While ideally your basement will be a fully poured 8″ thick concrete wall, sometimes, depending on overall costs, labor availability, and climate this isn’t always an option. So then what do you do… The practice of using cinder blocks and then pouring the cores full of concrete has led to some extremely sturdy and solid basement walls. When full poured walls aren’t an option, this is a great way to get a budget friendly and still incredibly strong foundation.
Perfect for the harder to access projects, using cmu’s with poured cores is a terrific solution. If for instance, the build is just in an impossible place for that concrete truck to reach, using more easily transportable block and then filling the cores of each of those blocks with concrete definitely helps make the wall a superior one.
The important thing to consider is the architect’s and engineer’s recommendations. Generally speaking at the very least, you need to pour cores every four feet with the inclusion of vertical rebar running down the core itself. Now, depending on overall site stability, backfill type, building design and structure, and intended use, this could vary. Often it is not uncommon for plans to dictate that every single core get poured. This not only helps with wall integrity but also with thermal mass.
Additionally, in pouring the cores full you are adding another level of potential waterproof protection. Damp and moist basements are certainly no fun. Contractors try to do everything within their power to avoid such a condition at all costs. Hollow block can potentially lend itself to cracks, and cracks lead to eventual seepage. By pouring the cores of those blocks, you are helping prevent and/or minimize cracks and thereby stop the water seepage.
Whatever route you take, the key is to do the job properly. Ensuring that the cores contain rebar first, that the proper mix and slump of concrete is used, and that it is allowed to cure are all vital when it comes to maintaining the integrity of your project.
The key to any successful concrete project is skilled labor if you as a homeowner are not completely comfortable completing the project. Local concrete contractors can be easily found by checking with your local ready mix concrete association or even a local business chamber of commerce can lead to qualified competent concrete contractors. You also might want to ask a friend. Sometimes the best contractors come by word of mouth.