My wife and I are in the design process of a 6998 sqft one story home.  What we seen with other ICF homes are that folks go for the stick roof WHY???

We thinking of doing a flat roof since my understating you can get not get a high pitch roof with ICF.  What you’re thought on a flat ICF roof? I would not think there be any leakage problem since it Concrete and has no wood for it to rot out.  I did check my restrictions they do allow built up roof which is a flat roof.

Thanks!

We sometimes install sloped Icf roofs here in Texas. See insuldeck.com. Regards.

Even a flat roof should have enough slope so that water will not pond on it.  Allowing water to stand for a long period is asking for a leak.  I think 1/4" slope per foot should be the minimum.

Posted By R9tobon on 16 Jul 2012 03:02 PM

My wife and I are in the design process of a 6998 sqft one story home.  What we seen with other ICF homes are that folks go for the stick roof WHY???<!--?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /-->

We thinking of doing a flat roof since my understating you can get not get a high pitch roof with ICF.  What you’re thought on a flat ICF roof? I would not think there be any leakage problem since it Concrete and has no wood for it to rot out.  I did check my restrictions they do allow built up roof which is a flat roof.

Thanks!

That's a BIG home. Where are you located at?

With flat roofs, if you live in a snow load area, you have to take into effect a snow load and the possibility of ice and snow building up on the roof. You won't find flat roofs in areas that get a lot of snow. You will find steep pitched roofs in such areas so that the snow and ice and slide off instead of build up and collapse the roof. Plus you have the issue of leaks in flat roofs.

The reason WHY people go with stick roofs is they are the most inexpensive and one can get the highest R-Value for the cheapest price (cellulose) with a sloping stick framed roof.

From what I read InsulDeck roofs can be made up to 6:12 pitches.

I've never seen a flat roof that didn't leak within 10 years of its install. With flat roofs you have a lot more maintenance than a sloped roof. If you get snow, get ready to climb onto your roof and shovel your roof during heavy snows.

InsulDeck/concrete is an option as is Steel SIPs, both of which do NOT include wood in their design. Have you looked at Steel SIPs?

You will find steep pitched roofs in such areas so that the snow and ice and slide off instead of build up

I agree that a steep slope would facilitate drainage during snow melting, but the slope does not lead to snow & ice sliding off the roof. That would be dangerous. Plus, such movement would destroy gutters and anything else in its path. Would a home with ICF walls and roof not withstand a much greater now load than a stick structure?

I've never seen a flat roof that didn't leak within 10 years of its install.

Are you referring to a flat wood roof, or the ICF roofing systems that are being discussed? Do you believe that (mostly) flat ICF roofs are a bad idea?

Posted By Lbear on 17 Jul 2012 02:23 AM

Posted By R9tobon on 16 Jul 2012 03:02 PM

My wife and I are in the design process of a 6998 sqft one story home.  What we seen with other ICF homes are that folks go for the stick roof WHY???<!--?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /-->

We thinking of doing a flat roof since my understating you can get not get a high pitch roof with ICF.  What you’re thought on a flat ICF roof? I would not think there be any leakage problem since it Concrete and has no wood for it to rot out.  I did check my restrictions they do allow built up roof which is a flat roof.

Thanks!

That's a BIG home. Where are you located at?

With flat roofs, if you live in a snow load area, you have to take into effect a snow load and the possibility of ice and snow building up on the roof. You won't find flat roofs in areas that get a lot of snow. You will find steep pitched roofs in such areas so that the snow and ice and slide off instead of build up and collapse the roof. Plus you have the issue of leaks in flat roofs.

The reason WHY people go with stick roofs is they are the most inexpensive and one can get the highest R-Value for the cheapest price (cellulose) with a sloping stick framed roof.

From what I read InsulDeck roofs can be made up to 6:12 pitches.

I've never seen a flat roof that didn't leak within 10 years of its install. With flat roofs you have a lot more maintenance than a sloped roof. If you get snow, get ready to climb onto your roof and shovel your roof during heavy snows.

InsulDeck/concrete is an option as is Steel SIPs, both of which do NOT include wood in their design. Have you looked at Steel SIPs?

I live in a high snow area, and we do flat roofs all the time. Almost all of our commercial stuff is flat (1/4" per foot). And we never shovel our roofs off. And they do not leak within 10 years either. You must not have seen very many flat roofs.... with that being said, pitched roofs are typically easier to maintain, many home owners find they look better (more traditional), can provide additional cheap storage depending on design and are easiest to achieve a high r, vented assembly. Which in a snow area, is a good idea.

insuldeck/quaddeck can be used for flat or sloped roofs with spans of over 30' between supports (walls to ridge, wall to wall). on shorter spans a ridge beam may not be needed if the structure is designed with the walls and roof acting monolithically, or as a folded plate or moment frame design. a capable pe with concrete design experience is the key.
slope can be anything from flat to any pitch needed.
depends on design and code restriction, if any.
email me and i'll send you info/pictures, and pe's in your local area.
[email protected]
[email protected]

I live in Houston TX so snow will not be an issue!

Cellular concrete is another option. Used as cast-in-place or panels, cellular concrete is portland mixed with a foaming agent to produce a lightweight material that has most of concrete's virtues plus some insulating value. Cresco Concrete in Houston does panels. Dunno about cast in place, which requires some fancy mobile equipment.

Posted By lzerarc on 17 Jul 2012 10:08 AM

I live in a high snow area, and we do flat roofs all the time. Almost all of our commercial stuff is flat (1/4" per foot).

I manage commercial properties and like you mentioned, most commercial properties have flat roofs. Maybe you guys build tighter and better roofs but our assessors give flat roofs a life expectancy of 10 years before they must be resealed. Flat roofs require yearly maintenance and the drains MUST be checked regularly to insure they are not clogged and draining correctly. Once they get clogged, things go downhill very fast.

It's all about drainage. One wants to get the moisture off of the roof as quickly as possible. When it snows and the snow melts on a flat roof it can refreeze at night and form a layer of ice. Then more snow falls on top and this process can continue for days or weeks until you have a ice layer numerous inches thick and the drains are useless. This standing ice rink becomes problematic in both leakage and weight capacity of the roof.

Flat roofs keep our assessors and roofers in business, that is why roofers like flat roofs.   Plus they are easy to walk on...

Posted By R9tobon on 17 Jul 2012 11:22 AM
I live in Houston TX so snow will not be an issue!

Then a flat roof will work out there.

I was told the average was around $22 per square foot for a pitched roof using InsulDeck/concrete. That includes everything, the forms, rebar, concrete, labor, etc.

So 100 sq. ft.=1 square so it $2,200 per 100sqft or $22,000 for every 1000sqft.
That roof better withstand the act of GOD!

If you are converting the ICF quotes into "squares", it appears as if you might be trying to compare the cost of roof coverings. ICF roofing would be the structure as well.

ICF roofs were offered to me in the design phase. I declined because I was put off by the thought of concrete overhead in what is a severe earthquake location. I went with sticks. However, after working through the engineering, I would reconsider it. I'm not sure we would have had the EXACT result we got with wood, but it would be possible to design a home with ICF overhead that made sense.

You asked the right question!!!! Don't build a stick roof on a fortress !! After the storm you wanted protection from is gone... You'll have walls and nothing elsr left... If you use NUDURA... Your engineer can design the transition from your ICF WALL TO THE ICF sloped ROOF...... Or for a Flat Roof, (1/4" slope per foot is allowed by code) look at insulldeck product... Kind of expensive... Best Regards , Rob

Question.. Are you in an high earthquake zone.. If you're worried about concrete falling on your head during an earthquake... You've got bigger problems than whether to have a stick or concrete roof.. Best regards... Rob

I hope to be starting our 7900sqft ICF house in a couple months. I looked for a while into doing a concrete roof, but the roof was pretty complex and broken up, so the engineer felt it wasn't going to work. I could have done a more simple roof design, but it wouldn't have fit aesthetically with the house and Mediterranean style we were going for.

However, the floors between level 1 and 2 and between level 2 and the attic will be concrete (Insuldeck), so that will afford some protection and add the the strength of the ICF walls.

Ultimately, I'm going with a stick frame attic roof over my concrete attic floor. As long as we over-do the stick roof, I think I will be safe in almost any storm down here. And I will always have my ICF storm shelter to go to if things get really bad.

If you're worried about concrete falling on your head during an earthquake... You've got bigger problems...

Really? Like what?

TICFS or Total ICF Structures are just about all we build these days. We still do the occasional Icf with wood roof. We can build any roof pitch above 6/12 with our system and park a truck on the roof,so no worries about earthquakes. For flat roofs you can use one of the light/ unsul-decks Etc.
To learn all the reasons we build ICF roofs, you can look at our website www.totalicfs.com .
Thanks Eldon

Shotcrete is often applied to vertical slopes/walls and could be applied to foam panels on a sloped roof (ie, like a SCIP but I suspect that reinforcing fibers could replace the steel mesh). Can you bevel, overlap, tape or caulk foam well enough to be the waterproof layer? - I don't know, probably.

We've used quad-deck for flat roofs in Austin.