Concrete block wall

Hey folks.

I am going to put some of the mechanicals in my shop in their own room (air compressor, expansion tank, water heater exc.).

I would like to make the walls from block but have never laid them.

I have don quite a bit of concrete work but not much masonry.

Should I try to gain that skill or would it be more fruitful to lay the block up dry and use surface bonding cement (block bond)?

Thanks in advance,

Brad

Call around it may just cheap to have an expert do it.
To make your mortar last take some lime put it in a large bucket with enough water to make aa slurry then let it set over night it bubble a d boil. When it settles down add a small amount to your motar. My grandfather alway did this and it sure makes a good strong motar. A out 2 cups per 50 lbs
The Romans did this and you know how long there work lasted.
Walt

I would not let the lack of experience stop me from using C.M.U. (concrete masonry units) I am not familiar with block bond, what is it ?

It starts with layout, is this starting from an existing slab, any stub ups or risers, electric, water or similar in the wall ?

From a level slab, or even if the first course has to take some slack on the bottom to level out, its not all that difficult, especially for something you are doing at home.

Layout the slab, drill and epoxy in, #4 deformed bar, (rebar) every few courses if you need to tie into the slab. You may not need to, but its a common detail with CMU construction. You need to set your corners, plum/level, and you can use a string line from the corners, start building the walls, use a level to check plumb and level, have your mortar ready, butter the preceding course, set, tap plumb and level, strike the joint soon after, and don't get in a hurry, odds are if you can keep plumb, level with any other type of construction, take a look on you tube or similar, its not really difficult at all.

Hohmann-Barnard is an excellent supplier of masonry accessories, commonly specified on many jobs I have done, ladder mesh is a nice accessory to reinforce CMU.


If you have any shear wall, no corners you will need to anchor the top of wall.

If you have electric or similar to stub up, you will need to coordinate that as you go up, meaning raise the conduit with the wall, set back boxes or anything in the wall, could go surface mount if need be.

If there is anything to be fastened to the walls it is wise to fill those cells or surrounding area for mechanical fasteners, hollow cells will hold, but its a much better job when solid.

I've been a project manager on many many jobs, with large amounts of CMU type walls, much of it reinforced correctional facility work, as well as high strength CMU, structural walls, but never laid a single CMU as a mason. I did a small CMU job to install a Bilco door to access a basement, I did the layout, and built it without any problems at all. Its all in the layout, keeping plumb/level etc. Its nice and neater to have a CMU wet saw, but I used a mason's hammer to make my cuts, regular strength CMU, was fine, I'd not do it with high strength CMU. I would not be intimidated by not having done it, jump in, try it, learn as you go, before you know it, you'll know how to do it.

Was an outside wall , but I just stacked them and filled with cement.

Laying block isn't all that difficult, and I think you'll get a much stronger wall if you lay them up the normal way with mortar between the blocks.

Keeping them level and straight is about the most important thing to do.

I think you can figure it out. I did a short 3' wall for the base of my shop without any prior experience. I was pretty slow at it as it took a week to lay 5 courses times 140 linear feet. It takes some technique that you will have to learn. Keeping sticky mortar is the hardest. It only lasts about an hour once you mix it and that is the key to working with mortar. You can fill the cores when you are done on a few block to strengthen it all if you feel you need to. Youtube has to have some how to videos that should help.

Good luck.

Thanks Billy.

I printed your post and will use it as a guide.

As I understand for the first course I can drill into the slab set rebar into the holes and fill the cells that lay over the rebar. Deformed rebar means bent so that it jams in the hole?

Should the first course Lay directly on the slab?

This is a simple square room and all accessories will be surface mounted with the exception of a was mounted commode.

I appreciate you taking the time to 'take me to school' on this subject and I am going to do this project myself.

P.S. Block Bond is a product that is mixed like mortar and has fiberglass fibers mixed in. It is intended to be used over a CMU wall laid up dry and is troweled on. I have never used it on CMU wall but it makes a dandy floor leveler under cementboard.

Brad

Thanks Bill.

I think that I am going to try the mortar route.

This old dog loves to learn new tricks!

Brad

Hey Walt.

Thanks for the tip. I think I will try that on this job. I will post some pics so they the YTers can see my work (and screw-ups).

Brad

No problem. Its probably ironic to give advice, and not be an experienced mason, if you know of anyone that is, locally that can help, it will get you through, there is nothing all that difficult about CMU walls. The attached video should help immensely. I have tried to explain basics from memory, to help, like John T says or does with a disclaimer, same thing applies, hopefully an experienced mason chimes in as well. Its all helpful.

First course you will set a bed of mortar down first. Now if that slab is really dry, you may want to soak it a bit first, or it will suck the moisture out rapidly from the mortar. Its a matter of preference, I prefer a little slower cure.

Your mortar needs to be mixed correctly, especially slump, (don't make it soupy). Strength too, and uniformly, so if you get a bagged mix, just follow the instructions, you can adjust a little either way, like concrete, there is a water cement ratio, that you don't want to deviate too much from. Most masons know how they like it, a little stiff from what I have seen in the field. As you are placing the CMU, you don't want the mortar squeezing out, and you only go so far in a given day. Typical joints are 3/8" give or take, I forget, its been awhile, you can look that up, research etc. As you tap the CMU level with the handle of the trowel, mortar will settle, you can screed that excess off, then strike the joint once its set up a bit.

When working on a concrete slab or floor, its a good idea to throw some sand on the base of each side of the wall, after the first course, or whenever works, that coating of sand will keep mortar droppings from bonding to the slab, even if it does, its usually not by much, but it was a common thing done on many jobs I've been involved with.

It sounds like that material "block bond" is a coating, or a "parge coat' like stucco, applying this to CMU will not hold a wall together, it would be dangerous, CMU walls are constructed with mortar joints. In the attached video, from Sakrete, he mentions a dry set wall, I am not familar with it, nor have I ever seen one specified in any building I have ever constructed, so I am relating what I know of from experience.

Deformed metal bar is just the terminology, most call it rebar, but in architect or engineer terms, and or specifications, thats what it is called. The surface of the deformed metal bar is what its called, see all the ribs or uniform deformities is to help achieve a structural bond, not slip, move with expansion or contraction, similar to how paint bonds better to a slightly rough or textured surface.

Another thing with layout, ( a good layout is highly critical) is the coursing, you will want to calculate how many course including the joints, (add it up) and see where the top of wall is. Maybe it will terminate with a full height block, maybe not. Its modular so you can adjust things, or use another type of CMU, block, brick of the right size to avoid cutting the tops off the last course. You have maintain tolerance as you build the wall, so that the joints do not grow or are short. The old saying measure twice, cut once applies here. Sketch it if you have to, but really look at the layout, working through to the top of wall. Your end cut CMU, to get that typical coursing pattern, (staggered) you can place those half CMU's at the ends but if hammer cut, you will want the square ends on corners and leave the uneven joint running into the course. Cutting those with a masons hammer will take practice, you'll figure it out. Wet saw is ideal, but may not be practical, you make up those cuts ahead of time so you have them when its time to set CMU. ( I see from the video they have these already made, perfect !!!! LOL !)


Take a look at the video in the link, there's a bunch you can learn off you tube about this and so many other things similar, I use it often for things I do not know about, I think its great people have taken the time post instructional material like this.
Sakrete building CMU wall

Hohmann Barnard

Brad, I've only put a up few block, but put over 20,000 brick on my house.

I would recommend getting a mixer. No fun doing it by hand.

I THINK there is a top side to the block, the side that is bigger, hold more mortar. If not, I do it backward, but it works for me.

I set up corners with a post and pull a string when doing brick.

I used a 4 ft level to keep my work as level as possible. Thay way you can level 3 block together.

Like everything, it works better if you start out level and square. I have a self leveling laser transit. Some will call it a laser level. All I know is it's nice to have to keep block and brick level.

I've never done this, but it's one of those things you may want to try. Some people use shims they can remove after the motar sets up. This way if your motar is a little thin, the block mashes down and rests on shim. I've heard some people use marbles to get a uniform motar joint. They leave them in motar. Again, I've never done it but some people say it works.

Take your time and I'm sure you can do it.

George

Hi Brad. I've don a lot of block laying in my time. Taught My son the way I was taught by my pal who had the patience to teach me many years ago. Some things will not be short cutted and if tried will make a sloppy and weak building. I suggest getting instructions from Google . Learn to make footings wide and strong enough to support a wall. Learn to set corners, laying first row as you would lay up any course. String wall. remember to turn the corners the correct way,use level to align wall so it is straight. 1/2 " MORTER JOINTS using small level to make sure the block sets level on the walls. Big 5 ft level to check the block on the outside of the wall so wall doesn't lean out or in. Lots to remember when laying block. Done several buildings and the last one was at my daughters home basement. Victor my son) can do a job of laying block as good as any block layer around. Here is a picture of My Garage and it was the same size as my daughters basement except I added an inside wall for an extra room besides a garage underneath. Do as much reading as .possible ,talk with a contractor who lays em up. Dont be afraid to give it a try. Start the corners right and most likely the rest will come into line. seek advice from one who does it for a living, is my best advice. Learning a new trade from the fellows who does it for a living is a big plus.Remember 3 -8" block equal 4 feet. Regards LOU

George, I have used 1/2"ss nuts if the motor was to soft to sustain block. Mixer is a good idea. however if no electricy isn't avaible, a motor pan can be used. I have used a crayon to mark the corners on the footings .Lots to remember like measuring cross corner to make sure the building will remain square. I'm sure Brad will be successful in his endeavor. Your post will help. Good reply. Regards LOU.

Worked a couple of summers as a hod carrier/laborer for a masonary contractor. Also done a lot of concrete work. Watched the masons work and although can easily duplicate the movements it is a lot tougher to put them in practice. Like playing an air guitar to an actual guitar. I have since laid a few brick, but am extremely slow and would hesitate to construct a whole building. Pouring/finishing concrete no problem and would probably pour the walls before attempting to lay many blocks.

I have built 4 block foundations on houses i have built, I set the first course on the wet footing or slab and have never uses dowels to the footing or slab. If the wall is going to sustain horizontal loads such as earth fill you will need to reinforce the wall vertically at a spacing close to the height of the wall.
If its just an interior wall you should be fine without reinforcing,If its on a hardened floor a layer of mortar under the first course will be needed.Build your ends/corners first up to half the wall height keeping it plumb and stepping the blocks back to the end. you now have half a block showing for each course and you can string a line from one end to the other, set each row of blocks on a mortar bed (i like 3/8 ")with the top at the line and make level the perpendicular dimension.

Look up speed block systems for dry layup and easy completion. Jim

Thanks for all the great advice!!

I am going to tackle that project after I get my well hooked up in the shop. Battling against the season.

Brad

I agree it's something you can probably learn to do. In my 36 years in construction I've laid just enough block to know I don't ever want to lay anymore!

If you're in a hurry you might want to consider hiring a masonry contractor. A good mason contractor will have at least a 3 man crew. Two block layers and a laborer to tend them. If you said how big the room is I missed it, but a 3 man crew would probably finish the project in the time it would take you to lay up a corner or two 4' high.

Would your time be used more efficiently laying block, or doing something else?

Will you have help? Having someone to mix the mortar and carry block will speed up the process.

Others have posted good advice. The one thing I disagree with is using nuts for permanent spacers or shims. Doing so can create a stress point and could cause the block to crack.

One thing I didn't see mentioned was setting a steel door jamb. It is CRITICAL that the jamb is set plumb and well braced. Don't forget to place a spreader (or 3) to keep the side jambs from bowing inward towards each other when you slug the hollow area between the jamb and the block with mortar.

You didn't say what size block you were going to use. I suggest 8". You could use 6" block but it's harder to get a quality job with the narrow block.

A friend put up a big building for his machine shop building using Blockbond. It has lasted very well. I have laid up block for additions to two houses by myself. I would not think for a second about going with Block Bond seeing both