Homes Heat Up in Central KY!
Wednesday, July 19th, 2017 by Joy Padgett
It is most definitely summertime! Summer in Central Kentucky is typically comprised of extreme heat plus extreme humidity. I mean, it’s like walking in soup broth….whew! And it’s normal to head off to work at 7:30am and be drenched is moisture by the time you reach your car in the driveway!
Have you ever stopped to think about how the conditions outside affect your house? I mean, it’s normal to think about such a thing after severe weather…like powerful thunderstorms, straight-line winds, or tornados, but what about something seemingly irrelevant….like extreme heat? What impacts does extreme heat have on a home?
With the extreme summer heat we’re used to here in Central KY, the roofs on homes in our area can reach upwards of 160 degrees! Ouch that’s hot! AND….that heat radiates downward into the attic where temperatures can reach a whopping 140 degrees! But this heat transfer doesn’t stop in the attic. It continues its downward movement through the drywall ceiling and into our living spaces.
Let’s read that again….the heat continues its downward movement through the drywall ceiling and into our living spaces. Well, it’s no wonder we’re hot even inside our homes during the summer! The reason for this movement is that hot moves to cold. The heat from the sun is being absorbed by the roofing materials (shingles, tin, etc.) which causes them to heat up. The roof deck underneath the shingles is cooler than the shingles and therefore the heat from the shingles naturally migrates toward those cooler surfaces. Once the roof deck is heated up, the air in the attic begins to heat up. The air in the attic is touching the attic subfloor which is then heated up. The subfloor is connected to the drywall ceiling of the rooms underneath, so the drywall begins to heat up…..you get the picture. It reminds me of that old kid’s song Dem Bones.
What this leads to is a house that is controlling us! We need to stop this from happening and regain control! We should expect more from our homes. After all, we are paying for them. And we can’t take rooms that are not usable due to temperature issues off our mortgage….but I wish we could!
So, what do we do to defend ourselves against the heat and regain control of our homes?
At this time of year, We begin by working on improving the conditions in the attic. Improvements vary house to house, but should always include air sealing and uncompromised insulation. Can light covers and chimney wraps may be needed if you have these features in your attic.
Air sealing….yes, I know, you’ve been following my blog and I’ve spoken of this before, BUT it is the keyto making your house more comfortable. You see, since heat can easily be transferred through the air, we need to trap the air where we want to trap it. For example, during the summer, knowing our attics are going to get hot, we want to trap the attic air inside the attic. The way we do that is to seal up all the gaps and cracks in the attic (or as many as we can find).
There are several different products that are used to seal up gaps and cracks depending on their location. We’re talking spray foam and caulks, mostly. These products prevent air from flowing through gaps, cracks and holes in various areas through the house, but we’re going to focus on the attic. What kinds of gaps and cracks am I talking about? Well, plumbing, electrical and HVAC penetrations for starters. These contractors usually drill large holes and run small wires or pipes or venting which leaves a gap around those components. That gap is a passageway for air flow, which means heat flow during the summer.
Uncompromised insulation is the next improvement I mentioned above. Most insulation over a few years old has probably been compromised…meaning a mouse, squirrel, raccoon, or insects have gotten into it and messed it up. Sometimes this means they have “re-arranged” it to use as nesting materials or used it as a potty. These things have compromised the integrity of the insulation and its ability to actually insulate your home. Add to that the fact that unsealed gaps and cracks beneath the insulation transform that same insulation into a giant filter by allowing air to flow through it depositing dust, pollens, and other particulates onto the insulation. Totally compromised insulation is the result.
Insulation that has been moved around or smashed down is not providing the r-value it should. Add to that the fact that most new homes don’t have the recommended levels for Central KY to begin with, and we can easily see the importance of uncompromised insulation. If you’re in Central KY where I am, the recommended R-value is 49 which or about 16 inches of cellulose insulation. R-values vary according to the type of insulation, but cellulose is a very commonly installed insulation, so I used that rating.
If your attic contains what I’m going to call “specialty items” those items can also have openings around them which allow hot air to transfer into room under the attic. Can lighting would be one of these specialty items. Although some can lights are now being manufactured to be more air-tight, most of them are not. If you look at them from inside the room they are being used to provide lighting for, they look wonderful! However, if you hold your hand up to them, you’ll probably feel air coming down around them….air from your hot attic! If you look at these lights from inside the attic, you may notice the insulation hasn’t been blown up right against them. This is because these lights are heat generating devices and cannot have insulation blown right up against them for safety reasons.
So, how do we address these recessed lights? The company I work for has rock wool can lights covers that are fire-rated and can be placed over the light. The next step is to seal the can light cover using a fire-rated foam or caulk. This will air seal the can light and prevent hot air from being able to more from the attic to the living space beneath during the summer. The photo below shows a rock-wool can light cover that has been sealed. This light had a pipe running right across the top of it, but the ingenious installers at the company I work for didn’t let that stop them!
Maybe your house is like mine and you have a chimney that goes through the attic. Any gaps around the chimney create pathways for air to flow. Hot air from your attic will again move through the gaps around the chimney and into the room beneath. And, like the recessed lights, chimneys are heat producing structures, so you can’t just put any kind of insulation up against them. We go back to the rock wool and have a special chimney blanket we can install to close the gaps around the chimney without sacrificing the safety of you and your loved ones. And, once again, air-sealing foam or caulk is used to seal the chimney blanket.
Now we can understand the importance of combining air-sealing techniques with insulation to create a sort of defensive shield in our attic to trap the hot air where we want to trap it….in the attic. This is a step toward regaining control of our home!