Straight, flat lumber without knotholes provides the best concrete forms. Thick concrete pours of greater than 8 inches may require a second round of stakes set a couple of feet behind the concrete form with kickers nailed to the bottom of the rear stakes and the top of the form stakes to provide additional stability.
Concrete is a strong and versatile building material. With the advent of ready mix cement, handy homeowners can do a lot of their own concrete construction.
When it comes to pouring concrete, everything starts with the forms.
Concrete Form Release Agent:
Ensuring your concrete forms are both accurate and strong will go a long way toward a finished project that will stand the test of time. For ease of use and versatility, it's hard to beat wood as the concrete framing material of choice. Determine the design of your concrete project.
Lay your outline on the ground. Use the tape measure to ensure correct measurement and the carpenter's protractor to verify correct angles. Drive stakes into the ground at each corner of the outline. Tie twine to the first stake and string it around the perimeter of the outline, tying it to each stake. Use the level to ensure a straight, level line.
Place the first piece of wood sheathing along the string line. The width and depth of the sheathing is dependent on the amount of concrete being poured. Thicker slabs require thicker sheathing, which may be pine boards or plywood. Drive sharpened stakes on the outside of the sheathing at regular intervals. A 4-inch pour normally requires a stake every 32 inches, depending on how firm the underlying soil is.
Decrease the spacing for deeper pours and for loose soil. Nail the sheath to the stakes as close to the string line as possible. Adjust the sheathing in or out by packing soil around the stakes. Use the builder's level to ensure the sheathing is plumb. Ensure that the string line remains above the concrete forms to provide a guide for a straight line.
Repeat these steps for each side of the perimeter. Ensure that the corners are properly joined to prevent leakage. Concrete should set for three to four days before removing the forms. Mike Parker is a full-time writer, publisher and independent businessman.
He helped launch DiscoverCard as one of the company's first merchant sales reps. Hunker may earn compensation through affiliate links in this story. Tip Straight, flat lumber without knotholes provides the best concrete forms. Straight lumber with no knotholes makes the best wooden concrete forms. Step 1. Step 2. Step 3. Step 4. Step 5.Next: Filling The Form. Concrete Form Release Agent:. There are a number of different mold releases for concrete that can make the un-molding process much easier.
The goal is to pick a concrete form release that coats the inside of the form but does not contaminate the internal hardware and structure inside the form. If you can use it PAM is the best release that I have tested. A light coat on the inside of the form and the casting comes out quite easily. Wax has its moment too because it can be applied and then stays on the surface until the concrete is cast. This is useful for complex forms with lots of internal structure.
It is important to follow these instructions when using wax as a release. Apply the wax before you assemble the form to make it as easy as possible. Make sure to buff off any white residue that forms on the treated surfaces. This cloud of wax will end up on the finished casting if you skip this step. The resulting headache is not worth it. Buff it off now A rag dipped in motor oil or vegetable oil can be used just prior to casting to give another layer of release to the waxed surfaces.
The goal here is to moisten the surface with the smallest amount of oil as possible. There is wax on there already so be miserly.
I have found the other products to be more effective but that could be operator error. Whatever you use try not to use so much release that it colors the concrete. Definitely avoid letting the release drip or puddle inside of the form.Pouring a circle of concrete requires a firm form. If the circle is to cover a large area, the sides of the form will need to be braced to prevent bulging or malformation of the planned shape. Concrete forms are usually made of wood; but wood does not readily bend into a circular shape.
The correct approach for creating a form for a concrete circle will be influenced by the size and purpose of the object. Pre-made industrial poly-forms may be the ideal form when working with circles with a three foot radius or larger. Although somewhat expensive, they are reusable, which would make them a good investment for small contractors.
Plywood can be used for large circles where the arc is wide and gentle. This will increase the flexibility of the wood as the cut spaces will expand as pressure is applied to bow the board. Poured slabs the surface of which will be level with the ground can be poured directly into a carefully dug space in the earth. Clay soil is ideal for this because it will hold its shape without slumping into the dug-out space.
Arcs can also be created using two-inch thick boards that are stacked in sections, somewhat like a Chinese puzzle or bricks. By layering them, and staggering the way the pieces are stacked together, a smooth curve can be achieved that is sturdy and resistant to bowing.
The wood pieces should be clamped or screwed together, and will still need bracing before the concrete is poured into the mold. Small concrete circles, such as might be used for paving stones, can be poured into small plastic commercial forms or into cake pans. Be sure to oil the form well before pouring! You should be able to reuse these forms several times.
Daisy Peasblossom Fernchild has been writing for over 50 years. Her first online publication was a poem entitled "Safe," published in Her articles specialize in animals, handcrafts and sustainable living. Fernchild has a Bachelor of Science in education and a Master of Arts in library science. Hunker may earn compensation through affiliate links in this story. Pouring round or circular shapes with concrete can be a challenge.
Daisy Peasblossom Fernchild. Show Comments.Advanced Search Search Tips. Are you working on a concrete sign project, and wondering how to make an impression, literally, into your concrete. We can help you with our concrete form letters.
We offer two varieties of our concrete form letters. The first of our concrete form letters, is our reverse cut MDF letters. These are generic MDF letters, that we reverse cut for you to place in your form, leaving an impression that is readable left to right.
The second of our concrete form letters, is our reversed, taper cut, mdf letters. These letters are tapered on the edge, to allow easier removal, as well as a distinguished look in the concrete when removed. The taper adds a bit of depth, as well as relieves some stress on the concrete, by not having a sharp 90 degree angle.
We can customize concrete form letters in nearly any font, and thickness, although the height, and font, determine the geometry of the letter. Please wait Search Advanced Search Search Tips. Home Concrete Form Letters. Concrete Form Letters Are you working on a concrete sign project, and wondering how to make an impression, literally, into your concrete.
Concrete Form - Reverse Cut Letters. Choose Options. Concrete Form Letters - Tapered. Current Top Sellers 1. Popular Products. New Products.Concrete Forms Time: Learn about the different sizes of forms, bracing, and how to properly square your forms. Concrete is a unique product that begins its life as a semi-solid, can be manipulated and worked to assume most any shape, and then hardens to assume that shape.
This ability to fill voids and assume shapes is what makes concrete the most-used building material on the planet. None of this would be possible without concrete forms. In simple terms, concrete forms are nothing more than a solid barrier that holds concrete in place or forces concrete to assume a certain shape. However, many newer forming systems serve other purposes as well, such as providing insulation or imparting special decorative effects.
Learn about the many types of forms available, from basic wood to specialty systems for decorative concrete. Forming Concrete With Plastic Forms Time: Forming concrete with plastic forms is an easy way to do curved radius patios, walkways, and other concrete slabs.
A square foot of conventional concrete weighs about pounds, and a typical concrete project may require hundreds to thousands of square feet of concrete to be placed at one time.
All that weight needs to be held back by concrete forms, which is why most forms are made from rigid wood or metal. In recent years, there have seen some advancements in concrete forms made of plastic, fiber glass and resins, but the cost and strength of these materials are slow to overcome the proven performance of metal and wood. Concrete forms are often categorized by where and how they are used. The best form for a particular project is often a function of the pour size, the amount of concrete the form needs to retain, and the pressure or weight that will be pushing against the form.
For example, the typical concrete forms used for flatwork such as a patio, driveway, sidewalk or road range in height from 3 to 12 inches. Because the majority of the weight of the concrete in flatwork applications is spread across a prepared subbase -- which relieves much of the weight pushing against the form -- these forms are most often wood, with metal being used for larger commercial or highway work. In contrast, a concrete form used to construct a bridge pier or high-rise building foundation will hold back hundreds to thousands of square feet of concrete, with the height of the form ranging from 12 inches to 20 feet.
Because of the massive amount of weight being exerted against these forms, they are made of high-grade steel and can weigh thousands of pounds. The most basic forms for concrete slabs where the concrete will not exceed 6 inches in height consist of wooden boards that are screwed or nailed to wood or metal stakes.
The stakes are driven into the prepared subbase, and by using leveling devices such as hand levels, laser levels or string linescontractors set the forming boards to the proper level or slope. Additional boards are then used to secure the areas where one board butts up against another. When turns, rounded edges or free-form designs are desired, thinner cross-section boards are used. To keep concrete from sticking to the forms, they are often coated with a low-grade oil, or form-release agent.
This also keeps the forms cleaner and allows them to be used multiple times before being discarded. In the case of forms used to pour walls or larger structures, such as piers or foundations, pre-manufactured forming systems are often employed. These wall systems, which are typically made from engineered wood with a metal frame or entirely from metal, are designed to attach to each other through a system of pins or latches. These types of form also use a system of ties to hold reinforcing bars in place inside the form and to secure one section to another when walls are being poured.
These forming sections come in a wide range of sizes and shapes, and most manufactures will produce custom sizes for specific projects. The trend toward energy-efficient home construction has led to the rapid growth of insulated concrete forms ICFs.
ICF systems are comprised of hollow blocks of insulating material usually expanded Styrofoam that fit together similar to children's building blocks. ICF systems are constructed on the foundation slab and remain in place to become the foundation and exterior wall system. A network of metal reinforcing bars is placed inside the block wall structure, and then the walls are filled with a high-slump concrete. The foam and concrete sandwich that is created is extremely energy efficient, and the foam becomes both the interior and exterior construction surface see How Do ICFS Work?
Using ICFs eliminates the need to remove forms, since the hollow block walls remain in place once filled with concrete. The cost to construct an ICF home is only slightly higher than for a comparable wood-frame home about 0.
This type of forming system and construction is more popular in high-energy-use regions where heating and cooling are required for much of the year. Forms for concrete countertops, furiture and precast concrete products like chairs, tables, planters and benches. The growth in popularity of concrete countertops, furniture and decorative precast products has led to new and innovative methods of forming see these videos of concrete countertop forming materials and techniques and mold making see Concrete Countertop Molds.Rest of the in-depth answer is here.
Also question is, what material is used for concrete forms? Can I use MDF for concrete forms? MDF and particleboard are useful sheet materials that are often more flat than plywood, and unlike melamine, they are ready for a coating. They are great for forms that will be coated with fiberglass resin or have laminate applied to the surface. It is not a great material for multiple uses, but it can be done.
Concrete Form Substrate Materials. Plywoodsteel, aluminum, and composite materials are used for both vertical and horizontal forming systems as a substrate material. Located behind these panels are an array of strong-backs, whalers, and trusses that also are made from woodsteel, or aluminum.
MDF for Detailed Concrete Formwork
For this type of concrete form, melamine -coated particleboard works best; it's readily available, inexpensive, and most important, concrete doesn't stick to it. Caulk all joints in the melamine construction to ensure that the concrete dries with neat edges.
Virtually any "Exterior" rated APA panel can be used for concrete formwork because all such panels are manufactured with moisture resistant adhesive. Great for making cabinet carcases because it wipes clean easily. Use it, as well, for shop fixtures or to make an economical router-table top.
Melamine is resistant to scratches, chemicals and staining. What forms to use for concrete countertops? The right way to build forms for concrete countertops. For flat precast countertop slabs, I use strips of melamine and steel angle iron on a steel-topped casting table.
For sink and faucet knockouts, I use blue insulation foam cut with a jigsaw or router and smoothed with a disk sander. I also use a router to cut the foam using a Masonite template as a guide. Can I rent concrete forms?
When you rent concrete formsthe service typically includes both the forms and transportation to the build site. Renting steel forms may seem like it would cost more in terms of both time and money, but it's important to realize just how much the high quality of steel forms will benefit your project.
What do you use for curved concrete forms? See Full Answer. How do you make curves in concrete forms? How do you make reusable concrete forms? How do you make a curved walkway? How do you make a sidewalk form? What kind of wood do you use for concrete forms? It is a popular and widely used solution for concrete forming.
It is a stable, high strength 7 ply Fir veneer. The outside layers are B grade, and are sanded providing for a smooth finish on the concrete. How long should concrete cure before removing forms? Is it OK if it rains after pouring concrete? Pouring Concrete vs Pouring Rain. If the rain occurs when the concrete is fresh about hours after mixingthe surface should be protected from the rain. If the finishing process was recently completed, rainwater may not cause damage as long as it is not worked into the surface and the slab is left untouched.
How do you install concrete forms? Can I leave concrete forms in place?E-Mail us and let us know what you think.
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