olletsocmit Posted October 29, 2016 Report Share Posted October 29, 2016 Hey guys I'm sure a few of you know that over the past month I've been fully finishing my garage (I have to update the thread I started & add tons of pictures, I'll link that later). I air sealed the entire garage, insulated, vapor barrier, hung drywall, drywall finishing, & 2 coats of primer so far + painted & installed molding around the doors and windows... my plans are now to do some work in the attic after I was up there today. I'm a little worried that it's unsafe... in the ceiling there's a built in pulldown ladder and 10 years ago or so my father had basically laid a layer of plywood in the center of the attic about a 20' x 12' section. It looks like he literally just cut pieces and screwed it straight to the 2 x 4's. most attics I've seen anywhere that people are walking they run a second layer of reinforced 2 x 4's or 2 x 6. this is literally just screwed straight down to a 2 x 4's that The ceiling drywall is hung from...Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
rrich1 Posted October 29, 2016 Report Share Posted October 29, 2016 Nothing wrong with what he did from my perspective. The plywood distributes the weight evenly and keeps you from going through the ceiling on a slip. My attic has plywood from a previous owner but are not screwed down. The rafters will easily be able to handle your weight if that is what you are wondering. Sent from my XT1254 using Tapatalk Quote Link to comment Share on other sites More sharing options...
KnarlyCarl Posted October 30, 2016 Report Share Posted October 30, 2016 Yeah that sounds fine, the extra width of the added 2x lumber simply allows for more insulation to lay in there. Quote Link to comment Share on other sites More sharing options...
comp56 Posted October 30, 2016 Report Share Posted October 30, 2016 ya I walk around my attic without the plywood so having it there is just a bonus I wouldn't have a party up there but its all good 1 Quote Link to comment Share on other sites More sharing options...
khariV Posted October 30, 2016 Report Share Posted October 30, 2016 7 hours ago, olletsocmit said: Hey guys I'm sure a few of you know that over the past month I've been fully finishing my garage (I have to update the thread I started & add tons of pictures, I'll link that later). I air sealed the entire garage, insulated, vapor barrier, hung drywall, drywall finishing, & 2 coats of primer so far + painted & installed molding around the doors and windows... my plans are now to do some work in the attic after I was up there today. I'm a little worried that it's unsafe... in the ceiling there's a built in pulldown ladder and 10 years ago or so my father had basically laid a layer of plywood in the center of the attic about a 20' x 12' section. It looks like he literally just cut pieces and screwed it straight to the 2 x 4's. most attics I've seen anywhere that people are walking they run a second layer of reinforced 2 x 4's or 2 x 6. this is literally just screwed straight down to a 2 x 4's that The ceiling drywall is hung from... Sent from my iPhone using Tapatalk So just to clarify, your garage ceiling / attic floor joists span probably 14'-16'+ and consist entirely of 2x4s? My garage ceiling is made of 2x8s and the 14' span is too much for that such that I'm going to need to sister the beams to reduce deflection. I don't know what the rest of the structure looks like, but I wouldn't want to put much weight at all on a floor built out of 2x4s. You'd really need 2x10s floor joists to be able to put any substantial weight on the decking. 1 Quote Link to comment Share on other sites More sharing options...
KnarlyCarl Posted October 30, 2016 Report Share Posted October 30, 2016 7 hours ago, khariV said: So just to clarify, your garage ceiling / attic floor joists span probably 14'-16'+ and consist entirely of 2x4s? My garage ceiling is made of 2x8s and the 14' span is too much for that such that I'm going to need to sister the beams to reduce deflection. I don't know what the rest of the structure looks like, but I wouldn't want to put much weight at all on a floor built out of 2x4s. You'd really need 2x10s floor joists to be able to put any substantial weight on the decking. If the rafters are built with the usual diagonal cross bracing, this reduces the unsupported span down toward the single digits tho How about it, @olletsocmit ? Quote Link to comment Share on other sites More sharing options...
khariV Posted October 30, 2016 Report Share Posted October 30, 2016 1 hour ago, KnarlyCarl said: If the rafters are built with the usual diagonal cross bracing, this reduces the unsupported span down toward the single digits tho How about it, @olletsocmit ? Perhaps, yes. However, I want to say that the maximum unsupported span of a typical pine 2x4 is only like 3 1/2' before significant deflection occurs. There are online calculators that detail the specifics with the variables being the species of wood and the expected live and dead loads. My concern is that he says that there's an existing 12x20' section that has plywood laid down - suggesting that there's at least a 12' span. Again, if it's properly trussed and braced, then I'm sure it's structurally sound, but able to serve as flooring is a whole different issue. 1 Quote Link to comment Share on other sites More sharing options...
olletsocmit Posted November 3, 2016 Author Report Share Posted November 3, 2016 Thanks for all the replies guys when I get home in a few minutes I'll take a bunch of picturesSent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
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