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| Feb 4 2011, 1:53 PM EST (current) | BigLoki | 1990 words added, 1 word deleted, 1 photo added |
| Feb 1 2011, 9:05 PM EST | Rocketman52 |
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This is an attempt to make basic wall construction available to any who are willing to put in the preparation, and physical labor involved in constructing a wall. These are fortress wall type of applications, and can be used for whatever scenario you may seem necessary. They can be adapted as bunker walls, or primary structures up to bridges in some cases. I will also attempt to give you all of the information I have available as to the durability of the finished product, the formulas that I know pertaining to the construction of the particular wall in relation to changing sizes, and the level of difficulty involved. Any ratings will be on a 1-10 scale for easy comparison.
Block Walls:
Difficulty 4, Labor intensity 7.5, Durability 8,6, Cost effectiveness 4
This is the easiest type of construction for those with no experience. It's essentially just stacking. The key is to run string lines across the top of each course (level of blocks) and use the butt end of your trowel to tap each block into the mortar level with the line. If one block is off, then each 2 blocks above it will also be off.
Materials:
2x6's: You will need these to “frame” the form to pour the footer. Dependent on wall size. You will need enough footage to make a square around the area to be poured.
EXAMPLE: a 10' wall, one course deep would be 21.5' of board.
Also one more to cut up and use as a skreet (to level and smooth the concrete footer.
Landscaping stakes: You will need to place 2 at each corner, and then one at every 18” interval down the form board to ensure the form stays in shape when the concrete is added. Also one at each end of the wall, and every 6 feet along the length of the wall to run strings.
Motor oil: Only a slight amount. You will need it to coat the inner sides of the board forms to ensure a proper release from the concrete footer.
Gravel: You will need to line the bottom of your footer trench with at least 4 inches of gravel to ensure A) a level pouring surface, and B) a drainage area under the footer for freeze/thaw.
This is important and can not be skipped unless you want a wall that is cracked down the middle after 2 years. Standard is Ca6, it's perfect for almost any concrete application.
The formula is as follows :
( WxLxD) width x length = ? x d = cubic feet. Any dimension that is not in feet must be converted to a percentage. 4 inches is 1/3 so .33 EXAMPLE : for an 8” x 10' x 4” pad: the math is: .65 x 10 = 6.5 x .33 = 2.15 cubic feet of gravel, or 230 pounds
There are 27 cubic feet in a cubic yard. If material must be by weight (some suppliers require this) Ca6 weighs approximately 105 pounds per cubic foot, or 2,835 pounds per cubic yard.
Concrete: You will need this to pour the footer. The average needed depth is 4” also for concrete, however in a tall wall application 8” is more desired as there is more weight on the relatively small footer. I myself figure for 8” to err on the side of too much rather than have a thin spot break down in an imperfect preparation of the footer trench.
The formula for concrete is the same as for gravel. Only change is that concrete is usually sold in cubic yards. So divide the result by 27 and you have the cubic yards.
Mortar: Most good mortar mixes are a 1:3 ratio mix with sand. You will need approximately (1) 60# mix for every 10 8x8x16 blocks.
That means (1) 20# back of mortar and (2) 20# bags of sand. This is approximate, but on the safe side, it's very close. I personally recommend (Type S) mortar. It isn't prone to settling or cracking, or flaking out. It's a bit more expensive than (Type N) but a repair will be more cost than doing it right the first time.
Blocks: I recommend 2 core blocks. The most common sized is 8”x8”x16”. These are fantastic for wall applications because of the dimensions. Structurally these make the best walls. You will need 113 blocks per 100sq.ft. Of wall. 2 core block also handle a fill pour very well should you choose to do so at some point.
Caps: These are usually found in 9”x12”x2” sizes, they are used to top the wall and not allow water, and other things enter an un-filled wall. One block per every foot of wall obviously.
Hand tamp: This is to set up the footer. All gravel must be tamped, or your footer will fail.
Mortar trowel: To apply the mortar, and tap blocks into place
Carpenter's square: To set strings for the footer
Framing level (at least 4'): For setting strings, and checking block cuts.
Mason's hammer: To cut and shape blocks.
Wheel barrow: To transport mortar.
Metal stiff tined rake: To ensure no bubbles in the footer pour.
Mixing drum: This is not “required” but I highly recommend it. Mortar can be mixed in a bucket, but god help you if you plan to do it this way. This wall will be labor intensive enough without the added work of hand mixing 6,000 pounds of mortar.
Bright mason's twine: Used to mark off the footer, and to set wall courses level and straight.
Step 1: Mark your footer.
Run a line the length you wish your wall to be, allow for a 1” overhang on each side (2” longer than the wall length) Keep in mind that you will have to cut at least one block on each course of this wall as an average. Keep the dimensions simple, or you will be cutting 2 blocks for each course as an average.
Set your stakes about a foot deep at each side, and tie it off, leaving the sting pulled straight across the ground, not high up in the air. Just high enough to not touch the highest point of the ground along the length of the string.
Using your square run the string out to your width (adding 2” for overhang on the pad) and wrap it around the stake. Run back to the beginning point, using your square to set the last stake, and finish the line to your first stake. There is room for error in this, so check it by: Run measuring tape diagonally from point to point. These lengths should be equal, adjust as necessary until it is correct.
Step 2: Set the form for the footer.
Once the lines are established correctly, start digging to the OUTSIDE of the lines, you need only dig out a trench roughly 8” deep all the way around the outside of the strings. Set stakes 1 3/4” from the edge of the string. Run your boards along the trench, and SCREW them to the stakes (if you nail it, it's a lot more difficult to remove the form.
Coat the side of the board facing the string in the oil. Dig the remainder of the footer trench to a depth of 12” trying to ensure that that depth is maintained, and consistent throughout the whole of the footer using your level,
and tape.
(this photo is not for a bearing wall, and lacks the gravel bed)
Set a level across the top of one of the long boards, and set it to level 12” above the bottom of the footer trench. Use the stakes for adjustment, move them up or down, not reattaching the board to the stake repeatedly. Make sure that the top of the board is at least a 1/2” above ground level, if not make it 1/2” above ground level and use that first board as your level point. A difference of less than an inch won't hinder you, the idea is to make it as close to “right” as possible though.
Drop the gravel in, and begin spreading and tamping. The surface should look extremely level and even. If it doesn't you are not done, and need to continue. This is the bottom of your footer, and if you don't get it right, there is no way to fix it after the pour, you just start over, which you DO NOT want to have to do, take your time, get it right.
You should now be looking at right around an 8” deep empty hole lined with flat tamped gravel. If not, you missed a step, look above.
Step 3: Pouring the footer.
This needs to be poured in one shot. I recommend having a mixer truck come in, it's not much more expensive than trying to mix that amount yourself. If you can't pout in one shot, then you need to section off the footer into sections you can handle in one pour, wait for it to set, and remove the inner form board, move it back, and repeat until done. You CAN NOT pour it in layers, only sections. You need a full 8” of concrete at a time every time.
Pour the concrete slowly from one end. Most mixes will begin curing in around 20-30 minutes, so plan ahead, you are on the clock at this point. As it's being poured on person (at least) will have to push the mix around with the rake. This is important and can not be skipped. The rake person is ensuring that the concrete is getting into every corner, and that there are no air bubbles left in the mix. The consistency should noticeably change as the air is removed, it will become thicker, and smoother. More like pudding than mud (for lack of a better analogy).
A finished pour should be rough looking, and slightly above the level of the boards. Take your extra 2x6, and place it so one of the short sides is pushed against the top of the form boards and drag in it one direction while pushing downward. This will create a relatively smooth, and completely flat level surface. The excess should be put into small piles at the ending end of the form. Keep them small, they will be heavy, and you will want to move them somewhere.
The concrete will need to cure for 48 hours preferably. Then simply unscrew the stakes from the boards, and remove them both. You now have a completed footer, ready to be built upon.
Step 4: Constructing the wall
Take a stake at each end of the form, and stretch a string across set level to a height of 8” (each block is in actuality 7 5/8” high, 8” will allow for even mortar coverage and spacing.)
More experienced Masons will lay courses out in sections. I myself am not a pro. I lay one course at a time from one end to the other, and then start the next course. This gives me a straight level course each course. I have no desire to catch a small mistake later down the road, and have a lengthy demo/rebuild process for my impatience.
Spread the mortar out in a base long enough for 4 or 5 blocks at a time, this is ample room to work at a time, any more that that is counter productive really. Lay the first block into the corner, and tap it into the mortar, level to the string. I take a landscaping stake (they are roughly 5/8” thick) and use it as a spacer to allow for a mortar joint between the blocks. Put the mortar on the edge of the block you intend to put next to the block already in place, and tap into place until it the mortar matches the depth of the stake's width (5/8”) Set the next block in the same manner down the line to the end.
I personally use a damp sponge to smooth the mortar joints out as I go. Some use a mortar joint tool, I find it to be a waste of time and money, and get better results from a simple sponge, but to each their own.
When you are required to cut a block, DO NOT try to hammer through the solid core. It will not work. You will need to chip the block past the center of the core. Splitting blocks is a skill, it may take a bit of practice to get a feel for it, but not usually more than a few tries. You will hear a “pinging” sound as you start, when that “ping” is more of a dull “thud” you are making progress, and need to back off a bit on the force you are using to make a straight crack. I know this sounds like a ridiculous description if you have not done it before, but I promise you that it will make sense after you have tried it. Thee are more complicated ways to cut a block, but they shouldn't be required it you plan your wall correctly.
All “cut” edges of the block should be pointed inward towards the wall for obvious reasons. If a cut doesn't turn out quite right, it is relatively easy to sand the cut side to make it right again. Cracks are not a big deal, and can be repaired with mortar. The mortar (if using Type S as I recommended) is actually stronger than the block, so there is no structural concern.
Caps are installed the same way. If you choose to fill the wall, rebar is not required when using a 2 core block. It won't hurt anything if you choose to incorporate the rebar, but it's not a requirement, and adds complication. I DO recommend that if you decide to fill the wall, you do so in stages while building the wall height, rather than try to pour it all in at the end.
Stage 5 : Crack a beer, congratulations, you have built a wall.
If you choose to add another row of block for depth, you do it in the same manner as you did for the original single course wall depth. You do not cap the first wall, cap it all at the end. Mortar will also have to be added to the back of the block towards the existing wall to join them together. This will effectively double your mortar needs. Do Not place a moisture barrier between the wall sections as this will make the mortar adhere to the barrier rather than the existing wall, you DO NOT want this.
Poured Form Wall:
Difficulty 7, Labor intensity 5, Durability 8, Cost effectiveness 4
Poured form walls are ideal for structures. They are seamless if done right, and are extremely durable. The drawback is that they REQUIRE a cement truck. There is no way to hand mix the extreme amounts of soncrete required, fast enough for the wall to cure at once. This method will yield a finished wall much faster than the block method, after the prep work is done. This is a project that CAN be done by a novice, however if you plan to have door or window openings it becomes increasingly more complicated with every opening. I will explain how to do all aspects of the form wall, but instruction is no replacement for experience when it comes to wall openings. I urge you to follow the instructions very carefully and pay attention to the details if you are undertaking this methof of construction for the first time. There is no way to correct an error with this method. Disassembling a poured form wall is extremely difficult, and should be avoided at all costs. Build your form, check it, and then check it again. Pouring is simple, it's the preparation that will make of break your wall.
Materials:
-2x6's You will need these to “frame” the form to pour the footer. Dependent on wall size. You will need enough footage to make a square around the area to be poured.
EXAMPLE: a 10' wall, one course deep would be 21.5' of board.
Also one more to cut up and use as a skreet (to level and smooth the concrete footer.
-2x4s: These will nee to be driven into the gound to a minimum of 2' up to the height of your form, every 4' along the length on both sides.
Also you will need them to use as supports to keep your form from spreading during the pouring process. One 2x6 will need to be angled from the ground, to the 2/3 mark up the wall; spaced every 4'
-1x8's: These will be needed to build your form. The outer of the form will need to be run COMPLETELY with these. If possible the easiets is to use boards that are the length of your wall. This is possible up to 16'. If your wall is longer than that (as most will be) I suggest pouring in sections. If this is not feasible, or desired than 4x4 posts will be required at the joints of each form, and the post will beed to be angle braced to the ground with a 2x6 in the dame manner as the rest of the form. Keep in mind that the actual width of a 1x8 is only 7 1/2"
EXAMPLE: Your wall is 10' high x 16' long. (10x12= 120 / 7.5 = 16 x 2 = 32) 32 1"x8"x16' boards will be required. if the wall is 12" wide, a braced 1"x12"x10' board can be used at each end to complete the form.
-1/2" Plywood: This will be required to line the inside of the form to prevent the concrete from seaping out between the boards, and to add strength to the form; preventing a blow out from the weight of the concrete during pouring. Use the same square footage you used for the mesh, multiply by 2 then divide by 32 for the amount of sheets you will need.
-Motor oil: This will be needed to coat the inside of the footer, and also the inside of the form. This can be used oil, vegetable oil, or an expensive purchased concrete releasing agent (which is usually recycled oil). You are only using it to be able to break the form loose from the concrete once it has cured. In a sprayer, one quart can cover roughly 300 square feet of surface.
-Landscaping stakes: You will need to place 2 at each corner, and then one at every 18” interval down the form board to ensure the form stays in shape when the concrete is added. Also one at each end of the wall, and every 6 feet along the length of the wall to run strings.
-Gravel: You will need to line the bottom of your footer trench with at least 4 inches of gravel to ensure A) a level pouring surface, and B) a drainage area under the footer for freeze/thaw.
This is important and can not be skipped unless you want a wall that is cracked down the middle after 2 years. Standard is Ca6, it's perfect for almost any concrete application.
The formula is as follows :
( WxLxD) width x length = ? x d = cubic feet. Any dimension that is not in feet must be converted to a percentage. 4 inches is 1/3 so .33 EXAMPLE : for an 8” x 10' x 4” pad: the math is: .65 x 10 = 6.5 x .33 = 2.15 cubic feet of gravel, or 230 pounds
There are 27 cubic feet in a cubic yard. If material must be by weight (some suppliers require this) Ca6 weighs approximately 105 pounds per cubic foot, or 2,835 pounds per cubic yard.
-Concrete: You will need this to pour the footer. The average needed depth is 4” also for concrete, however in a tall wall application 8” is more desired as there is more weight on the relatively small footer. I myself figure for 8” to err on the side of too much rather than have a thin spot break down in an imperfect preparation of the footer trench. The same formula is used to calculate the amount needed to pour the wall. You will need to figure the area for any openings, and subtract that from the total amound needed.
The formula for concrete is the same as for gravel. Only change is that concrete is usually sold in cubic yards. So divide the result by 27 and you have the cubic yards.
-#5 Rebar: There are other sizes, but I prefer #5 for wall reinforcement. Depending on your application of the wall there are one, or two things to calculate the amount needed. Firstly we'll go with required. You will need a length of rebar that will go at least 24" into the ground (I myself prefer 36", it makes it easier to deal with) and end roughly 2" before the top of the wall. These will need to be spaced every 36" throughout the wall. If you are making a "fortress wall" supports will need to be run horizontally every 36" also.
-Tie wire: This will be needed to secure things to the rebar, or the rebar to itself. It is sold by the row, and is fairly cheap.
-Wire mesh: This is needed for reinforcement of the wall; whether you choose to run horizontal supports or not, it is still a necessity. It is sold in rolls, but you will be more interested in the square footage. Simply figure the height of your wall x the length of your wall.
Step 1: Pouring the footer
This is done exactly the same way as above. The difference is th rebar. Rebar should be put 3' into the ground before the footer is poured. Take the height of your wall, and add 2' 10" to it. Cut your rebar to that length. Mark 3' on your rebar, and sink it into the footer trench to that mark. Space thses every 36" alowing 6" from each corner. Pour the footer same as above.
Step 2: Set your rebar
Standard wall: Take the wire mesh, and fold it out against the vertical rebar. Attach it to each rebar post by twisting the tie wire around the rebar, through the mest, and back around itself. I usually cut the wire into about 4" pieces for this. It doesn't have to be pretty, nobody will ever see it, but it DOES have to be as tight as possible to the rebar. I ususally tie to a post every 8" or so of height.
Reinforced wall: Take your length of rebar, and tie it to one of the end posts roughly 36" up from the footer. Go to the other end, and do the same. go along the length of the horisontal piece of rebar, and tie it to each post with the tie wire. Repeat this process all the way to the to, spacing roughly every 36". Then attach the mesh in the manner described above.
Step 3: Build your form
The outer of the form will need to be run with 1x8s. If possible the easiest is to use boards that are the length of your wall. This is possible up to 16'. If your wall is longer than that (as most will be) I suggest pouring in sections. If this is not feasible, or desired than 4x4 posts will be required at the joints of each form, and the post will beed to be angle braced to the ground with a 2x6 in the same manner as the rest of the form. Keep in mind that the actual width of a 1x8 is only 7 1/2"
Pound 2x4s into the ground to a minimun depth of 2 feet up to the height of your wall. Place these right at the edge of your footer, and place them every 4 feet along the length.
Next attach your 1x8s to the inside of these all along the inside of the 2x4s. Get them as tight to eachother as possible, you want to avoid any potential for failure.
Attatch the plywood to the 2x8s by running screws from the outside, through the 2x8, and into the plywood. 1 1/4" drywall screws are the cheapest, and work fine.
Spray the inside of the form with whatever you have chosen to use as a releasing agent. Coat it thoroughly, and completely, you will regret it later if you miss a spot.
Finally set your 2x4 braces. Set them to creaet a lot of tension on the form. Concrete is heavy, you want to avoid any bowing. If you can damage your form by setting an angle brace to hard, then you have skipped a step, or cut a corner, and your form will fail anyway. Set them like you mean it.
Step 4: Pour your wall
Form walls are poured with a hose attachment from the concrete truck. Using the hose, run the length of your wall with it rather than staying in one spot and trying to allow the concrete to spread on it's own. If you do that you put all of the weight on one area at once, and risk a catastrophic failure at that point. Try to keep the pour as even as possible.
You won't be able to get a guy in there with a rake like you did with the footer. Instead, using just a pole, (I use a piece of 1 1/2" PVC pipe) just move the pole around in the pour area to increase the settling of the oncrete. With the pouring methof there is little chance of a lot of air bubles being accumulated, but it does happen, and the movement in it with the pole will limit it.
Pour the concrete to the top of the form, and skreet it the same as you did the footer. Allow a minimum of 72 hours before you remove the form. That's it, nothing to it.
** If you are creating openings**
For any window/door openings, you eill have to adjust the placement of the rebar, and mesh so as no to interfere with the opening. During the form building process, you will also need to frame out that opening, and build headers for them. Make sure the Headers and sides atr secured to the outer wall of the form to prevent concrete from seeping in, and filling your opening. Then pour as normal.
Block Walls:
Difficulty 4, Labor intensity 7.5, Durability 8,6, Cost effectiveness 4
This is the easiest type of construction for those with no experience. It's essentially just stacking. The key is to run string lines across the top of each course (level of blocks) and use the butt end of your trowel to tap each block into the mortar level with the line. If one block is off, then each 2 blocks above it will also be off.
Materials:
2x6's: You will need these to “frame” the form to pour the footer. Dependent on wall size. You will need enough footage to make a square around the area to be poured.
EXAMPLE: a 10' wall, one course deep would be 21.5' of board.
Also one more to cut up and use as a skreet (to level and smooth the concrete footer.
Landscaping stakes: You will need to place 2 at each corner, and then one at every 18” interval down the form board to ensure the form stays in shape when the concrete is added. Also one at each end of the wall, and every 6 feet along the length of the wall to run strings.
Motor oil: Only a slight amount. You will need it to coat the inner sides of the board forms to ensure a proper release from the concrete footer.
Gravel: You will need to line the bottom of your footer trench with at least 4 inches of gravel to ensure A) a level pouring surface, and B) a drainage area under the footer for freeze/thaw.
This is important and can not be skipped unless you want a wall that is cracked down the middle after 2 years. Standard is Ca6, it's perfect for almost any concrete application.
The formula is as follows :
( WxLxD) width x length = ? x d = cubic feet. Any dimension that is not in feet must be converted to a percentage. 4 inches is 1/3 so .33 EXAMPLE : for an 8” x 10' x 4” pad: the math is: .65 x 10 = 6.5 x .33 = 2.15 cubic feet of gravel, or 230 pounds
There are 27 cubic feet in a cubic yard. If material must be by weight (some suppliers require this) Ca6 weighs approximately 105 pounds per cubic foot, or 2,835 pounds per cubic yard.
Concrete: You will need this to pour the footer. The average needed depth is 4” also for concrete, however in a tall wall application 8” is more desired as there is more weight on the relatively small footer. I myself figure for 8” to err on the side of too much rather than have a thin spot break down in an imperfect preparation of the footer trench.
The formula for concrete is the same as for gravel. Only change is that concrete is usually sold in cubic yards. So divide the result by 27 and you have the cubic yards.
Mortar: Most good mortar mixes are a 1:3 ratio mix with sand. You will need approximately (1) 60# mix for every 10 8x8x16 blocks.
That means (1) 20# back of mortar and (2) 20# bags of sand. This is approximate, but on the safe side, it's very close. I personally recommend (Type S) mortar. It isn't prone to settling or cracking, or flaking out. It's a bit more expensive than (Type N) but a repair will be more cost than doing it right the first time.
Blocks: I recommend 2 core blocks. The most common sized is 8”x8”x16”. These are fantastic for wall applications because of the dimensions. Structurally these make the best walls. You will need 113 blocks per 100sq.ft. Of wall. 2 core block also handle a fill pour very well should you choose to do so at some point.
Caps: These are usually found in 9”x12”x2” sizes, they are used to top the wall and not allow water, and other things enter an un-filled wall. One block per every foot of wall obviously.
Hand tamp: This is to set up the footer. All gravel must be tamped, or your footer will fail.
Mortar trowel: To apply the mortar, and tap blocks into place
Carpenter's square: To set strings for the footer
Framing level (at least 4'): For setting strings, and checking block cuts.
Mason's hammer: To cut and shape blocks.
Wheel barrow: To transport mortar.
Metal stiff tined rake: To ensure no bubbles in the footer pour.
Mixing drum: This is not “required” but I highly recommend it. Mortar can be mixed in a bucket, but god help you if you plan to do it this way. This wall will be labor intensive enough without the added work of hand mixing 6,000 pounds of mortar.
Bright mason's twine: Used to mark off the footer, and to set wall courses level and straight.
Step 1: Mark your footer.
Run a line the length you wish your wall to be, allow for a 1” overhang on each side (2” longer than the wall length) Keep in mind that you will have to cut at least one block on each course of this wall as an average. Keep the dimensions simple, or you will be cutting 2 blocks for each course as an average.
Set your stakes about a foot deep at each side, and tie it off, leaving the sting pulled straight across the ground, not high up in the air. Just high enough to not touch the highest point of the ground along the length of the string.
Using your square run the string out to your width (adding 2” for overhang on the pad) and wrap it around the stake. Run back to the beginning point, using your square to set the last stake, and finish the line to your first stake. There is room for error in this, so check it by: Run measuring tape diagonally from point to point. These lengths should be equal, adjust as necessary until it is correct.
Step 2: Set the form for the footer.
Once the lines are established correctly, start digging to the OUTSIDE of the lines, you need only dig out a trench roughly 8” deep all the way around the outside of the strings. Set stakes 1 3/4” from the edge of the string. Run your boards along the trench, and SCREW them to the stakes (if you nail it, it's a lot more difficult to remove the form.
Coat the side of the board facing the string in the oil. Dig the remainder of the footer trench to a depth of 12” trying to ensure that that depth is maintained, and consistent throughout the whole of the footer using your level,
and tape.
(this photo is not for a bearing wall, and lacks the gravel bed)
Set a level across the top of one of the long boards, and set it to level 12” above the bottom of the footer trench. Use the stakes for adjustment, move them up or down, not reattaching the board to the stake repeatedly. Make sure that the top of the board is at least a 1/2” above ground level, if not make it 1/2” above ground level and use that first board as your level point. A difference of less than an inch won't hinder you, the idea is to make it as close to “right” as possible though.
Drop the gravel in, and begin spreading and tamping. The surface should look extremely level and even. If it doesn't you are not done, and need to continue. This is the bottom of your footer, and if you don't get it right, there is no way to fix it after the pour, you just start over, which you DO NOT want to have to do, take your time, get it right.
You should now be looking at right around an 8” deep empty hole lined with flat tamped gravel. If not, you missed a step, look above.
Step 3: Pouring the footer.
This needs to be poured in one shot. I recommend having a mixer truck come in, it's not much more expensive than trying to mix that amount yourself. If you can't pout in one shot, then you need to section off the footer into sections you can handle in one pour, wait for it to set, and remove the inner form board, move it back, and repeat until done. You CAN NOT pour it in layers, only sections. You need a full 8” of concrete at a time every time.
Pour the concrete slowly from one end. Most mixes will begin curing in around 20-30 minutes, so plan ahead, you are on the clock at this point. As it's being poured on person (at least) will have to push the mix around with the rake. This is important and can not be skipped. The rake person is ensuring that the concrete is getting into every corner, and that there are no air bubbles left in the mix. The consistency should noticeably change as the air is removed, it will become thicker, and smoother. More like pudding than mud (for lack of a better analogy).
A finished pour should be rough looking, and slightly above the level of the boards. Take your extra 2x6, and place it so one of the short sides is pushed against the top of the form boards and drag in it one direction while pushing downward. This will create a relatively smooth, and completely flat level surface. The excess should be put into small piles at the ending end of the form. Keep them small, they will be heavy, and you will want to move them somewhere.
The concrete will need to cure for 48 hours preferably. Then simply unscrew the stakes from the boards, and remove them both. You now have a completed footer, ready to be built upon.
Step 4: Constructing the wall
Take a stake at each end of the form, and stretch a string across set level to a height of 8” (each block is in actuality 7 5/8” high, 8” will allow for even mortar coverage and spacing.)
More experienced Masons will lay courses out in sections. I myself am not a pro. I lay one course at a time from one end to the other, and then start the next course. This gives me a straight level course each course. I have no desire to catch a small mistake later down the road, and have a lengthy demo/rebuild process for my impatience.
Spread the mortar out in a base long enough for 4 or 5 blocks at a time, this is ample room to work at a time, any more that that is counter productive really. Lay the first block into the corner, and tap it into the mortar, level to the string. I take a landscaping stake (they are roughly 5/8” thick) and use it as a spacer to allow for a mortar joint between the blocks. Put the mortar on the edge of the block you intend to put next to the block already in place, and tap into place until it the mortar matches the depth of the stake's width (5/8”) Set the next block in the same manner down the line to the end.
I personally use a damp sponge to smooth the mortar joints out as I go. Some use a mortar joint tool, I find it to be a waste of time and money, and get better results from a simple sponge, but to each their own.
When you are required to cut a block, DO NOT try to hammer through the solid core. It will not work. You will need to chip the block past the center of the core. Splitting blocks is a skill, it may take a bit of practice to get a feel for it, but not usually more than a few tries. You will hear a “pinging” sound as you start, when that “ping” is more of a dull “thud” you are making progress, and need to back off a bit on the force you are using to make a straight crack. I know this sounds like a ridiculous description if you have not done it before, but I promise you that it will make sense after you have tried it. Thee are more complicated ways to cut a block, but they shouldn't be required it you plan your wall correctly.
All “cut” edges of the block should be pointed inward towards the wall for obvious reasons. If a cut doesn't turn out quite right, it is relatively easy to sand the cut side to make it right again. Cracks are not a big deal, and can be repaired with mortar. The mortar (if using Type S as I recommended) is actually stronger than the block, so there is no structural concern.
Caps are installed the same way. If you choose to fill the wall, rebar is not required when using a 2 core block. It won't hurt anything if you choose to incorporate the rebar, but it's not a requirement, and adds complication. I DO recommend that if you decide to fill the wall, you do so in stages while building the wall height, rather than try to pour it all in at the end.
Stage 5 : Crack a beer, congratulations, you have built a wall.
If you choose to add another row of block for depth, you do it in the same manner as you did for the original single course wall depth. You do not cap the first wall, cap it all at the end. Mortar will also have to be added to the back of the block towards the existing wall to join them together. This will effectively double your mortar needs. Do Not place a moisture barrier between the wall sections as this will make the mortar adhere to the barrier rather than the existing wall, you DO NOT want this.Poured Form Wall:
Difficulty 7, Labor intensity 5, Durability 8, Cost effectiveness 4
Poured form walls are ideal for structures. They are seamless if done right, and are extremely durable. The drawback is that they REQUIRE a cement truck. There is no way to hand mix the extreme amounts of soncrete required, fast enough for the wall to cure at once. This method will yield a finished wall much faster than the block method, after the prep work is done. This is a project that CAN be done by a novice, however if you plan to have door or window openings it becomes increasingly more complicated with every opening. I will explain how to do all aspects of the form wall, but instruction is no replacement for experience when it comes to wall openings. I urge you to follow the instructions very carefully and pay attention to the details if you are undertaking this methof of construction for the first time. There is no way to correct an error with this method. Disassembling a poured form wall is extremely difficult, and should be avoided at all costs. Build your form, check it, and then check it again. Pouring is simple, it's the preparation that will make of break your wall.
Materials:
-2x6's You will need these to “frame” the form to pour the footer. Dependent on wall size. You will need enough footage to make a square around the area to be poured.
EXAMPLE: a 10' wall, one course deep would be 21.5' of board.
Also one more to cut up and use as a skreet (to level and smooth the concrete footer.
-2x4s: These will nee to be driven into the gound to a minimum of 2' up to the height of your form, every 4' along the length on both sides.
Also you will need them to use as supports to keep your form from spreading during the pouring process. One 2x6 will need to be angled from the ground, to the 2/3 mark up the wall; spaced every 4'
-1x8's: These will be needed to build your form. The outer of the form will need to be run COMPLETELY with these. If possible the easiets is to use boards that are the length of your wall. This is possible up to 16'. If your wall is longer than that (as most will be) I suggest pouring in sections. If this is not feasible, or desired than 4x4 posts will be required at the joints of each form, and the post will beed to be angle braced to the ground with a 2x6 in the dame manner as the rest of the form. Keep in mind that the actual width of a 1x8 is only 7 1/2"
EXAMPLE: Your wall is 10' high x 16' long. (10x12= 120 / 7.5 = 16 x 2 = 32) 32 1"x8"x16' boards will be required. if the wall is 12" wide, a braced 1"x12"x10' board can be used at each end to complete the form.
-1/2" Plywood: This will be required to line the inside of the form to prevent the concrete from seaping out between the boards, and to add strength to the form; preventing a blow out from the weight of the concrete during pouring. Use the same square footage you used for the mesh, multiply by 2 then divide by 32 for the amount of sheets you will need.
-Motor oil: This will be needed to coat the inside of the footer, and also the inside of the form. This can be used oil, vegetable oil, or an expensive purchased concrete releasing agent (which is usually recycled oil). You are only using it to be able to break the form loose from the concrete once it has cured. In a sprayer, one quart can cover roughly 300 square feet of surface.
-Landscaping stakes: You will need to place 2 at each corner, and then one at every 18” interval down the form board to ensure the form stays in shape when the concrete is added. Also one at each end of the wall, and every 6 feet along the length of the wall to run strings.
-Gravel: You will need to line the bottom of your footer trench with at least 4 inches of gravel to ensure A) a level pouring surface, and B) a drainage area under the footer for freeze/thaw.
This is important and can not be skipped unless you want a wall that is cracked down the middle after 2 years. Standard is Ca6, it's perfect for almost any concrete application.
The formula is as follows :
( WxLxD) width x length = ? x d = cubic feet. Any dimension that is not in feet must be converted to a percentage. 4 inches is 1/3 so .33 EXAMPLE : for an 8” x 10' x 4” pad: the math is: .65 x 10 = 6.5 x .33 = 2.15 cubic feet of gravel, or 230 pounds
There are 27 cubic feet in a cubic yard. If material must be by weight (some suppliers require this) Ca6 weighs approximately 105 pounds per cubic foot, or 2,835 pounds per cubic yard.
-Concrete: You will need this to pour the footer. The average needed depth is 4” also for concrete, however in a tall wall application 8” is more desired as there is more weight on the relatively small footer. I myself figure for 8” to err on the side of too much rather than have a thin spot break down in an imperfect preparation of the footer trench. The same formula is used to calculate the amount needed to pour the wall. You will need to figure the area for any openings, and subtract that from the total amound needed.
The formula for concrete is the same as for gravel. Only change is that concrete is usually sold in cubic yards. So divide the result by 27 and you have the cubic yards.
-#5 Rebar: There are other sizes, but I prefer #5 for wall reinforcement. Depending on your application of the wall there are one, or two things to calculate the amount needed. Firstly we'll go with required. You will need a length of rebar that will go at least 24" into the ground (I myself prefer 36", it makes it easier to deal with) and end roughly 2" before the top of the wall. These will need to be spaced every 36" throughout the wall. If you are making a "fortress wall" supports will need to be run horizontally every 36" also.
-Tie wire: This will be needed to secure things to the rebar, or the rebar to itself. It is sold by the row, and is fairly cheap.
-Wire mesh: This is needed for reinforcement of the wall; whether you choose to run horizontal supports or not, it is still a necessity. It is sold in rolls, but you will be more interested in the square footage. Simply figure the height of your wall x the length of your wall.
Step 1: Pouring the footer
This is done exactly the same way as above. The difference is th rebar. Rebar should be put 3' into the ground before the footer is poured. Take the height of your wall, and add 2' 10" to it. Cut your rebar to that length. Mark 3' on your rebar, and sink it into the footer trench to that mark. Space thses every 36" alowing 6" from each corner. Pour the footer same as above.
Step 2: Set your rebar
Standard wall: Take the wire mesh, and fold it out against the vertical rebar. Attach it to each rebar post by twisting the tie wire around the rebar, through the mest, and back around itself. I usually cut the wire into about 4" pieces for this. It doesn't have to be pretty, nobody will ever see it, but it DOES have to be as tight as possible to the rebar. I ususally tie to a post every 8" or so of height.
Reinforced wall: Take your length of rebar, and tie it to one of the end posts roughly 36" up from the footer. Go to the other end, and do the same. go along the length of the horisontal piece of rebar, and tie it to each post with the tie wire. Repeat this process all the way to the to, spacing roughly every 36". Then attach the mesh in the manner described above.
Step 3: Build your form
The outer of the form will need to be run with 1x8s. If possible the easiest is to use boards that are the length of your wall. This is possible up to 16'. If your wall is longer than that (as most will be) I suggest pouring in sections. If this is not feasible, or desired than 4x4 posts will be required at the joints of each form, and the post will beed to be angle braced to the ground with a 2x6 in the same manner as the rest of the form. Keep in mind that the actual width of a 1x8 is only 7 1/2"
Pound 2x4s into the ground to a minimun depth of 2 feet up to the height of your wall. Place these right at the edge of your footer, and place them every 4 feet along the length.
Next attach your 1x8s to the inside of these all along the inside of the 2x4s. Get them as tight to eachother as possible, you want to avoid any potential for failure.
Attatch the plywood to the 2x8s by running screws from the outside, through the 2x8, and into the plywood. 1 1/4" drywall screws are the cheapest, and work fine.
Spray the inside of the form with whatever you have chosen to use as a releasing agent. Coat it thoroughly, and completely, you will regret it later if you miss a spot.
Finally set your 2x4 braces. Set them to creaet a lot of tension on the form. Concrete is heavy, you want to avoid any bowing. If you can damage your form by setting an angle brace to hard, then you have skipped a step, or cut a corner, and your form will fail anyway. Set them like you mean it.
Step 4: Pour your wall
Form walls are poured with a hose attachment from the concrete truck. Using the hose, run the length of your wall with it rather than staying in one spot and trying to allow the concrete to spread on it's own. If you do that you put all of the weight on one area at once, and risk a catastrophic failure at that point. Try to keep the pour as even as possible.
You won't be able to get a guy in there with a rake like you did with the footer. Instead, using just a pole, (I use a piece of 1 1/2" PVC pipe) just move the pole around in the pour area to increase the settling of the oncrete. With the pouring methof there is little chance of a lot of air bubles being accumulated, but it does happen, and the movement in it with the pole will limit it.
Pour the concrete to the top of the form, and skreet it the same as you did the footer. Allow a minimum of 72 hours before you remove the form. That's it, nothing to it.
** If you are creating openings**
For any window/door openings, you eill have to adjust the placement of the rebar, and mesh so as no to interfere with the opening. During the form building process, you will also need to frame out that opening, and build headers for them. Make sure the Headers and sides atr secured to the outer wall of the form to prevent concrete from seeping in, and filling your opening. Then pour as normal.
