attic insulation and compressing

[TXST8tj]

*I realize this is not a garage, but I figure ya'll would be able to help anyway*

Our house has been complete and us moved in for a month now. When it was being built, they builder put in a utility 'access' panel leading from one wall in the upstairs gameroom to a large open area above the kitchen.
The only thing in there is blown in insulation and some ducting.

Instead of them installing a functional door here, they just framed the hole and put a piece of wood over it; painted and trimed to match the rest of the trim.

We wanted to use this space for storage, as the attic does not offer much space with the A/C and furnace occupying a lot of it.

My buddy works for Bison and he got a door made for us to replace this panel. It is an exterior (solid core) door that has weatherstripping and an alum. threshhold. It is otherwise identical to the rest of the doors in the house.

We just had it installed yesterday. I am waiting for the next crew to come out and do the sheetrock repairs and finish-work and paint on the door and trim.

Before (during construction, obviously):

Now:

Here come the questions.....

As mentioned, the plan for this space is for storage (christmas decorations, high school/college stuff, baby toys, etc). Everything is in sterilite tubs (oh my what an investment!!!).

My plan is to 'deck' the area with 2x10s spaced a few inches apart. I chose 2x10s for a couple reasons. I figure they will support my weight walking around on them, and of course the weight of the tubs on them. I can make one cut for length with my 12" miter saw, and they are just cheaper than 2x12s. Spaced a few inches apart, I can cover a good amount of area and still have plenty of support for the tubs.

How bad will it be to compress that sprayed-in insulation? I should say, how bad will the kitchen beneath suffer from the insulation being compressed under the lumber?


These are some quick pictures of the area as it is before any floor being layed down.

The pictures don't give much perspective on size, but it is roughly the size of our kitchen and the "ceiling" is at least 11ft in there. The house does have Tech-Shield/radiant barrier.

 

[Gary S]

Insulation works because of the air trapped in it. If you compress 12" of insulation down to 6", it won't be any better than having only 6" in there, and likely worse because it is compressed.

Personally, I'd leave the insulation alone so it can work and toss the Christmas decorations in the trash can where they won't do any damage.

 

[TXST8tj]

Well, I ended up building the floor up a bit. There is still several inches of insulation under the floored area, and there is spacing between each board. Nothing is compressed, there is just a little less of it in certain spots.
I still need to deck one more area, but it turned out great and is super supportive.

 

[DZL JIM]

I designed and built houses for almost 15 years, and we would use a door like you originally started with just so you couldn't use the space for storage. If there was any chance that the house's structure would support storage, we would do everything possible to make it usable.
And yet we were always challenged by the homeowner as to why we recommended NOT to use that space for storage. Most simply didn't understand that it was in their best interest.

Hopefully you fully researched what is holding up your new 'structure' and you won't have issues with cracking ceilings, or worse a complete ceiling failure, later on (seen it, easy to happen.)
Good luck.

 

[fefarms]

That space is likely to get quite hot in summer (140 plus degrees). Such temperatures may be hard on the items stored within it.

 

[Falcon67]

What DZL JIM said - I'd watch what you stored in there, especially after you floored it with very heavy wood. 19/32 OSB might have been a better pick if you could get a larger sheet in there - it would spread any load across the joists. The joist design may be in the 5 to 10 lbs/sq ft range, and it's easy to go over that if you are not careful. Nail pops and joint cracks, paper tears, separation of the kitchen ceiling may show up if its overloaded. Hopefully there is a vent somewhere in there.

 

[neverenoughtools]

What DZL JIM said - I'd watch what you stored in there, especially after you floored it with very heavy wood. 19/32 OSB might have been a better pick if you could get a larger sheet in there - it would spread any load across the joists. The joist design may be in the 5 to 10 lbs/sq ft range, and it's easy to go over that if you are not careful. Nail pops and joint cracks, paper tears, separation of the kitchen ceiling may show up if its overloaded. Hopefully there is a vent somewhere in there.

X2

 

[dlenkewich]

I've got nothing to add that hasn't already been stated.

But the blown in insulation is blow in to a certain depth for a reason. While density in insulation isn't bad, you are loosing R-value by compressing it. Also, it's fibreglass, I deal with that stuff day in and day out - but you shouldn't be disturbing it in your finished home, fine grains of fibreglass will travel through your home every time you're messing around in there.

My concern would lie more with how that attic is frame out. Truss designs here are webbed or sissored and they support themselves throught the span, I don't see much support in that attic that would make me comfortable storing items in it.

There was likely only access there because of a regional code, you can see ducting, and I would assume there's electrical there, too. It's to bad they didn't just close it off completely(Sometimes they can get away with framing an access and drywalling over it so it's hidden, and it's noted in the plans for future purposes) to keep inquiring minds out.

People don't mess with the brakes on there daily driver but for some reason you give them a house and all they see is something built out of wood, which can be altered by the tools they have in the garage. Both could be dangerous after un-educated alterations.

 

[TWX]

If I had been the one doing this I probably would have pushed the blown-in stuff to the narrow, far end, including removing most of it from between the joists, then I would have insulated the area under the roof and any other outside walls, then put in the floor, effectively for environmental control's sake turning it into part of the house. Depending on temp I might even have added some kind of vent to it if it needs it to keep the temps down. Still though, as the others pointed out there's the load capacity of the floor to worry about.

 

[digdug18]

I think I can at least somewhat solve your problem, simple answer is yes you can compress the insulation, but your going to lose some insulation value. I'd install the beams as you want to do, but also install batts of your insulation of choice on the ceiling/roof, leaving room for air circulation to prevent ice dams mind you. I'd create a semi conditioned space in that room, meaning that the room itself isn't conditioned, but will get warm/cold based upon the heated/cooled house from the adjoining rooms doorway to it.
Doing this will cut down on the amount of heat loss that you'll suffer from. Another option is building a raised platform to stack your boxes on, but as stated above I think that the heat will do bad things to the things you are storing up there, discolor plastic, moths, etc.

No matter what your final plan is the first thing I'd do is add a couple of inches of insulation to the back side of the door, to try and keep as much conditioned air in your house as possible, the solid core doors (unless it is an actual exterior grade door, with the insulated center section) tend to let lots of conditioned air into the un-conditioned space, through conduction of the wood door itself.

Andrew