Lumber vs. ICF Costs
srasic
| Posted in General Questions on
When lumber prices first skyrocketed in 2020 there was a lot of talk about ICF being comparable in terms of pricing a wood framed house. Curious if people think this still holds true today or will in 2023? I know lumber prices have gone down but they still seam to be a lot higher then pre-pandemic. When comparing I’m looking at ICF vs a high performance ZIP sheathing & externally insulated house. Factoring in extras like rebar and savings on insulation.
I know you can’t predict lumber prices for next year but I’m just trying to gage how much of a premium ICF still is in terms of your exterior walls. Thanks!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
ICF (for some reason) will always cost more than wood it seems. I don't understand why they're not just taking over the industry by offering moderately priced products.
Why do questions like this keep getting asked, with barely a comment on how ungreen concrete and foam are? Is this "green building advisor", or "who cares about green building advisor"?
It's especially frustrating that, despite ICF being one of the most expensive ways to build, people still try to find any excuse to use it. The reason ICF is so costly is because of the enormous energy and resource inputs. They can't take over the industry by undercutting on price, thank God, because clearly nothing else is stopping more people from using it.
It aint easy being green!
As Armando said, there's a ton of reasons to choose ICF's over stick framed houses. There's also a ton of definitions on what it means to be green.
1. My def. of green is constructing something that is going to last a very long time, with repairability, durability, and beauty built int. Maybe it's laden with XPS, concrete, and steel extracted from the core of the earth, but If it lasts 300 years, it's greener than building two lesser structures. That may sound like a pipe dream, but I assure you, there are people living in 300 year old houses spread out over the world., with plenty of 100+ here in the US.
2. The conditions, as stated, may require strengths that unreinforced masonry, dimensional lumber, straw bale, adobe, or metal can't provide.
3. The local trades may have specialized in concrete over wood frame.
4. have an inside connection to cheap ICF's.
For the most part, buildings don't get torn down because they wear out, they get torn down because they're functionally obsolete. Wood frame buildings can last hundreds of years if they are valued.
Since the start of the pandemic there's been a building boom on (although it seems to have cooled ever so slightly in the past few months). Being in the city, that means that small houses are being torn down and replaced with large houses or multi-family dwellings. Those small houses aren't being torn down because they're worn out, they're being torn down because the land they sit on is valuable. They were built 100 years ago in a way that made sense given land prices then, but no longer does. If ICF had been around 100 years ago they'd be carting a lot more waste to landfills.
For the most part, concrete can be recycled into aggregate, if people were willing. It's not done much around here as far as I can tell. The EPS is probably a lost cause, but the steel could also be salvaged, at least in theory.
When concrete is recycled the embedded energy in it isn't reclaimed. It's not like aluminum.
The ecological problem with concrete is that it takes an enormous amount of energy to produce, and its production process releases large quantities of greenhouse gases independently of the energy consumed by releasing carbon sequestered in the raw materials. "Recycled" concrete isn't really recycled, what you get is a substitute for the crushed stone that is a raw material into the concrete-making process. It would be like turning processed aluminum back into bauxite and trying to recycle it.
@DC_Contrarian
Thanks for explaining this, not so much for me as for others. I've read that 10% of the CO2 in the atmosphere that is contributing to climate change comes from the manufacturing of the ingredients for concrete. It's way up there. If you don't absolutely have to have a concrete intensive structure, then don't build one.
There's only one planet. Don't crap in your tent. Everything else is just excuses.
Not all old houses get torn down because the land they sit on is valuable, in many large cities, lots of old houses have so many structural issues or have been abandoned for long time to the point that there is no way to fix them.
Many other cities have total dilapidated and ramshackle neighborhoods making it available to developers to take advantage of low land prices. Often they come in, bulldozing and revitalizing large areas of the town. It’s not all bad.
For many folks, the lack of funds and the headaches to fix a terrible old house is not worth it, and it’s easier to sell, so someone else can build a new one. I’ve known many folks that after they were done remodeling a house, they wish they had torn down and rebuild new for less money and less problems.
The same reason people reply to threads only to complain without answering the question at hand. There's a lot of people who are members of the group who either like ICF or have experience that can share their insight. If you don't like ICF no problem, don't use it. But I am considering it for our build so the question is for anyone who has used it recently and can offer helpful insight to its actual cost vs a high performance construction model.
Again appreciate any insight people can offer.
For me, one word…Resilience. If I lived in a coastal area prone to hurricanes, or the Midwest prone to tornados, or maybe some other area with natural disasters, an ICF house is a great choice, especially when you account for costs of rebuilding or remodeling a house after total or partial destruction.
A builder friend of mine here in Texas builds exclusively in ICFs, and not long ago he mentioned that the cost of building with ICF was cost comparative to wood. I suppose regional costs can differ, but I think it’s a legitimate question.
Being judgmental doesn’t help, especially when you don’t know other people’s reasons and situations. Not any different why people building mansions or spending fortunes in fancy vehicles, great vacations, expensive clothing, or even smokes, alcohol or a vice.
Appreciate the insight. I figured the cost will still be a little higher but the added benefit of simplifying the building envelope balances it out. We've self-built our last two homes where I acted as the GC and found it difficult to get the sub-trades to really get the details right for anything other then minimum code which the majority of them are use to. The only alternative was to be on-site micro managing them all day which isn't feasible. We're looking at this build as our forever home so I don't mind paying a bit extra for really high performance that will pay back over time.
I guess "simplifying" means different things to different people. I would check with the tradespeople who are going to be finishing the house before assuming anything. Conventional construction is popular because it is versatile and contractors are familiar with it. It seems to me that everything from plumbing and wiring to drywall and hanging cabinets is more complicated with ICF.
The frame of the house might be 10 or 15% of the cost of a finished house. I don't see ICF making that other 85-90% cheaper or simpler. To the contrary I see it driving those costs up.
"Green" means many things but when it comes to construction it always includes environmental impact, and ICFs are among the worst ways you can build from an environmental perspective. ICF homes can be durable, safe, and efficient to operate, which are also usually elements of "green," but if you're not considering your short-term impact on the planet, and there are equivalent, lower-impact options, you aren't really being green.
I'm not being judgmental; I use materials that are not green when there are good building science-related reasons to do so and no low-impact, affordable alternatives. But I don't pretend that those projects are "green."
I recently got introduced to ICCF based on Ben Bogie's videos on this site. I got curious about it. Since I've build a foundation wall with ICF, I was curious about ICCF. How it gets put together and its costs in comparison to a wood wall that I'd build.
I'm not going to get into the merits and greenery of ICCF vs ICF, I'll let you guys on this post squabble about that.
However, based on my curiosity, I took an hour of my time to do a very simple estimate to compare cost of a wood wall with ext. insulation vs ICCF. The OP asked that same question (ICF vs ICCF is roughly same cost for materials) and I noticed no one answered it. So here is my spreadsheet. Its a ROUGH cost comparison, but it gives me an idea of what we're looking at.
Notes:
Costs are in CAD
I refuse to use Zip until Huber gets it act together in Ontario.
I would use more ext. insulation in real life but wanted to compare similar wall thickness and R-values.
Please let me know if I missed anything.
Jamie
"I refuse to use Zip until Huber gets it act together in Ontario."
Can you elaborate on this statement? I'm also considering Zip for an upcoming build in Ontario -- would love to know going in if there are issues I should be aware of.
Thanks!
maxwell_mcgee,
As usual, this will get complicated:
1. Cost
A sheet of 7/16" Zip (no insulation) at Home Depot in the states $35.85USD = $47.77 CAD
A sheet of 7/16" Zip at the one and only builders supply that carries it in Toronto = $100+ CAD (if you can get it, the price is vague becasue I just called the store to verify the price and its not in stock)
A sheet of 7/16" OSB $22 + two coats of Vapour permeable roll on membrane @ 32sqft $10 = $32
A sheet of 1/2" Plywood $44 + two coats of Vapour permeable roll on membrane @ 32sqft $10 = $54
I know there's the argument that the zip OSB is better than standard OSB. Its not apples apples, but I think you get the gist of this of the pricing issue.
2. Permeability
Zip is great for the states where their building codes often does not require interior vapour barriers. The whole point of zip is that the WRB serves as the air barrier. Here in Ontario, the OBC prescriptive codes require interior vapour barriers becasue they haven't adjusted to exterior air/vapour barriers in building materials yet. something along those lines. (Malcolm or Akos, you'd have better on-hand knowledge of this before I start digging through the OBC)
Thus, if you want to use zip, its fine, you just have to ensure your wall assembly dries to the inside, which means no interior vapour barrier, which means you might have a building examiners, or even worse, building inspectors take issue with it.
3. the WRB
The whole value prop of Zip (non Zip-R) is that it eliminates one step: applying the wrb. However, you still have to detail the seams, and probably the nails as well. So it helps and all, but you're still spending time on ladders and scaffolds to handle the details.
Moreover, being in colder climates of 5-6 in Ontario, these days we need exterior insulation. Since exterior insulation sits on top of the sheathing, it comes time to question the merit of the zip wrb. For instance, if you're doing a vapour open wrb, I posit that using Rockwool comfortboard on top of tyvek is a pretty good system. The comfortboard protects the tyvek. I question the need for the tyvek at that point but regardless, tyveks cost of $0.15/sqft or $5 per sheet of sheathing where it likely will not ever see water. (I haven't done a functional test myself but I do enjoy this video https://www.rockwool.com/group/advice-and-inspiration/why-stone-wool/product-benefits-stone-wool/water-repellency-video/).
If you're doing foam exterior insulation, properly detailing it is important as it will also act as a water and air barrier. Although, I am not a fan of foam exterior insulation mostly due to fire spread reasons. Fire is bad.
4. Zip-R
This is the pinnacle... or is it? The value prop: insulation sheathing and wrb all in one install.
Well I can't even get this product in Toronto. If a regular sheet of zip costs $100+ here, I don't even want to know what a sheet of Zip-R6 or R9 costs. (actually I do)
But, to make things even more complicated, we've discussed here on GBA some of the possible detriments to having the sheathing on the outside, vs the 'inside', covered by exterior insulation.
5. My personal preference for building
I like plywood better. If it gets wet a bit from a bad detail, it will still be ok. If I used 3/4" Plywood, I can screw my furring to it rather than trying to hit a stud through 2" of insulation. If I'm doing 24"OC studs, I have a bit more confidence as the 3/4" plywood makes for a better structure. I am not worried about poorly applying a liquid membrane because I'm the one doing it or I have dedicated a guy to solely do caulkwork like a master for the job (aka the Caulkmaster), which includes waterproofing details like roofs, windows and other membranes. In other words, I don't ask a framer to roll on a WRB.
So, until Huber gets their act together in Ontario, and makes it comparatively cost viable to use their product, or dare I say, cost beneficial to use their product, I refuse to use it or suggest it in within a wholistic design.
Hope this helps,
Jamie
Hi Jamie,
Thanks for this detailed summary. Very helpful and a lot to think about as we plan for our build.
From what I hear, ICF runs about $20/sqft installed. This of course is different in higher cost of living areas like the coasts, or in areas where more rebar is required. ICF construction is a bit more sensitive to corners and so on as well, between the higher cost of corner blocks and the labor time it adds.
Are there realistic options for homeowners to reduce the carbon in concrete? I know there are some options out there to reduce it, but not sure how much they really do. Sometimes the latest and greatest might only be available to commercial building before it trickles down to residential.
Is that per square foot of floor area for the building, or per square foot of ICF wall?
Per Sqft of the ICF wall.
To answer my own question above. I did a little digging, and near me there is a ready mix plant offering a couple different reduced carbon options for concrete. Looking at 10-20% reduction in carbon costs I think, not a ton (literally here), but something.
jberks thanks! This is exactly what I was hoping to see. I've updated the costs to reflect what using Zip would be. I only called one lumber company for a price so I'm sure I can get it cheaper but this gives an idea of cost. The two systems are very similarly priced which is what I was assuming.
A point about simplifying the build process. My experience with my last two builds - at least in my area - is that it is very difficult to find sub-trades that are experienced and/or willing to build beyond minimum code. The few that do are very expensive, and not reasonably so. You have to spend a lot of time on site managing the details which isn't practical. So as I see it the advantage of ICF is that it's a lot easier to get the building envelope correct to achieve NET Zero which is my aim.
I'm also looking at doing a prefab panelized solution for the framing & exterior envelope but am having problems finding any company that is anywhere near cost feasible. If anyone can recommend a company in south-western Ontario I'm happy to get a quote off of them.
Thanks again for all the input.
This is my repost from a previous thread question. I've built both with ICF and wood frame. I believe ICF is the way to go in the desert southwest (Zone 4B) and will build with ICF for my future house. Main reasons:
1 - Fire resistance. Living in a wildfire area, the 6-8 inch thick concrete walls provide better fire/heat resistance than wood frame walls. 15-30 minutes (wood) vs 4 hours (ICF concrete). Of course, installing a steel roof completes the enclosure. Having a house burn down or destroyed by a tornado, only to rebuild it again with wood, to have it destroyed again, is a bigger waste of energy and is definitely not being "green".
2 - Pest/termite resistance. Every wood home in my area eventually has termite infestations in the structural walls. With ICF, the EPS foam provides no nutrition for termites and even if they do get into the EPS foam, the concrete core provides the structural so the foam being damaged will not affect anything. Unlike wood frame, which if not addressed, will cause the walls to sag and eventually fail. In addition, every wood frame home in my area gets scorpions, mice and even rats infesting the wood wall cavities. Scorpions will easily get through the weep screed, crawl into the wood walls, and come out through the baseboards, light fixtures, electrical outlets or any gap in the drywall. This is not possible with ICF walls. Not having scorpions in my house is alone worth the price of ICF :) Mice and rats will chew threw wood OSB & studs and make their way into walls and attics.
3 - Sound/wind protection. The ICF walls are rated for 200 mph winds. Hopefully I never see that type of wind but in high wind events there is dead silence and no wall movement or wall noise. My wood frame home walls would creak, pop, flex, when we would experience 60+ mph winds. ICF walls have a STC rating of 50+
4 - Energy efficiency. Yes, most ICF walls will have a true R-23 rating. There is almost zero thermal bridging in an ICF wall, unlike wood frame which has a thermal bridge each time there is a wood wall stud present, especially around doors and windows which is stud intensive with 2x's stacked on each other or large wood headers. Living in the desert southwest, I experience vast diurnal temp swings. It can be 95F in the daytime and then 55-60F at night. ICF does very well in these conditions. In these conditions, ICF will perform like a R-50 wall. Now, it is also true, if you live in an area that does NOT have vast diurnal swings, then the ICF wall will not perform like this and you will see a steady state R-23 wall.
I am NOT knocking wood frame. In climate zones that don't experience what one experiences in the desert southwest, wood frame is a great choice and one can attain high R-Values with a wood frame wall. I believe building methods are zone/climate specific and there is no one size fits all approach.