How to Lay a Cinder Block Foundation
When dealing with cinder block and mortar, timeliness is of utmost importance. Laying a cinder block foundation requires working at a deliberate pace because of the fast-drying cement, so you have to work fast. Cinder block is quite different from concrete. Concrete is made of sand, gravel and aggregate, and is considered more durable. Cinder block is composed of cinder and ash from coal deposits. Here are the important steps in laying a cinder block foundation: Does this Spark an idea?
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Things You'll Need
- Cement
- Cinder blocks
- Mortar
- Mortarboard
- Trowel
- Float
- Measuring level
- Masonry chisel
- Bricklayer's hammer
- Wooden planks
- Jointer
Instructions
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Preparation
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1
Before you begin, you need to know your area's frost line, the point which frost penetrates the earth. It varies depending on the climate in which you live. Knowing the frost line will help determine how much cement to buy, along with measuring the length and width of the foundation area.
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After you've bought all the materials, outline the size specifications of the foundation by laying out wooden planks. These planks should effectively make a box and will serve to hold the cement in place during the pouring. Use wooden stakes to support the planks.
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3
Lightly hose the foundation area to moisten it. Pour the cement in the foundation, using a tamper or float to smooth it out. Because the cement will harden in a matter of hours, it's a good idea to periodically check it with a measuring level so that you can compact it, if necessary.
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4
Once the top layer of the mortar has set, you'll need to cut grooves in it so that it can "breathe," which serves as a stress-reliever. You can fill the grooves with thin pieces of cardboard or sheetrock, which will expand and contract with the temperature.
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After several hours, the foundation will harden a bit. Lay the cinder blocks in the corner first, then lay the rows for the walls. As you lay the blocks, it's a good idea to smudge away excess mortar with a trowel to keep it looking clean. Just like you did with the base, use a level periodically to check for evenness.
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Tips & Warnings
Before you start your project, be sure that your foundation doesn't impede rainwater run-off.
Make sure you account for electrical wiring if you plan to run outlets out of the walls.
To lay cinder blocks without using mortar, consider using surface cement bonding.
To avoid flooding issues, consider laying a drain line around the edge of the foundation.
Avoid working in direct sunlight. Mortar sets incredibly fast under extreme heat.
References
Resources
- Photo Credit Concrete mixer image by zalisa from Fotolia.com
