This may be interesting to some. - Contractor Talk - Professional Construction and Remodeling Forum

**joasis** · 10-13-2007, 05:28 PM

The new home plans are progressing, and as you long term members know, I do a lot of steel erection....so it is a natural fit. So here it is....a steel main frame(s) 36 feet wide at the base, 30 feet @ 18 feet, transitioning to a 2/12 rafter. The ISP rep I was talking with said the 8-1/2 inch panels will span the 10 feet with a L/320 deflection of less then 1/2 inch, have an R value of 45, and a direct cost to me of a little more then $5 a sq/ft of panel. The panels come 8 feet wide and custom lengths up to 24 feet, and they will manufacturer them for my application. My idea is simply to attach the panels to the main frames (4 X 6 X 3/16 wall) with the self drilling screws supplied, and rock or panel the interior. The panels have provisions for electrical chases, and I would use solar guard and steel 26 gauge panels for the leaning walls and roof, brick on the endwalls. The basic floor dimension is 36 wide by 60 long, if you guys are picturing this....if I had more skills, I would draw this shape and post it for critical input.

So guys, what do you think? BTW, the sq/ft cost of this home may be really low, since only interior walls and the second floor loft (half of the main floor) will be framed.

bobcaygeonjon · 10-24-2007, 02:04 PM

See you havent had any replies yet. I for one am very interested. When are you thinking of building?

**joasis** · 10-24-2007, 06:10 PM

I hope to start in a month or so, as soon as the details work out. Before I pour the footings, I have to decide whether it will be ISP's. An engineer is working out the frame details for me.

gregj · 11-01-2007, 11:49 AM

Any reason your not using ICFs for the walls?

**joasis** · 11-01-2007, 02:34 PM

You have to visualize this: A rectangle, 60 feet long and 36 feet wide. The walls "lean" in about 10 degrees, so the actual rafters will only be 30 feet wide. In other words, a slope wall building. The only ICF system that may work is the vertical panel system, and the numbers don't work compared to ISP's.

gregj · 11-01-2007, 02:45 PM

I see, I missed the part about the wall slope. So these ISPs are like the panels of foam sandwiched between OSB except with metal skin instead of OSB?

**joasis** · 11-01-2007, 06:44 PM

I will sheet them with 26 gauge steel over double bubble reflective insulation for a barrier. At least I am thinking about this....the other plan is to build it conventionally in steel, and then use foam insulation sprayed in the interior, and furred out......

Milhaus · 11-12-2007, 11:47 PM

Is this 'your' house or for a customer? Where did the idea come from? Sounds interesting...

what is L/320 deflection?

**joasis** · 11-13-2007, 07:36 AM

My own home, and L numbers describe load calculations for structural members. When you look at span calculations on floor joists or other items, like engineered wood products, you will see tables describing the deflection (allowable bend) and the higher the number, the less it will bend. Very important say when you design a home...use the wrong calcs, and you will have sagging ceilings or bouncy floors.

I guess in specializing in remodels, you don't ever do new construction?

Milhaus · 11-15-2007, 12:25 AM

Other than my own addition/home, I haven't gotten into new housing yet. It is on the list, but I have to get the plans figured out first. Thanks for the info. I've seen quite a few of your posts - you're really into steel, eh? Good idea.

What is the insulating material in the ISPs?

Mark

**joasis** · 11-15-2007, 06:36 AM

Polystyrene, or EPS for short. I have elected to go with standard construction, since I figured out a way to insulate it with cellulose.

The geo thermal bid is in, $16,700 + 5 wells for another $5,500 (wells added into the monthly electric bill)....I have to redraft the plan to accommodate changes for the hvac runs and mechanical room, then I am ready to break ground.

TomHay · 11-15-2007, 06:44 AM

Why nor foam it yourself?

Milhaus · 11-15-2007, 07:37 AM

Good for you going with a geo system. I can't wait for mine. The 5 wells added into the electric bill - what do you mean? They're in addition to the original system?

So you're not going with the steel frame now? Or standard construction in between the steel frame?

**joasis** · 11-15-2007, 08:04 AM

Quote:

Originally Posted by TomHay

Why nor foam it yourself?

I may have a low expansion foam coating shot to the underside of the steel and endwalls, $1.25 a sq/ft here, but, laying a blanket of solar guard, and then cavity filling with cellulose will do as much. I like the idea of a tight envelope, but, I like th idea of a little breath ability as well...the jury is still out. We have the insulation blower, not the foam rig, so it would be self contained.

I just looked at your video and the fastkick gun system, pretty neat! Something to consider...especially adding that to our existing insulation business.

72chevy4x4 · 11-15-2007, 12:49 PM

wow-R45 sounds great.

your design sounds like a gambrel roof...can we call it a gambrel house?

**joasis** · 11-15-2007, 02:01 PM

Yep...slope walls, so the siding on the slopes will also be the roof.

**BuiltByMAC** · 11-15-2007, 11:07 PM

Hey guy,

Congrats on getting the house going! It's always the biggest PITA to schedule your own work, but when it's done it's so nice!

Definitely post some pics of your progress - I'm interested in the slope wall design.

Mac

Milhaus · 11-30-2007, 12:23 AM

Joasis -

I looked at an office space today that is having problems with the exterior walls. They are steel stud framed, with fiberglass for insulation. Do you know if spray foam on steel would insulate enough to cause the temp of the steel to maintain a moderate temp, rather than transferring cold exterior temp through in the winter, or warm exterior temp through in the summer time. I think there is a hell of a mold problem in this wall mainly due to the difference in temp/moisture vapor and steel studs. and I want to find a way to fix it for good. I thought spray foam may work.

Mark

**joasis** · 11-30-2007, 06:14 AM

Well....steel can transfer temps well....that is why in tradition steel erection, we roll vinyl backed insulation over the steel purlins and girts, and then the sheets are attached. I know when I was considering the closed cell foam, a tech guy told me the panels need a "thermal break", or the steel structure would conduct the outside temps inside. The rolled insulation acts like a "gasket" between the panels and frame. Without this, they recommend using a gasket tape to achieve the break.

What is the mold growing on?

A possible fix would be as I am thinking of doing, a one inch foam sprayed to seal the building shell, and then cellulose sprayed to wall level.

On my home, I intend to fur out from the steel with 2X's and drywall, so the cavity behind the rock will be completely filled with borate treated cellulose.

Milhaus · 11-30-2007, 07:56 AM

I don't know for sure that there is any mold growing, it's just a hunch. There is a layer of dust on the interior wall along every stud on the exterior wall in this office. The dust is attracting to moisture vapor from what I understand. The vapor is moving in/out of the wall depending upon the ex/interior temps and pressure.

If there is a constant moisture vapor difference in the cavity between the steel stud and the fiberglass, then you would think condensation has taken place time and time again without being able to dry out because of the fiberglass. I posted this article from the AIA/Dow on the commercial forum...here it is again. It's a good read.

http://www.dow.com/PublishedLiteratu...ge=BasicSearch