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I know some of y'all are builders, or otherwise know a LOT more about construction than I do, and I have a simple question. My attic is unfinished, and filled with about 2' of loose (blown?) pink fiberglass insulation.
I'm tearing up some underlayment in the master bedroom, in preparation for hardwood flooring. The underlayment is heavy particle board, and I'd like to reuse it as crude flooring in the attic, for storage, and ease of access to wiring, etc.
Can I just cut strips of it, squeeze down the existing insulation, and screw it into the joists? Am I losing any insulation value, by compressing it like this? Is there any building code I'm violating? Or should I move out the blown stuff, where I want to put the "floor boards" and replace with rolled insulation? *Thx*
Can I just cut strips of it, squeeze down the existing insulation, and screw it into the joists?
Yep
Quote:
Am I losing any insulation value, by compressing it like this
Yep
Quote:
Is there any building code I'm violating?
Nope, but if you re-sell the house, you might be...if you dont inform on yourself.
Quote:
Or should I move out the blown stuff, where I want to put the "floor boards" and replace with rolled insulation?
Insulation 'specs' call for so much space for installation. For example, in a ceiling that is roof overhead, you want a space for airflow, in order to move excess heat. It depends on some specifics, and some manufacturers recommendations. In some cases, you can void any warranty or reduce the insulating value to the point that a good close inspection will make your property un-saleable.
I'm an electrician, but I have built my own house, and many others. I can't give you specifics, but heres a start.
Can I just cut strips of it, squeeze down the existing insulation, and screw it into the joists?
Yep
Quote:
Am I losing any insulation value, by compressing it like this
Yep
[/quote]
Thx, Semi! That was what I was afraid of....Since I don't really need the space, I 'll go to plan "b" and just make a 1' wide 'cat-walk' so I can get to the various corners of the attic without stepping through the ceiling of my office, or guest bedroom, and forget about flooring-in a large area.
Given PSNC's gas rates, I'd just assume NOT lose any insulation value!!
Your ceiling joist are what size lumber, 2 x 4" - 6" - 8"? I'm taking you are saying you have 2" of blow in above the joist, am I correct?
For starters, the more you disturb the blow in the more the insulation will mat = reduced R value, so disturb it as little as possible.
Next off, geee I wouldn't say you have enough insulation up there. Remember insulation does two things.
1) insulates from the cold.
2) insulates from the heat.
I know up here, (generally) with a blow in, insulation depths could be as much as 24". As I said, insulation reduces cooling costs as well as heating costs.
Now if I were to be doing what you are doing, I would do this:
- scab 2 x 4s or 6s or 8s (edge to edge) to effectively raise the height of the exciting ceiling joists.
- the wood you use to raise the height of the ceiling joist I would drill a series of 1" holes along it's length to provide ventilation inside the cavity that you are making. Without the ventilation you will have condensation problems = NOT GOOD.
- I would only use screws for securing the scabbing material and the sheet goods - you don't want plaster falling down from the ceiling.
As someone who used to install this crap for a living (worst job ever), I'll vouch for what Semi said. Blown fiberglass is primo stuff... much better than kraft-faced batts (what you're normally used to seeing). I'm guessing that at 2' deep its about an R30 value... which won't decrease over time as blown cellulose will as it loses loft. But smashing it down will cause it to lose much of its insulating value... so be prepared to put some bats in your rafters. Cellulose is cheap, but it's crap. Only about an R5, at best. Oh, and the rats love it.
If you are doing work on your master bedroom, consider having glass blown into your sidewalls. It acts as a much better acoustic insulator than does the low- to mid-R-value batts they put in interior walls for that purpose.
I'm tearing up some underlayment in the master bedroom, in preparation for hardwood flooring. The underlayment is heavy particle board, and I'd like to reuse it as crude flooring in the attic, for storage, and ease of access to wiring, etc.
No,Particle board does not have the strenght to carry a load 24" between ceiling joists....for a person walking in the attic could break through the particle board and stick a foot through the ceiling..
This is why particle board is not used for subfloor and is used for flooring underlayment
You need a differant type of sheeting
BUT,,,,Smashing the insulation is a bad idea.....
I would not do it
If you really wanted to cover that insulation, you could use pieces of 2X2 running crossways to the joists. Then you could lay your flooring on top of them. To avoid cracking the 'lifters' drill them before nailing them to the joists.
I have loose insualtion in my attic too and wanted space for light storage. I did not have to use 'lifters' but I'm glad I coverred the insulation. There was a small floored space*already but it was very dusty moving around up there because enough wind would blow through my vents to stir up the fluff sometimes too.
I was also worried about making a mis-step and going through the ceiling.
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Garrett, the insulation is about 2' deep, from the lowest point; Nat, I think the joists are 16" oc, and not 24", but I can check. I don't even like going into the attic, since every time I pull down the stairs, some insulation comes along with it.
Sounds like flooring it in properly *can* be done, but is a much bigger undertaking than I care for, especially since I don't need the space.
Really, I all I want is to be able to move around relatively easily and safely up there, which is why I'm thinking long strips of this particle board would work fine. But if there's an easier way...I was up there a few weeks ago, pulling UTP cable from one room to the other (pci wireless NICs #%(% stink, but that's another story), and ended up buried in that pink stuff like a mole, and lost a really nice tape measure, besides.
But I think I understand the principal behind not compressing the insulation -- like the difference between a down-filled jacket, and one that's been pressed flat?
I don't even like going into the attic, since every time I pull down the stairs, some insulation comes along with it.
Generally one gets this because of the vacuum of the hatch being opened.
There is a few simple things you can do to curve this tendency:
1) crib the opening several inches higher then the insulation is.
2) if you still get a bit of pink after doing the above, you can staple on a foot or so of 4ml poly to the four sides of your cribbing. You MUST leave this poly laying loosely on top of the surrounding pink.
3) or do both. :thumbsup:
Yah I've got to go with not likely you've got 24" centers up there :roll - after all your home is in a hurricane belt.
If you do end up using the underlay (what is it 3/8"? I know our underlay is 1/4 fir ply) you could always double it up for more then enough strength. Just remember to provide plenty of ventilation in the cavities you create or you will have problems later. :(
The job really isn't that bad once you get setup.
- go down to Auto Zone or somewhere like that and buy yourself a pair of disposable coveralls.
- get yourself a pair of kitchen rubber gloves
- a cheap mask
- a roll of masking tape
* install all gear and tape up your ankles and wrists.
- have all of your material cut and ready to go, including plenty of screws.
- have the extension in place and close the access hatch.
- rake out the pink with a garden rake to expose the joists.
- install your wood.
- rake your pink back in place and level.
- install flooring
- remove protective clothing while in the attic and place in garbage bag.
*** DO THIS WORK ON A COLD DAY *** TRUST me on this one - it can WAY TO HOT to @##$%ing fast up there. :o :roll
WE are all keepers here in our household - what a mess.
I am with Nat - if its of the sort of value that you would keep it in the attic - sell it or throw it out. Do it now before its too late and your attic is full of junk like mine.....
__________________ 1st Cav Div Air Assault Infantry RVN
-Can Do........ and .......Carry On -
If you got 2x4 or 2x6's for ceiling joists I would not store anything more than insulation in your attic. 2x8 and up... light storage. This all depends on what it was designed for (ie 30# psf live load and 10# psf dead load or 40# LL, 50#LL). You also gotta find out if the builder, put continuous ceiling joists in or did he just sister together a bunch of smaller pieces he had laying around to just get rid of them. Ive done enough field surveys for clients and found this to be the case. If so, stay out of the attic, or limit your walking around to areas you know are directly over a wall below.
Assuming you have 2x6 or 2x8 cieling joist, which will become floor joist for the attic, on 16" centers. You can floor the attic with 1/2 decking and it will be plenty solid enough to walk on as long as the open span on your floor/ceiling joist does not exceed 14' and the sheeting is nailed/screwed down very well.
Insulation 24" of blown in fiberglass is about R-30, but if you squeeze it down to 5-1/2" it becomes R-19. Not adaquate for your ceiling even though the sheathing product will add some minimum amount of R value.
To maintain R value and provide some additional structural strength, you can nail/screw lathing crossways the joist. Using 16" centers for 2x6s or 2x8s, then add your decking material on top of that. That will give you an insulation depth of 10 1/2" to 15" plus the thickness of the sheeting. You would end up somewhere around an insulation value of R-26.
Can it be done? Yes! Worth it? It was for me and I haven't had the slightest problem. Other than the wife might decide tomorrow, that because we have all that storage in the "attic" she would like to see me haul "Noah's Ark" up them pull down stairs. The pull down stairs in fact have become the limiting factor on what can go up there.
__________________ Cape Horn 17, Yamaha F115
with
Elmo the Boat Dog
For your imformation: probably every war time home ever built in North America came with and still have a 2 x 4 floor joist construction. So I hardly see a problem with occasional use of the attic.
After today, I have decided if I never see particle board again, it's TOO F****** SOON!
Ripped out 280 sf of the stuff. The only way to effectively do it, was remove every nail, first, before prying it out. I think there was literally a nail every 6", and of course they'd been shot in with some gun, and were countersunk, so I had to take a cat's paw to each, with a good hammer.
Even if I wanted to put some pieces up in the attic, I couldn't, as they're all bashed up.
I'm beginning to see why the estimates charged as much to remove the carpet and underlayment, as to actually *install* the hardwood flooring. I'm also wondering why I didn't write a check.
Unless your house has 2x4's for floor joists, I have never seen in my professional experience (Architect) in the N'or East a 2x4 floor joist except in trusses. I was just stating from a design stand point and I know all about over designing safety factors into framed house, but when 2x4's and 6's are used for ceiling joists the Archtect and/or structural engineer designed the ceiling for just the dead load of the whatever the ceiling material is (ie gyp bd, plaster lath, etc...)and the occassional inspection of the attic and roof and not for long term storage. With that said, I was just passing along a word of caution, from my experience in the field, that is all.
Just my .02
Now that it's all out, installing 3/4" pre-finished hardwood strips is no trivial task either, I'm finding. However I don't need the tip of my thumbs to type.
basic attic insulation q. for builders? 
1st Cav Div Air Assault Infantry RVN
