Worthy ��" Thanks for the link (walkpads) This quote from the link summarizes my concern. âÂÂIt is a common misconception that cover boards are not needed and that the polyisocyanurate insulation has a high enough compressive strength to support the roof loads. Roofing manufacturers don't typically require cover boards, and so they're often eliminated from the roofing system to reduce costs. Cover boards should always be considered in roofing systems, specifically for protection of the insulation and for the benefits of prolonging the roof membrane itself.â The web site also says that when walk pads are used, workers tend to walk in random patters anyhow. Walkpads are not practical for my residential application. RmtDoug ��" This tells me my situation is borderline as to whether I need a cover board. My walking will be OK, but I never know what someone else might do. According WorthyâÂÂs research paper (This) the small deflections you are causing in the attic will have only tiny, almost negligible, impact on thermal performance, so you are OK. However, on a roof, the dents could become puddles. MorkigTenSur ��" This is good news that you do maintenance on the roof with no deflection. I also feel confident when I am up there I would have no problem, since I am aware and careful. However, who knows if a contractor in the future (plumber, painter, window cleaner, satellite dishâ¦) is not careful, etcâ¦. Also, Intuitively, I donâÂÂt see how having some kind of cover board between the polyiso insulation and the membrane would cause the problem your contractor spoke about. Maybe this would not apply to TPO or PVC membranes? In fact, WorthyâÂÂs link says that cover board should be considered. Now I need to figure out what type of cover board to use. It needs to be as thin as possible, since I need clearance for a short door step. I could use ü inch plywood. I am not sure if roof board comes that thin. Any thoughts? Also, how is it installed? I assume long screws with those 3-inch plates. Can these same screws be used and go through the insulation into the deck also be used to hold the insulation down? Or do you first need a separate set of screws to attach the insulation?

David- The point is not that doubling the insulation won't cut in half the remaining rather small energy loss. It's that, when you start with R-20 and double the insulation to R-40, you go from cutting your heat loss by 91% to cutting it by 95%. Hence, the improvement is very small compared to the fact that you have to put in twice as much insulation to get it, and possibly have had to use much larger framing to accomplish that. There isn't even enough room to achieve R-40 in a 2X6 wall cavity with fiberglass, mineral wool, cellulose, polystyrene or polyurethane board, or open or closed cell spray foam. You might be able to achieve it with foil-faced polyisocyanurate, but all the other insulating types would require anywhere from 2X8, to 2X10, or even 2X12 walls to achieve R-40, depending on which type of insulation you were using. When we are talking about these higher and higher values of insulation to save a couple of percentage points more of energy, the diminishing returns are trivial, especially in light of the cost of the much larger amounts of high end insulation and the very significant costs of much larger framing. The breakeven point for investments like that is so far out in the future that many homeowners won't live long enough to see it even if they live in the home their whole life.

I hear or notice the noise way less now, but still hear it from time to time when walking over an area for the first time. We have a couple of seams that have a small gap forming. As others have pointed out and i have come to learn, the problems that we have with the floors are caused by the unevern (not flat) subfloor. So, from that perspective, i cant blame flooret. However, most people that are buying these vinyl floors are doing so for the advertised ”value” and installing them in extisting homes. When you consider the time and expense to make old subfloors PERFECTLY flat, they are no longer a good value. That is my biggest complaint at this point; they drastically under communicate the amount of time and money required to achieve the desired outcome. To those of you who installed these Flooret floors, im sorry and hang in there. The noise and /or your attention to it will improve greatly over time.

Resummarizing here because it wont let me edit my main thread, with photos.. plywood is often used for observatory builds because its a smoother surface to seal off, i assumed it was ok.. Summarizing again: I've tried using some online deck building tools to generate the materials needed for what should really be a simple build for this, but i'm getting weird results and had some questions. I thought home depot had an online one, but only found an offline tool, lowes online did work, but in both cases they generated ridiculous materials lists and prices close to $10k. I know that a build like this should only cost $300 to $400. (with everything i have below and $69 to ship, its around $480 as of now, so higher than planned) On top of the deck will be the nexdome with 2 bay (astronomy plastic dome weighs around 300lbs i think). The first issue is the soil/ground. I have to make things level, so that i dont need extra height on a concrete pier, to keep the whole structure say 12" off the ground and not need a railing. Here is a shot of my ground so far, i wasnt sure if i should just get a bobcat and push it forward till level, or if tossing the extra dirt that is "high" on the upper part, to the lower part would suffice or cause a settling issue later? Either way, once down to level, i figure ill either just leave it as just dirt under, or put down plastic to block weeds and cover with a thin layer of gravel. Back to the deck build itself: 12x6 vs 12x8: I've seen many do the 12x6 route, but I wasnt sure, so for now i have it figured as roughly 12-13 12x8s? I have two 4x4x8's figured, but i'm thinking there will be at least 6 posts, with the deck surface at least 12" off ground, may need a few more to go into cement block Onto the blocks (going with blocks instead of posts in the ground, so when we move, we can just take the whole thing and go, or disassemble): I think these are the right concrete deck blocks? But now that i'm thinking about these, it looks like they are really meant to go under the 12x6 going longwise? So perhaps for the posts that will be 12-14" tall, i need something else here? (I figured 6-9 of these max) One of the online builder tools generated the list using these wood to wood triple zinc framing angles, again i'm not sure these are needed? I know i need joist hangers, unsure on the quantity, but these 2"x2x18 gauge triple zinc face mount joist hangers **the part on these i'm unsure on, is since this is low to the ground, how ill go about attaching these,since the floor needs in place, so i guess i need to tilt the whole structure to do this Many regular decking forums dont suggest using plywood for the floor, but i've seen many nexdome floors done with it, i was assuming it was this plywood: Severe Weather 3/4 inch common square southern yellow pine sheathing 4x8's $39? I was estimating i need 3 of these. Then I was figuring using all deck screws and not nails (in case i need to remove them), or maybe nails (which type?) for the hangers. These #8 2" ceramic I thought were the right ones? (or maybe 2.5") Here is the view of the joists as generated by the home depot offline tool, generally i was figuring a joist every 16, not sure about the extra ones near the pier location: Another question is on the underside, in the one online generator it shows these things that i'm not sure on, ie: the posts have those brackets and there are i think the right angle brackets: The other part i think i'm missing here are "toggle?" bolts that go into the posts? With nuts on the other side of some size? Any thoughts on all this so far, is this a pretty accurate list of things to do this simple deck?