Insulated Concrete Forms

[Pat]

Gary, Don't you just love it... two liscensed communicators and it took how many retries?

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[Adron]

Just (almost) finished a home addition with about a 500 s/f partial basement + safe room. (6' x 8' Safe room held 8 people and 2 dogs while the ceiling braces were still there. F3 missed by ½ mile). So far I love the ICF. The fact that we are able to install dry wall with no additional furring (sp?) strips, and the electrical boxes and wiring are recessed is saving a lot of $ in finishing the basement. Also everyone has commented on how quiet it is. Even miles from the nearest traffic light there is always some background noise.

[midlifecrisis]

We built a split level and used 4 course of ICF and a 4 ft. 2X6 stud wall on top of that. It gives us a full 8 ft. under duct work and about 8'9" of finished ceiling in all the other rooms. The transformation from ICF to stud wall leaves us with about a 7" shelf on the perimeter walls (can anyone follow this)?
If I had to do it over again, I would insist on ICF.
Don't forget the dropped footing under the walk out.

[Pat]

Adron, Yes indeed, MUM is the word. So quiet that it is literally hard to hear thunder. Knowing this, part of my original design/requirements notes included a section on exterior michrophones to feed a mixer that would "include" ambient environmental sounds into the interior of the house.

With the windows open I can hear tree frogs, leopard frogs, bull frogs, whip-poor-wills, mockingbirds, turkey, geese, coyote, a neighbor's wind chime over a quarter mile away, crows, woodpeckers, water draining from pond to pond when there is an overflow, and a host of other environmental sounds. With the windows closed I can hear my pulse pounding in my ears or the radio, or my wife tracking me down with the intercom and just about nothing from outside the house.

I haven't done the outdoor listening thing yet as it is not hi-pri but it may need to be done later so in the hotest and most humid part of the year I can listen to something more interesting than the soft rustle of mechanically circulated air interrupting the sound of my pulse. I got a low-fi preview of the "ambient sound system" by pressing the door answering button on the intercom and listening to the outside bird song and stuff that way.

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[bullzibart]

I'm building my first home and plan on living there along time. So I'm gathering from this post its going to be better to spend the extra on this type of foundation and see where I can cut cost elsewhere.

[GaryM]

I have the ICFs at my place. If you are going to finish the space surrounded by the foundation walls, I'd use the ICF. If it's going to be an unfinished space, with little heating and cooling, your benefits will be much less.

[Pat]

bull, It depends. Hard to advise someone or even comment on their ideas if they give no idea as to what they are trying to do.

Do you want a basement?
Will it be a walk-out?
Do you have expansive soil?
Where is your water table?
How does the soil perk where you plan to build?
Will you be going one story or more?
Stick, ICF, formed and cast, SIP, tilt up, precast, or what?
Earth sheltered/earth bermed or what?
Slab-on-grade, crawl space, or...?

One size (Or style) definitely does not fit all when it comes to foundations. Without a sufficient foundation in both design and implementation, well matched to the structure it is to support, you endanger ALL the rest of the invested resources.

I bet if you answer these questions that you could then get some decent advice from several folks here.

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[bullzibart]

Pat, I started a thread on styro foam foundations not knowing what this one was about. I will have a walkout basement with two sides exposed and two below grade. The basement will be finished with at least one bedroom and family/bar room hpefully with radiant heat. I'm planning on putting up a two story cape (modular). Right now I'm dealing with ledge while trying to dig for my foundation. If I go this way I will be using Logix Insulated Concrete Forms.

[GaryM]

As Pat posted after me and started with the word "bull" I thought he was referring to my post! [img]/forums/images/icons/frown.gif[/img]

Anyway, it sounds as though ICFs might be a good match for your project.

A home near mine, OK 20 miles away, was done with ICFs and they had ledge to deal with. They were able to cut the bottom of the ICFs to match the ledge and create a foundation wall with less trouble than if they had used conventional forms.

[Pat]

Bull, If this is a DIY deal then ICF has a bonus. ICF are easier to do than conventional forming, especially for a DIY because most of us don't have forming materials/equipment and really good forming skills. Still, I've seen some pretty bad ICF work by amatures and also professionals. Be sure to stretch a strings vert and horiz to ensurre your walls are straight and true. A simple plumb bob beats a spirit (bubble) level any day to check wall verticality. Repetitively as you poor your lifts, check the strings to ensure you are still straight vert and horiz. You need to make any corrections/adjustments in the first few minutes.

I personally recommend you use a water reducer plasticizer additive. If you thin the crete enough for good flow you really weaken it. The additive makes it flow really well, as if it were mixed too wet but doesn't require extra water and keeps the PSI rating nice and high. For the slight difference in cost I like to get a min of 4000 PSI and more is better, especially when you don't ruin it with excess water.

Concrete finishers like to "pour" concrete whereas concrete engineers like to "place" concrete. The difference being in ease of working vs cured strength. With the water reducer plasticiser yo get the best of both worlds. NOTE: the Additive can't be added at the plant as its pot life is short. They should add it to the redi-mix truck on-site, stir well, and pour.

The water reducer plasticiser will probably reduce the height of the lifts you can do without danger of a blowout as the crete is very mobile when fresh. It runs around rebar and V-Buck or however you frame windows with way better than without. My ICF sub cut big holes in the window sills (V-Buck) so he could monitor proper fill and add crete through the holes to get a good fill. With the water reducer we had guysers we had to plug.

I have been cutting 8 inch wide 6 ft high chanels in the ICF down to the concrete and so I get the opportunity to see how well we did with the pour. No honeycombing, voids, or other visible defects. We got a good fill. I suspect a lot of ICF jobs would look pretty bad if inspected with honeycombing and voids and separated gravel and ...

Are you going to do radiant slab, baseboards, ceilings, or what. I recommend the guys over at the RPA (Radiant Panel Association web forum as a great resource on radiant heat.) I put R-11+ rigid foam under my basement slab and 16 inches of washed septic gravel under that. The slab tends to take on the average room temp which doesn't vary all that much night to day or winter to summer. I haven't needed to run heat in the basement but I have an equipment space down there for hydronic distribution and a geo heat pump so leakage heat tends to keep the basement cozy during the heating season and now that we are in A/C weather I haven't used A/C down there and get about 70F all the time. Maybe when I get the wainscot on the walls and have 6-12 people there proving body heat I'll be glad I have A/C ducts and a zone controlling 'stat.

Of course I have only one exposed wall (12 inches of concrete) and the others are earth covered and have R-11+ insulaltion on the outside. I don't know the thickness of the EPS on your particular ICF but you should do really well if it is close to mine. I have 2 1/2 inches on each side of my ICF so it performs very well.

I sympathize with your "LEDGE" situation. We broke a 4 ft bucket off of a BIG track hoe excavator and had to get it welded back together to continue excavating. I rented a Bobcat with a 500 pound hydraulic chisel to attack some difficult areas and to "square off" interior corners where the big excavator couldn't get.

What is your drainage system plan? I have French drains. I have one French drain that completely encircles the basement foundation on the outside of the stem (at foundatioin height) and another all the way around on the inside of the stem. They drain to daylight at a pond downslope in the backyard. I also have a trench on the uphill side of the basement about 8 ft from the basement foundation with a French drain in it. This one intercepts underground water coming downhill toward the basement and gets a lot of it before it gets to the other French drrains. Working great so far. My basement floor is a few feet below the prevailing water table but the bare concrete walls and floor are so dry that even covered with plastic taped down to trap moisture as a test they didn't even slightly discolor much less show evidence of condensation.

If you have any thoughts of carpet on the basement floor you should consider radiant heat in the ceiling rather than in-slab. The radiant energy from the ceiling will warm the floor where there isn't any furniture or anything to shade it from the ceiling. Still you want subslab insulation even with in-ceiling hydronics.

For my basement ceiling I used a product called PanelDeck which is a horizontal analog to ICF. So my basement ceiling is a concrete slab with EPS insulation on the bottom. The insulation keeps the heat from the in-slab hydronics above the ceiling in the floor slab of the room above. The EPS of the PanelDeck has cavities in it for A/C ducts and water pipes or electrical conduit.

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