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BillArchtx
Registered Users
Posts:24
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| 10/13/2000 10:11 AM |
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I really read this as Cost Saving SIP Design - much can be done here that has a positive impact on first costs. I see two categories here; direct savings of the initial panel construction cost due to economies in the design/installation of the panels themselves and first-cost savings that the project enjoys due to the "side effects" of panel construction. Of course the industry has lots of solid documentation to substantiate the fact that operating costs are always significantly lower than those of a comparable stick-built structure.
1. Direct cost savings can be realized by working economically with standard panel dimensions so as to minimize waste during manufacture of the "kit."
I advise that one lower the top floor plate height to somewhere between 4 and 7 feet depending upon plan/headroom requirements, and go with "cathedral" or "vaulted" roofs/ceilings. The overall volume is reduced as well as the wall surface area resulting in lower operating costs as well as lowered first costs of the panel kit. Cathedral roof construction is the application where panels outshine sticks the most. In order for sticks to match the r-value AND infiltration resistance of the panels, the sticks must be deep enough to accommodate deep batts - expensive enough - but also have additional depth to provide for proper venting. Most times, this kicks one into sizing the members for insulation, rather than for structure and often as not requires specifying composite joists over solid sawn at an additional premium. If the building is only one story, dropping the plate height to about 7 feet - but also being sure that the wall panels drop down outside the floor deck to bear directly on the foundation sill plate and insulate the rib band location properly - allows the use of economical 8 foot panels.
2. Balloon that structure! The conventional procedure has the G.C. or owner hiring a panel erection crew - oftimes "imported" from a distance so travel and accommodation costs may become considerable. This crew then will erect the first floor exterior panel walls, some interior walls so as to be able to install the second floor deck, and finally put up the second floor walls and post up the roof panels. If one designs foe balloon wall construction, the panel crew barrels through, putting up the walls and the n posting up the roof and then they're on to the next job. Local guys get to do the inside work.
3. Bear with me here - this isn't exactly a pitch for steel framing……but designing/building as described above ALLOWS for a natural division between trades so that light gag steel framing may be used for both the internal walls and the floor framing. The advantages to doing so are briefly as follows:
A. The guys who frame with light gage steel are usually the same guys who install the gypsum board, so there's one less trade to coordinate.
B. No more complaints, therefore, by prima donna rockers about the quality of the framing.
C. Screws ONLY used to hang the rock so nail-pops are gone forever!
D. Mechanical trades greatly appreciate the reduced need for drilling. This may even be reflected in their price!
E. Obviously, steel doesn't split, warp, twist, shrink, etc.
F. The "shrink-resistance" of the steel makes it far more compatible with the panels.
4. Panel construction, with it's associated reduced envelope losses, has a very positive impact on the design and cost of the mechanical system.
I think these are the major cost impacts I can think of now, I'm anxious to see what other may say.
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Steve Andrews
Registered Users
Posts:334
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| 10/17/2000 11:57 PM |
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Bill,
Could you provide a little more detailed explanation of one part of your post... What's your preferred sequence and/or attachment scheme for your second floor when you balloon-frame the first and second story walls?
Steve Andrews
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BillArchtx
Registered Users
Posts:24
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| 10/19/2000 10:34 AM |
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Steve & Co - We put in the second floor AFTER the roof panels have been put on - posted, as may be required. Using a carefully calculated and engineered screw schedule, a ledger is attached to the inner skin and top-mounted joist hangers sre ffixed to it and carry the second floor framing. If light gage steel framing is utilized - which I strongly recommend - a track section is affixed to the wall with the same screw schedule as calculated for the 2x ledger and the steel joists screwed to the flanges of the track. There are a few specific notes. In checking the capacity of the wall to carry the required load, use the Assymetrical loading charts as opposed to those for symetrical loading. You will find the listed capacity ratings less than those for symmetrical loading, but well within safe limits of your loading requirements. Also; be sure to utilize the correct ratings of screw-holding capacities in the 7/16" OSB for the particular screw diameter - AND FIELD CHECK THIS! Hope this helps, Bill
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ICF501
Registered Users
Posts:109
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| 10/19/2000 12:47 PM |
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Hey Guys and Gals
Bill is hitting on what I consider to be the very most absolute way to cut costs using SIPS. USE AND ARCHITECT OR ENGINEER THAT FULLY UNDERSTANDS WHAT A SIP CAN AND CANNOT DO!!!!
I consider Bill to be one of the most agressive and educated architects in the field of SIP construction. I may agree or disagree with his take on metal studs, I think that has a lot to do with locality and sub expertise, but thinking a project thru and allowing SIPS to be used to their fullest capacity while not taking them for granted will help with the launching of SIPS in the industry.
A fabricator or material supplier can accomodate any type of use of SIPS but they cannot allow for individual and site specific concerns. An architect that has studied our product will help you in not oversizing wood members or structural elements. My observation is that when a designer, architect or engineer comes up against a problem that he or she does not understand, they will revert to standard "wood frame experience and or tables to comply with the problem. The building officials do the same thing, especially with the outsourcing of plan checks. Get a goo intial design and you can't lose. The logistics of the rest of the project are up to the fabricator, the contractor and good common sense. Thanks Bill.
Ed Stahl
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BillArchtx
Registered Users
Posts:24
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| 10/24/2000 10:02 AM |
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Ed -
Thanks for your kind words.
SIPs are fundamentally different than sticks structurally and thermally. Sticks collect and distribute small point loads with some welcome redundancy, SIPs are akin to shell structures that disperse loads continuously and more or less evenly over their entire surfaces.
Thermally, in cold climates with heating systems and in hot climates with A/C systems - where the stick building is constructed tightly to today's standards which are much higher than traditional usage - condensation and rot which threaten structural integrity are a real problem. Panels, which are their own vapor barrier, need careful sealing at seams - particularly those subject to the greatest vapor drive such as ridge joints. Knowledge of all of these properties should be giving us superior buildings BY DESIGN, not just stick translations. A proper architect should be integrating these understandings into the production of integrated designs that really raise the bar by any measure for residential, commercial and institutional buildings.
The design community needs to be HAMMERED by those who are SIP-knowledgeable to "get off the stick" and start building with SIPs, their clients, our society, our environment deserves no less.
Bill Chaleff
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George O`Neil
Registered Users
Posts:1
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| 10/27/2000 11:30 PM |
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I am acting as my own GC in the construction of my single family home using baloon construction, in a Timber Frame Home.
Your the experts, but we need some standards/codes for the installation of the SIPS. My project manager has about 4 different ways to install the material, and as a customer - - it does not warm the heart to ponder which method is best.
I have one question. I am using 8" EPS with OSB on the sides, the windows are cut, and the contractor aligns them, nails them and fills the voids with foam from a can which seals the voids. The conventional stick construction calls for layers of building felt and vapor covering over the entire home.
Is the foam adequate to prevent water, and air infiltration? The contractor claims it is, the code is written for stick systems and doesn't speak to SIPS?
What is the best "standard" installation practice for installing metal clad windows in residential construction using SIPS?
Comments?
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ICF501
Registered Users
Posts:109
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| 10/28/2000 12:37 PM |
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We need to use a bit of common sense when knowing what SIPS can and cannot do.
due to the nature of SIPS, having a tight almost monolithic shell is a great added benefit and to why one should build with SIPS. Foam core panels do not allow for vapor buildup within the wall or roof, therefore moisture or vapor cannot condensate within the wall and create moisture. Vapor remains in a vapor state. This is good for us and is why SIP mfgs do not call for a vapor barrier to be placed on the exterior of the structure. However.......Let's use a bit of common sense here. I
I build in a climate primarily subject to 75" of rain, and sometimes this rain is wind driven to and excess of 60 mph. This can create havoc to siding applications, whether stucco or wood or both. Brick and stucco applications still require felt to be placed on the structural exterior shell. Masonry products will retain and pass water thru. I always use a barrier between my SIPS and exterior finishes. The best carpenter in the world will not be able to completly seal siding against wind driven rain, and the felt or other barrier will protect my OSB on the sips.
With regard to windows, Expanding foam is adequate for use as an infiltration inhibitor but not completly adequate. If you filled the window and door voids thick enough to block air chances are the window and door frames will bow. Be sure to use a low expanding foam. I stuff fiberglass very densly after foaming in place, but the best defense I have found is to flash window and doors as per usual practice, and then use bituthane on the outside flanges all around. I know this is redundant, but it has stopped wind driven leaks in the shell.
SIPS practices are flexible enough to be used at differnect architectural applications. This I think is plus not a negative for the use of SIPS construction. Joint and spline configurations should always be sealed from an infiltration point of view. You can place tape and/or caulk small openings if not planned correctly or if that fluke application pops up all of a sudden(Murophy). Flexibility is what makes sips techniques better than stick framing.
Try the bituthane. I use grace Ice and Water. It is spendy but not as much as callback costs.
Ed Stahl]
Sunworks
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