My house was newly built.The
My house was newly built.The contractor used R-13 for 2×4 walls.We still feel cold in the house..Going forward what would you recommend?..

Allison,
Allison,

Thank you for the comments and the additional information. An update on progress: we had a local spray foam rep come over for an inspection and recommendation yesterday. He, too, said get rid of the fan, seal the top and side ventilation up, then spray the ceiling and walls with a continuous coating of foam. He recommended we use open cell for 2 reasons: 1) the fiberglass will need to expand and contract due to weather changes (southern Missouri so we have all 4 seasons) and he was worried about allowing expansion room, and 2) he was concerned about moisture coming in through the seams at each of the 16 panels or a leak in the roof (which there is evidence of and will be addressed). He concern was if any moisture did get through, it could create mildew and be really bad before we ever knew it. He suggested closed to allow it to drip on through then we would know. He said we need to install a moisture control system, as Thomas mentioned, to prevent moisture on the inside because the assumption is any moisture will not escape through a solid fiberglass roof.

By the way, the floor is concrete slab. The picture I uploaded still had the dingy 1970’s carpet and, yes, it looks like dirt in the picture.

Thank you,
Greg

Kevin,

Kevin,

Good questions.  The photo at the top of this article doesn’t show any depth markers but this attic definitely had them.  It also had the card showing depth, bags, square feet, and R-value.  That’s something most insulation contractors do get right, in my experience.  Maybe they didn’t have quite enough markers to meet the 1 per 300 sf, but they were there.  This was a Habitat for Humanity house and they do a pretty good job, at least on the ones we verify for ENERGY STAR, which this was.

Even better, I think most contractors around here have realized they can no longer get away with cutting the first few inches off of the markers. ;~)

~ ab3

Roy,

Roy,

Excellent point!  We’re definitely dependent on those who do the dirty work to make buildings live up to their design.  Everyone needs to be on board.  I wrote an article a couple of years ago about this topic:

In Praise of Those Who Do the Dirty Work

~ ab3

Greg,

Greg,

Here are some more articles you might find helpful:

Make Dew Point Your Friend for Humidity

Two Rules for Preventing Humidity Damage

What Happens When You Put a Plastic Vapor Barrier in Your Wall?

Accidental Dehumidification – A Preventable Mess

~ ab3

Greg,

Greg,

There’s a lot to say about this house and the things you’ve written about it.  First, Thomas is absolutely correct about controlling humidity.  You’re in a humid climate so the first step is to make sure you have adequate control layers for heat, air, and moisture.  The problem you’ve had with condensation at the roof is because fiberglass insulation, whether in the form of batts or blown, is a control layer for heat only.  A drop ceiling doesn’t control air so when that was in the house, humid outdoor air could easily go from the “attic” to the conditioned space below in summer, causing the indoors to be too humid.  It could also lead to mold growth.  In winter, the humid air would be in the heated space and with an air permeable drop ceiling, that moisture can get into the “attic” and condense on the cold surfaces of the roof.

Here’s an article I wrote a while back about control layers:

Be a Controlling Building Enclosure Control Freak with Control Layers

That fan in the central opening of the roof would only make things worse by moving more humidity through the house.

From photo of the inside of the home, it looks like the floor might be exposed dirt.  Is that the case?  I see concrete around the outside so maybe it’s actually carpet or something else that just looks like dirt.  If it is actually dirt, that needs to be covered with a Class 1 vapor retarder (a vapor barrier like polyethylene) and sealed.  Exposed dirt can add a lot of moisture to the indoors.

Regarding spray polyurethane foam (SPF) insulation, I agree with Thomas that closed-cell SPF (which is about 2 lbs/cubic foot) is the better way to go.  Open-cell (~0.5 lb/ft^3) can work, too, but the contractor who said you would need that to allow the moisture to escape is wrong.  You need to control the moisture indoors with control layers first.  Then with air conditioning.  Then with supplemental dehumidification if necessary.

~ ab3