Need help with attic construction????

[Bionik Kronik]

So my roof - attic space is framed with trusses every 24" o/c, and these trusses and my roof rafter are constructed of 2x4's.

How do I add floor joist to support the weight of some plant and equipment?

 

[hkush]

Some 1x6's set down in the other direction will spread out the load. 2x6's or 8's would be better. And I'd stick to the area with a load bearing wall below it. You don't want to be in the middle of a 2x4 span as it will eventually micro-crack the ceiling below. As for adding floor joists, that sounds like quite a job. You also need to make sure its waterproof or the ceiling below will be ruined.

 

[eglider]

I've sistered up 2x8"'s alongside the bottom chord of the 2x4" truss by cutting the roofpitch angle in one end of the 2x8" and running the other end over a bearing wall opposite, exterior wall plate to center of house (or some) wall below. You will see the plate of the wall because the drywall on the ceilings below will butt up to it. I would predrill and use 2 1/2- 3" drywall screws to fasten joists because hammering on them will pop nails in finished ceiling below. Even with all that done my concern would be water weight and your span. I'm a fulsome figured fellow and 2x8"'s and 3/4 osb board on a 12' span would be the minimum I would go. Then I would go with tongue and grooved sheeting because of the 2' joist spacing or you could space your 2x8"s @ 16" o.c. I would think long and hard about wanting to put a 40 5gal dwc up there.
You could be ok if the resses were small and spread out at the bearing wall. In any event you wont be calling in inspectors anyway ....lol
No offense meant to you hkush and I love you dearly but Bionik, PLEASE do not lay 1x6"'s on those 2x4"s and try to walk on them. I got lucky.... I was tearing out the whole ceiling anyway to put in a massive skylight when my 2x4 broke. Good thing I had moved the dining room table even though I was just laying out the cut. I did find a fatal flaw in Wifey's character however, as she laughed her ass off once she realized she wouldn't taking care of a parapelegic forever.
Remember....It may not be smart and it may not be pretty, but it IS do-able.

amendment: unless you have a regular stairway up there you wont be able to get sheets up so you would go with 5/4 x6" p.t. outdoor decking. Cheaper and stronger than #2 pine.

 

[Bionik Kronik]

Here is the space.

 

[PharmaCan]

Trusses are not engineered to support weight in the manner that you want them to. Run some 2x6 or 2x8 joists supported by the walls (exposed plates) and bypass the trusses altogether. Putting much weight on those trusses could do some serious damage to your house.

PC

 

[Bionik Kronik]

Yeah so you can see in the previous pic, this section does have supporting walls beneth. So I was going to run 2x6's sistered every 12" on center with spacers and then covered with 3/4" TNG Plywood.

 

[Bionik Kronik]

My bathroom is underneath and measures 5' by about 8 1/2'. You cant really tell by pictures but in the tallest space I can fully stand with about 6-8" to spare and Im 6'.

 

[PharmaCan]

Kronik - Let me put this as succinctly as I possible can - Don't touch the fucking trusses!!! Really, dude, they are an engineered unit that need to be left exactly as they are.

PC

 

[Bionik Kronik]

I am not going to be doing any cutting of trusses, truss me.

 

[Bionik Kronik]

If you look up Bender's Stealth Insulated Attic Grow on the DIY page, I want to do something like he has done.

 

[PharmaCan]

I am not going to be doing any cutting of trusses, truss me.

Who said anything about cutting the trusses? You can't nail to them, sister them, put flooring on them - nothing! Hanging a couple lights from the rafter section of the truss won't hurt anything but, other than that, you want to leave them untouched.

PC

 

[Kerosene]

You definitely have potential with that. Before we realized we had a loadbearing wall underneath our attic, we decided that anything requiring a reservoir was out of the question. We wanted to keep the final weight distribution as low as possible. We have 17/32 plywood as our floor system with a copious amount of fastening. The trusses are also 2x7 or 2x8. They aren't standard dimensional lumber; some unfinished rough wood. They were designed to cross a 30ft span w/o central support. I would be worried about cracking a finished ceiling with any weight on a 2x4 frame.

 

[Richard Gozinya]

Bionik, it can be done but I would plan this out really good. I grow in my attic and the real prob is the temps are crazy. And you will need to plan on how you will do you ducting and such as once you set it up getting to the sides that don't have flooring will be very hard. Also noise can be an issue. The real prob is temps though, my attic runs 20 degrees hotter than outside. But it can be done just more stoner engineering needs to take place. Good luck on this