UPDATE: - Moisture buildup and ice under Sofit


We’ve recently finished building our custom home which we oversaw all of the trades, made sure we used the best in the city.

Our home has a flat roof with an unvented attic which has been spray foamed. The flat roof is not parapet and uses the conventional gutter and downsprout drainage. We began noticing ice building up underneath the soffits during the Winter months. It got to a point where during warmer Winter days we had leaks through our potlights. We ended up losing many of the lights as they flickered and then burned.

My roofer has been by several times doing water tests since and telling us that the problem is not the roof but that it may be condensation due to the change in temperature between the sprayed insulation in the cavities and the outside weather.

I should add that the insulation company we hired did not used board stoppers when they wanted to spray the cavities to the outside and only used pink insulation during the spray.

This issues has resulted in the formation of mold on the rim board and headers and we’d like to know the source as our experience with our new home has been somewhat ruined.

Any input would be greatly appreciated!


Spray foam has to be all or nothing. If everything is not sealed tight, which that picture shows is definitely not, you WILL have condensation issues. It is not the roofers fault.


Thanks, even tough there is sprayed insulation behind the pink insulation? They just used the pink as a stopper while they were spraying from the inside.

What should be used normally and what do think I should do now that the work is done this way?

Am I missing something? What is the open space in your picture?

You state that you “oversaw all the trades”, did you also write the specs?

Is the pic an I joist? or the underside of the roof deck?

This is a common issue with foam.

It can be very bad.

thanks, we hired a technician to do the specs, though not much illustration, please see picture.

The picture is an I joist, as you can partially see the soffit is mounted underneath.

any input regarding the remedy would be appreciated!!

Any input regarding the remedy would be appreciated,


In a similar case local to me, the house was torn down and rebuilt.

They didn’t catch the mold issues in time.

it is the space/cavity between the facia board and the sprayed insulation.

I believe our situation isn’t that severe, thanks

The case I was referring to was a completed home approx 3 yrs old.

I don’t deal with ice in Texas. Your problem seems to be in the soffit area. You mentioned its unvented. I’m thinking you have heat escaping the home, right at that wall with the batt of insulation. It creates moisture when cooler air is on the other side of the roof deck. I think I would try several things. Leave an area of soffit off during summer rains, to make sure it’s not the roof leaking. Keep it off during winter and see if equalizing the ambient temp stops it.
I think you might need to vent the soffit or foam the rest of the overhang. Something as simple as warm air touching the roofs, eave metal can cause condensation. See if you can find someone with an energy, infrared gun. They can see your loss of air at that point and moisture.

Thanks so much,

Yes we are in Ontario Canada and our temperature goes from +30 to -30 degrees over the Summer to Winter months.

Just wanted to clarify that the pink insulation you see in the picture was only used as a stopper by the insulation company to do the spray foam from the inside.

Just out of curiosity would this happen of they used any other type of stopper?

That batt of insulation has no purpose other than keeping foam from spraying into the soffit. It could be newspaper rolled up, cardboard… I doubt the can lights are creating any heat. Probably LED. The envelope is probably leaking at the top plate. Could be any penetration. Wall plug, mechanical, plumbing. Ask the insulation guy if he has an infrared gun.

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Is the spray foam past the top plate all the way to the outside of the wall assembly? If you have 30+ on one side and 30- on the other, and a 10’ stack of insulation in between, there will be a dew/condensation point in there somewhere.

Good diagnosis rooferama.

As others have suggested, spray foam doesn’t look like it is covering the top of the wall, which is arguably the most important spot. Probably worth pulling all soffits, pulling fiberglass and sealing wall with more foam regardless.

Does every soffit bay have mold or just a few?
If you find a section of soffit where they sealed the wall properly (foam all the way to outside of wall) and there is no funky mold, you may have a smoking gun. If you find a section near a high humidity room like a bathroom with more mold, it would also support the condensation theory.

You mention that the roof is not parapet, Is it pitched to drain on some sides and not others? Many leaks happen at the eave detail where all of the water drains to. Any correlation to presence of mold there? Be careful with this one as northern and shaded sides are naturally more susceptible to mold.

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Thanks, we used a posi-slope insulation to get a 2% pitch which drains in three directions into the gutters.