Didn't want to completely hijack R9tobon's thread, so here goes:



I'm at the same point too.  Going to make an offer on a lot in
the highest fire zone in CA this week (and also happens to be a ways from
fire trucks).   Heavy sierra snow loads @ > 6000' elevation.  They got
4' in 1 day the last time I was there in winter.
Big fire burned 100 houses nearby.   Big propane heating bills according to
everyone in the neighborhood.  Sometimes big trouble getting the propane
trucks to everyone.   Being efficient enough to do backup electrical
heating would be good.


Luckily, I did a basement with help from Mike Morrison (Medford, Oregon Nudura
dealer) several years ago.   Polyform Pro or something like that.   He's agreed to help
on this one too.    I've got a good GC in the area, but he's somewhat new
to ICF.  

Mike came down as a consultant, drove the forms down, lent me his
braces, and worked with me a couple of days.    It was easy, hasslefree,
and my walls MIGHT have moved a few millimeters.   Got another guy
to pour the concrete.   My inspector was excited.  First one he'd
personally been involved in.   I had a lot of rebar since it was a
retaining wall/slab in high earthquake zone.   Wish I'd done the
floor above it too.   Got sick of joining I-joints with metal connectors
between every piece of wood.

We used Xypex in everything.  Added 25% to the concrete cost if
I remember right, but it's completely waterproofed.   I didn't use the slurry
on the joints like they recommend.   We vibrated well, and there was
essentially no leakage.



However, this one will probably be a 6BR complete house.   I've got
to do concrete roof, but need to decide how.    Otherwise, it's heavily
insulated stickbuilt and I pay my insurance and take my chances.

Option 1:
flat concrete roof and sacrificial upper roof.   Upper roof will probably need to be
12" i-joists for snow load.   Could steeply pitch roof.

Option 2:
flat concrete roof.   uggh, and snow pooling up.   I'm sure waterproof roofs
can be built, just not by your average contractor.  

Option 3:
5/12 pitched concrete roof.    snow load design 100psf?

Option 4:
steeply pitched concrete roof to shed snow.    Not sure if it's possible
unless you wanted to do superdry concrete and shovel it on by hand.



So assuming I'm leaning to #3, any ideas from everyone on details?

1.  Shoring on the roof--should this be done before or after floors are
put in?   Leaning to bolted ledger and plywood i-joists for floors.  
(i.e. shore to ground slab or 1st floor after it's built?).   I know
the floor would need to be engineered for that.

2.  I'm leaning to extra spray foam on the main house using 2x4 furring
(easier trimming and services too).    Anyone done something like building
a light subroof with i-joists, putting the ICF forms on top, and then pouring?
The i-joists would hold the sprayed insulation later.   You're eliminating
an easy step, the shoring;   but I'm not sure if my GC has shoring local.
Either way, it's going to be 100 miles roundtrip with it.

3.  I'm guessing with enough rebar at the ridge (both directions;  up/down and
across) and the magic PE stamp, I can make a structural "ridge" and not
have to worry about  resisting roof spreading forces (cathedral ceiling without
collar ties).

4.  Roof details.   Xypex waterproofing in concrete + EPS is barrier 1 & 2.
Tar paper or membrane on top of that?   or mop on?    = barrier 3
2x1 furring strips (pneumatic nails?  tapcons?)   and then
steel roof (the flat type with the overlapping seamed edge) = barrier 4


Thanks,
allan

Hi Allen,
No problem I forgive you ;-)
Best of luck!

I found out two thing
The Icf roof is not able to have a large slope like an conventional roof. Most owners do not want a " flat" roof so they end up going conventional with it.  The roof is is actually stronger in high winds with the Icf walls due to the fact that the walls do not flex or allow air in creating suction on the roof and preventing it from being blown off.  
&
We will support the Insul-Deck product on any ICF brand of installation. Insul-Deck roofs are not as common of an installation on an ICF home as we would like to see.
P.S
People just do not whant to spand $$$$

Posted By R9tobon on 18 Jul 2012 05:12 PM
I found out two thing
The Icf roof is not able to have a large slope like an conventional roof. Most owners do not want a " flat" roof so they end up going conventional with it.  The roof is is actually stronger in high winds with the Icf walls due to the fact that the walls do not flex or allow air in creating suction on the roof and preventing it from being blown off.  
&
We will support the Insul-Deck product on any ICF brand of installation. Insul-Deck roofs are not as common of an installation on an ICF home as we would like to see.
P.S
People just do not whant to spand $$$$

InsulDeck roofs do not make economical sense UNLESS you are looking to make a tornado/hurricane resistant shelter. Your R-Value will always be higher and for a lot less money with a wood roof & cellulose or even a Steel SIP roof.

It always comes down to $$$. InsulDeck roofs are by-far the most expensive roofing types out there. Not too many installers out there with experience in doing an InsulDeck roof. You don't want an installer learning on your project on how to do a concrete roof. One can do a wood frame truss roof with cellulose (R-60) and it will cost 1/2 of what it would in InsulDeck, plus you get a higher R-Value with wood/cellulose.

Through my research, Steel SIPS are a better alternative to InsulDeck roofs. They are much, much lighter but have a lot of strength in the steel panel. IF you go with the 12" EPS core, you can get a R-50 out of it.  Plus being steel they are fire resistant.

Posted By Lbear on 18 Jul 2012 07:54 PM


Through my research, Steel SIPS are a better alternative to InsulDeck roofs. They are much, much lighter but have a lot of strength in the steel panel. IF you go with the 12" EPS core, you can get a R-50 out of it.  Plus being steel they are fire resistant.

thanks, I had no idea steel sips even existed.   I'm not sure how EPS's fire resistance of
950F translates into real world fires.   But I imagine this would be lots easier
to do than a concrete roof.

One question--if you need ceiling boxes/wiring, what it the best way to go?
fur it out completely?   most places there would be an attic, but not everywhere.
I can't imagine the steel being easy to cut through.   is the steel light enough
for self drilling sheet metal screws to go in, or will every hole need to be predrilled?

or are they available with steel one side and OSB other?


thanks

Posted By allan-sf on 18 Jul 2012 09:03 PM

thanks, I had no idea steep sips even existed.   I'm not sure how EPS's fire resistance of
950F translates into real world fires.   But I imagine this would be lots easier
to do than a concrete roof.

One question--if you need ceiling boxes/wiring, what it the best way to go?
fur it out completely?   most places there would be an attic, but not everywhere.
I can't imagine the steel being easy to cut through.   is the steel light enough
for self drilling sheet metal screws to go in, or will every hole need to be predrilled?

or are they available with steel one side and OSB other?


thanks

EPS has fire retardants in it but as with all insulation, it must be protected either by drywall or some form of fire barrier. With EPS being in a steel sandwich, you are in a lot better shape than EPS being sandwiched between OSB wood.

We plan to fur out the ceiling in order to run wiring and secure drywall to the ceiling.

Steel SIPs are manufactured with 26 gauge steel on both sides. They DO NOT make half OSB and half Steel.

Chris the Steel SIP rep should chime in here shortly....

Our system eliminates all the concerns 1 through 4
So assuming I'm leaning to #3, any ideas from everyone on details?

1.  Shoring on the roof--should this be done before or after floors are
put in?   Leaning to bolted ledger and plywood i-joists for floors.  
(i.e. shore to ground slab or 1st floor after it's built?).   I know
the floor would need to be engineered for that.

• Our system is self shoring.

2.  I'm leaning to extra spray foam on the main house using 2x4 furring
(easier trimming and services too).    Anyone done something like building
a light subroof with i-joists, putting the ICF forms on top, and then pouring?
The i-joists would hold the sprayed insulation later.   You're eliminating
an easy step, the shoring;   but I'm not sure if my GC has shoring local.
Either way, it's going to be 100 miles roundtrip with it.

• Additional insulation is not really necessary, as we use the same ICF forms for the roof as we do the walls

3.  I'm guessing with enough rebar at the ridge (both directions;  up/down and
across) and the magic PE stamp, I can make a structural "ridge" and not
have to worry about  resisting roof spreading forces (cathedral ceiling without
collar ties).

• Yes a stamp is necessary. Typical rod is 16” on center each way.

4.  Roof details.   Xypex waterproofing in concrete + EPS is barrier 1 & 2.
Tar paper or membrane on top of that?   or mop on?    = barrier 3
2x1 furring strips (pneumatic nails?  tapcons?)   and then
steel roof (the flat type with the overlapping seamed edge) = barrier 4

• Plywood with or with furring strips can be attached directly to the ICF studs. Metal roofs or clay tiles can be attached with furring strips, or even an Durarock type stucco can be used as roofing.

TICFS or Total ICF Structures are just about all we build now. We still do the occasional Icf with wood roof. We can any roof pitch above 6/12. We've poured as much as 12/12 pitch with our system and can park a truck on the roof, no worries about earthquakes.
To learn all the reasons we build ICF roofs, you can look at our website www.totalicfs.com .
Thanks Eldon

Posted By ICF372 on 03 Aug 2012 01:06 PM
Our system eliminates all the concerns 1 through 4

TICFS or Total ICF Structures are just about all we build now. We still do the occasional Icf with wood roof. We can any roof pitch above 6/12. We've poured as much as 12/12 pitch with our system and can park a truck on the roof, no worries about earthquakes.
To learn all the reasons we build ICF roofs, you can look at our website www.totalicfs.com .
Thanks Eldon

So your roofing is different than the typical "InsulDeck/QuadDeck/LiteDeck" roofing system in that it is basically like an ICF wall form, with the concrete sandwiched in-between the EPS. With the other roof ICF systems the concrete is exposed to the exterior and the EPS is underneath it.

Question is how do you get the concrete to consolidate in that roof form? With an ICF wall form, gravity does a lot of the work and then it is vibrated. With a 5/12 roof pitch or lower, it wouldn't be steep enough to have gravity do most of the work.

What is the ballpark costs for the roofing system per square foot? Is it less than $25 sq.ft. for form work, concrete, rebar, labor?

Can one do 12" or 24" overhangs?

Since fire is the concern, I'd use a metal roof but put the insulating board that they use for fireplace hearths under it. Trusses could be wood or steel.

For walls, I'd be more interested in SCIPs than ICFs with foam on the outside. Or a wood frame + stucco applied to the same fireproof insulating board.

Posted By jonr on 04 Aug 2012 02:15 PM

For walls, I'd be more interested in SCIPs than ICFs with foam on the outside. Or a wood frame + stucco applied to the same fireproof insulating board.

Wouldn't a wood frame + stucco + insulating board, still have EPS foam underneath the stucco? That is standard practice; to put EPS on the exterior and then apply chicken wire and stucco.

With ICF, the foam is covered with stucco or a fireproof insulating board, so the EPS is protected either way.

SCIPs is very regional specific but I believe the OP is set on ICF.

The thought was that stucco/shotcrete would be applied directly to the fireproof insulating board. Any foam would be inside of that. While stucco over foam is common, stucco sticks to many other things.

The TICFS with encapsulated forms makes sense. No worries about too steep of a pitch. I haven't seen this before. On overhangs I see no reason why a 12" cantilever wouldn't be possible although I didn't see that in the videos. However my current plan has a wrap around balcony on the south and west sides which would reduce the need for an overhang for sun reasons, since the roof could span over the 8' balcony and then tie in to supports. I assume some sort of threaded bolt or wood\metal furring strip can be placed in the fascia area to attach gutters. The roofing material would be best suited for larger metal plates (e.g. standing seam) than smaller shingles due to the limited places to tie them in since it is not continuous like an OSB roof for example, unless you put a solid layer of OSB on top of the foam. Also using some sort of cement\stucco roofing on it would concern me - walking on such a roof may crack as the foam underneath may give a little. (?)

Posted By sharter on 07 Aug 2012 12:04 PM
The TICFS with encapsulated forms makes sense. No worries about too steep of a pitch.

In the end it comes down to $$$. At $23 per square foot, it is not a cheap route to go with. On a 3,500 sqft roof area (including overhangs), you are looking at $80k. That same roof can be done for $25k with wood truss and R-60 cellulose. Is it worth 3 times the amount to get a R-30 concrete roof? Unless you are only doing it for tornado/hurricane issues, I don't see the benefit.

There is a REASON WHY these roofs have never really become popular, even though ICF walls have taken off, ICF roofs have not. When one can do an ICF wall for $12 sqft OTD, its a good deal, but a roof at $23 sqft is really not a good proposition. Especially since 2012 IRC requires R-48 and a R-30 roof is not that energy efficient.