Thoughts on building a house with ICF's.

[Bryan Berguson]

We've found ourselves needing to move so we need to build a new house. I've said for a long time, "If I ever build another house, I'll build to the roof with ICF's". This would be basement and first floor. We live in the Northeast so insulation is a major consideration. Anyone have thoughts, good or bad, on building with ICF's?

The other unique feature I'm considering is putting my woodshop under the garage. Right now the woodshop is in our basement which I said I'd never do again. However, I need to consider cost(s). Any thoughts on this? Garage will be 26X30, which would be a little bit smaller shop than I have now but just a little and no support posts so I won't be sacrificing much.

Thanks

Bryan

[Ted Calver]

ICF's ???? Plus additional question marks to meet minimum length reqts. :)

[Brian Libby]

@ Ted ICF's are insulated concrete forms

@ Bryan : I have a friend who thinks ICF's are great - He built his house with them 3years ago. A shop under the garage sounds like a great idea !

[Mark Bolton]

Not that it means anything but been in the building trade through much of my teens and adult life. Personally I wouldnt go with them on the first floor simply because you will have the added cost of the ICF's coupled with a lot more costly details associated with every other aspect of the project, deck framing, wiring, plumbing, window and door fenestrations. Unless you find a contractor who is specifically specializing in complete ICF envelope construction I would wager it will be a challenge, and very costly.

Being from the North East (MA originally) I completely understand where you're coming from. My advice would be 100% for the ICF foundation and then look into super insulated framing techniques for the structure above. You can really do a lot with a building envelope 2x6, stack framed, 24" o/c, header hangers, and even an exterior wrap of 1" ISO. You can easily get close to an R25 envelope. If you can do everything possible reduce the wood in the wall and trade it for insulation you can really make great gains. You will be confronted by a lot of "I would never not go 16" o/c" but its whooey. Do your homework and you will find you do a lot with a conventional frame. Its the habbits of the US builder that keep our envelopes so inefficient.

Just my .02

Mark

[Brian Libby]

Re-read your thread- I agree on only doing the basement - that is what my friend did.

[Bryan Berguson]

Not that it means anything but been in the building trade through much of my teens and adult life. Personally I wouldnt go with them on the first floor simply because you will have the added cost of the ICF's coupled with a lot more costly details associated with every other aspect of the project, deck framing, wiring, plumbing, window and door fenestrations. Unless you find a contractor who is specifically specializing in complete ICF envelope construction I would wager it will be a challenge, and very costly.

Being from the North East (MA originally) I completely understand where you're coming from. My advice would be 100% for the ICF foundation and then look into super insulated framing techniques for the structure above. You can really do a lot with a building envelope 2x6, stack framed, 24" o/c, header hangers, and even an exterior wrap of 1" ISO. You can easily get close to an R25 envelope. If you can do everything possible reduce the wood in the wall and trade it for insulation you can really make great gains. You will be confronted by a lot of "I would never not go 16" o/c" but its whooey. Do your homework and you will find you do a lot with a conventional frame. Its the habbits of the US builder that keep our envelopes so inefficient.

Just my .02

Mark

If I go with conventional framing (which I'm leaning towards), I was planning on dense pack cellulose. If I have sheet insulation on the outside, does it go under or over the OSB? I'm thinking over and then just use longer nails for the siding? I've done it on the inside of the stucture with drywall over it but it's difficult to say the least.

24" oc 2x6's would be equal in strength to 16" oc 2x6's wouldn't it? But, if wrapped with 1" of insulation, does 24 oc vs 16 oc really make much of a difference? Insulation wise.

thanks

[Matt Meiser]

Are you sure you don't me SIPs?

SIP = Structural Insulated Panel (2 sheets of OSB with foam between)
ICF = Insulated Concrete Form (2 sheets of foam with plastic ties between to be used for concrete forms, then left in place)

Both look really interesting if one is building but I'm not sure ICFs would make for a good roof :)

[Bryan Berguson]

Re-read your thread- I agree on only doing the basement - that is what my friend did.

Thanks Brian. That's why I'm asking here... lot's of experience and common sense! Did he put radiant heat in his floor and if he did, what kind of insulation did he use?

[Mark Bolton]

If I go with conventional framing (which I'm leaning towards), I was planning on dense pack cellulose. If I have sheet insulation on the outside, does it go under or over the OSB? I'm thinking over and then just use longer nails for the siding? I've done it on the inside of the stucture with drywall over it but it's difficult to say the least.

24" oc 2x6's would be equal in strength to 16" oc 2x6's wouldn't it? But, if wrapped with 1" of insulation, does 24 oc vs 16 oc really make much of a difference? Insulation wise.

thanks

Whatever insulation you choose is fine, spray foam would of course likely be the highest R value but its whatever the best you have available (and in budget). You can install the ISO directly on the studs and omit the OSB all together though you have some issues to contend with. Many super insulated shell's opt for OSB on the corners only for stability with 1/2" ISO everywhere else then another complete wrap with 1/2" ISO to get you to the 1" (except on the corners where you will have 1/2" OSB/1/2" ISO). Others omit the OSB altogether going for Z strips on the diagonals at the corners, let-in to the studs. This allows you to go with a 100% ISO exterior. Super tight. If you think of 1" of ISO at an R8 plus your interior walls at their lowest being an R19 fiberglass) you are already at an R27. If you pop your cavity insulation you can break R30 in a 6 1/2" thick envelope easily.

Omitting the OSB, in my opinion speaks more to what your exterior siding will be more than anything else (fastener spacing)

Have you looked at buildingscience.com ? You will have to look into many issues such as vapordrive, fresh air exchange, and so on.

Mark

[Jerry Bruette]

Bryan

Pick up the January edition of Fine Homebuilding. they have three articles you'd be interested in, Energy smart foundations, Attic insulation fiberglass vs cellulose and The American House: Where did we go wrong. All three articles talk about insulation and maybe more importantly infiltration, stopping air from entering and moving around in your house.

My house is over 20 yrs. old and I have conventional framed 2x4 walls with 1 inch of foil faced ISO on the outside and dense pack cellulose. I think wrapping with the inch of ISO is better than 2x6 framing because the ISO gives you a thermal break which you don't have with the 2x6 frame. You may have a higher R value with the 2x6 frame but you won't have the thermal break at each stud without the ISO wrap.

I would also consider trusses that hae the extra height where they meet the wall for insulation, around here they call them energy trusses. Might go by another name where you live.

If you can't find the Jan. issue of Fine Homebuilding I'd be happy to send the copy I have I'm done with it.

Jerry

[Mark Bolton]

the ISO gives you a thermal break which you don't have with the 2x6 frame. You may have a higher R value with the 2x6 frame but you won't have the thermal break at each stud without the ISO wrap.Jerry

Why dont you have the ISO break? You can still frame 2x6 with no exterior sheathing and just ISO on the exterior. I am not sure I follow you here? A thicker was is just that, a thicker wall. Provided you fill it with insulation (and can afford to), its always going to be better. Super insulated walls of old were 10" thick with fiberglass.


Mark

[Bryan Berguson]

I'll look for that issue Jerry. Thank you - if I can't find it, I'll take you up on that offer.

Bryan

[Jerry Bruette]

Mark

Many of the contractors in my area convince home buyers that a 2x6 wall has a higher R value, which it does. But that's only half of the story. Without a thermal break on the inside or outside of your studs they will be a cold spot (or hot) in yor wall.

I suppose a 2x6 frame with a sealcoat of foam sprayed inside the stud cavity, finished with cellulose, and wrapped with one inch of ISO onthe outside would give you the ultimate in tightness and insulation value if you can afford to do it.

Jerry

[Chris Damm]

You say you want to put your shop under the garage with no support posts. This would require prestressed concrete planks or a lot of very big steel beams. That would be very expensive and require expensive equipment to place them.

[Brian Libby]

@ Bryan- I think my friend used radiant heat
I know of at least two neighbors that have used the prestressed concrete for garage floor. - added cost IMHO is worth it.
In the same foot print you get all that added clear span space

[Jim Becker]

If I go with conventional framing (which I'm leaning towards), I was planning on dense pack cellulose.

Closed cell spray foam will allow you to use 2x4 construction and still greatly exceed code when it comes to R-value as well as have a stiffer frame. Your initial investment will be slightly more, but the payback in energy efficiency will be notable. We built our 2200 sq ft addition this way two years ago and it's outstanding. Let's put it this way...we doubled our house, added a second HVAC system, and our energy bill only went up about 25%.

[Art Mulder]

SIP = Structural Insulated Panel (2 sheets of OSB with foam between)
ICF = Insulated Concrete Form (2 sheets of foam with plastic ties between to be used for concrete forms, then left in place)

Both look really interesting if one is building


We've found ourselves needing to move so we need to build a new house. I've said for a long time, "If I ever build another house, I'll build to the roof with ICF's". This would be basement and first floor. We live in the Northeast so insulation is a major consideration. Anyone have thoughts, good or bad, on building with ICF's?

The other unique feature I'm considering is putting my woodshop under the garage. Right now the woodshop is in our basement which I said I'd never do again.


In contrast to Bryan, I've "always" said that if I ever get a chance to build, I would seriously look at building with SIPs for the walls, and maybe the roof as well. Superior insulation, Quick installation, flatter walls, are the main reasons there.

I do know folks who've built foundations and first floor with ICFs. One big deal there is that they sweated bullets about every door and window, since once the concrete is poured, you will likely never be able to move one!

I have a basement shop and I've quite liked it. The advantage of building new is that I could design the basement shop "right": 1- build 10-12" taller basement walls. 2- bigger windows. 3- better access (either a door if the grade is sloped, or a direct wide staircase from the shop to the garage or outdoors, for loading tools and lumber)
All of those would also apply to putting the shop under the garage. But I agree with the guy who questions the cost and complexity of putting in such a large garage basement with no poles in the middle.

[Matt Meiser]

I've seen a few houses around here go up with SIPs. The structure goes up VERY fast. One down the road from our old house there was a foundation one day and a complete shell the next. The guy we had install all our windows builds houses with them and likes them. I get the impression they require more careful up-front planning because the manufacturer cuts everything to size and its like a big set of Legos that get snapped (well, screwed) together on site. So there's no adjusting for a mistake in the foundation. I assume you need to pre-plan all the opening locations still so they can install some framing around the opening--otherwise you'd be installing windows into OSB and foam. Still, you could fill an opening or cut a new one on site, cut out the foam and install blocking.

Some friends of ours have a basement that would be great for a basement shop--semi-walk out basement (there's 4 or so steps), 9' ceilings, big windows that look out on the golf course. Of course doing something like that would probably be banned by their HOA.

[Mark Bolton]

I've seen a few houses around here go up with SIPs. The structure goes up VERY fast. One down the road from our old house there was a foundation one day and a complete shell the next. The guy we had install all our windows builds houses with them and likes them. I get the impression they require more careful up-front planning because the manufacturer cuts everything to size and its like a big set of Legos that get snapped (well, screwed) together on site. So there's no adjusting for a mistake in the foundation. I assume you need to pre-plan all the opening locations still so they can install some framing around the opening--otherwise you'd be installing windows into OSB and foam. Still, you could fill an opening or cut a new one on site, cut out the foam and install blocking.

They are pretty easily cut and modified but as you say, the plan has to be followed as its best for the panels to fit right off the truck. Depending on the style of window there often times isnt a need for blocking so cutting a window in isnt always a big deal.

The biggest drawback with all of these things is that the cost usually takes 90% of the consumers out of the equation instantly. As I mentioned earlier, even though something may be a great decision, and have great payback potential it doesnt mean a customer can just conjure up the money. We have often times quoted spray foam insulation on projects and even though it is a fantastic addition to most projects it rarely goes through in our location. Same with SIPs, we have priced several projects using them and even with the labor offsets due to speed, the cost of the panels, the crane, and the trucking, usually takes them out of contention.

Location would be everything, northern climates likely have spray foam contractors competing for business and it is more common so costs reflect that. Here there is one insulation contractor doing spray foam and being a rural area travel times really affect the price of everything.

Mark

[Bryan Berguson]

Closed cell spray foam will allow you to use 2x4 construction and still greatly exceed code when it comes to R-value as well as have a stiffer frame. Your initial investment will be slightly more, but the payback in energy efficiency will be notable. We built our 2200 sq ft addition this way two years ago and it's outstanding. Let's put it this way...we doubled our house, added a second HVAC system, and our energy bill only went up about 25%.

That's something I really like about the closed cell foam, the stiffer frame. It really "glues" everything together. My basement floor is partially sprayed the this foam (we were doing it for a sound barrier from the woodshop in the basement) but they were having trouble with their gun and didn't finished. When they came back, we had decided the fumes were too bad (we had a 1 year old boy at the time) that we didn't want to risk any more fumes then we'd had already. Part of my garage had unfinished walls so I had them spray an inch in those cavaties. Our house is insulated with open or soft foam and I can't say I'm all that impressed with it's insulation value. It stops all the drafts but the R value is pretty low. It and fiberglass will not be considered at all in the new house.

[Bryan Berguson]

You say you want to put your shop under the garage with no support posts. This would require prestressed concrete planks or a lot of very big steel beams. That would be very expensive and require expensive equipment to place them.

I would love to do it with no supports but I haven't seen any costs on the Spancrete yet. I'll have to see what the budget will allow.

[Bryan Berguson]

While we're talking about houses... The builder I'm using really likes to use Superior Walls for basements. Do you guys have any thoughts on them?

[Chris Damm]

I have plans to build a new house using Superior Walls and SIPs. I have looked at building a well insulated home and this has been the best chioce I've seen. I watched a basement go in one day, the floor built the next, the basement floor on the 3rd day, and 2 days later the whole shell was up. It is about 3400 square feet of heat space with a walkout basement. Their NG bill is less than $60 on average. They have a gas stove, dryer, WH, and radiant floor heat. The owner said the up front costs were more than a conventional build but the payback was about 10 years. The house is very comfortable to live in for a family of 5.

[Douglas Lee]

Bryan,

We built a full ICF (foundation + exterior walls from ground to eaves) house in 2005. I'd do it again because the house is exceptionally quiet and energy efficient. Though as noted by others in the thread, there are advantages in terms of construction speed with an ICF foundation and SIP construction. One thing that we didn't do was install a SIP roof . . . we went with conventional framing for the roof plus 2 ft. of blown in cellulose insulation. Effective from an energy efficiency standpoint but a pain in the rear if you want to get into the attic to check things or drop a new light fixture.

A few caveats to keep in mind:

1. Plan carefully. You need to have a very complete set of contruction plans that accurately call out all your window, door, electrical, plumbing, and HVAC details. It's unlikely that you'll be able to cut in additional windows or doors after the fact because most ICF systems require additional rebar laid in above the wall openings - something that you won't be able to easily add after the fact. Plan for the future as well. As an example, if you think that an aux. generator is something that you'll install "someday" be sure to include a conduit sleeve in the wall where you'll be bringing the line in. Where you might envision an "add-on" to the house, plan your rebar installation accordingly.

2. When it comes time to waterproof the exterior foundation wall, use a spray on sealing system approved by your ICF manufacturer. You can then put up some roofing felt, cardboard, quarter inch ply, or similar to protect it from dings and penetration as the foundation is backfilled. The rubberized membrane systems are far too fussy.

3. Install your siding using a rainwall approach. Generally, this will be a given for ICF construction as you'll fur out from the wall anyway. However, some ICF manufacturers don't clearly call this out and some contractors won't think it through.

4. If you do an ICF wall above grade, it will be 10" thick (typically 2" foam-6" concrete-2" foam). You will have deep window and door wells. Expect to spend additional money finishing out your doors and windows on the interior. We did not purchase extension jambs from our window manufacturer - we completed this with trim custom dimensioned on-site.

The list could go on and on. You're welcome to pm me with specific questions. Regardless of the final construction approach that you choose, consider incorporating two foot eaves in your house design. This will keep the summer sun from streaming in to your windows but allows the winter sun in the NE to stream in from one side of the house to the other. Besides, it makes for a much more pleasing appearance than the micro-eaves so prevalent in modern construction <smile>.

[Dave Ogren]

I have seen 6" ICF used for as tall as a 6 story hotel. I person would have their design down pat and not want to do any engineering changes later. For me I think that it is great for the basement and or garage/work shop area.

Good Luck,

Dave