ricky_005
Basic Member
Posts:313
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| 05 Aug 2014 11:03 PM |
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Was pondering the idea of the possibilities of building this house. My main concern is the cost of the exterior wall construction, as we all remember the Dryvit failures from the 90's. If I build the home, the wall construction would need to be designed for the Hot Humid South in the Atlanta Georgia area. The setting will be in rural area where termites and carpenter ants love to destroy homes. My Question is....- What would be the most economical (CHEAPEST) exterior wall construction/method which you wouldn't have to be to concerned about water/insect damage?
Requirements...- Construction methods need to be where their are no problems insuring the home.
- Exterior cladding - Dryvit/EIFS
- True R value of the exterior walls needs to be between R-20 to R28
- No rain screen which would severely handicap the R value of the insulation foam or what ever you may suggest.
- No ICF walls, must be cheaper to construct than ICF construction.
- Method/System needs to be Air Tight!
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arkie6
Veteran Member
Posts:1453
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| 05 Aug 2014 11:40 PM |
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Brick veneer over wood framed wall. Wet sprayed cellulose for the cavity insulation is the best R value for the $ out there. Cover wood framing with 7/16" OSB for strength. Install two (2) 1" thick layers of borate treated EPS foam with seams staggered. That will give you about R19 whole wall R value with a 2x4 wall. You could bump up the framing from 2x4 to 2x6 and that would increase the whole wall R value to around R23. You could also replace the 2 layers of R4/inch EPS with 1 layer of R6.0/inch polyiso with taped seams. If you go with 1" foil faced polyiso with seams taped, the radiant foil facer with 1" air gap between the foil facer and brick will add another ~R2.5 effective R value. Combine that with the 2x6 wall and you will be at ~R23 whole wall. If you increase the polyiso to 1.5" you would be at ~R26 whole wall.
Down here in the south, brick is relatively cheap, durable, and nearly maintenance free. I'm having brick installed on the exterior of my ICF home for ~$4/sq ft including materials and labor. King size Acme brick manufactured in Oklahoma City will cost me $375 per thousand delivered. It takes 5 king size brick to cover 1 sq. ft. That translates to $1.88/sq ft for the brick. Labor to install the brick is $0.35/brick and that translates to $1.75/sq ft. Masonry sand, cement, and brick ties are estimated at <$0.50/sq ft. This doesn't include lintel steel angle for over windows and doors, but I estimate that to cost <$500 for the whole house.
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Jelly
Veteran Member
Posts:1017
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| 06 Aug 2014 05:26 PM |
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ricky, all of your requirements point to steel SIPs, and Atlanta is right in the middle of the industry. |
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ricky_005
Basic Member
Posts:313
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| 06 Aug 2014 06:14 PM |
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Two story structures and using the steel SIP exterior panels to support the floor joist is a scarey thought when it comes to fires. My guess would be in a bad fire it would collapse in a matter of minutes. Was thinking it would require the second floor joist to be supported with stick framing to withstand a fire. |
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arkie6
Veteran Member
Posts:1453
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| 06 Aug 2014 11:37 PM |
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Did I miss the requirement for Dryvit/EIFS exterior or was the original post edited and that requirement added later? |
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ricky_005
Basic Member
Posts:313
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| 07 Aug 2014 01:45 AM |
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Sorry I did an edit... |
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Alton
Veteran Member
Posts:2164
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| 07 Aug 2014 07:22 AM |
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Ricky_005,
For comparison purposes, why not get a quote from http://nexgenframing.com/ My understanding is that this company will furnish an engineered home with whatever amount of on site work you want done. Let me know if you hear differently since my last contact was some time ago.
The insulated panels are made in a factory at Melbourne, FL with some options for the amount of insulation. The closed cell foam covers about one half of the steel stud and then extends beyond the studs to insulate them. The other half of the stud is insulated after utilities are in the wall.
The walls are made in sections with the steel in each section riveted together (Stronger than screws - designed for high wind areas). The sections are then assembled with screws on site. Wall sections are ready for EIFS. Depending upon span and loads, the roof can be C-channels or steel trusses.
The roof is insulated with spray foam also. I would prefer that some of the insulation be outside of the steel trusses just like with the walls.
I have some pictures of this technology that were taken at the South East Builder's Show in Orlando a few years ago, if anyone wants a copy by e-mail. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Jelly
Veteran Member
Posts:1017
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| 07 Aug 2014 10:49 AM |
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Posted By ricky_005 on 06 Aug 2014 06:14 PM
Two story structures and using the steel SIP exterior panels to support the floor joist is a scarey thought when it comes to fires. My guess would be in a bad fire it would collapse in a matter of minutes. Was thinking it would require the second floor joist to be supported with stick framing to withstand a fire.
If you're talking about a fire that hot (for example carpet-bombing from above) then it would destroy any framing as well. |
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ricky_005
Basic Member
Posts:313
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| 07 Aug 2014 09:46 PM |
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If you rely on just the external steel SIP to support the floor joist and roof above, it would NOT take long at all compared to wood for the heat from the fire to cause the metal skins and EPS to structurally collapse. All I'm saying is a home built with steel SIP with no heavy steel or wood framing supporting the panels in a fire would seriously compromise the structural integrity of the structure in a MAJOR WAY, like TOTAL STRUCTURAL FAILURE. |
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Jelly
Veteran Member
Posts:1017
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| 07 Aug 2014 11:55 PM |
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ricky, no that's not correct. The fire ratings of steel SIPs with EPS cores are similar to those achievable with wood framing with 5/8 drywall. Hanging a joist system from the external SIP panels is not the same as just hanging a joist system from sheet metal. The engineering is solid on this. |
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Lbear
Veteran Member
Posts:2740
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| 08 Aug 2014 01:22 PM |
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I think what he (Ricky) is saying is that a steel SIP with an EPS core would melt the EPS at 180F+ and once the EPS core is melted, the integrity of the SIP is completely compromised since the EPS core is the structural "I-Beam" of the SIP, not the skins, and if the I-Beam/EPS melts, then everything attached to it will collapse with it. Steel SIPs with EPS have a Class "B" fire rating but they must be covered with 1/2" or 5/8" drywall for protection.
Heavy timber does REALLY well in fires since it will char and not burn and it takes a long and hot fire for them to finally fail. Even dimensional wood will easily handle 250F-300F without being compromised. Polyurethane has a higher fire rating (Class A - Class 1) because it does not melt and will only char at temps reaching 750F.
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Jelly
Veteran Member
Posts:1017
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| 08 Aug 2014 04:29 PM |
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Regular wood framing would have a 1 hour fire rating, as would steel SIPs with EPS cores. So after an hour of fire within the structure the EPS may reach 180 and start to degrade. That's a lot different than the total structural failure within minutes he was talking about. You're not going to be able to just sweep out a wood-framed house and hang some new sheetrock after such a fire either. Nor could you do the same with an ICF structure.
We can talk about adding components to any building method, whether heavy timber or heavy steel or reinforced concrete, to make them more resilient to catastrophe. But the OP shouldn't rule out the best construction method that meets all his requirements simply due to misinformation.
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jonr
Senior Member
Posts:5341
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| 08 Aug 2014 05:22 PM |
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It could certainly be built with SCIP construction, but there seems to be little info on cost. You can also do cellulose, fiberglass or spray foam filled, rigid foam covered stick construction but with steel studs instead of wood. Or double wall w/o rigid foam (use DensGlass). Or maybe even well dried treated wood studs. |
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robinnc
Advanced Member
Posts:586
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| 08 Aug 2014 07:22 PM |
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Why have you ruled out ICF? With ICF, you have allot less wood to buy, insulation already on outside walls, less tons for HVAC....etc.
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Lbear
Veteran Member
Posts:2740
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| 09 Aug 2014 12:37 AM |
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Posted By Jelly on 08 Aug 2014 04:29 PM
Regular wood framing would have a 1 hour fire rating, as would steel SIPs with EPS cores. So after an hour of fire within the structure the EPS may reach 180 and start to degrade. That's a lot different than the total structural failure within minutes he was talking about. You're not going to be able to just sweep out a wood-framed house and hang some new sheetrock after such a fire either. Nor could you do the same with an ICF structure.
We can talk about adding components to any building method, whether heavy timber or heavy steel or reinforced concrete, to make them more resilient to catastrophe. But the OP shouldn't rule out the best construction method that meets all his requirements simply due to misinformation.
No offense but you are wrong. The minimal Residential Building Codes require that thermal
plastics (EPS/Polystyrene) to be covered with an approved 15
minute thermal barrier like 1/2” or 5/8" drywall in order to pass the 15-minute fire rating test. Then you have the 1-hour fire rating and in wood stud construction, the hourly requirement can be achieved with a single layer of drywall because the
exterior surface of a stud will char in a fire. The charring protects
the inner core of the stud and allows the stud to continue carrying structural loads. So only a single layer of gypsum
will provide the additional fire protection the stud needs to meet the 1-hour fire requirement.
In a EPS SIP the EPS is the core. The EPS begins to melt at around 180F
so the drywall protects the skin of the SIP from getting too hot and
melting the EPS core. Drywall has water bounded within its core properties and when heated the water keeps the surface of the SIP cool. As long as the drywall water content is there it will keep the EPS from melting but once the drywall liquid content is depleted it will begin to transfer the heat and melt the EPS core. So the EPS core needs to stay below the 180F melting point
in order to continuing supporting the skins from buckling and failing. So within a few minutes of a house fire a single layer of drywall will
cause the EPS core to melt and the SIP will buckle and fail.
Therefore, it requires two layers
of 5/8" Type X drywall, plus spline dimensional lumber connections, to provide enough fire/water protection to keep the EPS cool enough to pass the 1 -
hour fire test. You will NOT achieve a 1-hour fire rating with just a single layer of drywall on a SIP with an EPS core. Two layers of 5/8" Type X drywall will be required along with dimensional lumber connections. Even then, most polystyrene SIP manufactures recommend you install a fire suppression system.
This was verified with two engineers I worked with and by the building department. |
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cmkavala
Veteran Member
Posts:4327
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| 09 Aug 2014 06:58 AM |
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Posted By Lbear on 09 Aug 2014 12:37 AM
Posted By Jelly on 08 Aug 2014 04:29 PM
Regular wood framing would have a 1 hour fire rating, as would steel SIPs with EPS cores. So after an hour of fire within the structure the EPS may reach 180 and start to degrade. That's a lot different than the total structural failure within minutes he was talking about. You're not going to be able to just sweep out a wood-framed house and hang some new sheetrock after such a fire either. Nor could you do the same with an ICF structure.
We can talk about adding components to any building method, whether heavy timber or heavy steel or reinforced concrete, to make them more resilient to catastrophe. But the OP shouldn't rule out the best construction method that meets all his requirements simply due to misinformation.
No offense but you are wrong.
The minimal Residential Building Codes require that thermal
plastics (EPS/Polystyrene) to be covered with an approved 15
minute thermal barrier like 1/2” or 5/8" drywall in order to pass the 15-minute fire rating test.
Then you have the 1-hour fire rating and in wood stud construction, the hourly requirement can be achieved with a single layer of drywall because the
exterior surface of a stud will char in a fire. The charring protects
the inner core of the stud and allows the stud to continue carrying structural loads. So only a single layer of gypsum
will provide the additional fire protection the stud needs to meet the 1-hour fire requirement.
In a EPS SIP the EPS is the core. The EPS begins to melt at around 180F
so the drywall protects the skin of the SIP from getting too hot and
melting the EPS core. Drywall has water bounded within its core properties and when heated the water keeps the surface of the SIP cool. As long as the drywall water content is there it will keep the EPS from melting but once the drywall liquid content is depleted it will begin to transfer the heat and melt the EPS core. So the EPS core needs to stay below the 180F melting point
in order to continuing supporting the skins from buckling and failing. So within a few minutes of a house fire a single layer of drywall will
cause the EPS core to melt and the SIP will buckle and fail.
Therefore, it requires two layers
of 5/8" Type X drywall, plus spline dimensional lumber connections, to provide enough fire/water protection to keep the EPS cool enough to pass the 1 -
hour fire test. You will NOT achieve a 1-hour fire rating with just a single layer of drywall on a SIP with an EPS core. Two layers of 5/8" Type X drywall will be required along with dimensional lumber connections. Even then, most polystyrene SIP manufactures recommend you install a fire suppression system.
This was verified with two engineers I worked with and by the building department.
To are all wrong! first off Jelly, I gave you some wrong info, it should have been 2 layers, I spoke without checking, but regardless any firefighter will tell you that in most cases the noxious gasses from furnishings burning will kill you before the fire ever gets to you, you would also succumb to 15 minutes of 180 degrees before the EPS degrades or before the fire gets to you Lbear, the 15 minute thermal barrier IS NOT A FIRE Barrier (it never states fire rating in the code), (wood stud walls require one layer 5/8" type X each side for 1 hr) it is also a requirement for wood framing using EPS insulation to have a 15 min THERMAL barrier, and is where this code originated from , code officials unfortunately lumped all EPS cored assemblies unto this same category Furthermore our Steel SIP rated wall in addition to the drywall has 1-1/2" steel high hat furring providing and air barrier to the skin and core , I have the photographs of the deconstructed wall and after the tests that show NO DEGRADATION for the 1 hour test assembly, where interior temperatures reached over 300 degrees CENTIGRADE at the peak of the test there is never "spline lumber" or any spline for that matter needed in the steel SIP assembly, 20 years in the business and have NEVER heard any steel SIP manufacturer recommend a fire suppression system !!Please let me know which ones of the "most" are telling you that?? Please private message me the names of the engineers and building official, as I would love to engage them in this conversation I will be glad to email the 36 page... 1 hour test report with the photos to anyone that wants it if they provide their email address in a PM to me, we also have corner room burn tests (ASTM E84-07) and roof assembly test available |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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Jelly
Veteran Member
Posts:1017
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| 09 Aug 2014 10:41 AM |
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Nice to hear from an expert!
Ricky, sorry your thread got hijacked and went off on this tangent. |
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jonr
Senior Member
Posts:5341
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| 09 Aug 2014 11:08 AM |
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My understanding is that a double layer of stucco wrap serves as a drainage gap without causing enough air flow to lose the R value of external foam. |
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ricky_005
Basic Member
Posts:313
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| 09 Aug 2014 11:51 AM |
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Posted By robinnc on 08 Aug 2014 07:22 PM
Why have you ruled out ICF? With ICF, you have allot less wood to buy, insulation already on outside walls, less tons for HVAC....etc.
I'm not totally ruling out ICF ... The idea was a much cheaper durable alternative exterior wall system for EIFS. EIFS systems have a bad history of causing serious structural damage to wood framing as you should all know. They always claim it is the installers fault which it was in most cases .... it just proves the system was to difficult for the majority of contractors to install it properly, or they just didn't care. The best system I have found to have a good chance of surviving the humid south is the Perfect Wall System http://www.buildingscience.com/docu...rfect-wallHere is a video showing a home utilizing the theory behind the Perfect Wall System https://www.youtube.com/watch?v=d8i-93ABo3I I still need to run some numbers to find the total estimated price for a Perfect Wall system surely it is cheaper than ICF just need to find out by how much. The standard construction method for the most part you just skin the entire wood structure with peel and stick water proof membrane. Not to much for a sub contractor to screw up. Dryvit has a trowel on membrane which I have not priced out but likely to be even more expensive and sense it is manufactured onsite I can imagine the contractor screwing up the membrane in some way or another. One last point is resale value ..... here in the south east you will have a hard time selling a EIFS home unless you can prove to a potential buy the construction method you used is sold and the home is insurable. |
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ricky_005
Basic Member
Posts:313
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| 09 Aug 2014 12:24 PM |
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Posted By Jelly on 09 Aug 2014 10:41 AM
Nice to hear from an expert!
Ricky, sorry your thread got hijacked and went off on this tangent.
The average house fire burns at a temperature of about 1,100 degrees Fahrenheit. I simply pointed out the structural issues of steel SIP's when you introduce fire into the equation and the outcome is total failure of the system. The cost to get an True 1 hour fire rated wall system to meet building code I think in most cases, you would better off with ICF or a system similar to the Perfect Wall System. |
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