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Old 01-14-2012, 04:03 PM   #16
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Smashing down blow in insullation


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Originally Posted by BackYardBuilt
What if they span 30 feet?
Edit: Oh. I see they're trusses.
Titan, I apologize for not using the correct terminology for you to understand my fundamental question which I was seeking advice on. (Which was about insulation and not rafters or joists) I do get some of these defining terms mixed up because I don't use them on a regular basis like I am sure many of you all do. Usually in my field of work we use calculus, physics and statics engineering to determine stress loads, material dimensions, sheer stress minimums, compare graphs, calculate bending moments, moments of inertia and lots of other analysis to make sure that things are safe and run efficiently. Please accept my sincerest apologies for not communicating these terms more clearly.

I find it funny how you seem to question the legitimacy of my being an engineer due to the mis-identification of some simple wooden parts in my attic. I wasn't saying I am an engineer and you should STFU, I was simply saying I am a man who has education in this area to know the limitations of what I am attempting. I really just wanted to end the discussion about, "Is what I am doing safe" and get the real question answered about my insulation dilemma. The pictures I posted clearly illustrate my goal.

[/QUOTE]

You said you are a mechanical engineer.
And there's no reason for such foul language.

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Old 01-14-2012, 05:02 PM   #17
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Smashing down blow in insullation


If there was a second floor (in place of the attic storage floor), it would be heated and conditioned, air-changes, etc. to remove the moisture one gets in a story above. Your proposal isn't heated, or vented to remove any moisture. Not insulating underneath would cause a cold area that would wick the heat from the room below.

The insulation would have to be kept back from the side walls (storage) enough to let it breathe, resulting in air movement (heat loss) and insulation loss= heat loss, you would be losing twice as fast or more, than just no insulation. Depending on the stillness of the attic air and currents there, not even mentioning the convective-looping possible.

Storage in attics is a bad idea, enclosed (no HVAC) storage is also bad, in my opinion. I see why our trusses incorporate storage in design, only because people will store there anyway:http://www.tricountytruss.com/CodeChanges.aspx

Perhaps others can suggest ideas?

Gary
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Old 01-15-2012, 12:17 PM   #18
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Smashing down blow in insullation


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Originally Posted by GBR in WA View Post
If there was a second floor (in place of the attic storage floor), it would be heated and conditioned, air-changes, etc. to remove the moisture one gets in a story above. Your proposal isn't heated, or vented to remove any moisture. Not insulating underneath would cause a cold area that would wick the heat from the room below.

The insulation would have to be kept back from the side walls (storage) enough to let it breathe, resulting in air movement (heat loss) and insulation loss= heat loss, you would be losing twice as fast or more, than just no insulation. Depending on the stillness of the attic air and currents there, not even mentioning the convective-looping possible.

Storage in attics is a bad idea, enclosed (no HVAC) storage is also bad, in my opinion. I see why our trusses incorporate storage in design, only because people will store there anyway:http://www.tricountytruss.com/CodeChanges.aspx

Perhaps others can suggest ideas?

Gary
Gary, I was thinking about the physics of this last night and I had a feeling that the air temperature inside the room would be an issue like you said above. Basically, wherever the warm air meets cold air, ( Or vice versa in the summer time ) needs to be inside of an open air attic so that this newly formed moist air can travel up and out the top of the ridge vent. As long as the air passes through different floors that are pretty much the same temperature, you wont be getting moist air formation on the underside of the decking.

So I started to think of it like this. What if I made this room with no insulation under the floor but insulated the entire outside of the room and ducted HVAC air into the room to keep it at the same temp that the rest of the house is.

There is a duct that I can see in cutout where all of the drain stacks, electrical, water supplies and the HVAC runs down to the furnace. I could tap into that duct and use it to heat the room.

There sure is a lot of work going into doing something like this right but I still am all for it if you guys think it will work.

Gary thanks for your patience and explanations. They are really making the understanding of all this easy.
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Old 01-15-2012, 12:49 PM   #19
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Smashing down blow in insullation


Exactly, it needs to be conditioned, essentially a "new room". Only problem (major) is that these are trusses, not joists. So, no-can-do..... Even with a "room" not touching the trusses, with its own floor system, it has to meet minimum building Code for attic storage (headroom, egress, etc.): http://docs.google.com/viewer?a=v&q=cache:EJENK_uA9RQJ:www.cr-ar.com/pdfs/Building%2520Code%2520Changes.pdf+R602.3(1)+2006&h l=en&gl=us&pid=bl&srcid=ADGEESh311Kosslp7jsjp9WhUX xZsgSiyNaWb-eW0YminVwmPUavLlW75BKLoV9em4LFCAydmTGQlkUFOPm8AqHk RP5wLQGQQGkwyzAGtlN4D2DqCiCLwprOpEbvvjeGk6CEhyHiVd tK&sig=AHIEtbRa4Ah_IICPQ3BR1txlzU01V4JQIg

I'd try another idea. Backyard sheds, etc.
Sorry we couldn't help more...

Gary
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Old 01-15-2012, 03:54 PM   #20
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Smashing down blow in insullation


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Originally Posted by GBR in WA View Post
Exactly, it needs to be conditioned, essentially a "new room". Only problem (major) is that these are trusses, not joists. So, no-can-do..... Even with a "room" not touching the trusses, with its own floor system, it has to meet minimum building Code for attic storage (headroom, egress, etc.): http://docs.google.com/viewer?a=v&q=cache:EJENK_uA9RQJ:www.cr-ar.com/pdfs/Building%2520Code%2520Changes.pdf+R602.3(1)+2006&h l=en&gl=us&pid=bl&srcid=ADGEESh311Kosslp7jsjp9WhUX xZsgSiyNaWb-eW0YminVwmPUavLlW75BKLoV9em4LFCAydmTGQlkUFOPm8AqHk RP5wLQGQQGkwyzAGtlN4D2DqCiCLwprOpEbvvjeGk6CEhyHiVd tK&sig=AHIEtbRa4Ah_IICPQ3BR1txlzU01V4JQIg

I'd try another idea. Backyard sheds, etc.
Sorry we couldn't help more...

Gary
Well it looks like this stuff will maybe have to go to a friends house! LOL It won't be long before my wife and I can move out of here anyway. We have absolutley no room in this house or a yard! We moved in here while I was finishing up college because it was CHEAP!!! After I got a job we just stayed because it was so close and convinient to my employer plus the payments were great too.

Plan is to pay down my student loan debt so we can have 20% to put down on a house in the suburbs.

Thanks for trying to help me out.
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Old 01-18-2012, 07:02 AM   #21
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Smashing down blow in insullation


I think you are overthinking this whole project. why do you want to build a room up there? Millions of homes in this country alone have attic storage on simple floors.

Now to give my opinion on your original question. The insulation as it is, is needed to keep the heat in your home. Removing it or compacting it will lessen the effectiveness of it. a simple solution would be this. Add some 2 x 10 floor joists over the current 2 x 8's you say are up there. But, instead of going right over the tops of the existing I would run them perpendicular 16" on center. This will then allow you to put down a plywood floor over the insulation. Depending on the size of the attic opening you may need to cut these down in size which will allow them to fit. Also leave a small (~1/4") gap between the sheets to allow for air movement. To prevent the vapor issue that was mentioned in an earlier post, ensure that the plywood has a ~1" air gap between it and the insulation. This will allow the plywood to breath and prevent the formation of condensation. Once the plywood is doen then load it up to your hearts content. Of cours this is providing that you did all of the load calculations needed to ensure the existing structure can handle the additional load

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