming out recently on air sealing your attic. And that is one thing that makes a big difference.

You don't want all that beautiful conditioned air that you're paying to condition in the summer to rise up and be lost into the attic. So that's an important fix. Good ventilation can extend your roof by 5 to 10 years. So think about that.

You can spend a few hundred or $1,000 on ventilation improvements and save a $20,000 roof another five to ten years potentially. So some very important considerations to think about with your attic ventilation. You don't want to put it off. At least take a peek up there.

If you don't feel comfortable doing that, call a professional to do it. You know something? You might have bought a house. You don't know anything about. What's up there? Maybe they've blocked off access. Whatever.

Call a professional to come take a look at it and make sure you're getting the most out of your house. Make sure you're not putting up with excess heat in your upper rooms. Make sure you're not cooking your shingles.

Make sure you're not creating conditions in the winter that would lead to potential ice dams and so forth. So we appreciate you watching and looking and listening to this video. Please take the time to share it, comment on it, ask us questions.

Most importantly, call us. Make sure your home is safe and comfortable this summer. Thank you for listening.

This week you can catch up on the latest episode of the Thoughts from the Crawl Space podcast on Spotify, Apple Podcasts and YouTube. For more information about Gold Key Inspection services, go to goldkeyinspect.com.