styrofoam concrete forms

[markct]

i have seen styrofoam forms used for pouring a foundation. they are made to be left on permanantly and act as the insulation. i was wondering if anyone has ever used these and how expensive they are, it seems that by using these you could pour your own foundation if you wanted to as you dont need to own any forms. thanks for any advice, also who makes these forms?

[BillG49]

Mark,

They are called Insulating Concrete Forms (ICF), and there are lots of discussion threads about them in TractorByNet. Just search for ICF. Also look at ICF Web for lots more information.

[Pat]

There are getting to be a lot of mfg of ICF these days. I am familiar with Polysteel, Arxx, and Amvic. There are a lot of others. Whe you talk to vendors they seem to want to talk about every conceivable benefit but don't mention price if you don't. If you are in termite territory, be aware that although termites can't derive sustenance from EPS (Expanded PolyStyrene) they will tunnel through it looking for a way to get to wood. There is at least one mfg with EPS treated with a termiticide (?) If you can design your building's dimensions to be a good fit for ICF blocks you will reduce the waste considerably and the cost. They are easy to cut and fit, that isn't the issue. They are expensive and the scrap pile can grow if your wall dimensions are not "tuned". Polysteel has galvanized steel connectors where many others use plastic. The polysteel dist makes a big deal about it but Arxx and Amvic are good product and easier to get a good fill than polysteel and able to take more vibration to avoid voids. There are brands that offer field adjustable thicknesses if you like dynamic engineering on the fly. I was away from ICF for a couple years and a lot of changes were made, new vendors etc. As a result of my ignorance I built a safe room using one foot thick concrete blocks because I was to lame brained to think wider blocks were available now that a few hears ago. Now you can get virtually any thickness (field adjustable). What you are trading here is cost of the ICF for ease of building a wall (no sore back picking up ICF) insulation inside and out as part of the wall. This saves having to insulate as a separate labor intensive (read expensive) step. If it is to be a finished space, with blocks or cast crete yo have to fir the wall before drywalling or panneling. With ICF their are strips to screw drywall to, just below the surface and they are marked on the surface. You can hang cabinets etc., just use the right screws and spacings. I have received estimates for cast in place steel rreinforced concrete walls that look real attractive but when you add insulation, firring, running electrical, etc compared to doing it in an ICF wall. It isn't cheaper to avoid the ICF. For a plain wall, cast in place might be cheaper, usually would be but for a finished wall with sheetrock and electrical outlets. ICF is competitive AND there are the thermal benefits.

About running wires and or conduits: util knife or hot knife makes a raceway in seconds. I have a HD right angle professional grade Milwalkee 1/2 inch drill for boring holes to string wires in studs. No way can I compete with a guy hanging electric in ICF if I have to bore holes in wood. Like I said, it is tradeoffs. If you are doing a finished space AND can get a concrete pumper close enough, consider ICF. If it is a breeding pen for pigs, maybe not.

Pat

[sbarr]

I am very interested in building with ICFs, however, I can't find much information regarding cost. Does anyone have any statistics that show the increased cost over stick building?

I have read most of the ICF manufacturer's websites, and they all state that you can save up to 70% on your heating/cooling, but they don't say how much this savings cost.

Thanks for any and all information!

Steve

[Pat]

Steve, You need to be looking at "Concrete Homes" magazine and several Portland Cement Association pubs. www.concretehomesmagazine.com (Do a search for portland cement association site, I don't recall the URL). PCA has oodles of pubs of interest to you. They have a failrly new one on concrete countertops similar to those featured a while back in "Fine Homebuilding" magazine.

Stats? Let me see if I can recall the quote... There are liers, **** liers, and then there are statisticians. My Amvic ICF distributor uses $7.50/sq ft as a general figure. Not for ICF walls but for the floor space enclosed by ICF walls. He figures it costs about $7.50.sq ft more to build with ICF, and do it right. I have also heard 7-10% more than traditional stick built house used by several different sources. Pretty close agreement. Check in with the ICFA (Insulalting Concrete Forms Association).

With 2 inches of EPS (Expanded PolyStyrene [ASTM C578] on both sides of 5 inches of concrete you get R-17 for abot 25-50 savings over a wood or steel framed house with a set point of 75 degrees F. You may have heard claims of up to R-50 for ICF. Not really true. Including the thermal mass of the wall along with the insulation you can get up to about an equivalent of about R-50. That is, you would have to have R-50 walls to cut energy costs to what you would have with an ICF wall. Once you put enough windows in the walls the quality of the windows becomes the driver in the energy equation, swamping out the difference in equivalent R-value between the stick and ICF walls. Taken to the extreme, consider if you put in all the widows that would fit. What difference would the wall material make? So, reducing fenestration will amplify the energy efficiency of the ICF over stick.

Of course, concrete doesn't allow much air infiltration so ICF houses have 6-35% less infiltration which lowers A/C and heating costs. Another HUD study compared block houses to ICF and to stick built. An 8 month average utility bill savings of $80 for block and $90 for ICF compared to stick for same size house with same occupancy etc.

By the way, if you have interest in a basement or partial earth sheltering or any below grade square footage i your house, take a look at the "Below Grade Waterproofing Systems: Part 1" in the latest "Concrete Homes". I wish they had started sooner, I want to see all the parts of the piece NOW!

Also, before you go for anything to save money, do a NPV (Net Present Value) calculation and see what the installed lifecycle costs (not just the purchase price + installation) do to your breakeven time. If you have a house you can heat with a candle and cool with an ice cube it isn't prudent to install a super high efficiency ground sourced heatpump and in-floor hydronic heat and separate A/C ducts for cooling.

Be carefull, there are a lot of guys out there selling ICFs and ICF construction who were selling used cars last week or after gradualting from the ACME school of broadcasting couldn't land a good DJ gig so they are selling ICF. If a builder can't show you three or more houses he is building or built recently (preferable in various stages of construction so you can see his work better, look for someone else. ICF is coming of age and is not all that rare anymore. Even here in rural central Oklahoma I have access to three distributor/bulders with years of experience. The closest has done 30 houses in 5 years.

Hope this will help you to start getting a handle on the available information that you need to make informed decisions.

Pat

[chrisinMI]

I too considered using ICF construction. Actually had the prices broken down between stick framing and ICF. I am a true believer in ICF and the energy efficiency involved, but the builder had difficulty with all the outside angles and also the spacing between windows and the ability to use the forms between/around these areas. Basically, we had to build part ICF and part stick framing. Therefore, I opted for stick framing 2 x 6 and Nu Wool insulation. With the Nu Wool insulation, I have almost the same energy efficiency as ICF. Now there is a little more air infiltration since the structure is not concrete, but it is very minimal . I paid higher energy [img]/forums/images/icons/smile.gif[/img] <font color="yellow"> </font color> bills with my 1100 sq. ft. home than my new 3600 sq. ft home

[BillG49]

Steve,

From the website that Pat provided, there is an article on how Lubbock Texas has dived into ICF construction. It also appears that they have done some cost comparisons:

"Before deciding on ICFs as a preferred method of home construction, Brad Reed, Senior Building Inspector for Lubbock, and the rest of the Community Development Team conducted research to determine the cost effectiveness of the ICF systems. The team concluded that although building with ICFs increased the cost of the homeowners' monthly mortgage by several dollars per month, the resultant energy savings were so significant that the net monthly result to the owner was a savings of nearly $ 33 per month."

There are also contact numbers that I will be following up on to see if I can get more information:

"For more information about the City of Lubbock Affordable Housing Reconstruction Program, contact Adrian King of the CCPC of Texas at 817-540-4437 or Jim Niehoff at the PCA at 847-972-9108."

[BrianP]

I built my house using ICFs. Actually, its a work in process. I paid for the concrete and brick work but did pretty much everything else myself. Mine is a 4000 sq foot bungalo with a full walk out basement (i.e. 8000 sq foot total). I know, thats huge, but I designed it and have no feel for how big things are. Once the hole was dug I realized ... ooops, but there was no turning back.

There are many advantages to ICF including energy efficiency, but the house is soooo quiet. You hear nothing. No creaking, no outside noises, etc.. Its also fire proof, and if a tornado comes I may lose my roof but the rest of the house will be there.

There are disadvantages too. Everything is non-standard construction, from the electrical to the plumbing to windows and doors. I have 12" think walls with 4" brick, so my window wells are about 16" deep. Every window and door had to be set in a 'box' about 12" deep. No problem, but try and get a stable wood plank 12" wide, so I had to use plywood. Then I had to figure out how to edge the plywood, and on and on it goes.

The biggest disadvantage is that workmanship on the forms is key. Concrete people are not known for their precision work, and once the concrete sets up, any mistakes or sloppyness is permanent. So I got a wall with a 1" belly over 9' high. So I had to shim out the whole wall to make it look right. Remember those window boxes? Each one had to be custom fitted to make it look right. [img]/forums/images/icons/mad.gif[/img] Of course, I had no prior experience with homebuilding, so some of the errors were my fault, [img]/forums/images/icons/blush.gif[/img] but, geeze 1" out on a wall?

Now, I would do it all again, (but I don't want to ever move again). I would plan things a lot more carefully and I would get some sort of performance bond out of the contractor for quality of work, etc.. If you decide to go ahead, I would be happy to talk you through the issue I encountered via email.

ps as for energy efficiency, sealing up is still a work in process. oye, there are a lot of windows and doors in 8,000 square foot of house.