I am putting on a 3 wall addition to tie into mu current foundation. I have gotten 5 icf bids and the lowest is $14,380. For 6” core nudura. My question is one of the addition contractors do their own block (cmu) foundation and is only charging $7000 for the same size basement. I have priced putting 3” XPS and waterproof membrane on exterior and 2” XPS with 2x6 studded walls with R-19 batt insulation and vapor barrier on the inside at $2,800. Both systems would need gypsum board so that’s a wash. So all total I would be at $9,800. I would be looking at a R-value at 44. Any advice would be appreciated if I am way off base or this cmu system I imagined is still inferior to icf. I would be doing all the insulation labor myself on the cmu. $4500 difference in price would go a long way to help in other areas but if the icf is far superior in terms of energy savings/room temperature to the 5” of foamboard and r19 2x6 walls please let me know. I am in climate zone 5.

1: Don't waste money on XPS. If you're going foam, go EPS. After a few years, the insulation value will be identical, as XPS off-gasses.

2: Any insulation below the slab?

Yes both systems will have 2” under slab. My question regardless of what type of foam board I use, will insulating a cmu wall in the manner I laid out above 5” foam board and r-19 batt provide a Similar if not better r- value as icf for 30% less cost?

Just ran a couple of quick calcs.
For both walls I went with 12' height, 95psf of wind pressure, with #5 vert @ 24" o/c.
6" core ICF vs 8" CMU.
Deflection for 6" ICF is L/401
Deflection for 8" CMU is L/158 - this is awfully low but OK.
Both were up there with max bending stress ratio although ICF about 7% utilized more.
Also - the ICF wall being only a 6" core should have the verts tighter together..

Also 8"CMU + 5"Insulation = 13" before finishes.
6" Core + 2 x 2-5/8" EPS = 11.25" before finishes.

Comparing 8" core ICF with 8" CMU - the ICF wall is twice as strong...

Also - make sure you shop around - sometimes certain installers want to retire on one or two ICF projects...

Baldwin2014. I appreciate your response. I have priced over 10 ICF builders and the $14,380 is the best price. However, I am more concerned with R-Value more than anything else. This basement is 100% just bonus room for me. I will not be using this space other than storage under my addition. I am not running any heating or water lines to it so I am trying to provide the most insulated product within reason for my budget, since this area will be under my addition above. My question is no different then before is 3" of EPS on the outside with another 2" of EPS with 2x6 full of R19 batt insulation inside similar to the R-value of a 6" core ICF system??

On paper, yeah. The ICF value will likely be greater.
The ICF wall will be more airtight than the CMU wall though.

Also, I'd recommend at least a MINIMAL amount of heating in the concrete/CMU basement.
Otherwise you'll find regulating temperature in the rest of the house more difficult.

Dilettante,
So are you saying that the ICF will be more insulated even though on paper the CMU wall has a greater R-Value? The main reason for this is do to air tightness? So I guess my question is, does it make sense to pay 32% more to install an ICF system? Seems to me that buying a $700 closed cell spray foam kit would eliminate some of the airtightness concern?

I would say, when it comes to thermal aspects of it, the two walls would perform very similar. The ICF wall is slightly more airtight, but the CMU has slightly more insulation...
Structurally the ICF wall wins.

Dayne, Not sure how you are able to have the CMU wall insulated on both sides with 2x6 studs and batt cheaper than 6" core ICF wall....
Something is not adding up... You sure labour is figured in?
Can you give us the size of the project? Number of corners, wall lengths and heights? any openings.

So you have:

1. ICF (forms, concrete, rebar horizontal + vertical, installation (forms, concrete bracin & removal), waterproofing)
vs.
2. 8" CMU wall, reinforced I hope? grouted very 24" o/c? With 3" XPS on outside and 2x6 inside wall (with top and bottom plate) insulated with batt + 2" XPS on top of the studs.

If you are sure the ICF is 32% more, go with CMU. I find this hard to believe - something is not right - just speaking from experience.

I concur, something is definitely not right with this cost assessment. CMU is much more labor intensive than ICF. Perhaps independently price the material for each so you can ascertain the labor cost embedded in each estimate. You should be able to do ICF for significantly less than CMU and about the same or slightly more than 2x wood. ICF is also relatively easy DIY compared to CMU, so that should help you in assessing the labor cost for each...

My project is a 3 wall addition 32 long by 24 wide. So I need 2 walls that are 32 feet and one that is 24 feet. The is only 2 corners so think 3 wall rectangle. If you put my dimensions into foxblock I need 124 straights and 28 corners. The icf panels through Menards came to $3,200. The approx 900 block needed for cmu is $1800. I need 15 cubic yard of concrete for the icf walls which is $2100. Both systems are using similar footers and same slab. Keep in mind I have gotten 10 icf prices ranging from $14,380 to $25,000. All for the same job. This is not including any excavation or stone. This is including the 4” slab for all. The cmu price is from a contractor who would also be doing all my framing. All icf bids are from me getting them subbed in. Trust me I know my numbers on this hence why I am asking if I can make the cmu work with the setup I described? I was dead set on icf until I got the contractors block price now I am trying to figure out if I can get a similar product as icf with cmu. Before you go down that rabbit hole this is a well respected and highly utilized contractor in the area. I think maybe the reason why pricing is so much different is all the concrete people are bidding the job as darts at a dart board for spring 2020 where as the contractor is actually trying to squeeze me in before housebuilding season. I am in western PA. Also 2 precast companies came in at $12000 without slab.

I need
5 rolls of leak barrier membrane at $139 equals $556
22 XPS 3” at $40 a piece is $880
Need 20 XPS 2” at $31 is $660.
Need 44 Pre-Cut 2x6 at $4.50 a piece is $198
Need 4 2x6x16’ treated at $11.50 is $46
Need 2 2x6x12’ treated at $8.50 is $17
Need 45 batts of insulation 9 batts per bundle so need 5 bundles at $55 a bundle for $275
All total $2,632 plus my labor bc I can do that all myself.

there Are no doors or windows in the walls. If anyone is in western Pennsylvania please come give me an icf bid bc no where in the 10 estimates is icf cheaper let alone not more than 25 to 35% higher.

Sorry don’t know how it triple posted and can’t delete post. Are you guys saying the ICF prices are too high or cmu too low? I priced the cmu material and the cmu price is 2x material which isn’t too unreasonably low considering his labor for framing is another $8900. All told he will will walk away with $12,400 cash for him and his workers for a months worth of work.

Well, I am thinking that your ICF labor cost is way too high... Here in southern OR, our ICF material cost (ICF block, rebar and concrete) is about $5 per square foot of wall area. This can vary somewhat based on building complexity and openings (e.g., doors and windows), but this is a good ballpark number here. Again, you should be able to price the ICF cost in your area.

The labor required to accomplish ICF is considerably less than that required to accomplish CMU or 2x wood. We can complete typical residential building walls using ICF in a couple days. Most of this time is spent placing and removing the bracing...which is should not be a high labor cost effort... Properly aligning the bracing and accomplishing the pour (which only takes a couple hours but does require experienced hands) so you end up with plumb and straight walls is where the higher labor cost may be warranted.

Over the years on this forum we have occasionally heard about excessively high ICF bids in areas where ICF construction is still relatively new and there are few experienced ICF contractors available, or in areas where there may be a group of ICF contractors that perhaps agree to set prices at a premium because they can. Again, ICF is way more DIY friendly than either CMU or 2x wood. Just do your research and take the training offered by nearly all ICF manufacturers if you decide to go that route.

I've got about $7,300 for every thing except mesh for the floor. Concrete, form a drain footings, waterproofing, pump, my mono pour system, assuming a 8' high wall no labor. Since the system could be put together in one day and the footings and wall and floor is done in one shot the labor is substantially less.

dayne
if you are building southern climates call/email me for an independent opinion...
peteratinsuldeckdotcom
772 225 5404

Me pricing the icf retail I come in at $3200. The slab, footer and walls will take 30 cubic yards of concrete. Which a cubic yard is $135 a yard. Which is $4200. Pumper truck is $675 a day in this area. How much rebar mesh and waterproofing cost? Looks like materials is around $9000 assuming mesh,rebar and waterproofing is around $1200. So is $5300 for labor that unrealistic??

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