Hello energy pros.

I need your combined wisdom before I proceed to help a client of mine address what appears to be mold growth and draftiness after I completed attic air sealing and other miscellaneous measures on her home.

The HO owns a split level in Northern VA. She, her husband, and three children have lived in this house for three years.

The house has existing exterior wall insulation, and some attic insulation. No rim joist air sealing or insulation and no foundation wall insulation. 

We sealed the entire attic above the two-story section of their split level (above the bedrooms), and replaced the existing blown-in fiberglass. We also insulated a section of exterior wall in their laundry room that was driving discomfort in their house with closed-cell spray foam. Finally, we insulated the floor between the 1st and 2nd story (between bedrooms) for sound attenuation purposes.

About one month after completing the work the HO e-mailed me to say that surface mold had begun to form on the exterior wall of the 1st story bedroom that we insulated the ceiling above and adjacent to the wall we spray foamed. This is the main concern at this point.

Before I run over there later this week and try to determine what is going on, I'd like to tap the knowledge that you all bring to the table.

My sense is that there is cold air rushing into this exterior wall through the rim joists in the basement. The cold air is mixing with warm conditioned air that is leaking into the walls through outlets and baseboards, and the air sealing of the top plates is keeping the air in the walls, but also allowing cold air to mix with warm, introducing condensation within the wall.

The HO also mentioned condensation on some of the glazing. One final detail I want to mention is that they have a gas insert in the 2-story section of the house (on the 1st floor).

Any ideas on what may be taking place, or tips on how best to proceed? 

Thanks in advance!

Views: 806

Reply to This

Replies to This Discussion

Thanks Kevin.

You leave me with a lot to consider.

I will likely need to follow-up on the matter.

Good point on the gas insert. Those do put out a lot of moisture.

 

The condensation on the windows is a clear indicator that humdity in the house is high enough to expect moisture accumulation on cold walls.

 

The question is whether the cause is a damp fall or a source in the house.

 

In my experience, DC houses that are weatherized don't typically have summertime humidity problems. AIr sealing sharply reduces the added humidity from infiltrating humid air. Since many projects don't improve wall insulation or glazing, AC loads don't go down all that much and dehumidification is adequate. In many cases the reduced humid infiltration seems to more than offset the lost dehumidification of lower runtime. In my experience anway.

Patrick, what is ACH50? ACHnat?

Where is the dryer vent located? Has it been moved or damaged during work? Was it inspected? Is the hose full of lint?

RSS

Featured Forum Discussions

Too many BTU's. Too much horsepower?

Started by Steve in General Forum. Last reply by Eric Kjelshus on Saturday. 4 Replies

Stack/wind pressure and flow networks.

Started by Daniel James Grundy in Training. Last reply by Daniel James Grundy Mar 23. 5 Replies

BDT with vermiculite in hollow CMU walls?

Started by Brad Cook in General Forum. Last reply by John Nicholas Mar 23. 2 Replies

Videos

  • Add Videos
  • View All

Latest Activity

Amos Dunham added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

insulmaxx 5000 insulation machine

insulmaxx 5000 machine low hours less than 100 hrs complete with hoses and cords very fast machine…See More
37 minutes ago
Adrian Sheils liked Home Energy Magazine's blog post The Elephant in the Room
4 hours ago
Adrian Sheils liked Sarah OConnell's blog post Crowdsourcing for Innovation
4 hours ago
Chris Dorsi commented on Home Energy Magazine's blog post The Elephant in the Room
"This was a great session, witness the fact that we had to schedule a second showing to accommodate…"
14 hours ago
Chris Dorsi liked Home Energy Magazine's blog post The Elephant in the Room
14 hours ago
eric anderson added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Equipement still for sail (what is left from what I was selling before)

For some reason I can't reply to my previous thread.  I sold the blower door and duct blaster/flow…See More
21 hours ago
Mark Sackerson replied to angela stanzione's discussion Used Weatherization and auditing equipment for sale in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Angela, Do you have any blower door sets left? mark"
22 hours ago
Mark Sackerson replied to Jeffrey Anthony's discussion Blower Door Kits in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Jeffrey, do you have any blower door kits left? mark msackerson@franzoso.com"
22 hours ago

Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service