I'm renovating my house, and I'm wondering what my options are as far as using the existing concrete foundation together with ICF walls above.  I searched here and did some googling, but couldn't find out much.  The foundation is in good shape and is about 10" thick.  Can I put ICF walls up on top of the foundation [max of 2 storeys above grade] and also use a Speedfloor or Hambro system?  I realize that an ICF foundation wall has advantages in terms of insulation and waterproofness, but the existing foundation is in great shape and I would hate to trash it if I didn't have to.  Thanks in advance!

I think I would consider having some one in your area who can look at your existing foundation from an engineering stand point to determine if it is capable of an ICF structure on top of it! Then if it is ok consider at least digging the dirt out, waterproofing the wall and insulating the wall. Oh and by the way if you are already dug out you should install a drain tile if there is not one there already.

Thanks Bill! Yes, an engineer has to check everything out first and give it the OK - this is one thing I don't want to take chances with. So, you think it's possible, assuming the foundation can handle the load? I suppose 6" concrete does weigh substantially more than 2"x4" framing and insulation. LOL

My own ICF home is ICF built on top of conventional concrete walls.

Yes, I encourage a review by someone who can inspect your existing foundation, then drill in and epoxy the appropriate bars, stack, and pour!!

The foundation wall is almost secondary to the footing. The 10" wall may very well be capable of holding the new ICF walls, but because the ICF walls are much heavier than frame walls, the footing underneath needs to be wider. You may have to dig down all the way to verify the footing width. If the footing isn't wide enough as is, you'll probably have to redo the entire foundation. As others have said, have a local engineer check it out.

After much digging and measuring, the structural engineer says that the footing/foundation can handle 3500 lbs/linear foot, and that ICF is an option. The design is pretty basic,with four corners and 7 openings on the main and 6 corners and 8 openings on the second floor, plus two cantilevers of 2' or less. At a guess, I'm thinking 1750 lbs/l.f. from the walls, plus roof and floors. Does that sound about right?

Boourns! The engineer followed up with his final assessment. We can do ICF OR cement slab floors, but not both. :( I guess ICF is out unless we win the lotto...

I'm digging this thread up from the grave to see if anyone else has done this (conventional formed basement with ICF on top). I'm looking at doing a 10" traditional basement wall with Integraspec ICF (11" total width) for the main level. Curious about repercussions of the 1" overhang and the cold joint between top of the basement wall and start of the ICF.

Same answer... Have an engineer look at what you have. It is your existing soil characteristics and footing dimensions that determines what you can and cannot do.

Yes you can, but why would you? I'm always open to new ideas.

This is new construction, so I don't have an existing footing. The primary advantage I see to a traditional basement is waterproofing. Water mitigation techniques for conventional basements are time-tested. Below grade ICF waterproofing is still fairly new. Reference David Campbell's "Waterproofing ICF Foundations: Two Steps Forward, Three Steps Back."

https://iibec.org/waterproofing-icf-foundations-two-steps-forward-three-steps-back/

You have existing soil you will be building on...

A basement is a future problem waiting to happen... Really only used to create more living space (and often less than desirable) when you have a small lot relative to house size and you need footings several feet below ground level because of frost issues. Best to stay above ground as long as you can...

I read the article and agree with almost everything. One point I disagree with is the idea that xps is the answer. It will absorb water. I have seen IRMA roofs replaced and the amount of water in the xps surprised me. What the article points out is the need for the proper waterproofing materials, attention to details and most of all a fully consolidated concrete wall. One advantage I have is that I pour my footing walls and floor in one pour. I never used peel and stick as a single waterproofing system. To say you have no chance to have a waterproof icf that last a long time is wrong.

I knew it had to happen sometime. I have to disagree with my friend from Borst Engineering. The lowly basement is easily the best insulated part of any house. Most of my sales over the years have been basement builds only, with stick on top. The reaction over the years has been that these customers wished they had gone all the way with icf. We hit -12 degrees this year and 96 a few weeks ago. My basement stayed 70 on both occasions without ac or much heat in the winter. The problem seems to be that there is no way to waterproof an icf basement to last long term. I disagree. With a basement your fighting one potential problem, above ground you have to contend with 3. He's my formula. Footings are done with Form-a-Drain. If you give the water a way out it won't go thru a wall. FD also has another purpose. Where I ply my trade, radon is a persistent problem. You don't know if you have until the house is sealed. FD is a great product for remediation if you set it up from the start. Next 2 coats of Black Jack 57 coating including the top of the footings. Dimpled membrane finishes it off. Hard to push water thru a wall if it drains to the bottom, where the FD is waiting. I can't even imagine how long this setup will last since the one thing that takes everything apart over time is absent. No sun.

Well, I can't say that I disagree with you... I am certain it is possible to make an ICF formed basement comfortable and water leak free. And I am also certain that you could do this with little difficulty.

I simply don't like basements...or any multi level residential buildings for that matter. I prefer single level residential buildings and wouldn't live in anything but single level these days. My preference in this regard is from having lived in residential buildings over the years that had basements (non ICF formed mind you) and multiple levels connected by stairways. Every basement I lived in always smelled damp and two of them flooded badly when the pump sump for outside perimeter FD system failed. I have lived and traveled the world in sailboats that felt less damp than the basements I have lived in. When I see stairs, I see wasted space that has to be cooled/heated and will become problematic as one ages.

I fully recognize that not everyone can construct a single level building on their property of the desired square footage because the property is small or they prefer to generate the square footage at minimal cost (and often more square footage than they really need) by consolidating all the levels under a smaller roof structure, etc. I was just suggesting that a single level home is far more livable than a multi level home, especially as one ages and one needs knee replacement and shoulder replacement from vibrating too many ICF walls...and I speak from personal experience about this. So I simply think and suggest that one should really do their best to construct a single level home if they want to live there until they depart this earth.

Ah, the afflictions of age have caught up with me as well. A one story house is preferable, but in my market, no one builds slab on grade. Anything without a basement is considered junk. My point in my answer was to refute the argument that you could not build below grade without eventual problems. Even though eps does absorb some water you can help defend against water migration with one of my trade secrets. If you promise not to tell anyone, regular garden variety silicone caulk glues eps seams together better than any other product on the market. Since we ship all our walls already pre built, it's what we use to hold the forms together during shipment. Plus it gives you a watertight seam.

As they say, you do what you must do... I have never let career, family, friends or anything keep me from living and traveling where I desired. I am amazed what passes for a home these days and why people would buy them and live there. I learned much from you over the years Smartwall.

As have I. On open mind is good. Especially what I have learned from the gentle lady at Borst Engineering

As have I. On open mind is good. Especially what I have learned from the gentle lady at Borst Engineering

As have I. On open mind is good. Especially what I have learned from the gentle lady at Borst Engineering