Filling only the top few blocks in a cinder block wall?

[ericm]

We're getting a house built. It's partially going on an existing walk in basement that was built in the 70s. The basement was built with cinderblocks. After removing the old house we found that the basement walls were a little too shaky, so the GC had the top 2-3ft cut off on thee walls. After doing so they found that the builders had stuffed paper in the cavities in the blocks so only the top couple rows had concrete. Below that they're empty. No rebar anywhere.

Was this a thing back in the day or were they being especially cheap?

We're going to have to cut the top off the remaining wall, build it back with blocks (it's against dirt) and then for all of them, place rebar and concrete properly.

 

[BillK]

Not sure about your area but around here I never remember seeing any block walls filled period. My parents house was built in 1956 and I have pictures of the build and there certainly was no filling in the block basement walls. Same with a later group of houses in that neighborhood around 1962. The first building I had my business in was Block with brick veneer and the block walls were all filled with some type of insulation, vermiculite I think ? I know when I drilled a hole in one wall to mount

I dont know when I even heard about filling block walls with concrete. Maybe it is for the seismic codes you guys have ??

 

[geneg]

We're getting a house built. It's partially going on an existing walk in basement that was built in the 70s. The basement was built with cinderblocks. After removing the old house we found that the basement walls were a little too shaky, so the GC had the top 2-3ft cut off on thee walls. After doing so they found that the builders had stuffed paper in the cavities in the blocks so only the top couple rows had concrete. Below that they're empty. No rebar anywhere.

Was this a thing back in the day or were they being especially cheap?

We're going to have to cut the top off the remaining wall, build it back with blocks (it's against dirt) and then for all of them, place rebar and concrete properly.

It was a cheap cut corner method that accomplished nothing. A bond beam at the top of the blocks stabilized the wall & adds bearing capacity. Bond beam blocks are u shaped with open ends so that continuous rebar can be embedded in the concrete. Also helps to have vertical rebar & core fills every so often or at critical load points.

Built in the 70's- your walls were probably CMU (concrete masonry units) not cinder blocks.

If you can, drill down into the footings & add vert rebar at 8ft intervals, fill the cores, & add a bond beam at the top. This will give you a block wall to resist the side loading from the soil against it. Also think about a drainage system along the backfill side.

Amazing what you find in existing buildings- isn't it?

A non reinforced block wall only supports vertical loads. A very small horizontal force WILL make it fail, even without seismic issues.

 

[billconner]

A question of what was required when it was built, how high is the unbalanced fill, and seismic zone. If it was fine for 50 years, not sure I'd change it. If however your making modifications, code may require it be brought up to "new". Iirc, rebar and grout every 4' or something like that.

 

[Copymutt]

This wall is fully grouted. A 3/4 ton chevy hit it and got totaled, B pillar strike. Absolutely no damage to the wall.

 

[nadogail]

When you have to fix what someone else saved money on, rather than did it right; you can expect to spend a lot more than the few dollars that was originally saved.

 

[Rusted Nut]

Never seen only top couple rows grouted before. Big question is what, if anything, will local building dept require? I’d demo old block, drill dowels and as others said follow code for unbalanced backfill reinforcement.

 

[BillK]

When you have to fix what someone else saved money on, rather than did it right;

If the house was built in the 70's that was probably normal procedure. Not necessarily done to save money.

 

[nadogail]

Half way measures often turn out to be very expensive.

 

[cmandp]

This wall is fully grouted. A 3/4 ton chevy hit it and got totaled, B pillar strike. Absolutely no damage to the wall.

That's a nice looking wall

 

[ericm]

It was a cheap cut corner method that accomplished nothing.

Cheap and half-assed kinda matches with some other features of the property.

A bond beam at the top of the blocks stabilized the wall & adds bearing capacity. Bond beam blocks are u shaped with open ends so that continuous rebar can be embedded in the concrete. Also helps to have vertical rebar & core fills every so often or at critical load points.

The blocks at the very top did not have that.

If you can, drill down into the footings & add vert rebar at 8ft intervals, fill the cores, & add a bond beam at the top.

I think we're getting the vertical rebar, filled cores and bond beam. No mention of drilling into the footings.

Bottom This will give you a block wall to resist the side loading from the soil against it. Also think about a drainage system along the backfill side.

Amazing what you find in existing buildings- isn't it?

The block wall LOOKED nice, like it was professionally mortared. When I saw the concrete in the cores at the top of the walls I thought I'd found something that had been done well. Both the GC and the engineer who looked at it (before demo of the house above) thought it was ok. But of course they don't have Xray eyes. Oh well it's only money. Better to find out now than when the Cascacdia fault finally slips.

 

[WildBill]

This wall is fully grouted. A 3/4 ton chevy hit it and got totaled, B pillar strike. Absolutely no damage to the wall.

Is that a concrete gate?

 

[cretedog]

We're getting a house built. It's partially going on an existing walk in basement that was built in the 70s. The basement was built with cinderblocks. After removing the old house we found that the basement walls were a little too shaky, so the GC had the top 2-3ft cut off on thee walls. After doing so they found that the builders had stuffed paper in the cavities in the blocks so only the top couple rows had concrete. Below that they're empty. No rebar anywhere.

Was this a thing back in the day or were they being especially cheap?

We're going to have to cut the top off the remaining wall, build it back with blocks (it's against dirt) and then for all of them, place rebar and concrete properly.

It was common practice back in the day. No rebar, no bond beam. Stuff empty mortar bags down the cells at the top and fill for mud sill bearing and anchor bolt placement. Much different and better today.

 

[Copymutt]

Is that a concrete gate?

Faux, 24ga. paintlock filled w/ styrofoam panels to absorb road noise. Even so each 1/2 is close to 300#.

 

[WildBill]

Faux, 24ga. paintlock filled w/ styrofoam panels to absorb road noise. Even so each 1/2 is close to 300#.

That's pretty neat.

 

[NUTTSGT]

I think around here in the early to mid eighties, they started to core fill block completely with rebar and for anchors...not every core but the ones getting filled.

I think it corresponded with poured walls becoming a "thing" around here.

 

[TurnipTruck]

My old (1972)daylight barn foundation didn’t have a single inch of rebar in it, just the upper two rows filled and very sporadic J bolts. No vertical concrete either.

I got to cut down several 8” spruce from up against the wall and dig out and replace the blocks.

 

[75gmck25]

We built a new crawl space foundation in 2019. The plans only required vertical rebar about every 4 feet, drilled and epoxied into the footings, and the cavities filled of the blocks that had rebar. It also has horizontal metal “ladder“ reinforcement every other row of blocks. J hooks were cemented into the top row of block.

 

[kyrbz]

I'm renovating a 50's era CMU and brick property. We wanted to raise and pitch the ceiling (it was a flat roof), so the entire roof was removed. There was no rebar or grout (cement) in any the walls. After adding the height and pitch I wanted, I added rebar and grouted every 4th cell. The remaining cells I filled with perlite. When adding the grout and perlite, I stopped 2 blocks short of the top. The top 2 courses were filled entirely with grout in which the j-bolted 2x caps were set. Similar to a bond beam but technically not one. On a bond beam the interior webbing of the block is broken out and rebar is laid horizontally. There are some sections I did bond beam construction due to the load bearings on the wall or over windows that came close to the top of the wall. To me, the advantage of initially only filling to two blocks below the top is that is gives you a more relaxed time frame in terms of filling the wall with perlite and much less grout needing to be mixed when you're setting your caps. A lot of people fill block with mortar or cement, but masonry grout has a much much higher psi strength than cement or mortar. The down side is it's 4 times the price of cement. If you can afford grout, I'd use it. If not, cement and rebar will a significant improvement over the original empty walls. The pic I attached is the structure I'm referring to during the block and brick work. All the unpainted block is new work added to the original structure. You can also see a change in the color of the brick where height was added.

 

[ericm]

My old (1972)daylight barn foundation didn’t have a single inch of rebar in it, just the upper two rows filled and very sporadic J bolts. No vertical concrete either.

I got to cut down several 8” spruce from up against the wall and dig out and replace the blocks.

Seeing that makes me feel a little better about spending the extra money to reinforce the walls.

Did that happen all at once or gradually?

 

[Hilltopmasonry]

If the house was built in the 70's that was probably normal procedure. Not necessarily done to save money.

Yes it was normal procedure then

 

[Hilltopmasonry]

I think around here in the early to mid eighties, they started to core fill block completely with rebar and for anchors...not every core but the ones getting filled.

I think it corresponded with poured walls becoming a "thing" around here.

Usually every 3rd cell gets filled nowadays for foundations unless otherwise specified

 

[tncatadjuster]

I'm renovating a 50's era CMU and brick property. We wanted to raise and pitch the ceiling (it was a flat roof), so the entire roof was removed. There was no rebar or grout (cement) in any the walls. After adding the height and pitch I wanted, I added rebar and grouted every 4th cell. The remaining cells I filled with perlite. When adding the grout and perlite, I stopped 2 blocks short of the top. The top 2 courses were filled entirely with grout in which the j-bolted 2x caps were set. Similar to a bond beam but technically not one. On a bond beam the interior webbing of the block is broken out and rebar is laid horizontally. There are some sections I did bond beam construction due to the load bearings on the wall or over windows that came close to the top of the wall. To me, the advantage of initially only filling to two blocks below the top is that is gives you a more relaxed time frame in terms of filling the wall with perlite and much less grout needing to be mixed when you're setting your caps. A lot of people fill block with mortar or cement, but masonry grout has a much much higher psi strength than cement or mortar. The down side is it's 4 times the price of cement. If you can afford grout, I'd use it. If not, cement and rebar will a significant improvement over the original empty walls. The pic I attached is the structure I'm referring to during the block and brick work. All the unpainted block is new work added to the original structure. You can also see a change in the color of the brick where height was added.

That is a beautiful wall.

 

[NUTTSGT]

Usually every 3rd cell gets filled nowadays for foundations unless otherwise specified

That's a lot better than it used to be.

I know when I built my garage addition, a few people thought I was filling too many cores. I was like what is it going to hurt ? Granted, I used bag mix but I spent an extra $50-60 over a ~$7K addition.

 

[billconner]

Just based on IRC, 8" block with 6'-8" Max unbalanced - rebar and grout every 4' (6 cells typically). As unbalanced fill increases, bigger rebar and or more frequent rebar/grout. As block thickness increases, rebar/grout spacing increases to 56". Seismic zone can increase this as well. Surface bonding decreases the requirement as it's stronger laterally.

When in doubt, build it stout.

 

[Fixr]

My last house had block walls that were fully filled... with empty beer cans. All the way to the top in every cavity. You can undoubtedly picture the quality of the rest of the construction.

 

[TurnipTruck]

Did that happen all at once or gradually?

I only dealt with the aftermath and repairs, but I imagine it took decades for the trees to do the damage.

 

[kyrbz]

My last house had block walls that were fully filled... with empty beer cans. All the way to the top in every cavity. You can undoubtedly picture the quality of the rest of the construction.

The building I live in now is a brick building built in 1897. One time I had to open sections of wall when I was working on running chimney liners for wood burning stoves. The interior of the brick walls were completely filled with whatever trash they had in the job site. Mostly whiskey and medicine bottles, but there was all kinds of stuff in the core of the brick walls. Another time I was demoing sheet rock and other renovations by the previous owner that were done in the 70’s. Above the ceiling was full of Budweiser cans that I guess the sheet rockers threw up there as they were working.

 

[NUTTSGT]

My last house had block walls that were fully filled... with empty beer cans. All the way to the top in every cavity. You can undoubtedly picture the quality of the rest of the construction.

"Aluminum rebar"

 

[Ricky Joe]

Commercial buildings require all saves to be filled, with rebar. Also, you are not allowed to “stick”, or add, the rebar after pouring.

 

[billconner]

Commercial buildings require all saves to be filled, with rebar. Also, you are not allowed to “stick”, or add, the rebar after pouring.

"all saves"? certainly not all cores. I work on a lot of schools and always ask for grouted walls for acoustic reasons and always get push back for cost.

 

[Ricky Joe]

I used to do inspections in Virginia, and it was required here and then. I did a lot of city schools and Virginia Tech new construction. I can’t say requirements haven’t changed, just that that was how it was then. Grout had to pass compression tests, so I had to take samples, and make sure the rebar was in place, specified size, and that the contractor met all specifications. Could be that those specifications were not required by code but by engineers. If it was in the plans, I had to check: why they were in the plans I can’t say.

 

[Uncle murph]

Not sure about your area but around here I never remember seeing any block walls filled period. My parents house was built in 1956 and I have pictures of the build and there certainly was no filling in the block basement walls. Same with a later group of houses in that neighborhood around 1962. The first building I had my business in was Block with brick veneer and the block walls were all filled with some type of insulation, vermiculite I think ? I know when I drilled a hole in one wall to mount

I dont know when I even heard about filling block walls with concrete. Maybe it is for the seismic codes you guys have ??

I’ve been laying block for 40 years,I’ve seen people do all kinds of things but I can tell you from experience that properly laid 12” block with factory made cap blocks are more than sufficient for any house.Lousy workmanship or poor grading will cause problems no matter how much you pour into the walls.as for the paper in the walls,that was common practice in the days before cap blocks became standard,what matters is that the top of the wall is smooth and solid.Radon gas and high labor costs have resulted in solid poured/formed walls having all but eliminating block foundations at least in houses with basements.

 

[egdede]

^^^ not in seismic zones ^^^ Fill more better in earthquake country. I agree, even filled it still must be "properly laid".

 

[ericm]

Just to close this out: My GC put rebar in and filled all the cells, after cutting the filled rows off the remaining wall and rebuilding it to height. The area doesn't have the same earthquake risk that we do in CA where we're close to a major fault but it's still a worry.

 

[BombShelter]

I usually see hollow blocks for foundations, buildings core fill 3 rows then leave something like 5 rows open between, and garages they flip the blocks over and fill the bottom 1/2 of the top block.

I've never seen your situation before, maybe they had way too much concrete floor mix? For the members that are familar with this, wouldn't you want the concrete closer to the floor instead of a large amount of weight at the top which now needs to be fixed?