Attic insulation and walkways
So I moved into my “new” (built 2003) house about 1.5 years ago. Been doing several projects, but one area I have not had much of a chance to check out is the attic. I have poked my head in there a couple of times, but it is not easy to access (small hatch in master bedroom closet) or walk around in. I’d like to be able to move around better up there, particularly after rain storms,etc. just to check for roof leaks, etc. I’d also like to beef up the insulation some (IIRC, about 12 inches of blown in fiberglass, not too sure on that though, and it appears “thin” in some spots, not very evenly distributed). So I have a couple of questions:
1. What is the best way to create some attic walkways? Plenty of headroom down the center of the attic. I was thinking (and this ties into question 2) of removing the blown in insulation from between the floor joists, replacing with rock wool insulation, plywood planking over that (maybe 2 foot wide for walking) on top of the joists, and then covering that with more rock wool insulation to desired thickness. My thought is the rock wool is easy to move when I need access, and then easy to put back when I am done up there so the walkway area is still fully insulated.
2. In order to beef up the insulation some, I was thinking of removing the blown in from between the joists, putting in rock wool to the top of the joists (likely R-15, not sure if they are 2×4 or 2×6 joists), and then replacing the blown in back on top of the rock wool. My reasoning for this is that I likely will not be able to do all this at one time, so hauling the blowing machine, etc., home multiple times as I do this in stages might be challenging. Just want to be sure I am not creating more problems for myself with two “layers” of different types of insulation.
As I do some of this work I also plan of getting rid of the single return air on the second floor (in the ceiling) and putting in ducted returns from each bedroom instead.
I am in climate zone 4 (almost into zone 5) in Maryland, almost into PA.
Thank You,
Neil
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Replies
Neil,
It's easier to just elevate the walkway above the level of the insulation.
There are two ways it is most commonly done:
- If there are trusses, run 2"x4"s horizontally between the webs. Run a 2"x10" on top.
- If there are ceiling joists, nail lengths of 2"x10" x the height of your insulation to the joists. Run a 2"x10" on top.
Both of the truss manufacturers I use consider these to be acceptable modifications to the trusses - as long as no storage area is created.
Neil, I have used both methods that Malcolm suggests, and they both work well. If you have a stick-framed roof you could also consider hanging the walkway from vertical 2x4s hanging from the rafters.
I agree with building a cat walk as described by Malcolm. The only change I’d recommend is make the walkway a little wider so that it’s easier to crawl around on without falling off. A 2x10 gives about 9.5” of useable width. A pair of 2x8s gives a bit over 15” of width of useable width if you leave a small gap between the two. It’s much easier to crawl on something that is wide enough you don’t feel like you have to keep your balance all the time.
Another tip: stagger the joints between the boards so that the ends of your 2x8s don’t land on the same supports.
Bill
Bill, I agree, but it's a balancing act in more ways than one. The wider the walkway, the more enticing it becomes as a storage area.
Bill, I agree, but it's a balancing act in more ways than one. The wider the walkway, the more enticing it becomes as a storage area - and for some reason people feel drawn to load their attics up with as much junk as they can get through the hatch.
That's one reason I like putting the attic access in an exterior gable wall, when possible. Still meets code and provides access, but it's much harder to get junk up there.
House designs really should include box rooms for storage. But if you do they quickly morph into home offices or spare bedrooms.
Malcolm, I agree. I recently designed a house without a basement or attic, and we designated a second floor room for mechanicals and storage. But it looks like a bedroom; I'm curious how it will be interpreted by banks and CEOs.
Good point. Attics are the residential equivalent of electrical rooms in the commercial world. Everyone piles random stuff in both.
I’d never store anything in my own attic. I hate working up there.
Bill
Thanks for all of the replies. I do not ever plan on storing anything in the attic, too much of a pain to get stuff up there and I have plenty of conditioned storage in the unfinished part of my basement. This is just for inspection purposes and, initially, to make it easier to get around and check air sealing around penetrations without creating new ones with my foot accidentally.... ;)
I'll poke my head up there in the near future to see what exactly I am working with. Haven't been up there since last fall, so memory is a little fuzzy on how the roof trusses are configured. My only possible concern is that I believe in the middle of the attic, right about where the hatch is, the trusses are fairly far apart, but I have to check to be sure.
If the trusses are far apart, you can build the walkway like a dock: run 2x4 or 2x6 beams out like joists, and put planks across them. Depending on the spacing, you may be able to span between them with 3/4” plywood.
You don’t need to worry much about span tables and floor loading here, just make it strong enough to hold up a guy and his tools. 2x4s are probably fine up to maybe a 4 or 5 foot span. It’s easy enough to test on the ground before you put it up. You’ll want to keep it light enough to be easy to build in the confines of your attic, so don’t overdo it.
Bill
I put a 2 ft. wide walkway made of leftover osb down the center of my attic, raised up to proposed insulation depth on 2x4s spanning truss web to truss web. It gave me a place to lay tools and a starting height for insulation.
What's the big problem with storing stuff in an attic, as long as it doesn't interfere with insulation?
Typical attic trusses are made of 2x4s connected together to make a sturdy structure. The problem is that since the bottom part (the bottom “chord”) of the truss is only a 2x4, it can’t handle much load if it’s acting like a floor joist holding up a bunch of stored stuff. The chords are supposed to be in tension, in engineering speak, which means they act like a tight string keeping the structure from pulling apart.
Think of the bottom chord of the truss like a piece of string keeping the ends (the eaves of the roof) from pushing outwards as the weight of the roof tries to flatten the truss out. Now think how much that string would sag if you add even a small weight hanging in the middle...
Attic “floors” aren’t really floors in a truss supported roof, so they aren’t built to hold up heavy loads like a real floor is. When people try to store stuff in attics like these, they risk deforming the truss, or worse, which can cause problems ranging from sagging ceilings and roofs all the way up to structural failure if the truss members separate. It’s rare to see serious failures, but sagging isn’t uncommon (I have to fix a sagging ceiling in my own garage because of the previous owner storing stuff in the attic above).
Bill
Our house was built in 1901 to be one story plus an attic. I have difficulty believing the attic was not then *intended* for storage (especially as the attic stairs present when we moved in appeared to be original -- by then a bedroom and bath had been added upstairs, without a change in the roofline). Since then we've built out to the back of the house and rearranged upstairs a good bit, but the eave closet to the front of the house is part of the original attic space, and the eave closets in the master bedroom were intended by the builder as storage.