Here is a picture of the house I audited last week.  These icicles aren't the biggest I've seen.  They do show the low level of insulation in the attic (3 inches of cellulose).

 

The more immediate problem was were the ice went when the icicle melted.  Below the eve was the condenser unit!  So, it was ice covered.  And at some point the morning I was auditing, shorted the fuse in the furnace.  So, not only did we not need the AC, but we didn't have heat either!

That is an unintended consequence!

 

 

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I agree with David and from what I gather from your conversation with the builder, Mark is that the walls are insulated with foam, what about the attic/roof.  Unless you are able to get to inspect one of his modulars, it's hard to make a determination.  Most builders and those in construction believe they are building great, tight and well insulated houses.  They are most likely not educated on or aware of the many various products that are more energy efficient today or how to install them properly.  And, they are probably very comfortable with what they know and are afraid of change.

 

By the way Mark, how are you doing?  We met last year at the ACI conference in Syracuse.

Not bad, Deb - of course I remember! How goes it with you?

As far as this particular building, the modular manufacturer insulates everything with filterglass, but then to add some strength and reduce cracking during transport, uses an adhesive foam on the studs during drywall installation - no "R Value" there, just some minor air sealing improvement, but they do njot foam seal the outlets or lighting penetrations...

Modulars, Like any home, have the potential to be real disasters. Some are overcoming this rep w/ advanced construction procedures. Others are not. In modular factories I've seen, The foam mentioned is usually just an adhesive to glue the sheetrock to the studs, remember that modulars are built from the inside out. The sheetrock is laid down 1st, (on a lg work bench) then the wall frame is laid on top of it, spray gluing the frame to the sheetrock. All the walls are stood up to start the box. The mechanicals happen,  then wall cavities are insulated, some very poorly. Then the OSB ext sheathing and vinyl siding is attached.

The marriage wall leaks to the vented attic and the really poor batt insulation strategy in flat attic floor bays along w/ many perforations will lead to poor performance and ice dams.

What's a marriage wall?
"What's a marriage wall?"

  It's the wall(s) where the two halves of a modular home are joined together

 

@Kevin - exacty right

John, to paraphrase Crocodile Dundee, these are icicles. I need to update this with some new ones that I have taken. That second image on my page is just a small sample of the massive ice cover that was on that building, but it must be OK because it's LEED certified.

The good thing about icicles is that they keep us entertained during the cold days(months?) of winter.

What I see is pictures of a mass of snow and ice flowing down an incline that has little friction (like a metal or membrane roof). Like a glacier. Does this have anything to do with heat loss?

Also, the pictures of bare spots on the roof around skylights can be sun melt. In my backyard, there is bare ground around every tree and even post. I think any penetration of the ground can cause some melting of snow around it because it provides a path for the sun's heat to enter the ground. Likewise with chimneys (even unused ones) and skylights on a roof.

 

David

Hi David,

I agree that these are massive ice flows, but in both cases the snow melt that led to the ice was caused by heat loss. The second picture is ice flowing down an asphalt shingle roof that is about 45 degrees. You can see the shingle pattern on the underside of the ice. The part I am under is the north side, the south and west sides got enough sun to break the ice off at the eaves.

The skylight are also north facing, this picture was taken in February and the sun wasn't touching the roof at that point. You are correct that you have to be careful to understand all the potential causes of a problem.

The municipal building building is really interesting. A garage and office combo, the office portion is insulated above the ceiling but the space above the insulation is separated from the heated garage by an uninsulated block wall. This was January as I recall so the sun wasn't up to removing the ice from the top and there was too much snow and ice for the indirect heat to fully melt. It did keep it loose enough to slide down the roof. It was the curling as the ice moved over the edge that appealed to me.

CLASSIC Hall of Shame picture -- The Murphy's Law of building science.

 

Thanks for this one!

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