Is attic venting necessary in St. Louis, Missouri?
The house is a 2-story, approx. 15 years old and additional insulation was added. The Insulation Contractor used Owens Corning R-13 faced batt insualation and loose blown in insulation.

The picture I have sent you represents the homeowner's house. There is a gable vent in the open attic area and a ridge vent in the knee wall living space area. There is also soffit vent through out the house exterior. In the knee wall section of the house the insulation contractor used Owens Corning R-13 faced batt insulation and installed it in between the roof trusses and put it tight against the roof sheating with no baffles. The Insulation Contractor also isolated the knee wall attic area from the open attic area with a wall of insulation. The soffit venting appears to stll be functional but the cross ventilation to the ridge vent has been blocked by the addition of the new insulation in between the trusses.

My concern is that since there is no ventilation in the knee wall section of the attic, the homeowner has a potential moisture/mold problem. To recap the situation, the knee wall is insulated with R-13 faced batt insulation (existing), in between the floor joists is insulated with loose blown insulation(added additional), and they installed new R-13 faced batt insulation in between the roof trusses, tight against the roof sheating (NEW).

The attic space is also unconditioned. I have talked to a Licensed Architect and respected insulation contractors and they all said the homeowner has a potential problem and also that money was wasted on the insulation added in between the roof trusses.

Can you please comment on this situation? The Insulation Contractor said he does this type of insulation practice all the time.

I was unable to print the picture, can you please go to the energy star site listed and refer to 1.2 Locating Air Leaks for the picture reference.

Thank you for your time,

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I just realized that I gave the wrong reference site. Sorry about that.

This is the correct site.

Jerry,  The link to the picture is incomplete so I get an error message when I click on it. Would you repost it with the whole URL address? Thanks!

If I understand the situation, unless they added blocking between the roof trusses at the roof sheathing, the fiberglass insulation will slow the movement of the air, but certainly not stop it.  Unless the air-sealing has been done, it sounds like the added insulation will have very little effect. 


It is not clear what how you fit into this circumstance.  If you gave the owner specifications or a recommendation - then use the illustration you linked to and clarify this how the finished product should look.  If you were called into advise after the fact you could provide similar advice - this illustration shows the way the air-sealing and insulation should be installed.  If you are paying for the work then you should have it done to your satisfaction or withhold some or all payment.


As for the question of attic ventilation:  Unless it is a sealed attic (i.e. spray foam) then the building code is looking for ventilation.


I came to the homeowners house to do some painting when the Insulation Contractor was leaving. The access to the attic is in the 2nd floor bedroom closet. I happened to be painting that bedroom so I opened the panel in the back of the closet to look at what was done. You are able to stand up in the attic next to the knee wall so I walked in and saw the insulation secured in between the trusses and tight against the sheating with no baffles. I was a Building Inspector for 10 years prior and new this was wrong. The City where the house is located does not perform insulation inspections so they had no opinion as to if the installation was right or wrong. I also work for the homeowner at a second job so I informed her that she has a problem. The Insulation Contractor offered to remove the Insulation and lay it on the floor of the attic as a good will gesture. I feel as though the Contractor should reimburse the cost of the Insulation and the labor to install it. The roof area is aprox. 400 sq. ft. I truly feel that the Insulation Contractor took advantage of this homeowner and installed something that was not worth the time and money.

Thanks for your response,



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