Just a question - curious - Contractor Talk - Professional Construction and Remodeling Forum

shanekw1 · 08-26-2009, 11:02 AM

I hear lots of talk about block foundations here and I can't figure out why it's used. I cringe when I see a house on a block foundation or basement. To me it does not seem like they have the strength of a poured wall to resist cracking and such.

So what is it?

Faster? Can't see that being it but maybe?

Cheaper? Can't see that either.

Both?

Is it actually stronger?

Again, I'm just curious, not trying to bash using block.

shanekw1 · 08-26-2009, 07:56 PM

Interesting.

CJKarl · 08-26-2009, 08:04 PM

I feel the same way, yet you go to different parts of the country and most of the foundations are block. Maybe in very rural areas redi-mix is too far away. I know in PA, where my brother in law lived, every new house had a block foundation.
Here in CT, there were a few built in the 50s-60s. Block is still widely used for a small kitchen or bathroom addition, but the main part of the house is poured concrete about 99% of the time.

4th generation · 08-26-2009, 09:13 PM

Depending on the location and /or configuration of the house, block can be faster & less expensive. A properly designed and built block foundation wall has all the strenght that is required of it. I feel that the ground that the footings are laid on and the footings themselves are more important than the material that the foundation is made of. I recall seeing a Holmes on homes show in which Mike after comparing block to concrete for foundation walls wonderd out loud as to why blocks arent used more often because the specs were actualy better for blocks. Many framers around here also prefer to build on block foundations than poured concrete. Block foundations are also arguably easier to repair if problems do occur, I have seen many poured foundations that have cracks in them. Having said all this I personally dont like doing them for all the work thats involved.

dakzaag · 08-26-2009, 09:14 PM

Cheaper and faster. Get a few bids and see that I tell you the truth.

On a basement, horizontal stress needs to be addressed with a few common sense items like truss wire, rebar and grout. Vertical strength is unsurpassed.

When the crete cracks no amount of waterproofing will bridge the crack.

The best reason is you will have your mason already lined up for the brick/ stone cladding.

fwiw, my house sits on a poured foundation and most houses with basements are poured in this area. Usually it's because the GC wants to deal with one sub for both the walls and the flat work. When you start looking at a crawl space then the block get a lot more common around here.

oldfrt · 08-26-2009, 09:37 PM

Quote:

Originally Posted by CJKarl

I feel the same way, yet you go to different parts of the country and most of the foundations are block. Maybe in very rural areas redi-mix is too far away. I know in PA, where my brother in law lived, every new house had a block foundation.
Here in CT, there were a few built in the 50s-60s. Block is still widely used for a small kitchen or bathroom addition, but the main part of the house is poured concrete about 99% of the time.

Which is a shame because with full basements ,and the lack of curtain drains,most of them leak.

Rockmonster · 08-26-2009, 09:48 PM

Very hard to compete with poured unless its a crawl, but I'll mention it since nobody else has. Good blockwork LOOKS way better than poured if you're going to leave it exposed. Did mine out of block, 9'4" high, it's bulletproof, and with UGL and one coat of latex, it looks dynamite....

oldfrt · 08-26-2009, 10:03 PM

Quote:

Originally Posted by Rockmonster

Very hard to compete with poured unless its a crawl, but I'll mention it since nobody else has. Good blockwork LOOKS way better than poured if you're going to leave it exposed. Did mine out of block, 9'4" high, it's bulletproof, and with UGL and one coat of latex, it looks dynamite....

Is Nantucket all sand?

cleveman · 08-26-2009, 10:25 PM

I'm waiting for the concrete mason from MN to chime in.

Block walls were the thing after the war. Up until the 70's or even 80's. There is no question that they are just as strong, built right. I suspect it is a labor thing.

It isn't a time thing. You can get a crew in and put up a block basement in a day and a concrete crew will have just formed up.

Like I said before, I'm waiting for the concretemason guy from Mn to chime in.

jomama · 08-26-2009, 10:28 PM

A few more things not yet mentioned:
- A block basement is generally drier due to the airspace in the cores.
- A block basement also has a secondary drainage plane (inside those same cores) should the exterior leak.
- Block walls are generally wider & contain MORE steel re-inforcement than the average poured wall. At least this is the case in my area.
- Block walls are almost always flatter, straighter, & squarer than any poured wall, making life easier for the framer.

If anyone doesn't agree with these statements, I can guarantee they've never meet a good masonry foundation contractor. Or the poured wall contractors are just that sloppy around here!

jomama · 08-26-2009, 10:37 PM

Oh, and Shane, your feelings of ill will towards block walls aren't uncommon. I spend alot of time trouble-shooting block basement problems in 60-70's homes. I always find that the foundations were just always under-built compared to today's standards. It def gives all masonry construction a bad name, but it's not much different in the rest of most of these homes from that era.

My home was built in the 70's & who thought it was a good idea to use single pane slider windows in WI? Or masonit siding? Or 3/12 roof pitches? Back then, I think they thought it was probably overkill compared to what they were accustomed to buiding a decade before. Same thing goes for the old block basements. The masons cut corners years ago as they had a false sense to the elements they were buiding in. Again, todays basements have far superior strength, due to what was learned from the past, and the subsequant guidlines/codes that ensued.

oldfrt · 08-26-2009, 10:40 PM

Quote:

Originally Posted by jomama

A few more things not yet mentioned:
- A block basement is generally drier due to the airspace in the cores.
- A block basement also has a secondary drainage plane (inside those same cores) should the exterior leak.
- Block walls are generally wider & contain MORE steel re-inforcement than the average poured wall. At least this is the case in my area.
- Block walls are almost always flatter, straighter, & squarer than any poured wall, making life easier for the framer.

If anyone doesn't agree with these statements, I can guarantee they've never meet a good masonry foundation contractor. Or the poured wall contractors are just that sloppy around here!

There must have been a run of bad masons here,because I've never seen a dry block foundation.
I'm not doubting your claims,just saying all the ones I've seen locally bare either cracked or leaking into the basement from mortar joints.
Since exterior waterproofing was not a general practice on these older homes,that could have been the cause of the problems.

BreyerConstruct · 08-26-2009, 10:58 PM

Block Builds Better Basements!

Poured is poor... think of the water added to the 2000psi mix to get it to flow... and in most areas I've been the crews are pretty sloppy.
Drainage is primarily an issue of back-filling and proper drain-tiles, etc.

Block is interlocked, and offers the cores for additional reinforcement possibilities, or additional insulation.

It's also easier to repair, and can retain strength when cracked due to the "block" design.

I may be a deck designer/builder now... but once upon a time, I moved a few block.
OK, I'll get off my high horses and wait for Concretemasonry to come by & set us all straight!

~Matt

4th generation · 08-26-2009, 11:00 PM

"Since exterior waterproofing was not a general practice on these older homes,that could have been the cause of the problems."
Dja think ?

oldfrt · 08-26-2009, 11:06 PM

Quote:

Originally Posted by 4th generation

"Since exterior waterproofing was not a general practice on these older homes,that could have been the cause of the problems."
Dja think ?

Or could have been poor footings,or bad mix,or lack of reinforcement.......

Why the sarcasism?

Just trying to get a good take on why they failed so much here!

jomama · 08-26-2009, 11:13 PM

Quote:

Originally Posted by 4th generation

"Since exterior waterproofing was not a general practice on these older homes,that could have been the cause of the problems."
Dja think ?

I don't know if the "waterproofing" or damproofing would be the main problem. The failed basement of yesterday seem to always have a lacking drainage system, though. In my area, it was def the norm in the 60-70-80's to set concrete draintile into the wet plastercoat, & then the masons used 5 gallon buckets to stone the draintile. Obviously, this was hard work, the stoning part, & generally yielded about 1-2" of stone over the tile, followed by 6-7 feet of clay backfill! This situation was destined to fail from the beginning. Again, this is what really gives the block foundations a bad reputation.

For what it's worth, the poured wall contractors seem to be falling into the same rut that the masons did of yester-year. They seem to be more concerned about prodution than longevity, & can get away with it for now, as in the 60-70's, there is little to no code for poured wall const., at least in my area.

wazez · 08-27-2009, 08:29 AM

Another reason some people have good results with block and others have poor could be the size of the block. My dad is from PA and he built basements all the time using 10" and sometimes 12" block . In this area if a block basement goes in 8" block is the norm. He built his basement 18 yrs. ago with 10" block and very little rebar and it doesn't leak or have anything other than hairline cracks. Block walls do get a lot of bad rap but I think with common sense and the right materials for the job they can be a good thing. Lets keep the opinions coming.

strathd · 08-27-2009, 09:12 AM

I'm not a mason but I believe location (soil) has a lot to do with the choice. Block is WAY cheaper. In my location all basements are poured walls. We have a lot of clay in our soil which results in too much hydraulic pressure on basement walls to use block. We use block for crawlspaces.

shanekw1 · 08-27-2009, 09:58 AM

Great stuff guys!

The only block basements in my area are on older, 60's 70's homes. And most of them done by the old farmers who lived in them.

These days, around here, there is no block in new construction, except for commercial buildings with block walls, but I'm sure even they all still sit on poured footings and foundation.

I totally agree that block looks nicer if it is going to be left uncovered, I see a lot of older homes with the foundation/basement walls that were poured with whatever junk planks they could find for forms, then have been parged out and had lines drawn in them to look like block.

Rockmonster · 08-27-2009, 01:35 PM

Yes oldfrt, it is almost ALL sand here except for a few veins of brutal clay, some of it 40 feet thick......NO bedrock whatsoever...so drainage is usually no problem....however, I still did a brushcoat of Thoroseal, and then a sprayed coat of waterproofing....dry as dry can get....but to continue the thread, most construction now is concrete below grade, blockwork above with infrequent exceptions....up until there was a batch plant here on the island, about 20 years ago, virtually all houses, AND commercial buildings had block foundations, with the usual problems that those underbuilt foundations had, cracks, leaks, and the mold problems that followed....I rebuild some from time to time and never see rebar, durawall, grouted cells, any of the stuff that separates old crap from new, well built foundations......