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Insulation project and weight concerns in attic

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by DavidV, Apr 5, 2006.

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  1. joshuaviktor

    joshuaviktor New Member

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    In shorter news, USE STEEL!!! Cheaper than wood, right now. And Box section steel will install pretty easily, be simple to visualize, and you will be able to span a lot more distance than wood.

    NOte: IANAC - I am not a carpenter.

    Good luck,

    Joshua

    P.S. (2x6)+(2x6) does not equal 2x12.

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  2. elkimmeg

    elkimmeg Guest

    Thanks Dylan got confused as did the thread as to who orginated it
  3. DavidV

    DavidV New Member

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    Richmond VA
    WOW I'm grateful for the responses. I just went up and did some measuring. Wish my digital camera hadn't disapeared or I would include photo's . I believe the house is 24 feet deep. Roof is centered. From the floor to the center support that runs the roofline is 8 feet. There is currently a 4 foot wide area that runs the roofline which is 7 feet high. taking away 6 inches would still give me 6'6" high walkway. Can't go by what anyone else in the neighborhood has done because almost all the houses are different.
    YES walk up attic with dedicated stareway. It is located directly above the stairway from the first floor to the second floor.
    After doign much looking at the way the trusses are put in I have noticed things about the way they built the house and did the load bearing walls. If you are on the first floor just inside the front door, you are looking up the stairs. to your right you a family room that is 13 feet by 23 feet. I believe the wall that is part of the stairway is loadbearing and basicly segments the family room and master above it away from the rest of the house....so to speak. Does that make sense? Above the master you have 13'6" 2x6's spaced every 16 inches(14 1/4" between them) running from the loadbearing wall that is part of the stairwell to the exterior wall that has the chimney. These are paralell to the roof line. 6'6" in from the load bearing wall that is part of stairwell you have a 14'6" 2x4 laying face down that is is nailed to the top of the 2x6's and roughly centered from front to back. next to that, sitting up on it's edge is another 2x6 of same length also nailed to the 2x6's These two boards are running from front to back of house. is this to prevent roll of the 2x6's?? does this description make sense yet?? or should I say still?
    On the other side of the stairway into the attic you have a centered (on the roofline) load bearing wall that travels down to the 1st floor there is 16 feet of this wall with 2x6 spanning front to back before I get to the HVAC lines. If I make the shelves 24 inches deep and leave 4 feet between them I will use an 8 foot wide run. on the left side of my stairs I will center this on the loadbearing wallspanning over it 4 feet to each side. Using the advice I have recieved here I will run the 2x6 supports (someone suggested steal???? I'm wondering if that is practical or possible?) paralel to the existing 2x6 supports...although they are 2 piece runs up there now. crossing over the loadbearing wall a couple inches in each direction. Still with me?? should I just leave the osb down, and build my frame above it??? currently you have about 12 feet from front to back of house, centered roughly in the middle that has osb down there is stuff scattered all over on top of it.

    What about the first area I described, above the master. That one seems a bit more of a challenge. I can paralell the current run of 2/6's but only will have loadbearing support under one side....since 6 feet in there is taht "anti sway bar thing".

    Suggestions?? And again thanks for all the advice. I am hoping to put this together this weekend.
  4. elkimmeg

    elkimmeg Guest

    Sounds like a strong backer situation, at the mid spand where bearing wall is not supporting, then hung from the roof. This is a common practice not only to prevent roll but to distribute weight. really should not load up that area other framing members you describe crossing the rafters are collar ties again another means of weight distrobution. Code calls for one every 4' I usually do every other one Sounds like a plan to load up over the support bearing walls. Forget steel light weight interior wall steel is useless for support stick with the 2/6
  5. Rhone

    Rhone Minister of Fire

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    You know, for spans and such you'd probably all be interested in the forestry's span calculator http://www.awc.org/calculators/span/calc/timbercalcstyle.asp

    Doesn't work with trusses, but it's what I used to determine my rafters and I get the sense HarryBack has been there before. He talks about dead weight, and live loads, deflection, he knows his stuff. This is how I understand how to use it. But, to warn I follow HarryBack's statement about trusses. Unless a truss is designed to have a floor or weight on the bottom you don't know what effect it will have on the entire "truss system". They can't even have holes in them if I'm correct, but again I'm not a carpenter and my sense about them is they're designed with surgical precision to handle a particular load, and if another load is brought into the equation they weren't designed around, you might screw up the balance and opposing forces designed into them and probably not pretty. So, if you don't have a truss system

    Species: Spruce-Pine-Fir <most wood at lumber yards is one of these>
    Size: 2x6 <in this situation>
    Grade: No 2 <is usually what you get at the lumber yard, your ceiling joists may be stamped with what they are>
    Member Type: Ceiling Joists <It lets you pick the most options later for loads>
    Deflection Limit: I'll explain. It's marked as L/360, L/720 but what does that mean? It translates into how much sag you're willing to accept. Say for example you do NOT want your ceiling to sag more than 1/2" and your joists are 12' long. Let's see if L/240 is over 0.5". You'd take (12' length / 240) * 12 inches = 0.6" sag on a 12' span. Nope, too much. Let's try L/360. (12/360)*12 = 0.4" which, less than a half inch and the closest to our max so the one we'd pick in that situation.
    Spacing (In): 16
    Exterior Exposure: No & No
    Live Load (psf): 30 <This is how much weight we'll be putting on it>
    Dead Load (psf): 10 <This is the weight of the ceiling drywall, weight of the wood itself, and weight of the floor going on top of it>

    Click calculate and you'll see we can't put 30 psf up there. The max length for 30 psf with a 10 psf dead load is 10' 3" and our distance is 12'. Changing the live load to 20 psf, is just a hair short but should work because our deflection was also a bit short of 1/2". I don't think it will apply to DavidV, if he doesn't have trusses, and puts 2x6's on top of his current 2x6's for the entire length (or as far as he can without hitting the roof) he'll make a stronger support than just a 2x6 alone.
  6. DavidV

    DavidV New Member

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    What I have decided to do.....sort of. I will use the 16 foot run that allows me to span the center loadbearing wall first. I will run the framework of 2x6 supports paralell and on top of the current joists. I can only go out about 10 feet from the center support before running into another into what I believe elk called collar ties. at the center support the current 2x6's over lap as they meet and are nailed together 2 12 sections of wood into one 24 foot section of wood and I believe this makes it the bottom piece of the truss. because the joists are connected to the rafter piece at the end (outside wall of their run.... I will use 8 foot 2x6's and make lay them along and on top of the current 2x6's although they will not be exactly flush with them because of the way the current joists are joined together in the middle. my 2x6's will be centered on the joining point of the current 2x6 so that it is 1 piece of 8 foot spanning the center cupport 4 feet on either side. I figure this will place the load more squarely on the loadbearing wall and less on the joist in it's unsupported areas. Make sense?? As it stands I will be relieving stress from the joists on the front of the house because mose of the stuff up there was on them and the rear area had a walkway that you kind of had to duc down to use. I will build a lighht weight (perhaps luan) knee wall around the entire structure which will allow me to insulate all the rest of the attic to a much higher level. I am hoping that this will provide me with enough storage when I am finished that I will not even need to use the area over the master and I can simply insulate that . I will keep everyone posted and try to take some pictures with my phone so I at least have some documentation. Thanks again for all the help. Gotta love it when the net is used for something productive and helpful.
  7. elkimmeg

    elkimmeg Guest

    Warren how is the ventalation? ridge vents sofit Vents. size of gable end vents. Part of adding insulation, is the ability of your attic to breath.
  8. Rhone

    Rhone Minister of Fire

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    Hmm... you wouldn't hit any collar ties by adding 2x6's onto your ceiling joists in the attic. Collar ties run horizontal to the floor from both sides of the rafters, if anything you'll be hitting your head on collar ties. It sounds like you have a truss system. Trusses are out of my department but here's a picture of a Non-Truss roof system that was the norm until about the 80's in my area. It distributes the weight of your roof and snow to the outer walls. If you want to add a floor in your attic, you just put 2x6's or 2x8's on top of the current ceiling joists which makes it stronger and put your floor on top. My roof system is like this. You can see the collar tie.

    It sounds like you have a truss system in your attic, which there are countless configurations so yours may look similar, or may even look nothing like it. Unlike the latter putting all the force to outside walls, truss systems cancel some forces by redirecting them into each other. Before you work on this project, I'd get the input of an architect, maybe an engineer who knows loads. It's not the same putting a 2x6 on top of a truss system, it may even be dangerous. Then again, an architect/engineer may tell you that your truss system was designed to handle a floor load and distribute the weight. Then you'll be in luck. Realize, this is a wood burning forum and not an architect/engineering forum, I'd probably find a forum that deals more with architect/engineering and get some answers there and forget what you've been told on here. They'll probably definetely need a picture though. Good luck!
  9. Sandor

    Sandor Minister of Fire

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    This is not rocket science.

    An Architect is THE ABSOLUTE last person I would call. They specialize in designing difficult and expensive structures to build, and I have dealt with plenty. (Looks fancy enough to take alot of your money)

    You were hitting cripples, not collar ties.

    If you are that paranoid, PM me and I will send you to a good structural engineer based in Gettysburgh, Pa. I have used him for complex structual supports, and he is self employed and not that expensive. His stamp gets me through the county, every time.
  10. DavidV

    DavidV New Member

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    Started Saturday. didn't take up the existing floor. laid the 2x6's over them directly over the existing 2x6's put some anti roll spacers between the 2x6's and poured in the cellulose insulation. since I am not blowingn in a lot of insulation I didn't ren the machine. Losening it b y hand is a pain. dirty job in a sweaty attic. got about 1/4 of it done. had to call it quits because house guests arrived. Sunday was working on another place andd monday/today was working on exteriour of the house. I'll get back to it this weekend. Sandor I'll be pming you because I have a load bearing wall I am movingn so I need a decent structural engineer for the stamp.
  11. elkimmeg

    elkimmeg Guest

    Warren if you use an LVL composit wood structure for a header, most lumber yards will spec it out and supply the engineering stamp accepted by building inspectors. What is the spand you are removing as I can advise what will work to transfere the load. Give me some details lenght holding second floor ? or just a ceiling attic area? Pm me if you wish I have the boca or Inbternational building code charts here to forward to you if needed You also can go th the state of ma Building codes spand charts as they mirror the National codes. I can supply you that link basically goggle bbrs. My advice is cheaper than engineers
  12. Sandor

    Sandor Minister of Fire

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    Your generous Elk, cause my guy won't lift a finger without a check with a least a couple of zero's.
  13. DavidV

    DavidV New Member

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    I have some decking to replace today (from tearing out the hot tub earlier this week) Siding to repair so it lasts another year before we do the whole place over, and screen to replace on the porch. So I'll have to wait till later this week to get into the attic again.
    The LB wall being removed is 13'10" on the first floor. Another load bearing wall directly above for the second floor and then the attic above that.

    David
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