ICF to the roof?

The thought that occurs with regard to using concrete for the entire construction is that, for a green property, concrete’s a bit of an evil substance – that is to say it’s (in the UK at least) considered to be one of the least green building materials. It has a high environmental cost – in terms of destruction of natural environment to get materials to make concrete and also the energy required to make it.

Certainly, I’d’ve regarded wooden structures (made from a renewable resource) as a more green option than building the entire structure out of concrete, even taking into account the enhanced R-value of the concrete one….and am interested to hear your thoughts on that.

It’s definitely a double-edged sword… and with anything, it’s all about tradeoffs. However I do believe the benefits outweigh the negatives (at least in our case).

First things first, it must be acknowledged that all building materials have some sort of environmental impact – the question is how much. I cannot deny that quarrying for the raw materials is disruptive, nor can I argue that it’s not energy intensive to process the materials.

However, the reality is that we won’t actually be using much of it (at least when compared to commercial buildings, etc. which literally use tons of it). We’d be using more than an average house, but our energy consumption will also be drastically less than an average house.

So which option is more “green”? Once again, it appears there are many shades of it. But everything I’ve read says ICF structures are the greener option, so in our case I have to believe it’s the correct approach.

I’m enjoying following your blog on the construction of your new home. I am pro ICF, I use them for the foundation of all of our new projects. That said, I have a hard time swallowing the inflated R-values that ICF manufacturers tie to their products. Thermal mass has no effect on the true R-value of a wall, you have to live in the right climate to take advantage of the thermal mass of the concrete. All of that said, R-Value isn’t a real good indicator of how efficient a wall is. You could have two walls that have the same R-Value, but with different building techniques one wall may really out perform the other. A wall that is completly air-tight and void of any cavities (limiting even small convection currents) would be much more effective than a wall that has the exact same R-Value but is not air tight and does allow convection currents (eg. arounf electrical wiring, piping, wall penetrations, etc.). I think that either one of your choices (ICF or Spray Foam) is a great choice for your wall system, Both will really out perform a batt insulated wall. We like to use ICF for foundations and spray foam above grade (although it is quite expensive) if possible. If our clients are looking to save money a common practice that we utilize is ICF foundation, spray foam all joist/box ends and cantilevers, and then do a dense packed blown in insulation in the walls. It has proven to be quite cost effective for us, the clients like the more efficient wall system, and it doesn’t cost them as much. I really try to push for spray foam in the joist ends and cantilevers as this is usually the most difficult area to insulate and vapour barrier properly.

Sorry for the extra long post, but I have strong opinions when it comes to insulation.

Steve

You’re very much correct – thermal mass has zero affect on the actual r-value (at least how that specific measure is actually calculated). However it does affect the “performance value”. Because the ICFs provide both an airtight seal, plus the added thermal mass, they always outperform the competitors. If I’m not mistaken, ICFs would also outperform Spray Foam, simply because of the thermal mass.

Either way, we have some specific insulating values we need to meet if we’re going to receive our government grants… and if we go with ICFs or stick and spray, we’ll still be further ahead than most.

Hi,
I’m enjoying reading about your project. I read about it in the Star. My husband & I hope to build new in a couple of years. We wondered how you go about hanging pictures or attaching cupboards etc to the walls if you build that way. Just a small thing,but.. We’re looking into structural insulated panels for the walls. Any thoughts on those?

Hi Lyn,

According to the Nudura site, it’s accomplished this way:

The NUDURA form unit has a fastening strip located every 8” (200mm) on centre. These fastening strips are continuous up the full height of the form unit, and have a patented mechanism that interlocks one fastening strip to the one below it or above it. These fastening strips are indicated on the surface of the form by a diamond pattern. They are 1 1/2” wide and have a higher pull out strength than a dimensional stud. Different types of cladding will have different installation procedures.

The bigger issue is running power… typically you’d just cut holes in the studs and run the wires, but you can’t exactly do that with ICF. You have to cut the foam, run wire, and then fill it back in. And now that I’m thinking about it, I’m not entirely sure you keep the outlets flush with the wall. Again, in a typical wall, you’d have plenty of room for the outlets… but I don’t believe the foam is deep enough to accommodate the standard outlet width, unless you cut the foam and insert an outlet BEFORE the pour. Hmm… I’m not too sure what we’re going to do.

Thanks for your thoughts. What do you think of the structural insulated panels above grade?
Lyn

Err, sorry but what part of this construction is ‘green’

Concrete is definitely not a ‘green’ product and neither is getting foam panels from across the country.

I know you say you’ll be saving energy and all that from these new techniques, but surely you should also be looking at where these materials come from, the inherent cost of getting them made and sent to you, ripping down a house with a large diesel guzzling JCB that came on the back of a huge flat bed, the masses of waste you’ve just created by taking down said old house (was this even sorted into lots of wood, glass, plastic etc to be recycled?)

I really am having trouble figuring out where this is green and how its not just an excuse to save yourself money

Am I missing something here?

Hey Sam – yep, you’re missing something here.

Our initial goal was to move into a larger home, however that proved to be unsuccessful. Toronto is filled with great places, but anything we liked was either out of our price range or out of the city… and neither of us wanted to commute. After that, we decided to simply “top up”, which is to say, add another story to the home. This is pretty common in our area, however it became problematic mainly because of issues with our foundation, the size of our lot, and the proximity to our neighbors. It was around this time that we decided to completely tear down the home and build entirely new.

Keep in mind, our initial goal was not to build the a greener home, but rather a larger home. I would assume this is probably pretty common for renovators, however we came to realize along the way that we should build ‘smarter’. My wife and I hadn’t a clue what would be involved with so-called green construction, but we were determined to figure it out.

Of course keeping the original structure would have been the greenest of options, however I don’t think people truly realize what’s involved with that. I’m not suggesting it was cheaper to do the full demolition, but when we ran the numbers it became quite clear that building on top of the existing foundation was not the way to go… mainly because of the work that would have been required to extend it, underpin, restructure, insulate and so on. At this point, it just made more sense to completely demolish and start over.

We recycled or gave away as much of the previous structure as possible before the demolition. Our hardwood floors, windows, and doors were given away and reused, and the demolition crew recycled as much as they could as well (metal was recycled, stone was separated for crushing, soil will be reused elsewhere… and the rest, unfortunately, will end up in the trash. We looked into a true recycling program for the demolition, but it was incredibly cost prohibitive and time consuming. Heck, we even called Habitat for Humanity, but they weren’t interested in what we had.

Regardless, a project such as this is all about managing tradeoffs. I suppose we could have pitched a tent and lived off the land… I mean, that would have been the greenest option, no? Or maybe we could have moved into a larger house elsewhere in the city and just pretended that its construction had produced no waste?

I admire what you are doing with presenting your project to the world, but whoa… you have some serious denial happening here about the “green” aspect. This is a hard one for you to dodge. Why not just admit that demolishing and building is a huge hit to the environment. It would give the rest of your opinions and perspectives a lot more credibility.

Hi Blair – I’m not trying to argue that demolishing and building is a huge hit to the environment – I’m simply saying that we tried to minimize that impact as best we could. That said, I just reread what I wrote above and I think I may have been, umm, overly hostile.