Existing home and wanting to increase/update the insulation.

When we bought the home in 2005, I remember measuring the depth of the exiting blown-in insulation in the attic. It was 8 inches in depth. It is pink, fiber glass tufts.

Now 17+ years later, I noted that it appeared more compacted and thinner. So I measured, it is an average of 5-6 inches in depth.

So we'd like to update the insulation. Do we look for a company that vacuums up the old insulation?? Or just have a new layer of insulation blown in on top?? What is the best practice in this area.

Thanks in advance for any advice/experience.

Andrew

All you need to do is blow in some more to get to the depth you need.

This is what I do for the maka-tha-monae. I have questions.

What region do you live in?

Is there any HVAC equipment in the attic?

When was the home built?

Is the wiring romex?

What is the ventilation in the attic space?

8" wasn't adequate then, it isn't now. There are a number of options.

Your answers may lead to more questions, good insulation isn't a cookie-cutter affair.

Thank you for your time Arc...

What region do you live in? Outside Memphis, TN. Temps are variable from 20-100F.

Is there any HVAC equipment in the attic? Yes, 2 units are in the attic. Trane 3.5 Ton 16 Seer, and a 2 ton, 16 Seer. They are both AC and Gas Furnace. The larger is a heat pump as well.

When was the home built?
1997 - original construction, slab.

Is the wiring romex? Yes

What is the ventilation in the attic space?
Ridge line vent was installed at the last roof replacement. In addition, soffit vents are installed and the paths are clear.


My intent was to determine if just another layer of blown-in insulation would suffice. Or removal of the old insulation is warranted.

Thank you for your time.

Andrew

Arc, I have a side question, if you might.....

Why don’t they use spray in insulation (like closed cell two part stuff) in attics? It would never collapse, compact or lose insulating properties?

quote:

Originally posted by MikeinNC:
Arc, I have a side question, if you might.....

Why don’t they use spray in insulation (like closed cell two part stuff) in attics? It would never collapse, compact or lose insulating properties?

Not Arc, but offhand it's probably too heavy to be sprayed on top of the ceiling drywall which also has to hold itself up and not crack. And it's expensive in a place where there is plenty of space to pile up cheap light insulation.

The old stuff doesn't really need to be removed unless you had roof leaks or critters living in it.

It would be a good idea to make sure your attic is properly airsealed before adding more blown in insulation though (wall tops, pens, etc.)

When I did mine I just blew in new on top of the 4" I had. I cleared out random junk previous owners left and blower equipment for solar heat I removed when I reroofed. Used the shreeeded newspaper stuff from home Depot. I think I used like $500 worth of the stuff, past a certain threshold the machine rental is free. My buddy and I did in in an hour or two. Your attic is many times larger than mine though, probably much more expensive and harder to maneuver around.

Not sure I did it the right way, but it's been damn effective. Best $$$ I've ever spent on my house, paid for itself many times and now my upstairs is closer to basement temp.

quote:

Originally posted by El Cid 92:
Thank you for your time Arc...

What region do you live in? Outside Memphis, TN. Temps are variable from 20-100F.

Is there any HVAC equipment in the attic? Yes, 2 units are in the attic. Trane 3.5 Ton 16 Seer, and a 2 ton, 16 Seer. They are both AC and Gas Furnace. The larger is a heat pump as well.

When was the home built?
1997 - original construction, slab.

Is the wiring romex? Yes

What is the ventilation in the attic space?
Ridge line vent was installed at the last roof replacement. In addition, soffit vents are installed and the paths are clear.


My intent was to determine if just another layer of blown-in insulation would suffice. Or removal of the old insulation is warranted.

Thank you for your time.

Andrew

You don't need to remove the old insulation. You can add more on top of it, but what you need to do is make sure that the soffit vents don't get covered over by installing propavents or similar. You also can't cover any electrical junction boxes, some locales allow them to be "flagged." You want to get to at least R30, and you could do it with loose blown in, or unfaced batts. The more the better really, but more than R60 is unnecessary. The location of that insulation isn't ideal, but it does work OK.

Due to the equipment in the attic, I don't recommend doing any more insulation on the floor of the attic. I'd recommend instead spraying foam throughout the roof plane. This will bring your HVAC equipment inside the envelope and allow it to work more effectively. The roof/attic would no longer need to be vented.

quote:

Originally posted by Strambo:

quote:

Originally posted by MikeinNC:
Arc, I have a side question, if you might.....

Why don’t they use spray in insulation (like closed cell two part stuff) in attics? It would never collapse, compact or lose insulating properties?

Not Arc, but offhand it's probably too heavy to be sprayed on top of the ceiling drywall which also has to hold itself up and not crack. And it's expensive in a place where there is plenty of space to pile up cheap light insulation.

Open or closed cell is certainly used in attics. I've done it a few times on the floor of the attic which is also the ceiling below, it can work. People strip any sheathing, spray open cell then re-deck, or you can spray closed cell, but I'd still deck over that as well if it is to be used as storage. It isn't too heavy, and it will not disturb the ceiling. Spraying the roof is way way better.

No matter what you do, insulating the ceiling isn't really ideal, due to utilities, penetrations, equipment, etc. It happens because throwing a bunch of loose insulation up there is easy. A lot of homes it is done haphazardly and not to a useful thickness. To make it effective, you can't have air moving through the insulation, which is why making sure any venting is done correctly is key. If venting is done incorrectly, you get wind washing through the insulation itself, making it basically worthless.

Also, I don't like premade products like propavents. They are rarely installed correctly, but if they are there it's better than if they aren't. Many times they aren't filling the bay, or they are crushed, and either way aren't working as intended.

When I do soffit venting I make the vents to fit out of 1" foil faced foam, and foam those in place. You need that air seal to make sure the vent has the right path for the air.

As far as spray foam and roofs goes, the reason roofs are vented is misunderstood. Roofs do not need venting to keep anything cool, venting of roofs and attic spaces is needed because of the temp difference inside and outside the home potentially creating condensation and that water then attacking the structure over time. A sufficient thickness of foam will successfully air seal and separate the two temperatures, so no condensation can occur.

Thanks for the answer Arc....now back to your regularly scheduled program