How to insulate an attic with no joists

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Old 02-20-18, 10:46 PM
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How to insulate an attic with no joists

I am trying to figure out how to insulate the following attic space:
A portion of my house has partial faux vaulted ceiling with an attic above the faux ceiling. I want to insulate that attic. The ceiling is made of 24" on-center 4x4's (actually not really 4x4's, but close enough for this question) with ollllllllllld particle board panels (83" x 24") between them, nailed down on top of the 4x4's. These panels then become the visible ceiling in the faux vaulted ceiling, and the 4x4's are visible from below to give it an exposed look. (BTW, I think this is stupid and favors aesthetics over function, but that's what we have and we will keep it.)
I am not able to get actual photos right now, but I am attaching my diagram of the faux vaulted ceiling (it's not a 3D image, so stop your brain from trying to see it that way). The second attachment is a photo from the interwebs that shows what the ceiling looks like from below.
From above (inside the attic), it looks like nothing. No joists sticking up to walk on like in a normal attic, though you can find the 4x4's and crawl on them. As noted above, the panels are nailed onto the top of the 4x4's, so no part of the 4x4's is actually sticking up or even really visible in the attic. I want to put down insulation batts, which I already acquired (and it wasn't easy), but I realized that if I do this, there won't by any visible structure to walk/crawl on. The next time someone wants to go into the attic, they'll fall right through.
So, how do I provide something that allows the next person (it's probably me) to know where they can walk/crawl? My thought is to get some 4x4's and just attach them to the existing 4x4's, so that they're at least sticking up 4". Then, the batts would go between them, and even though the insulation would be thicker than the 4x4's, at least I'll be able to see and step on something solid between them. Does this sound like a good idea? I am worried that I'll be adding a lot of weight to this odd design just to have a weird system up there..
I am guessing someone is going to suggest getting some other kind of insulation, maybe spray foam on the underside of the roof or something, but for the sake of discussion, let's stick with batts on the attic "floor."
So, yeah.
Thanks.
Mike
 
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Old 02-21-18, 12:52 AM
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My first suggestion is always to use Cellulose vs batt for the simple reason that attempting to haul batts up into an attic is a royal PITA, not to mention the amount of work trying to lay them down on or across the joists.

So you know where the structure is currently for initial installation!

Either you assume you will never get back into the attic, or put up something to indicate where they exist.

What about installing 2x6 perpendicular to the beams as a walk way across the attic space?
 
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Old 02-21-18, 06:06 AM
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Hi Mike,
I didn't see ventilation mentioned or your climate region, maybe I missed it.
It is a pain when construction gets off to a poor start making it difficult for everyone in the future. Your concern about future visits to that space is valid and I have seen contractors go right through a ceiling, messy.

My suggestion would be to fix both problems, the insulation and the safety as Mark suggested, with some perpendicular joists spreading out the load across all of those 4x4's.

Looking for pictures.

Bud
 
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Old 02-21-18, 08:17 AM
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Bud,<br />
You suggested perpendicular &quot;joists.&quot; Are you thinking of 2x6's standing on their edge so that it looks just like regular joists in an attic? That seems to be different from a platform.<br />
Thanks for your response.<br />
Oh, and ventilation is through gable end vents at the top near the peak. There are no soffit vents. We live in San Diego. The weather is beautiful, but the downstairs is occupied by my mother-in-law, and she is cold all the time in part because the downstairs gets little direct sunshine and in part because when she does turn on the heat, it just rises right up through the roof. Thus, the insulation.
Mike
 
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Old 02-21-18, 08:25 AM
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Marq,
Thanks for the suggestion. When you say a 2x6's perpendicular to the current structure, are you thinking of something elevated above the batts, laying flat like a platform, or are you thinking of 2x6's standing on their edge so that it looks like joists in a normal attic?
I can't decide which one makes more sense to me.
Mike
 
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Old 02-21-18, 09:27 AM
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My initial thought was to have them flat and just lay the insulation parallel to these boards.

If you had to get up there you would just pull the one piece of insulation off the 2x6 and there would be your cat walk!
 
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Old 02-21-18, 12:34 PM
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Flat would probably be easier as Marq suggested and being in a warm (wonderful) climate you would not need the extreme amount of insulation like we do up north. Of course my shaky bones would prefer 2x8 or larger, maybe even 3/4" plywood cut 16" wide. But 2x6 would be ok to cross a 24" span.

As for ventilation, if it became an issue they make under shingle vents for low intake ot shingle edge vents.

Bud
 
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Old 02-26-18, 10:35 AM
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I would go a lot simpler

I don't know about you, but I rarely visit my attic. Putting numerous boards across the space just for the ease of infrequent use seems like a lot of work for minimal return.

If the structure is sound (despite not being ideal) and all you want to do is note where the structural 4x4's are below then:

Go buy those wire markers with flags (the ones they use to flag underground utilities or sprinkler heads in lawns). then with a drill, and a small drill bit, drill holes an 1" or 2" deep, up & down the center of those 4x4's placing a flag in each hole. This works very well if your insulation is run vertically along the incline. If you run it horizontally, then you will need to measure up where the insulation seams are, then drill the holes accordingly.

If the insulation is run horizontally & you want a method of holding it up so that it does not slide down the slope, you could switch to small wooden dowel rods. Adjust your drill bit size to that of the dowel rod size & cut the rods to maybe a foot or 8" each.

It's not like it will be seen by anyone, serves the purpose very easily, and no added weight on the ceiling. Good luck & pick a cool day or early morning to be working up there. Attics get hot really quick. Mike
 
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Old 02-26-18, 10:49 AM
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Thanks for the suggestion. Marking is a good idea, but I already put a foot through one ceiling panel, trying to crawl around on there (no room to stand up), so i don't want to take any chances. I've added some 12" wide planks, some elevated above the insulation, some below that will require pushing insulation aside. So far, it seems to be a good solution as posed by previous respondents. Not great, but it seems workable.
I rarely go into an attic, for sure, but I do see some issues up there that I'll need to deal with sometime, so i am preparing ahead of time.
Thanks.
Mike
 
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