Concrete home construction

[Paddy]

I think you nailed it on the head, pardon for the pun, engineers in the US have wood on the brain. Contractors too. If it were not for my travels, I would too. I was a carpentor for many years before an injury pushed me off to engineering school. hence the travels...

Local building codes are based on local experince. There was a case in Indiana where a home owner wanted to construct an addition on a post foundation. Code said NO WAY. He took it to court and won. I guess the judge had a beach house where the code required posts! In South Carolina open crawsspace and no gutters is the norm, up North, we'd think some thing was wrong.

I find it amazing a two story home of 2x4 walls, braced with osb in the corners, sheated with 1/2" foam and covered with vinal siding meets code.

 

[_RaT_]

DFKrug, I will PM you with my experience, I wanted to let you know where I am coming from with regards to ICF and the SF Bay area. Rather then take up a bunch of room here for something quite specific to us. Great information you offered up. Mark

 

[Paddy]

All good points. I know my project will not be cheep or even close in cost to a wood framed home. I'm looking for a non-traditional look an feel. The pay back wont be measured in $$ in xx years. I can't justify the extra expence but it will certainly be soild and efficient. The home will be built on a South facing hill on lake front property.

I will use Geo-Thermal heating, and yes years for the pay back.

 

[dfkrug]

People want it soooo easy. Wood frame construction, $x per sf.
Concrete bock construction, $y/sf. ICF construction? Oh, that'll
add 5% to the cost of construction. I have heard that number for
many years. It is extremely tough to compare seemingly identical
houses, one built of 2x6s, one of ICFs. I have never seen a contractor
quote an ICF house on a per-sf basis. Or per-unit-lenght of wall, either.

Until an area has ICF specialists, 2x6 construction of the outer
frame of the house will generally cost somewhat more (above grade).
5% of the the cost of the whole house? I doubt it. These days, the kitchen
often costs more than the frame of the house. 10% has been tossed
around as the usual typical value of the frame of a conventional house.

Agonizing over a "small" perceived additional cost of construction is
really not seeing the bigger picture that includes other savings, incl
energy, smaller HVAC, less repairs, etc.

To touch on earlier posts, I installed European Rolling Shutters inside
my thick outer walls, and I was forced by the gummint to put in interior
fire sprinklers.

 

[vmarc]

Superior Walls makes precast basement walls .They are insulated and need no framing to finish the inside walls.Strong enough to support a log home.I don't know if they'll support a concrete roof.The rep tells me that lots of folks are are putting them above ground for homes.should be cheaper than poured.They'll configure windows and doors any way you like.I don't know if this is an an option for you,but I'm kicking myself in the rear for not considering this for my horse barn instead of pole construction.....Too soon old and too late smart.

 

[HGM]

First off, I'm not a contractor, so my info is more from what I have seen and others will be able to provide more technical info...

I lived in the Miami area most of my life.. EVERYTHING down there was at least CBS construction(cinder block).. My townhouse(built in '94 by Pulte Homes) was poured concrete in the form of a figure "8".. The ends were blocked up and a gable roof was added for appearance.. The place was a bomb shelter.. Very quiet, even from the neighbors, and though we didnt get any hurricanes while I lived in it, I was totally convinced it was among the safest buildings arround.. The cooling, with little to compare it to, was reasonable.. The cost, for 1100sq ft was $80,000, in Weston Fla(booming, wealthy area on the golf course).. Compare that to a regular 1500sq ft home in the area at time going for $150-200k with CBS construction.. This was 12yrs ago, the boom has turned into an explosion.... My townhouse(of course I dont own it anymore) is going for $280,000 and homes in the area start arround $5-600k.. Anyhow, the cost thing may be off to todays standards, but my point is that much of Floridas cost is due to the land, not so much the construction.. As some have mentioned, this is likely because, this is the way its done down there.. You cannot build a stick home in South Fla as per code.. The modular concrete mentioned above sounds really interesting.. I would immagine what you are considering is more of a commercial build for your area, so maybe a commercial contractor could provide area specific costs for that type of construction????

 

[Paddy]

Agree. Comercial contractors would be the likely 'most experinced'. I did chat with a concrete contractor while back. They had poured walls as second levels and second level floors, but no roofs. He said the raised floors he had done were either formed in place with beams/slab in one pour or steel frame and then the slab. He said for 1000sq-ft floor, figure $3000 above a standard slab on grade. Formed walls add 50% for scafolding and elelvated work. Many of my second story walls will be set in from the lowers walls for patios/porches. So those walls would not require scafolding.

The old 5% more cost is generally stated as the final cost of the house. I'll bet $5 a sq-ft for the ICF foam blocks and ?? in concrete, is 2x the cost of framing. In the end, you more than twice the wall too.

Since I plan to stuco inside and out, the maintanace should be very low.

The preformed panels require a crane and have many joints I would like to avoid. I could use them in the floor system. I have seen them in hotels and on semi flat beds. It's amazing how thin the slab and beams are.

Enjoying all this discussion

 

[_RaT_]

Enjoying all this discussion

I am too. While far from an expert on ICF, I am seeing more of it all the time and learning from it. When I took the class for ICF from Nudura, there were architects, city inspectors both of whom got the class at no cost. There were contractors such as myself and there were owner builders, even a husband, wife and teenage daughter. The California Highway Patrol even sent a couple of guys who build some kind of repeater stations in very remote areas that need tough, efficient structures to house the equipment. The fella giving the lecture, Murray (one of the owners) was as sharp as could be. He is from Canada but realized his market was the US. They built two ICF plants in the US, one in the East and one in the West. His biggest problem was getting the many local counties to not only understand the ICF procedure and engineering, but to pass it! He would basically come down to this argument. "Do you allow poured concrete walls re-enforced with rebar per local codes? Do you allow those walls to be formed so as to ensure the integrity of the concrete during and after the pour? Do you allow foam as an insulator? What if I use foam to be the form and leave it there after the pour mechanically bonded to the concrete?" He knew the answer to the questions but wanted them to understand that the procedure really was no different then conventional methods. There are a few things that you must consider with ICF. 1. you must use a air exchange system to remove the small amount of moisture that will be released continually into the house for the first year while the concrete is curing. 2. you must cover the exterior foam up in a reasonable amount of time with either parging or an exterior siding. It is not UV resistant.

 

[Jagmandave]

I've been an ICF evangalist for about 5 years now, they just make so much sense to me, especially here in the midwest where we have such a variety of weather, and bugs as well. I just can't see building my $300k new home out of termite food! I can also see the advantages for other climates, but here it makes sense even more.

Across the street from my plant they're building a series of single story on slab office buildings - with ICF's - they go from slab to walls to roof to weathered in with windows, doors and stone and stucco exteriors in about 3 weeks!

I think building a strong, weatherproof, bug proof home that will still be standing 100 years from now makes more sense that the current way - it may be cheaper to construct with wood, but factor in labor, repair and replacement cost and it's a short term advantage only. Just my 2c...........

 

[dmccarty]

When I was looking at ICFs, one of the problems with ICFs that was being discussed was termites. While the wee little wood eaters would not eat the insulation or the concrete in the ICF they would tunnel in the insulation to get to wood in the house/attic. The ICF made this worse since the termite tunnels would not be seen since they are inside the wall. One of the recommendations at the time was to NOT use ICFs below grade for this reason. One ICF maker was treating his insulation with borate(sp) to prevent this. Makes sense that it could happen I suppose.

I don't worry about termintes in our house since there is no likely path for them to get to the structure of the house without being seen. One thing that I kinda wish I had done was spray the studs with borate to kill the wee little wood eaters if they did get in but this was something I had just read about and did not have time to look into. My builder did use this on his next project which was a light commercial building.

My house will be here in 100 years. It won't fall down because its stick built. Just because a house is made out of wood does not mean it will last. We looked at two properties that had houses around/over 100 years old. One was in great shape. The other one not so much. But then it had been built cheap to begin with but it still was standing and habitable. My wifes mother is living in the house that has been in the family for generations and is around 100 years old. Its wood frame house. They put up brick veneer a few decades back. Well maybe more than a few since I think they made the bricks on the farm. Tain't nothing wrong structurally with the house and it has been through many many hurricanes.

Later,
Dan

 

[dfkrug]

My wife's cousin (who happens to be CEO of Ecoblock) sent me a video
a few years ago of a tornado scoring a direct hit on an ICF house in
Kansas. The roof flew off, but there was no significant wall damage and it
was rebuilt. The adjacent houses were flattened. Amazing that the
camera operator survived.

There is a full cover photo in Concrete Construction Magazine from last year
that shows a single house standing in an area of total devastation in
New Orleans. It was built of ICFs.

 

[dfkrug]

This house in Danville, CA is about 17,000 sf and has taken about
5 y to build.

 

[dmccarty]

I saw a picture of an ICF house in a subdivision that had been hit by a tornado. It was the only home left. A large hardwood had fallen on the roof and the only damage was the that tree poking holes in the roof.

There was a house in CA a few years ago that was part of a famous picture. The whole neighborhood had burned down but the house did not due to its design. I can't remember if that one was an ICF house or not. Seems like it had stucco walls and it had no roof eaves to speak of which kept the flames from getting up into the attic of the house.

Later,
Dan

 

[dfkrug]

The wall to the right is a 20-ft tall retaining wall, built with 8" Polysteel
ICFs, concrete pilasters, and 30-ft drilled tiebacks. I am an experimenter
and I have not heard of any ICFs rewalls this high.

 

[dfkrug]

There was a house in CA a few years ago that was part of a famous picture. The whole neighborhood had burned down but the house did not due to its design. I can't remember if that one was an ICF house or not. Seems like it had stucco walls and it had no roof eaves to speak of which kept the flames from getting up into the attic of the house.

The Oakland Hills Fire was 15 y ago, and it destroyed nearly 3000 houses.
Three houses to survive were built of Polysteel ICFs. I met the contractor
once about 11 y ago. I have never seen good photos, however. Maybe
yours were from that fire?

 

[dmccarty]

I don't know if the picture I saw was the fire you mentioned. Seems like 15 years ago would have been to far back but it good be. Polysteel was the brand of ICF's we where thinkng of using.

In your picture of the wall, is that tree really as large as it looks to be in the picture?

Later,
Dan

 

[Paddy]

The roof blowing off is one reason I will have a concrete roof as well. Nice systems out there, www.insul-deck.org
I will have a flat roof with 3' half walls extending up above the roof deck. It will be like a elevated patio. Since my home will be lake front, tall is good for great views. Nice part to is the property tax dept will call it a roof, I will use it as a patio!

 

[dfkrug]

In your picture of the wall, is that tree really as large as it looks to be in the picture?

I live in a coastal redwood forest. The tree in the foreground is
really 3 redwoods, all 100-120ft tall.

My recommendation for first timer ICF installers: work with a nearby
distributor who can provide local help. The help I used to provide
included consultation with the designer/architect/engineer BEFORE they
started, consultation during permit process, on-site training of the
installer, pre-pour inspections, and I usually directed at least the first
pour. Don't try to save a few cents/Form by going long distance. Now
finding a builder, that was always hard. The better approach seemed to
be an owner finds a builder willing to learn. Not ideal, but it often
worked out. Whenever there was head-to-head competition of ICF
vs conventionally poured, ICFs always won.

 

[BobRip]

I have been living in an ICF house made from Polysteel forms for about 11 years. It is about 3500 sq ft in the Richmond Va. area. We have R55 celulose insulation in the attic (14 inches thick). We had 4 people living here. Our average heating a cooling bills for the first 5 years was a little less than $30 per month. The base electric bill was about $100. Last month in July the total bill was $123, but we are now down to two people.
During hurricaine Isabel, we could barely tell there was a hurricane (slight exageration). My wife says we missed it. The sound proofing is excellent.

It did take 8 months to build the house. This was the third house that the builder had done with ICF. The framer lost money on his bid and he built other house two days a week and mine the other three. There is some important experience to be gained from prior builds. If you don't brace the forms properly then the walls can shift during the concrete pour. If you don't put the concrete in evenly (i.e. fill one cavity mostly full before starting to fill the next) you can get blow outs. This is not a major factor, but you need to know how to deal with it.
I really like the ICF and would hate to bo back to a stick built, but have it built by somebody who has built them before.

 

[Paddy]

Is your house one level? Sounds like your happy with concrete!