Concrete Block Walls

[wrench409]

I've seen older garages with the 8x16 inch concrete block wall construction for the whole wall all the way up. Then it's capped with a wood frame truss system with standard hip roof for the upper part of the construction.

I haven't seen any in here since my arrival a short time ago.

Anyone here use that method? I've not seen any plans for this type on the net either. Not that it's much more complicated than lego's

Pro's or Con's?

Thanks,

 

[Bolt11]

It works, but make sure you fill with concrete all the way down, of course. We have done it for many walls, some load bearing, others just standing inside or outside a steel structure. The nice thing is your wall is finished, no sheeting, etc, you can hang anything anywhere, no looking for studs. Downsides, minimal insulation value, cost, need to hire mason.

 

[carguy123]

Why would you fill with concrete? I have lived in those homes in Fla lots of years and the air space is part of the insulation factor.

Quite comfy.

 

[Bolt11]

If they are not filled, the blocks can shift, you can knock one loose by hand, and the air will blow right through the new cracks.

 

[sharpshooter]

absolutly fill the blocks not for insulation but support, I worked for a concrete company for a few years and I have seen several non-filled block walls come crashing down even with out a load on them. it maybe a little more expense but its good piece of mind. If you choose not to fill the blocks you still need to tie them in together somehow.

 

[DIGGER_DAVE]

If they are not filled, the blocks can shift, you can knock one loose by hand, and the air will blow right through the new cracks.

Because both side walls of my shop sit on my property lines; fire code required that I use a "Fire Rated Type of Material."

The most economical way (to meet requirements) was to use "hollow block" concrete blocks. Mine are filled with INSULATION. (vermiculite - a fire proof granular material)

During the construction; a wire reinforcement "grid" was placed between EACH ROW of blocks. (imbeded in the mortor)
BOTH side walls are "load bearing."

These walls were constucted 22 years ago; and with weather that can range from - 40 F to + 95 F; and having been bumped into, (HARD) shelves hung off of,
NOT ONE has ever SHIFTED or cracked.

I'm only guessing; but if you have experienced - "you can knock one loose by hand" - someone doesn't know how to mix mortor correctly. (or build concrete block walls!)

 

[PAToyota]

Umm... As an architect I have to step in and say that most concrete block walls leave the cores open. Filling them with concrete (or grout) actually lessens the insulating properties - a solid material conducts heat better than one with an airspace in it.

Now, you do have to reinforce the walls - both with the ladder reinforcing every other course and depending on application with grouted cells with rebar every two, four, or eight feet (usually).

As for why you don't see them as much - because it is cheaper to bang together a bunch of 2x4s than be out there setting block.

 

[DIGGER_DAVE]

As for why you don't see them as much - because it is cheaper to bang together a bunch of 2x4s than be out there setting block.

You can "bet your bippy" on that statement!!
Our fire code required a five hour rating on walls that were on the property line. (and abutted other structures)

To create a rating of five hours with a "stud" wall was going to cost ALMOST as much as the concrete block.

 

[Ironcrow]

I have a 12 inch thick block wall on my shop. It is 14 feet tall and is a retaining wall. The grade behind garage goes up another 9 feet. Yes, the back of my garage is, essentially underground. Did I mention my lot is steeply sloped? In my case, the 12 inch CMU (Concrete Masonary Unit - "block") wall was selected as an alternative to a formed and poured solid concrete wall. There are two 5/8 inch rebars in every cell, four per block. The entire wall is poured full with 3000 psi grout. This is more rebar than the architect and engineer came up with, but I got a good deal on the rebar and I like overkill.

 

[wrench409]

Great dialogue going on the subject.

The rebar/filled wall is really going to weigh though is it not? Seems the extra weight would more than double the load on the slab and footings risking the slab with cracks.

The block wall with mortered joints sounds like the best route to take. I like the idea of the rebar. Perhaps some like every 4th cell a stick of rebar and filled with mix?

I did finally find some info on the net about building retaining walls with block.

My big question really is my local building code. That's the hardest stuff to find at this time.

Thanks for the responses.

 

[burger]

so just how expensive is concrete block? like actual numbers, not just more expensive than wood.


thx
ed

 

[boiler7904]

Wood trusses on top of a block wall isn't a challenge - we use the combination all the time. I just finished a fire station with an apparatus floor that measured 80' x 80' x 24'. Wood trusses clear-spanned the space.

The trusses bear on a pressure treated plate (or two) or that gets run around the top of the wall and get anchored using hurricane clips. The plate is fastened using standard anchor bolts that get set into a continuous grout filled bond beam at 4' or 6' on center and within a foot of plate ends and the building corners.

Keeping in mind that on average 12" thick masonry weighs about 60 pounds per square foot of wall area (not including steel reinforcing or grouted cells), I would say that if you're going to use masonry walls you should pour a footing and frostwall to give proper bearing capacity. Over time, a floating slab with a thickened edge would likely crack at the interior face of the wall.

I would say that your local building code would have no problems with you building out of CMU since the wall by nature is fire rated and get a high rating by filling cores, etc.

A few pointers:
- Design the building on 2'-0" modules (16" block + half of 16" block) since corners get alternated. You'll also be on the same module as your trusses and most concrete formwork without a bunch of custom work.
- Use doors and windows that fit into the 8" module system of cmu construction - cut blocks (other than halves) look like **** and show that you didn't really plan to well.
- Never use a stack bond pattern (vertical joints line up floor to ceiling) for structural walls - its a recipe for disaster.
- Include masonry control joints at 4' from building corners, every 20' along a wall, and at each lintel location. The control joints in the building I'm working on now have moved almost 3/8" since installed over the summer. The point is, masonry will move. If you don't account for the movement, you'll end up with cracks and a failing wall.

There are a few disadvantages to the system:
- Everything gets harder to attach to the walls including doors and windows.
- You'll use a lot of steel as lintels over every opening. $$$
- Masonry in itself is expensive and the cost goes up if you start using splitface or decorative block or a brick veneer.
- May not be allowed by zoning for your neighborhood for appearance reasons.
- Flashing gets to be trickier at some locations - depends on roof design and type / style of openings.

Good luck if you decide to go this route.

 

[Pops]

My shop is 20 x 30 concrete block building. It was built in the mid '60's with wood trusses on top. It has two 9' overhead doors and one walk through. I've built hot rods in this shop for 30 years.

J.

 

[Ironcrow]

... I would say that if you're going to use masonry walls you should pour a footing and frostwall to give proper bearing capacity. Over time, a floating slab with a thickened edge would likely crack at the interior face of the wall.....

.....You'll use a lot of steel as lintels over every opening. $$$ ....

Yes, I agree here. Plan on a footing. In my case the footing is 5 feet wide, a foot and a half deep and has two mats of rebar in it.

For openings, you can use a built up CMU and grout "beam". Much cheaper than steel lintels. You shore it up, lay block across it, and fill it with rebar and grout:
http://www.powerssteel.com/lintels-new/l2-lintel.html

Doors and windows are harder. Since I had the opportunity, I used a heavy steel frame commercial man-door, ran the bond rebar out to the edge of the door opening, bent it up, dropped the frame in, and ran the block over it, etc, and filled the door frame with grout when I filled the cells. Pretty secure.

Roll up garage doors are pretty standard, but again, you are fasteneing them to blocks instead of screwing to wood. It's a pain.

 

[DIGGER_DAVE]

Keeping in mind that on average 12" thick masonry weighs about 60 pounds per square foot of wall area (not including steel reinforcing or grouted cells), I would say that if you're going to use masonry walls you should pour a footing and frostwall to give proper bearing capacity. Over time, a floating slab with a thickened edge would likely crack at the interior face of the wall.

This is something I missed.
Because of the wide variations in temps., (cold = -40 and hot = +95) to insure no frost heaving could damage my concrete block wall; they are placed on 36 inch deep "frost walls" (with lots of re-bar; both vertical and horizontal) set on 16" wide x 6" thick footings. (ALSO "laced" with re-bar)
Even though concrete blocks were only used on the side walls; the frost wall runs the entire perimeter of the shop.
(40 feet wide - property line to property line - x 24 feet long; MAXIMUM the city would let me build)

The vertical re-bar in the frost wall extends ABOVE the wall, and is "hooked" to the bottom row of blocks. Only 6" of the frost wall is above grade.

The interior "floor slab" (floating) is placed INSIDE the frost walls with expansion joints between the walls and the slab.
NO blocks sit on the floor slab.

The initial cost of doing the concrete walls this way was QUITE expensive; (sorry don't remember the actual cost) but the end walls (with frost wall, footings, blocks, masonry work and digging the trenches) ran over $6,000.00.
Keep in mind this was 22 years ago!!
But in my mind it was worth the cost.
NO cracks or settling!

 

[thefairlaneman]

Great dialogue going on the subject.

The rebar/filled wall is really going to weigh though is it not? Seems the extra weight would more than double the load on the slab and footings risking the slab with cracks.

The block wall with mortered joints sounds like the best route to take. I like the idea of the rebar. Perhaps some like every 4th cell a stick of rebar and filled with mix?

I did finally find some info on the net about building retaining walls with block.

My big question really is my local building code. That's the hardest stuff to find at this time.

Thanks for the responses.

We call them cinder block buildings here in NC .

 

[bhelton]

Just built a block garage with wood truss roof system--no problems at all. The garage is fairly small 24' x 24'. Block were $1.23 ea, $1.20 ea to lay plus sand and mortor. Its done in my area often. I will be bricking the exterior.

 

[boiler7904]

For openings, you can use a built up CMU and grout "beam". Much cheaper than steel lintels. You shore it up, lay block across it, and fill it with rebar and grout:
http://www.powerssteel.com/lintels-new/l2-lintel.html

This paragraph seems a little contradictary. On one side, you're saying to use a cmu bond beam lintel instead of a steel lintel. Then you give a link to a metal fabrication for a lintel. Doesn't make a lot of sense to me.

If someone was to DIY a block garage, a steel lintel is most likely the better way to go. It eliminates the need for blocking out the opening and temporarily supporting the head of the opening while it sets up. Steel angle and plate (wide flange beam if the opening is wide enough) is readily available in all parts of the country. You don't have to wait for a steel lintel to cure before building above it.

I'm not saying that you can't build an opening without using a steel lintel, it's just easier for the average DIY to use a piece of steel.

 

[Ironcrow]

This paragraph seems a little contradictary. On one side, you're saying to use a cmu bond beam lintel instead of a steel lintel. Then you give a link to a metal fabrication for a lintel. Doesn't make a lot of sense to me. ....

I'm making a distiction between a steel I-beam (or angle) and this folded piece of sheet I linked to. If you look on the link, the advantages are listed on that page. The Powers Steel thingy is 1/10 the cost, 1/10 the weight (no crane needed) compared to an I-beam. Stronger, lighter, cheaper, and easier for a DIY'er... But, if a guy didn't like the idea...it's a free country.

 

[boiler7904]

I'm making a distiction between a steel I-beam (or angle) and this folded piece of sheet I linked to. If you look on the link, the advantages are listed on that page. The Powers Steel thingy is 1/10 the cost, 1/10 the weight (no crane needed) compared to an I-beam. Stronger, lighter, cheaper, and easier for a DIY'er... But, if a guy didn't like the idea...it's a free country.

I wasn't saying it was a bad idea. I was saying that you proposed two different ways to build the opening (powers steel fabrication and what is essentially a masonry flat arch) and that's where my confusion came from. My bad. I'm all for using something like that if it makes things easier, cheaper, etc. and is code accepted.

 

[Ironcrow]

Sorry for the confusion. Yeah, a masonry flat arch would work with minimal shoring for a small opening, like a window. I would do that as an economical solution.

But, once you're spanning 8 feet or even 16 feet, serious metal like an I-beam or that Powers Steel lintel would be the plan.

Oddly, I used the Powers Steel lintels and then ended up sistering pretty heavy angle up next to them to support the heavy stone facade across the opening (design change). If I had known about the facade in the first place, I could have just started with the heavy metal...

 

[Down Under Bloke]

I live in a city that was blow away by a cyclone (hurricane) in the 70's. When rebuilding occurred almost every thing was built of core filled correct blocks with reo from slab to roof truss connections.

Insulation was not considered a requirement as the climate is hot, which is fine until the concrete gets hot (DOH). While concrete block are a solid method of construction there is just one issue with them THEY ARE BUT UGLY. My entire office building is made of them and just paint inside and out, all the walls are covered in conduits for network, a/c, phone etc etc.

 

[URY914]

The steel lintels that are shown in the link are nice because they are galvenized. I often see steel angles used for lintels that are cold rolled steel and only shop primed. These end up rusting and running down the wall of the building. Looks like **** before the building really needs to be repainted. I would use a simple pre-cast concrete lintel. Thier simple and cheap and of course don't ever rust.

Also running empty conduit in the walls for electric/data lines is easy. But your ceiling must be below you bond beam so the conduits can turn out above the ceiling but below the beam and into the attic space.

 

[rodwerkz]

my shop was built in the 40's using 8x16's. They are a bit strange looking. The edges are actually tapered where they meet giving it kind of a castle wall look. They also have very coarse agregates in them, some the size of a pebble. They are not filled and i have had some problem with blocks shifting and stress cracks. Luckilly the whole perimeter of my shop is framed out with 18" i-beams so it's not going anywhere. I spent most of the summer "tuck pointing" and grouting the lossened blocks and it's now good as new.

I'm an engineer and not an architect however i do feel that a full fill of the walls is overkill and would definitely kill the insulating properties. I know that filling a few specific sections and the use of rebar is a suitable way of doing things. Thats the way my buddy did his a few years ago and it came out great.

Honestly a block garage is the best thing you can work in if you are heavy fabricator. I definitely would have burt down a wood framed shop by now

 

[Vermaraj]

If your going to grout the entire block wall. Wouldn't it make more sense to try an ICF system?

Steel & footing requirements would be approximately the same. Increased cost of concrete would be offset by labor and insulation savings.

Anybody tried one of these systems?

 

[boiler7904]

ICF would make sense assuming that you're planning on finishing the interior of the shop. Exposed foam is a huge fire risk when you start doing metal fab in a building.

Labor savings would only apply if the owner DIY'd the project. Unless you are in an area where there are a few ICF contractors, it is a pretty specialized trade and higher labor prices.

On the plus side, it is supposed to be very energy efficient since the walls have both insulation and thermal mass.

It would be something to consider for the right project.

 

[jamesgpeck]

This is dry stack concrete block made of a concrete with high insulating value. they claim R34. This looks like it can be laid by a DIYer. Has anyone had experience with the stuff. It looks like a way I could get a masonry garage at a reasonable price.

http://crescoconcrete.com/

 

[kbs2244]

The biggest problem in a cold climate is no insulation.
In the days of 22 cent gasoline nobody worried too much about that.
The smart way to retrofit them for today’s energy costs is to insulate and side them on the outside.
That lets you use the “thermal mass” to your advantage in damping out the temp swings.

I have a son that is a mason and done more than his share of big box stores.
The wire goes in the mortar on every other course.
That stops the zig zag cracks you see in older walls.
Plan on 4x4x1/4 inch angle iron over any window and an "I" beam over any opening more than 5 feet wide.
They only fill with grout on the top course which is a "U" shaped block designed to have rebar dropped in it and then filled with grout. That is to keep the wall from bowing.
But there is a lot of structural iron in these buildings.
They are made of block for fire code reasons.

Block comes in at least 3 weights.
"Cinder Block" is lightweight, plain, and very porous.
"Cement Block" is heavier, plain, but smoother and still kind of porous.
"Heavy Block" is made of concrete like your garage floor.
It is smooth, but real heavy.
Then there is "Rock Face" or "Split Face."
These are a man killer. It is over sized and very heavy.
That is what you see your Wally's and such made of.

 

[jkeyser14]

My garage is 20x25. It's concrete blocks with wood trusses for the roof. The outside of the garage is finished with clay brick all the way around.

 

[lh4x4]

When a friend of mine retired to Punta Gordon a number of years ago, he built a block house. He related to me that it was required to drop in rebar and then fill with concrete. That seemed like a very good method to build a cinder block house that could withstand high winds. That would not increase the cost very much but sure would make much stronger walls.

 

[Ramblur]

My 35x60 is almost 13 years old now. 10" thick aac with 1/2" all thread
(and couplers) from footer to lentil on 4' centers.At the time they were
building a plant locally so I got a killer deal on the block and masons
for the garage and 2100' house. Whole deal cost me less than the price
of concrete block alone,plus they delivered about 70 loads of fill dirt
from their plant site forfree. Took forever to get it up as it was all ojt
for the masons that wanted to learn it and the building dept. hanging
out inventing code for it. Doubt that I would do it again tho unless the
planets were in that same alignment. It continues to serve me well and
has weathered the hurricanes...
http://www.aerconfl.com/

 

[bigdav160]

This is dry stack concrete block made of a concrete with high insulating value. they claim R34. This looks like it can be laid by a DIYer. Has anyone had experience with the stuff. It looks like a way I could get a masonry garage at a reasonable price.

http://crescoconcrete.com/

I didn't check your link but I recently built (two) 6ft high, dry-stack/surface bonding cement walls. I went this way because it seemed the simplist way to achieve the look of traditional stucco as required by my neighborhood.

The other day I accidently backed my trailer into one and was very impressed that there was no damage to the wall. It seems much stronger than it would appear.