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-   -   Basement Foundation DIY (http://www.diychatroom.com/f105/basement-foundation-diy-178130/)

AlphaPilot 04-26-2013 07:24 AM

Basement Foundation DIY
 
As a DIY I don't have access to concrete forms for the desired 8' basement walls. I was wondering about what ALL the drawbacks are to block wall foundations? I would probably not be mudding each brick unless someone convinces me it's not as bad as people say.

I was thinking of stacking them square and plumb, with staggered joints, then adding rebar in each cell and having the concrete truck come, pour in each cell, vibrate it and let it set. Is this not logical...or a good idea? What drawbacks do I have doing this over mortar brick walls, and poured concrete walls for basement foundations?

I've heard about 'dry stacking' and using some fancy chemical bonding on both outside ends of the blocks since there is no mortar to seal each block. I was curious what your opinions were on this too.

joed 04-26-2013 07:41 AM

That does not sound like a good idea to me.
Have you considered Styrofoam? They stack like Legos and then you fill them. You end up with a wall and insulation in one job.

http://www.foamequipment.com/Portals...ion%20crop.jpg

AlphaPilot 04-26-2013 07:59 AM

Quote:

Originally Posted by joed (Post 1167543)
That does not sound like a good idea to me.
Have you considered Styrofoam? They stack like Legos and then you fill them. You end up with a wall and insulation in one job.

http://www.foamequipment.com/Portals...ion%20crop.jpg

Could you say why?

And that looks pricier :wink: ... Thing is I have heard termites love ICF around here...and that is foam, too. Thoughts?

jomama45 04-26-2013 09:41 AM

Reasons I can think of off the top of my head not to drystack block and fill with concrete:

- Footings have to be 100% exactly flat or the top of wall won't be level.
- Concrete block can vary significantly from one unit to another, but when you add 12+ courses together, it can be substantial.
- CMU are typically modular and rely on a 3/8" joint to reach 8'0". Dry-setting would result in a loss of 4.5" of height. You can make that up with a half course, but there's more material cost in doing so.
- Wall will be extremely tippy until concrete sets. A bump from the concrete truck chute could easily bring your plan tumbling down.
- Concrete would cost many times more than mortar.
- Every cell w/o rebar would be useless.
- The interior cavity in block offers a secondary envelope to stop water intrusion, if built correctly, and filling with concrete would plug this path up.
- It's simply non-conventional, and if the foundation needs to meet a local building code, it will be non-prescriptive to this style of construction, so you'll likely spend a large amount of money on engineering to get it OK'd by your building department.
- Conventional CMU construction is far too simple, recognized and customizable to not consider doing it the "right" way..........


I'm sure there's other reasons i could come up with as well. I think that you may be thinking that installing the block on a 4 corner basement is more complicated than it really is. If you're looking to save some money, I'd ask one of your construction buddy's if they have the name of a mason or 2 that could help you on the side for a few days. You do all the hard labor, they bring the skill-set........

Nailbags 04-26-2013 10:37 AM

Quote:

Originally Posted by AlphaPilot (Post 1167561)
Could you say why?

And that looks pricier :wink: ... Thing is I have heard termites love ICF around here...and that is foam, too. Thoughts?

Termites only eat wood. Just hire some one to do a monolithic pour. And be done with it.

AlphaPilot 04-26-2013 01:56 PM

Lotta reasons not to go with drystack I see. Thanks :thumbsup:

Some of those issues could be resolved with specific blocks made for the job, at least I was told there are such a thing that are smooth.


So why drawbacks are their to a block wall with mortar compared to a single pour foundation. A block wall with mortar is something I think I could MAYBE accomplish because it doesn't require concrete forms.

AlphaPilot 04-26-2013 05:00 PM

Sources on termites and my concern with the use of ICF.

http://www.amvicsystem.com/termites-...f-construction

http://www.nachi.org/icf-termite-inspection.htm

http://www.greenbuildingtalk.com/For...c/Default.aspx

I understand termites don't eat foam. But they seem to bore through it, like the moisture caused after boring, and have it serve as a nice home for their trails and other uses.

joed 04-26-2013 07:25 PM

Termites are not a concern in my area so I never considered that aspect.

AlphaPilot 04-27-2013 12:25 AM

Quote:

Originally Posted by joed (Post 1167952)
Termites are not a concern in my area so I never considered that aspect.

They seem to be here. It's not really just the rotten wood termites, but the subterrain type that like dirt and stay in it and tunnels. The issues are that they seem to drill through the icf that is covered in dirt, tunnel up between it and the concrete wall, through the sill plate or house wrap, through the studs, up to the trusses...munch away and you only know it after the major damage is done. Ooops, hunny why is the roof caved in on that corner? :laughing:

Nailbags 04-27-2013 01:59 AM

a Monolithic pour is stronger has zero cold seams. is cheaper and quicker to do. Just hire some one to do the pour for you it will save time and hassle use min #4 rebar. run in your footing two rows on each side of number 4 and then run two runs of #4 a third of the way up from the footing then a nother two run a thrid from the top and every 18 incches run two vertical from footing to 4 inches from the top of the stem wall. have it all tied good and your foundation will last.

Mort 04-27-2013 09:41 AM

Mono foundations would be nice, in theory, but usually the footing and stem walls are poured separately. With a mono, concrete can ooze out the top of the footing form if its too wet, and create a bunch of rock pockets in the stem wall if its too dry. To solve this, the first part of the load is poured dry, allowed to set for about 1/2 hour, and then wet up and poured into the wall forms. And this creates, you guessed it, a cold joint.

So you might as well just pour them separately like everybody else does.

jomama45 04-28-2013 12:22 PM

Quote:

Originally Posted by AlphaPilot (Post 1167734)
Lotta reasons not to go with drystack I see. Thanks :thumbsup:

Some of those issues could be resolved with specific blocks made for the job, at least I was told there are such a thing that are smooth.


So why drawbacks are their to a block wall with mortar compared to a single pour foundation. A block wall with mortar is something I think I could MAYBE accomplish because it doesn't require concrete forms.

Not much for drawbacks from a DIY perspective IMPO. The only one that really comes to mind is that the wall typically needs to be a little wider than the poured wall alternative, taking up additional minimal space in the basement. There's postives to a properly constructed and re-enforced CMU foundation IMPO..............

RWolff 04-28-2013 01:08 PM

Quote:

Originally Posted by AlphaPilot (Post 1167523)
As a DIY I don't have access to concrete forms for the desired 8' basement walls. I was wondering about what ALL the drawbacks are to block wall foundations? I would probably not be mudding each brick unless someone convinces me it's not as bad as people say.

I was thinking of stacking them square and plumb, with staggered joints, then adding rebar in each cell and having the concrete truck come, pour in each cell, vibrate it and let it set. Is this not logical...or a good idea? What drawbacks do I have doing this over mortar brick walls, and poured concrete walls for basement foundations?

I've heard about 'dry stacking' and using some fancy chemical bonding on both outside ends of the blocks since there is no mortar to seal each block. I was curious what your opinions were on this too.


I added a small, about 9x12 modelling room on the back of my house in 2005, I hand dug down the whole space about 7 feet down, and dug for the footing which I poured with my cement mixer.
I embedded rebars in the footing and laid the first 2 courses of block on, and then filled the cavities of the blocks with concrete and tamped it down nicely, and built the rest of the block walls up, putting rebar down in the cavities and filling the cavities with cement. I also embedded long threaded rods into the top for attaching the plate, and filled all level with concrete.
The outside of the walls have plastic sheeting and 1" styrofoam board insulation.
I only needed 3 walls since the room was put in a corner between existing.
I also added a center footing and wall to run perpendicular to the joists.

I anticipated I would have 1,000# to a ton of clay stacked in a corner at any given time and wanted a good solid everything under it, so it's all a lot beefier than usual.

The block wall works fine for small projects like my room- the wall was only about 7' high and 12' long with a perpendicular wall in the middle. I had to do a similar block wall in another area- under the kitchen which never had a foundation at all, but for an 8 foot high wall or longer foundation poured concrete would be better I'm sure.

http://i.imgur.com/Hhig2WW.jpg
http://i.imgur.com/MvAlvVR.jpg

I had to add a sump pit which can be seen, as there was an old drain pipe 8 feet down that tended to collect ground water from the field, my house was built over 2 of them in 1930 and they just took the sections of pipe out, so every spring melt my basement got water. I dug 50' of the pipes up with an excavator 3 years ago when the city and county said they had no record of such pipes and it's older than 1880. Since then I had no water come in from them.
http://i.imgur.com/ealISmW.jpg

http://i.imgur.com/dXPGmPW.jpg

I've never heard of any chemical bonding dry stacking blocks, sounds like the lazy man's way to built a temporary building to me, use mortar.

stadry 04-29-2013 05:52 AM

why anyone would build w/o using icf's beyond me,,, the addl cost is easily amortized be lower utility bills, stronger walls, & a MUCH more quiet home,,, w/o a doubt, our next home will be icf's from the footer to the eaves :thumbup:

jomama45 04-29-2013 08:55 PM

Quote:

Originally Posted by itsreallyconc (Post 1169231)
why anyone would build w/o using icf's beyond me,,, the addl cost is easily amortized be lower utility bills, stronger walls, & a MUCH more quiet home,,, w/o a doubt, our next home will be icf's from the footer to the eaves :thumbup:

I'll bet you my left nut that you'd never re-coupe the costs of ICF in a basemtn from lower energy costs, well at least at your "elevated" age.............:laughing:

Honestly though, I'd never use an ICF foundation for myself, there's just far more cost efficicient ways to insulate, and I'm a firm believer that a large percentage of ICF walls will have early repair issues when given some time. That said, I think there are huge benefits to be gained by using ICF's above grade........


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