strategery

I've got some foundation/basement issues that while not immediately threatening my house, will only get worse with time and eventually will need replaced or addressed.

My basement floor is in terrible shape. Replacing it with the proper thickness of a new floor will make it impossible to walk in this basement (going from 2 to 4" thickness). One wall has sunk about an inch and 3 of the walls are bowing in anywhere from 1-1&3/4". Also, the mortar is soft and crumbling everywhere. I've addressed the moisture issues which caused the damage, but the damage is done. Rather than chase each issue one by one throwing good money at a bad foundation, I just started looking at doing a complete foundation replacement including the floor.

The first guy I got a bid from uses insulated concrete forms only. He's got a great reputation and been in business a long time. He's also expensive. I don't know if I'm allowed to say a price on this site but he quoted me just a little north of 50k. It is a lot but it would double the square footage of my livable space by jacking up the house and digging a little deeper when pouring the new foundation. It would involve a house mover to pick up the house while the work is being done and that is expensive. It might also require that the sewer line be redone so the basement's plumbing can flow (or I think I'd have to install a pump). The foam on the inside of the concrete allegedly creates a nice comfortable dry quiet basement and it has places for furring strips to directly hang drywall (no framing needing). This route is more expensive up front but the savings on finishing costs and energy could make up for it. The bid also includes a sump pump drain tiles damp proofing etc.

My other bid is for traditional cmu foundation. It will cost half as much for the same job, but it won't have the insulating foam on the inside and may require stud framing to finish it. It's also cmu blocks which I am not sure are as strong as concrete (but definitely better than what I have now). Bid also includes sump pump drain tiles foam board on the outside and damp proofing.

I forgot to mention that both of these include replacing my wood center beam and posts with a new seamless steel beam with steel jacks. Another nagging issue that will need attention before long.

Anyone ever consider these approaches before? What do you think? Thanks for reading.

nealtw

It's hard to compare quotes when you are comparing apples and oranges. If you like one idea more than the other get more than one quote for that.
Here all foundations are poured concrete and the foam foundation forms are availble but are not used very often because of price. We use rentle forms and then build the wall inside that for insulation but that would only save maybe 1k.
Either way you want an engineer to check the soil condition and design the footing, that's one place you don't want to save money.

BridgeMan

Based on the quoted figures, paying $25,000 more for the luxury of not having to fir out interior walls is quite a premium. Wouldn't be worth it to me, but it's your $$$, not mine. Contractors love foam-forms, primarily because they're quick and easy, with a high profit factor involving little skilled labor. And despite all the hype from the foam-form industry, their walls are not nearly as strong as solid, reinforced concrete walls.

Do yourself a favor, and get a third quote for reinforced concrete. Wall thickness as specified by your AHJ (I prefer 10" myself, unless warranted more by the IRC for your soil type and height).

strategery

Thanks for your input.

I've actually had some difficulty finding a good contractor who does complete foundation replacement using poured. Actually, the guy who bid my cmu job says that he prefers cmu over poured because you get "better bang for your buck." I actually asked him to explain that more than once but I can't understand how. His cmu work would have reinforcement rods in every third cell and it would have concrete poured inside the cmu holes for a solid fill. Does that make sense?

Also, I asked him if he would insulate the outside of the foundation with foamboard before damp proofing, which would perhaps give me some of the benefits of ICF.

nealtw

Call your local ready mix companys, they should be able to help you find some one or google "concrete form rentals" and ask them.
The people that work on new construction often don't advertize, but work cheaper than the the guy that does.

BridgeMan

Anytime I hear a contractor say "more bang for your buck," it tells me he's found a system he can successfully compete in/with at a profit. Nothing necessarily wrong with that. And infilling all the CMU cells with concrete, with alternate vertical rebar (doweled into the footings) will result in walls almost as strong as CIP reinforced concrete.

mudmixer

I think the contractor referring to "more band for the buck" may have experience with underpins and the logistices and handling of materials on a more manageable schedule. This is especially true if the home is just jacked up enough get working area for motrar and to raising the house to gain space by going up and redoing.

You really don't need that much insulation for heating purposes because of the latent heat and heat storage of the soil since the below grade soil temperatures are much warmer the what the thermometer exposed to cold air shows. It is not like the fictitious, prescriptive, arbitrary "frost line" that shows up in some codes as a "red line" on the interior surfaces.

Bridgeman is correct that a partially reinforced block wall can be a strong or even stronger than a poured wall of the same thickness. For vertical loads without retaining soil a 6" CMU is enough to support a house, but that is not the habit.

Dick