[Coolhandluke31]

The upstairs of my house gets pretty hot when the temperature goes above 75. Shocking, because the house really only gets 6 hours of direct sun during the day, it is well shaded before 10am and after 4pm.

The attic has 10X15 vents on either end. When the roof was redone last summer, I had a ridge vent installed. Cooler but still hot. I rolled out a layer of unfaced R-30 (OC, perforated pink plastic coated) in the attic, over some 35 year old faced, R-9, faced towards living space. Still hot upstairs. I rolled out another layer of unfaced R-30 on top, leaving 7 inches on the end, I didn't want to plug the soffits.

My neighbor who seems to know a lot tells me I over insulated and this is going to cause a lot of sweat in the insulation and mold down the road. Plus I won't realize much savings with the extra layer.

Should I take the second layer out? If the insulation isn't faced, I never hear of over insulating before??

[smoothy]

You neighbor is full of it. A long as the vapor barrier in this case is towards the living space and not sandwiched. Being overly air tight is another issue... but not in older houses.

I have R-39 in my Attic (wish I could have more). Yeah it does get hot, but its from solar radiation hitting the roof from outside... just like a hothouse. Remember Infared radiation is at play here more than direct visible light.

And having a LOT of insulation will help the cooling and heating costs stay lower. I think a better example to show how well it works is how cold it is in winter. And it should be quite cold.

I do hope you also plugged holes where wiring enters the attic, you will lose a lot of heat in winter due to all thoise holes Romex is pulled through.

[ballengerb1]

The insulation will not sweat the way you installed it. Eave or soffic vents will allow more air to enter the attic and vent out the top. Check to see how many you have, if any

[creahands]

U can install a roof mount exhaust fan on back of roof. Do this below line of sight. It looks like a large silver mushroom.

Or u can install an exhaust fan in the gable end of house.

Set them up to be turned on and off by thermostat.

This will cool attic as well help keep rest of house cooler.

I have a 48 inch with a shutter vent in hallway ceiling and the draft it causes will close doors. Have not used a/c since I put it in 3 years ago.

Good luck

Chuck

[KBC]

As ballengerb1 said,the soffits need to have positive airflow to the peak.

The larger the vents,the more air can move past the heated roofline(from the inside)

Solar heat (as smoothy said) is the culprit here,take that heat add it to a roof that can't rid itself of that heat, meaning,trap all that heat up near the attic, but it stops just before it reaches the attic, if there is insulation covering the area between the roof's rafters, then the heat is trapped below the area which is now adequately vented(with the ridge vent and gable openings)

The eaves and soffits need to be kept clear of all insulation and the flow can't be restricted below the roofline.

Hope this makes sense to you.:)

[manhattan42]

I rolled out a layer of unfaced R-30 (OC, perforated pink plastic coated)

This wrong and your neighbor is partially correct.

The plastic on this type of 'wrapped' insulation IS a vapor retarder and cannot be sandwiched between successive layers of insulation as you have done it.

The only location this type insulation can be placed is between the attic floor joists immediately on top of the drywall of the ceiling below with all other types of unfaced insulation above it.

Placed as you have it will absolutely cause condensation issues within the wrapped plastic insulation and in insulation layers below it.

Vapor retarders need to be located immediately against the warm-in-winter side of the attic, which in your case, is the attic floor/ceiling of the room below. You need to remove the wrapped plastic and all layers and install them properly.

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Side note:

You need at least 1 square foot of attic ventilation for every 150sf of attic floor space. You can reduce that amount to 1 sq ft of ventilation for every 300sf of attic floor space if you use a vapor retarder on the attic floor.

But you CANNOT co-mix vent types. Gable vents and ridge vents cannot be used together. If you have gable and ridge vents, you need to remove or close up the gable vents. Having gable vents will 'short-circuit' the venting capacity of the ridge vents making the ridge vent almost useless.