Master Bedroom is dramatically colder/damper (new construction)

11 years ago

We recently finished construction of our new house, and have been living here for just under 3 months. Our home is 2-stories, but the garage and master suite are on the side of the house almost like a single story addition.

We live in central Florida, so I've come to expect the overall humidity levels in the house to be higher than other parts of the country. However, our bedroom is remarkably colder and more damp than the rest of the house. You can feel a distinct difference when crossing the threshold into or out of the bedroom. We finally placed thermometer/hygrometers in various places in the house to take some readings and confirm what we suspected. With the outdoor weather in the 50s-60s, inside the majority of the house, we are reading 72 degrees and 60% RH. In the bedroom, the readings are 68 degrees with 76% RH. This makes the bedding feel damp to the touch and not at all cozy like you'd want a bedroom to be.

While this house was being built, we rented a house with a similar floorplan down the street from the same builder, and hardly ran our heat at all during the winter. But we have to run it constantly now to help dry out the air. This, in turn, makes the rest of the house too warm for comfort, and thus our programmable thermostat is virtually useless.

The builder brought in the HVAC installer to do a rebalance, but we don't notice a huge difference. Plus, that fix only applies its minimal improvement if we run the heat, which I prefer to not do. With most new construction, the house is very well insulated, and has features like the double pane Low-E windows, etc.

I'm wondering if it has anything to do with our attic space above the master suite being shared by the garage? There is deep blown cellulose above us, with batts around the eaves. The garage walls that touch living space are insulated. Perhaps it is because the master bedroom is cement block all the way around, but then again so is the rest of the first floor. Maybe it's due to being a single story vs two?

Any ideas or suggestions? We're pretty miserable and I really am not ready to break out the unsightly dehumidifier in our brand new house. :(

Featured Answer

energy_rater_la

11 years ago

you hire someone to blower door test the house
and do a duct leakage test on ducts.

www.resnet.us is one source of energy raters.
bpi is source of auditors
some utilities do blower door testing.

closing the vents on the first floor doesn't
put the air into the other rooms unless they
closed dampers of these ducts at the plenum.
just shutting the supply grills the air is still
being sent down the duct run to the supply.
doesn't provide any extra push of air into
other duct runs. and can really change static
pressure of ductwork. not a good thing.

best of luck.

Comments (7)

live_wire_oak
11 years ago
I'd suspect the space is inadequate insulated from the garage below.
BlackAce
Original Author
11 years ago
Sorry, I wasn't clear. The garage and master bedroom are on the same level. It's a slab construction, so nothing under the floor. The garage is in the front of the house, with the master suite connected behind it. This is the only single story section of the house, everything else is 2 story except the garage and master suite.
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ionized_gw
11 years ago
There are several problems possible. Insulation might be good, but maybe you have air leaks in the bedroom. Is there a separate return to that area? Are your ducts inside the house envelope or outside in a vented attic? You could be sucking a lot of humid air into the house because of leaks and pressure imbalances.

Keep after the builder. 60% RH is too high, not to mention 76%. It is no wonder you are uncomfortable.
BlackAce
Original Author
11 years ago
Thanks for the response so far. Today's readings were 74% in the bedroom, 71% outside and 63% in the main area of the house. Based on the outside temps today, I'd say the a/c probably was on for 25% of the time I was gone (about 9 hours), but that's just an educated guess.

The ducts are in the continuously vented attic. I went up to examine the insulation myself and discovered that contrary to what I originally believed, the blown insulation only covers the bedroom/bathroom. Garage ceiling has no insulation. There are batts in the walls that separate the living space from the garage.

How do I test for air leaks? Should I be running the a/c more than I am? The house is comfortable from a temp standpoint, but the dampness in the bedroom particularly is not pleasant.

When they rebalanced the system, he closed most of the vents on the first floor, including the master bath and master closet in an attempt to force more airflow into the bedroom. But won't that make for a more widespread humidity issue?
ionized_gw
11 years ago
This time of year will be difficult to control humidity because the system is not running much. That said, if the contractor is trying to fix it by closing supplies, it is not a good sign. (I hardly call that a "rebalance".) High humidity might also be caused by air leakage. The other houses on the block might have been built by different subcontractors and crews. Sometimes workmanship is not so great. I hope the HVAC system or house are not entirely FUBAR. There may be a simple fix, like a huge duct leak somewhere. That could cause outside air to be sucked in if the ducts are outside your building envelope. Your cooling could be way oversized. That can cause high humidity as well.

At this point, I think that hiring an impartial energy rater would be a very good idea. You should be able to find out what is wrong and that will allow you to tell your contractor what needs to be done to fix it. You should not be suffering these problems with a new house.

In the meantime, some details about your house might help some people that are smarter than me point to something obvious assuming that your house is built to current building codes. What is the square footage of your house and what does it say on the nameplate(s) of your HVAC system?

In the meantime, you should probably consider getting a portable dehumidifier so you don't start growing mold, Keep a log of indoor and outdoor temp and humidity without a dehumidifier. You've got to take the worst-case in mind and assume that you are going to have to take your builder to court. An energy rater's evaluation will help there too.
Mariam Hoffman
2 years ago
I have the same exact issue and can’t seem to find the solution. Did you ever solve this?