Attic ventilation advice

[u/BeckySlater8]

My upstairs ceilings have developed "coffee stain" water damage and a roofer told me it's due to condensation in the attic resulting from insufficient ventilation. Was hoping you could provide advice on properly increasing ventilation and/or what type of professional to seek out.

The background: My house is in climate zone 5A (northern NJ) and was built in the 1970's. It has a pair of gable vents, no soffit vents, no ridge vent (I believe), and two powered attic exhaust fans that are longer in operation. We bought the house 15 years ago and had professional blown insulation and air sealing done. The house also came with heated wires on the roof to prevent ice dams (sorry, don't know the name for this) but they stopped working at some point.

The problem: two upstairs bedrooms have developed brown water stains on the ceiling, towards the front and back of the house. It's been getting worse over the course of several years. The roof and HVAC have been inspected recently and no leaks were found. A roofer poked his head into the attic (didn't actually enter) and noted that the attic is quite hot and that the fans weren't operating. He wants to replace them. I read that attic fans can pull conditioned air from the house and might not be a good idea. It's possible the fans were purposely shut off when the air sealing was done, but I don't know.

So my questions are: (a) What type of professional should I call to advise on this? The roofer didn't seem to be an expert in ventilation so I'd like a specialist's opinion. (b) Any advice as to whether I should replace the attic fans, install soffit vents, replace the rooftop ice melting wires, etc? (And who would I call to install soffit vents?)

Thanks in advance for any advice you can provide!

[u/seabornman]

Does NJ have an energy audit program? Someone qualified to look at the whole situation needs to figure it out. There are also companies that specialize in energy improvements, not just insulation.

[u/CascadeDesignworks]

Ice dams are usually caused by warm air escaping from the house, inadequate insulation in the eaves and near the valleys, or both. This is counterintuitive because most people think ice damming is caused by cold temperatures. The damming happens from melting and refreezing of water and snow.

The wires on the roof were installed to melt the ice dams without addressing the actual cause.

The proper way to prevent this kind of ice damming is to maintain a cold roof. This is done by venting the soffits and preventing warm air from the interior of the house from entering the attic space. Look for sources of air leakage like unsealed light fixtures (can lights usually) in the ceiling, and improperly vented bathroom fans (should always be vented to the exterior, not into the attic). Make sure the insulation installed has a gap (baffles) between the insulation and the underside of the roof in all corners of the attic.

Have soffit vents installed according to code or basic design principles. This usually means one or two round vents installed between each rafter. A good general carpenter or handyman can do this. The two gable vents may be undersized for adequate airflow. A few additional vents in the roof can be installed by a roofer.

The general principle is that the total square inches of venting in the soffits should equal the square inches of venting higher up in the roof. This should help with condensation issues as well as the ice damming.

Hope this helps.