ICFs, insulated concrete forms
Hudson Valley Carpenter
| Posted in Construction Techniques on
Anyone using insulated concrete forms, ICFs? Please write about your experience.
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My house was done with Blue Maxx.
I think they are all very similar. In general, contractor have to tak a great deal of time bracing, etc., otherwise the walls end up with 'cast in place' bows, etc. These can be easy to deal with with on the outside if you've got brick, but a major PITA for interios walls. I had to 'blow out' one interior wall because of a combined 3/4" bow and tilt.
The contractor says they 'shave' these out, but they disappear once the money is paid.
In general, very solid, quiet house. Lots of grief dealing with windows, doors, etc., due to the wall thickness, and electrical and plumbing has to be thought through.
But the bows, etc. as a major problem, so chose your contractor wisely.
Try the advanced search feature. There are two active threads right now already on this subject.
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Hudson Valley Carpenter.
I'm a do-it-yourselfer with a little experiance with ICF's.. My addition was formed by using them and I can't say enough about how simple they are to do.. I started mine and then went on a road trip. When I returned my back was ruined. I mean I was heavily sedated just to control the pain. Nothing to do with the ICF's,- bad seat in my new car and 24 hours of driving..
My sister-in-law with no construction experiance other than she painted her bedroom and replaced some wallpaper once, finished them for me with maybe a 20 MINUTE LESSON. (I can't be sure what I said,, I was heavily drugged)
When I did the pour a few days later I had a neighborhood kid hold the hose and I just gave him directions (you pump the concrete into the forms not pour it) Took maybe two hours including clean up. Walls nice and straight no problems. sorta minor issue was that to help me save money my sister in law didn't line up the cut offs with each other so every layer had the hard spots where you can screw stuff into in a differant place. Simply a matter of my being cheap and my sister in law not knowing.. Now that I know better I'd waste a few inches of one form to keep everything in alignment and make follow up work easier. not impossible but I did have to be a bit clever to get myself out of the mess I created..
I saved over $10,000 by doing it myself over the lowest estimate I got, and what's more I will be doing it again in a few months when I build a 1/2 round portico foundation.. Don't build round or bowed if your not really confident.. This is kinda advanced stuff, not really for a novice do-it-yourselfer unless you have a great deal of courage.. and foresight.
I used rewards forms and simply had the local cement company drop them off, figure out the spec mix, how much I needed rebar and heck everything.. I (and my sister-in-law) just built leggos! (and it was just about that difficult too) I didn't have a single bit of trouble building the bucks for the entry doors and windows. real basic building stuff..
The house above the foundation I did in SIP's due to superior insulation but if I had it to do all over again I'd build using ICF's and then add a layer of interior foam to gain back the little added R value of SIP's over ICF's
Using a hammer drill it's easy to add wires or plumbing etc. if you forget them. and If I ever get to add to the house in the future it's just as easy to get a diamond wheel chop saw and cut right thru them to add windows doors etc..
Merci, mon ami. That's just what I needed to know.
Hey, I can feel my sciatica starting to act up. Can I borrow your sister-in-law for a few days? ;-)
Peter
Hudson Valley Carpenter,
I'm certain that if you honestly needed her help she'd be there for you.. she's that generous a person!
But you'd be disappointed.. Heck building those walls was actually fun! Sorta like putting together Leggos. Holding the hose was work but if it would have been any bigger I would have found someone to help the kid.. I bought a tool to bend the rebar and that made it a bunch easier so when I'm finally done I'll sell the tool and it will cost me maybe $7.00
Wear those disposable gloves or you'll get foam on your hands that just won't come off. (yeh you spray a small bead of foam to ensure everything stays together)
Use plenty of bracing. My place lends me bracing for no charge. it's a combination bracing and walkway..
Some forms go together extremely easily and well while other foams are a disaster waiting to happen.. price doesn't determine which is which. Go around and find out what the pros in your area use and frankly you should spend a day watching the pros.. I picked up a lot of pointers watching for a few hours and since then I've picked up even more.
Contact your cement companies and see what sort of deal they have available.. I get a sizeable discount by working thru the local rep rather than going to the office and simply ordering them..
frenchy just curious on how you installed your floor joists. did you imbed simpson icf joist hangers directly in the forms or install a ledger? also: v-bucks or wood bucks, & if wood did you use pt, borate or std stock wiyh a moisture barrier against the concrete? i plan to start one in a few months, also reward wall. thanks, frank
fpopjr
I did 6 inch SIP's above a 12 inch rewards form ICF. I put a plate across the Rewards forms made from a 2x 15 (actual not nominal) Tamarack bottom plank. thus I covered the joist area plus cantalevered another 3 inches.. I was able to set my joists right on top of the plate and the bearing end of the joist was 5 1/2 inches over the wall plus the 3 inch cantalever.
Hmm that's as clear as mud,,
Ok I split the 12 inches of form between the SIP and the joists. Is that a little more clear? The sip was completely on the form and the joist had nearly half of the bottom plate to rest on..
If I were to do an All ICF house here in Minnesota I'd most likely use a inner stick built (2x4) wall and I'd set the joist hangers on that.. Frankly we need all the insulation we can get. On a typical 3000 sq.ft. house you are likely adding another 2000 dollars or so but because it's stick built and electricians and plumbers won't get all scaredy cat on you and raise the price 16 times because they've really never done a ICF house before..(in spite of what they say)
Less than 2% of all new homes are built with alternative construction methods. That includes SIP, ICF, straw bale and whatever else is out there.. So 98% of the sub contractors won't have any real experiance. and will charge for the lesson.. The little added costs will be more than saved with lower electricain and plumbing costs.. Yes you will loose a little interior space but nothing of any real signifigance.. besides when the guests see those deep jam extensions around the windows there will be an impressive amount of deferance shown to you simply because of those.. Your wife etc. will have a whole new area to display knick knacks on and cats will love you..
Frenchy, I can appreciate your desire to superinsulate.
The secondary inside wall sounds simple enough. It has a few positives as well as negatives.
2x2's in the rough, with foam sanwhiched was your first suggestion. Now you're going with wood frame.
What about moisture and mold that might be trapped between the layers?
blue"...
keep looking for customers who want to hire YOU.. all the rest are looking for commodities.. are you a commodity ?... if you get sucked into "free estimates" and "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead high...."
From the best of TauntonU.
"What about moisture and mold that might be trapped between the layers?"You had to go and ask didn't you?;)
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Blue-eyed-devil
Since you'd need to seal the outside of an ICF to prevent water from leaking in, I would assume that you'd also need an interior vapor barrier..
The moisture path in a ICF starts at the footings, goes thru the poured concrete and would escape thru the top plate if that is not sealed off.
I have wondered if it would be possible to put a 5 mil poly vapor barrier down prior to pouring the footings but haven't done enough research to verify it's effectiveness.
Frenchy - fab-form has moisture migration from the footers as a big selling point. That might be a good place to start research.
I think my concrete is close to bone-dry from the times I've cut through the foam to mount things, etc. (footers enclosed in plastic, dimple mat over bituthane exterior)
Since my house is ICF, and winter is half over, I would add from experience that ICFs alone are very good insulation, and diminishing returns might kick in if you add foam. I would spend the $$ sealing the attic.
Treat every person you meet like you will know them the rest of your life - you just might!
Brain
Insulation is not the prime reason I would do an interior stud wall and foam it.. Frankly less than 2% of all sub contractors have ever worked in anything but a stick built house.. they will price all their bids like they have to invent the moonrocket. Give them familar 2x4's and the bids will be competetive.. Yeh it adds a bit to the cost but that should be more than made up by the lower electricial and plumbing bids.
Frenchy, I wouldn't let the mechanicals dictate to me what they are going to plumb my house for. It works the other way around. So, I would either provide the chases if I really wanted a certain plumber or electrician and he tried to bump the labor.
blue"...
keep looking for customers who want to hire YOU.. all the rest are looking for commodities.. are you a commodity ?... if you get sucked into "free estimates" and "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead high...."
From the best of TauntonU.
Blue-eyed-devil
Actually if they really wanted to get into a growing market they should be willing to toss you a deal. Figure this one is a learning curve sort of approach. But then I know how scared most subs are whenever they are outside of their comfort range..
ICF's are growing and it's a a great end of the business to get into.. right now homeowners are looking for those willing to take on the task.. in the future that won't happen but by then you'll have established yourself as an ICF expert and capable of leading the market rather than following behind..
It was that way when I started selling Telehandlers.. Had to do a lot of selling untill the average contractor figured out that they made you money instead of costing you money.. then sometime in 1997/ 1998 I literally could stand back and sell whatever I could get. they came to me instead of I went looking for them.. I'm proud of the fact that even though I could have I never gouged a customer back then..
So on a house with 30'x40' footprint you're thinking 120 linear feet of walls per floor, combined with a usable square footage loss of 40 sqft per floor is cheaper than finding subs that have worked with ICF walls?
The square footage loss alone would need to be made up with larger exterior footprint, or to convince the clients that what they really wanted was a slightly smaller space. "Oh yeah, we're actually going to build you a 2,400 sqft house for more than a 2,500 sqft."
Sounds good in theory, but it's much better to find more experienced subs or spend more time talking through how the subs should handle the ICF issues.
We see very little if any extra charge from our subs, even for subs who have never built around ICFs before. As we walk through a project it's an easy matter of pointing out problem areas that might cause alarm and to discuss how they should be handled, which calms most fears of the unknown.
Making allowances in the ICF walls for the various subs is simply good design, so there should be very few issues that would slow down anyone on ICFs.
Good building.
Beer was created so carpenters wouldn't rule the world.
Idaho Don
You must have better subs than what's available here locally. I speak to ICF builders all of the time as well as SIP builders. Electricians and plumbers always seem to command a real premium to bid on new types of construction.
Yes we both know there really isn't an difficulty doing either a SIP or an ICF building.. Maybe with the currant slow down there is a more willing attitude regarding alternate construction methods. The two new ICF homes under construction nearby seem to reflect that. But one contractor is doing both of them so maybe he's already got his subs over the training hurdle.
Actually What I'd do is make a feature of the thicker walls. yes there is a loss, in the case you listed 40 sq feet per floor. Like most negatives it also has a positive side which is what I would point out.. In southern states where added insulation doesn't really translate to energy savings potential I'd find the good subs train them and be willing to accept whatever consquences that results in.
Actually I would do no such thing!
I was taught the method of the mini close decades ago. Once I've sold the concept of ICF I would offer both approaches to the customer, Oh, and for only $x000. I can provide another layer on insulation with the following benefits,....A-B-C and consider the design possibilities that offers........
or I can build with the standard ICF and you still get all the benefits ICF offers..
It's a mini close because at this point you make them select. Once they've made that minor choice you've actually sold the house, the rest is just details.. If they don't like the concept or they object, you still haven't lost the sale because you only offered it as an option.. Not as a make or break decision.. it allows you to take the customers pulse and find out just how much effort you need to spend without the customer really knowing that they have committed to using you..
In effect it's just a polite way of asking if they are real..
"In southern states where added insulation doesn't really translate to energy savings potential "You really gotta quit plucking ideas out of thin air! Most of the ICF manufacturers started out in the southern states - plaes like Arizona where their energy costs for cooling rival your energy costs for heating and where stucco or EFIS type stucco was already common making ICF a reasonable choice for their slab on grade homes.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffan,
In the southern parts of the country where heating isn't the major energy user like it is in northern states the added insulation doesn't offer any real potential savings.
Look at adobe homes. with no insulation they remain relatively cooler than framed houses will.. ICF's are really a hybred adobe home. The reason they work well in northern climates has more to do with their air inflitration abilities than any thermal mass or insulational quaities..
I'm not really sure I made my point clear..
I see you haven't lived in the south.I have.
Florida - three years
N Mexico - in an adobe for nearly a year
West Texas - for two yearsCooling is a substantial cost.And adobe does not offer insulation. It is thermal mass. When days are hot and nights are cold, it helps, but after that twelve hour swing it doesn't. If you get three days of hot days and warm nights, it is an oven radiating heat from the walls to the interior. It is only in cool desert conditions that they operate efficiently. ICFs take the combination of mass and insulation to make a vastly superior home. to what adobe can provide alone.
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Piffan.
Does 7 years in San Diego count? I mean we used to spend a great deal of time out in the desert around Holtville so I might have a tiny bit of experiance with desert heat.
You did a nicer job of explaining it than I did. thank you.. I'm glad we are in agreement.. However in our Northern climate where heating costs dominate the added insuklation offers benefits and the possibility of an energy payback not to mention the advantage of having a material everybody is familar with so electricians and plumbers don't go off, heck even the sheetrockers would feel comfortable.
I have not lived in San Diego, but from what I have heard, it would not qualify. They say that because of the southern location combined with the proximity to the sea, that it has one of the most comfortable climates in this country, free of the geeater temp swings most of us experience. If that is so, then heating and cooling costs are negligible and explain your misunderstanding of how expensive cooling costs can be.
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Piffan
Yes heating there is less important than air conditioning.. explain about the cool ocean to me in July or August will you? IN fact Let's go down to a beach in La Jolla or on North Island off Hotel Del Coronado and you can walk barefoot in the sand and explain to me all about how cool it is.. (don't mind me I'll be the one back in the airconditioned bar siping a cool drink)
If You had lived there you'd know where Holtville is.., think desert! heck just drive say 50 miles from the ocean and explain to me about how A/C isn't important during the summer.. (it's cheating if you get to altitude in the mountains) it's less than two hours to the dry lakes and if that doesn't meet your definition of desert I doubt you'll find one in the US..
OK so you DO understand there are a lot of cost involved in cooling then!
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What kind of foam do you need to add on the interior? Why do you need it?
blue"...
keep looking for customers who want to hire YOU.. all the rest are looking for commodities.. are you a commodity ?... if you get sucked into "free estimates" and "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead high...."
From the best of TauntonU.
Blue-eyed-devil
ICF's aren't quite as efficent thermally as SIP's are. (There is 4 inches of foam at most compared to say six on a six inch SIP. The differance can easily be made up with an extra layer of foam on the interior. Remember, I'm from the school of somes good, more is better, and too much is just starting to be fun! <G>
Actually IF I add another two inches of foam it would probably only add $2000 to the cost of building but it would most likely save me $20,000 worth of energy costs. Besides you could get clever and do all sorts of things with wiring, plumbing, and structure to allow standardized interior construction.. another words have studs etc. to nail stuff to so you aren't retraining plumbers or electricians.. bound to lower your costs..
I'd still do SIP's for roof panels..
Lets assume I decide to put 2" of foam on a sip. What do you use for trim nails? Barn spikes LOL?
blue"...
keep looking for customers who want to hire YOU.. all the rest are looking for commodities.. are you a commodity ?... if you get sucked into "free estimates" and "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead high...."
From the best of TauntonU.
blue-eyed-devil
I'm not sure barn spikes would even work <G> two inches of leverage? I mean the foam would afford very little in the way of resistance to bending of the nails. That's why I'd stick 2x2's onto the ICF's you could screw them in nicely with sheetrock type screws (I know Piffan but bare with me) ;-) the only load on the screws would be in tension and darn little of that because if you torqued too much you'd strip the nylon/ metal strap that holds it in place. I think there would be more pressure holding a piece of sheetrock in place. (OK Piffan?)
Once in place, the 2x2 (actual not nominal) could then be used to provide conventional wire chase access, plumbing access etc.. You could then spray foam or fit foam panels in place. No thermal bridging since the 2x2 is right against the foam.
If energy consumption was a real major issue you could actually use a 2x4 on the interior and screw the 2x4 to the strip.. Then you'd have 3 1/2 inches of added foam! You could probably warm that house with a warm fart in febuary!
There you go exagerating again!;)You won't live long enough to save twenty grand on energy savings,
and -
Every ICF type I have seen has a min 2.25" offoam and some more than that.Don't forget that when calculating your energy savings there is a grading curve. Once you have dealt with air infiltration and effectively have no convection loss, and have radiant and conductive loss controlled, there is a declining measure of payback on adding more insulation, especially in a house with windows and doors.
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Piffan,
Yeh, I stabbed that number. but it might not be so far off!
I mean assume energy costs continue to rise at the same rate they currantly are rising that means energy bills will more than double in 7 years. Figure out that compound rate and while you're doing it remember that oil reserves etc. are finite. Maybe I'm too old a fart to see that sort of savings but I suspect some of our younger readers would easily see that sort of savings potential..