Attic insulation question....

Most attic insulation videos or write ups talk about not restricting airflow from soffit vents to avoid mold growth in attic. My house was built in 1942 and has no soffit vents or overhangs (attic airflow is from two gable vents on north and south side and roof exhaust vents). Do I still need to be careful about not pushing insulation all the way to the attic edge and make sure none of it touches the attic roof? Or does the absence of soffit vents mean that I can blow loose fill in there to required depth and not worry about contact with roof decking around the outer edges.

Well.. if you do not have soffit vents then no.. But, Ideally you would cut in soffit vents and a ridge vent, it works better that way. Of if you really want to be up to speed you would spray foam the underside of your roof and make your attic a conditioned space.. So yes and no.

Ridge vent has its own set of problems. He said, if I'm reading this right, there are no soffits at all? If you're spending money on this get a fan to help with air flow also.

While soffit and ridge does provide better flow, and therefore cooler attic space, you are fine to not add them. The cost would be so much more than you would ever recover and be economically wasteful. The only thing I would look at is an encapsulated batt on the attic access panel and possibly encapsulated batting around the bathroom fan ducts (hood duct if from the kitchen as well). Adding a power venting might be a good thing to look at, but the configuration of such really depends a lot on the attic, exposures, etc. to make sure you have good flow. In some cases, loose blown insulation can become displaced if you let too much wind blow through the attic.

Here are some pictures to put question in context..... No real soffit just new hardie board covering gap under and behind board gutter will be mounted to. I marked the outside wall header and know that I need insulation on top of that but should I push the insulation out to make contact with the hardie board. Or just like I need to make sure I am not contacting the roof decking with insulation do I need to leave that open for air circulation. I took one picture of the area with flash and one without so you can see that there are some openings that have not as yet been sealed with caulking on the new hardie board.

https://i.imgur.com/LbWxUc3.jpg

https://i.imgur.com/Hz4AAFz.jpg

https://i.imgur.com/34kFwnC.jpg

https://i.imgur.com/ljstQla.jpg

Since you have the insulation out, it'd be easy to work on whatever you'd like to do.

I have the same tiny over hangs as you do, and only two soffit vents, both half clogged with paint. It'd be very simple to purchase some narrow floor registers and install them as soffit vents. Then, take some cardboard and staple it across the rafters on either side of the vents. Run the cardboard up about 12" higher than you plan on putting in your insulation. Then when you blow it in, you can just fill everything up to your hearts content as long as you don't go over the cardboard. Since you have gable vents, you could also invest in some type of solar fan and point the fan out of the gable vent. Then you're drawing cooler air from under the eave, out the gable, and will have airflow without it being "windy" in the attic.

I added more blown-in at my house and two other houses in the neighborhood last fall, and it's pretty easy to leave a gap between the fill and the roof where ever you want. I had the idea of doing exactly what I told you to do, but was too lazy to actually do it myself. Instead, where ever I could see sunlight from the eaves, I just filled as close to the roof as I could while still seeing sunlight.

Blow-in is cheaper than the Cellulose or whatever the gray stuff is. The gray stuff is supposed to be better than the fiberglass, but it's gray because it's just chopped up newspaper, supposedly.

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Originally Posted by Irving

Since you have the insulation out, it'd be easy to work on whatever you'd like to do.

I have the same tiny over hangs as you do, and only two soffit vents, both half clogged with paint. It'd be very simple to purchase some narrow floor registers and install them as soffit vents..

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New roof and a roof mounted solar powered fan are going on in the next few weeks.. Had not thought about mounting a fan at the gable but roof fan hopefully will accomplish same purpose as it supposedly is active based on temperature in attic.

The area behind the gutters is at most two inches and roof venting is being handled via gable and roof vents. So there are no soffit openings except the as yet incomplete caulking on the new Hardie Board. I know I am over thinking it I am just worried about how far and how much to push insulation over the wall headers and beyond close to the Hardie board.

As far as the insulation itself all I see in the stores for cellulose insulation is the batts and the blow in, are there rolls of cellulose insulation similar to the fiberglass rolls? I had planned on putting the fiberglass in as shown and then either blow over that some cellulose or the thicker cellulose batts on top of it to get to correct R value. I am not very inclined to do the blown in because I am also still dealing with electrical work up there.

I've never heard of cellulose batts, just blow-in. Every batt I've ever seen has been fiberglass. I had some electrical that I wanted to clean up in my attic, but once I blew in insulation, I can't see it anymore so I don't think about it. :)

The solar power attic vent is what you want, but I didn't suggest it because I thought the roof had already been replaced. Adding soffit vents to work with the powered attic vent would be ideal, but I understand the issue of the narrow soffits and Hardie Board being more difficult and less desirable to cut a bunch of holes in. As an alternative to a heat register, strips of pegboard can be pieced in between rafters, then painted to match. That's probably what I'll do on my own house. I'm envious of you having an empty attic to work with.

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Originally Posted by Irving

. I'm envious of you having an empty attic to work with.

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Lets just say I hope I wasn't dealing with something that had some asbestos content when I removed it. And at this point I don't want to know.

That's my house too, except that I pretty much expect it if I don't know for certain. Fortunately, I didn't have to mess with mine as it wasn't original and I just blew over the top.

Going from memory of a picture from my dads attic, so this could be off. For the vents they installed plastic baffles extenders so that the insulation would not cover the vents. Then they just put in insulation as far over as possible.

Edit, foud them. Look for soffit vent baffle.

Hmm, if you leave those openings there instead of sealing them with caulking, I might be inclined to use soffit vents, like "Accuvent". Accuvents are cheap and easy to install, especially with what you have. Alternatively, you could enlarge some and seal some, like every other if that is convenient. If you push the insulation into the corners, you want it totally sealed, or with a soffit vent "chase" to allow the pulled in air to go up and over the insulation. With tacstrip and foam board, you can also make your own soffit vents if the manufactured ones won't fit right.

I'd never add cellulose loose, or rock wool loose or batt. Higher dust, critter, mold and mildew potential. The antimicrobial does diminish over time. Foam board with taped batt on it can be made to fit odd shapes if you want it to be able to be moved, removed at some point down the line. Otherwise, just buy bags of loose fiberglass.