How much weight can a plastic anchor hold in concrete?

Overall, plastic expansion anchors are the least strong of all the anchors discussed here, with actual pull-out strength of around 30 pounds in concrete but as little as 10 lbs in drywall (depending on the anchor and screw size). Unfortunately, many people use plastic anchors in drywall when they shouldn't.

naturalhandyman.com - You Can Hang ALMOST Anything With Wall Anchors

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You Can Hang ALMOST Anything With Wall Anchors

Use the right anchor... if it's worth hanging, it's worth hanging right!!

Every day... somewhere... something near and dear falls off someone's wall or ceiling! To that end we offer this collection of information, a primer as it were, of experiences and common sense to help you keep YOUR wall hangings where they belong! (Even if you think you know everything there is to know about anchors, there may be something here for you, too!)

What is an anchor?

An anchor is a fastener that can attach one object to another in situations where screws, nails, adhesives or other simple fasteners are either impractical or ineffective. Two common surfaces where anchors are useful are 1) on extremely hard surfaces such as concrete and 2) on hollow surfaces such as doors, walls and ceilings...especially where there is no convenient wood stud or beam behind the surface. There are many styles of anchors, each one having different strengths and weaknesses... literally! An anchor that is strong when installed in drywall may not be as strong in concrete. Or visa versa! Perhaps the biggest problem with anchors is almost all of them "feel" strong when first installed. Over time, though, an anchor that is mismatched to the wall material will eventually loosen up causing damage to the wall, your hanging and whatever was underneath it! This confusion is compounded by manufacturers who sell towel bars, small cabinets and other "hung" items with anchors that are not strong enough for the job. In the interest of "economy", the least expensive anchors are sometimes included with no instruction concerning safer, alternate mounting methods. How much weight can an anchor hold? That depends on how much you trust my disclaimer... Trying to pin me down, huh? I wish I could tell you with precision, but the strength of any anchor is subject to a number of variables, such as 1) the type of object being hung, 2) the type of surface the anchor is installed on, 3) the condition of the surface... and, of course, 4) the type of anchor! For example, you might successfully hang a 25 lb.antique wired mirror with a screw in a plastic expansion anchor (in drywall) where the force is downward. The same anchor and screw might not be able to support a 25 pound cabinet if the cabinet tends to pull the anchor outward... which means destroyed valuables!! It's all relative. Strength, that is. I will be including some load data on each type of anchor, but take this more as a measure of relative strength between the types of anchors... not a rule or firm guideline! If your wall is structurally weak, has been repaired, has water damage, etc., it is impossible to know the true strength without on-site testing. Of course, that's up to you 'cause you're there and I'm way over here!

Types of anchors and their uses...

All anchors can be divided into two basic types... expansion anchors and hollow wall anchors. 1) Expansion anchors are used in thick, solid materials... concrete, brick, mortar, metals or even wood. They work by expanding when a screw or bolt is threaded into them. If you remember anything about expansion anchors, remember this... Expansion anchors are only as strong as the material they are installed in!! If an expansion anchor is installed in a soft material (such as drywall), it may appear to be strong but don't be fooled... the strength is minimal and it will eventually loosen and/or pull out if too much stress is put on it. 2) Hollow-wall anchors, on the other hand, will not work in solid materials. Instead, they are designed to be used in thin materials or on hollow walls. They each have a unique way of spreading within the hollow of the wall. Once spread, the anchor cannot be pulled back through the smaller installation hole. The strength of a spreading anchor is proportional to the size of the "spread"! Those are the basics... now lets look at some specific anchors from the least strong to the most strong. We will investigate specific concrete anchors in another article.

Plastic (and other) expansion anchors

Plastic expansion anchors are one of the most commonly used... and abused... wall anchors. They are available in a number of sizes and designs (see graphic). Larger plastic anchors will accept larger screws and therefore have greater holding capacity. The more heavily "ribbed" anchors will give the greatest gripping strength, regardless of the wall material. When a screw is installed into a plastic anchor it expands, exerting force against the material it is installed in. As with all expansion anchors, they are strongest when used in a solid material, such as concrete. Their strength is even limited in concrete, though, because plastic is not indestructible... hence they may pull out because of anchor breakage! (For this specific application there are expansion anchors made of lead... there is one in the graphic above in the upper left corner. More in a future article on concrete anchors!) Installing a plastic anchor is a matter of first making a hole for the anchor in the surface. This can be done with a drill in hard materials, or an awl in drywall. I have always preferred using an awl in drywall since there is no dust produced. However, if you prefer using a drill choose an old, worn drill bit if you have one available. Drywall is very abrasive and will dull a good drill bit! Then just press the anchor into the hole until it is flush with the surface. It is preferable that the hole be slightly smaller than the maximum width of the anchor so, if necessary, tap the anchor flush with a hammer. Caution here... if the hole is too small the anchor will collapse when you tap it in! Overall, plastic expansion anchors are the least strong of all the anchors discussed here, with actual pull-out strength of around 30 pounds in concrete but as little as 10 lbs in drywall (depending on the anchor and screw size).

Unfortunately, many people use plastic anchors in drywall when they shouldn't.

When can you safely use a plastic anchor in drywall?

When the load is light and the force is perpendicular to the anchor. You can hang rather heavy pictures or mirrors using plastic anchors, placing the wire or picture hanging hooks onto the anchor's screw. Use two anchors and screws whenever possible... the additional strength is desirable plus doing this is good picture hanging practice, anyway. Ask any professional picture framer!! To "steady" or stabilize a wall hanging that is being held up primarily by another, stronger anchor. This method of hanging is useful on towel bars or curtain rods that have two closely-spaced holes. Use a strong anchor such as a toggle in the top hole and a plastic anchor in the bottom hole. (More on this issue under "toggles"). Never use a plastic expansion anchor in a ceiling under any circumstances unless you are hanging something extremely light, such as a smoke alarm! You will be sorry!

Removing an expansion anchor...

If it didn't already pull itself out... insert a screw partially into the anchor and pull it out. Wiggling while pulling may help free up the anchor. THE SCREW, I mean!

Threaded Drywall Anchors

Known by the trade names such as EZ-Ancor (not a typo!!)or Zip-It, this type of anchor is a basically a large, outside-threaded nut with a point on the end! The large threads are intended to hold strongly into drywall and will accept #6 or #8 sheet metal screws. To install these anchors, it is advisable to first use an awl to punch a small hole the size of the "point" in the drywall. Though they are designed to be "self-starting", providing this starter hole will give you a more accurate installation. Then screw the anchor into the drywall with a Philip's head screwdriver until the head is flat against the wall surface. These can also be installed with a screw gun or a regular power drill with a screwdriver attachment. The surface of the drywall may distort, tear or slightly "buckle" as the anchor is installed... this is perfectly normal and to be expected. As you can see from the graphic (left), the pointed end of the metallic version spreads open in the wall when a long screw is installed. This spreading does not add any strength to the anchor... the points are just getting out of the way of the screw! In fact, the points can be broken off before installation if less penetration into the wall is desired. You would need to predrill a slightly larger hole for the large threads to grab the drywall, however. Threaded drywall anchors are available in both nylon and metal. In my opinion, forget about the nylon type. They are not very sturdy and are more likely to break when installed than the metal ones. The price difference is so slight that I don't understand why they are manufactured. I guess (choose one) either someone else likes them OR there is always a market for a cheaper product!

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How strong are threaded anchors? They have somewhat more holding strength in drywall than plastic expansion anchors... what doesn't... but not a lot more. Probably about double the strength... up to 15 lbs to 25 lbs on a good day. Over all, they are meant for the same, non-critical light-duty hangings as plastic expansion anchors, and shouldn't be relied on in critical applications.

Removing a threaded anchor...

Insert a screwdriver into the head of the anchor and turn counterclockwise until the anchor is free. The spreading "points" may enlarge the hole slightly as they emerge. Part of the game!

Threaded Drywall Toggles

These are the "big brother" to the threaded drywall anchor. They combine the threaded anchor's ease of installation with some of the strength of a toggle. To install, first screw the toggle into the wall. As you can see in the graphic, a toggle-like arm swings out perpendicular to the anchor as the screw is installed. Then, the toggle pulls towards the inside of the wall until flush to the wall. When installed properly they are quite strong... up to 40 lbs or more. That is, if they install properly! I have used these on four and only four occasions. On each occasion at least half of the anchors failed in one of two ways... either the "toggle" did not turn and engage the screw OR the screw strips the toggle. And I was forced... while gritting my teeth... to use a standard toggle to replace it. So... again only citing personal experience... I cannot recommend this type of toggle in its present design.

Removing threaded drywall toggles...

The toggle is not spring loaded, so removing the screw won't necessarily allow you to remove the toggle. When the screw is removed, the metal toggle might drop free. Then again, it might not. So you might not be able to remove this toggle. You have a few options... Use a screwdriver to turn the anchor counterclockwise to unscrew it from the wall. If the toggle prevents you from further removal, use a pair of snips or cutting pliers to cut the head off the body. Yuck! The body of the anchor will drop into the wall. You can then 1) repair the hole with lightweight spackle or drywall compound or 2) use a real toggle in the old hole to reinstall your hanging provided the wall isn't too damaged. If you can't cut the threaded drywall toggle apart, you can instead tap it into the wall by inserting a screwdriver into it and banging the end of the screwdriver with a hammer. Pound gently but firmly until the anchor is beneath the surface. If you continue to tap you will eventually push the anchor completely through the wall. If you are satisfied with a cosmetic repair and don't want to hang anything in the same location, tap the head slightly beneath the surface of the drywall and repair the hole with lightweight spackle or drywall compound.

Winged Plastic Anchors

This special type of plastic anchor is a compromise between strength and cost. They are much less expensive to manufacture than metal anchors, but offer more than double the strength of plastic expansion anchors. To install, first drill an appropriately-sized hole in the drywall. Then fold the wings towards each other and push the anchor through the wall. A special pointed tool is supplied with the anchor that is used to push the center of the wings out so that they properly expand in the wall. The anchor will not function properly unless this is done, even though it may feel strong when screwed into!! If you don't have the tool, a small screwdriver inserted into the screw hole will do the same job. Once the screw is installed, the wings are pulled firmly against the wall. Because these anchors is made entirely from plastic, they must be installed with some care. Too much force can rip the screws out of them or, even worse, collapse the wings. If they pull through the wall they will leave a large hole in their wake. Tightening the screws too much during installation or using too large a screw can also cause the threads to strip, making the anchor weaker. Given these drawbacks, though, they are still a decent choice for towel bars and other medium weight hangings. They should be able to support from 25 to 35 lbs each in drywall... adequate for most towel bars, toilet paper holders and other medium weight hangings. To my delight, some "enlightened" manufacturers are now beginning to supply this type of anchor with their towel bars and toilet paper holders. Hopefully more will follow suit!

Removing a winged-plastic anchor...

Turn a screw slightly into the head of the anchor and pull. It should come free. If it resists too much, you can use a 1/4" drill bit and drill the head off the anchor. The body of the anchor will drop into the wall.

Sleeve-Type Hollow Wall Anchors... a.k.a. Molly Bolts

Molly bolts are a mechanically-interesting anchor. They combine the ease of installation of a plastic expansion anchor with much greater strength. The largest mollys can hold up to 50 lbs. Essentially, a molly bolt adds permanent screw threads to any material it is attached to. Thus, anything installed with a molly can be installed and taken down a number of times with no loss of strength. Viewing the graphic at the left, the topmost molly is designed to work with very thin materials. This style is typically used to add support to hollow doors for hanging towel bars, coat hooks and even "dummy" doorknobs. The second and third mollys are called "drive mollys", the second designed for 1/2" thick drywall and the third for 5/8" thick drywall. They both have a combination metal/plastic point that supposedly allows them to be driven into drywall with a hammer. Don't count on it! More later... The lowest molly in the graphic is an original-style molly... sans point! Mollys come in sizes from 1/8" to 1/4" (that's the screw size). As with most anchors, use the largest size that will work for the task at hand since the larger the molly, the greater the strength! To install a molly, first drill a hole the diameter of the molly in the desired location. Predrilling is important even with "drive mollys" since they can be bent or distorted if the wall is too hard. For smaller mollys, an awl can be used to form the hole as described for installing plastic expansion anchors (above). Tap the molly into the hole until the head is flush with the drywall. Molly's have metal "teeth" that grip the drywall, and it is important these teeth are firmly embedded. Then turn the molly's screw clockwise. This pulls the base of the molly towards the inside of the wall while expanding the metal legs. A tip... though most molly screws have a combination Phillip's/slotted head, use a slotted screwdriver... the Phillips may slip and cause damage to the wall! Stop screwing when you feel strong resistance and the top of the molly has pulled tightly against the wall. The graphic (left) shows what you can't see... inside the wall. There is a pliers-like tool known as a molly setter that can be used to expand mollys without the use of a screwdriver. The tool pulls the screw head straight out, expanding the legs. This tool is a real timesaver for a pro, but is somewhat expensive for the weekend molly installer! The graphic to the right shows NH wasting another molly during a demonstration. Oh... the humanity! Perhaps the best reason to use this tool instead of a screwdriver is there is no "torsion" or twisting force on the molly head. The head of a molly bolt has two sharp points that dig into the drywall to hold it in place while you turn the screw. Unfortunately, turning the screw can cause the molly to spin, especially if the installation point has been repaired before OR if you are installing the molly on a hard surface such as on a hollow-core door. With the tool, you can install a molly on most any surface... drywall, wood or even metal! (On hard surfaces, you can bend the points inward to get a more flush fit.)

Removing a sleeve-type anchor or molly bolt...

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Mollys are not as easy to remove as plastic anchors or toggles, since the expansion is permanent. But there are a few tricks..

Try to remove the head from the molly bolt...

Sometimes, it is possible to twist the top of the molly bolt off by inserting one point of a small needle nose pliers into the bolt hole and with the other side grasp the outside edge of the top. Wiggle back and forth and (if you're lucky) the top will release without too much damage to the wall. Use a screwdriver to push to body of the molly into the wall, leaving you with a reasonably clean hole.

Alternatively, you can drive it into the wall...

If you're not going to hang anything in the same location, place a screwdriver or nail set onto the head of the molly and tap in gently till it pushes beneath the surface of the wall. Then repair the wall with lightweight spackle or drywall compound. Good as new! If you want to reuse the hole for a toggle, tap the anchor through the wall. Then select a toggle bolt sized to easily span the now gaping hole! Or you could be daring and try to drill the molly out. Select a very sharp drill bit at least twice the size of the molly's screw. Drill directly into the screw hole, while pressing firmly so that the molly does not spin. With any luck, the head of the molly will break free and the body will fall into the wall. If your luck has run out, the molly might begin to spin in the wall. Then, your only option is to tap it through the wall and pray for deliverance!!

Traditional Toggle Bolts and "SnapToggles"

Traditional toggle bolts are the Cadillacs (or Lexus', if you prefer) of hollow-wall anchors. They consist of two parts... the toggle itself (which looks like a pair of spring-loaded metal wings) and the accompanying machine bolt. The SnapToggle, on the other hand, uses a solid bar, not hinged wings, and has the unique feature of retaining the threaded bar's position so you can remove and reinstall the bolt. Read more on the toggler in the next section of this article.

Toggle bolt basics...

Toggle bolts are sized in two ways... by the diameter of the machine screw and by the length of the machine screw. The larger the bolt diameter, the larger and stronger the toggle since larger bolts mean beefier toggle wings. Also, the longer the bolt, the thicker the material that can be hung or the thicker the wall it can be used in! Toggles are massively strong. A "puny" 1/8" toggle can safely hold 30 lbs. on 1/2" drywall... a 3/8" toggle over 50 lbs.! Four 3/8" toggles can easily hold up most kitchen cabinets on solid 1/2" drywall (though you should, in the "real world", have at least two screws into a wall stud, one upper and one lower). That is, as long as the wall is strong enough! Note in the charts below, provided courtesy of Powers Fasteners Inc., how dramatically different the load bearing ability of toggle bolts in wallboard compares to that of toggles in hollow masonry walls. That's because the wallboard will fail before the toggle!! Keep this in mind when using this type of fastener on wallboard!! Toggles are the toggle of choice for hanging most anything from ceilings, too, such as hanging plants, mobiles, etc. The major exceptions would be "dynamic" objects such as ceiling fans, which require attachment to structural members. Also, though excessive weight may not break a large toggle through the ceiling, the ceiling itself may pull away from the joists! To install a toggle, first drill a hole in the desired location. Here is a drill sizing chart...

Now it's time to assemble the toggle...

Push the machine bolt through the object to be fastened first, then spin the toggle onto the bolt. Thread the toggle far enough that the bolt extends far enough through the body of the toggle to keep the toggle from turning sideways (graphic to left). Otherwise the toggle may not open properly in the wall (graphic stage right). Raise the object into position and push the toggle(s) through the predrilled hole(s) until you hear or feel the toggle snap open. Then pull back on the object or the bolt to keep the wings from spinning while you tighten the screw. One problem with toggles is that they do not give you a precise location as do all the other anchors we have discussed. So once the toggle is almost tight, check the position of the object and then fully tighten the toggle. Don't overtighten the toggle in drywall or you might either break the toggle or break the wall!

Tricks with Toggles!!

1) Some towel bars may have their bolt holes very close to the edge. This can cause a problem with a toggle because of the large hole needed to install them. To make this situation workable, first position the towel bar and mark the holes. Then drill the appropriately sized hole "offset" so that the hole is fully concealed behind the towel bar BUT still allows the molly screw to be in the right location.

Look at the crudely-drawn (but with love) graphics below. The left one shows the outline of a towel bar with the toggle centered over the left hole. See how the toggle hole extends beyond the towel bar? Now, on the right is the same towel bar with the toggle offset so that the hole is hidden by the towel bar. Neat trick, huh?

2) As mentioned earlier, one problem with standard toggles is that they do not tighten to a precise location. Instead, you need to position them as they are tightened. This can be a pain! The solution is to use a toggle in one hole to supply strength and a plastic expansion anchor in the second hole to get the bar into the correct position.

Removing a toggle bolt...

Toggles are the easiest anchor to remove. Just remove the bolt, which causes the toggle wing to drop into the wall. Repair the wall or cover the hole with a picture. Done.

"Green" toggle removal...a.k.a. "Save the Toggles!!"

Though they are inexpensive and (as far as I know) not an endangered species of anchor, I have nevertheless been taken to task for my last statement, being accused of being "wasteful". There is a way to save a toggle in some circumstances. If you go back a few paragraphs to my tutorial on "assembling the toggle", I mentioned that you should screw the toggle bolt far enough in to the wings so they do not twist sideways. You can do the reverse when removing the toggle, provided the object you are hanging allows you to: Pull the toggle out so there is some friction between the toggle wings and the inside of the wall. Unscrew the toggle till it is almost completely out of the wings. Insert a piece of wire through the hole and push the wings so they are at an angle (graphic right). Pull wings through the hole. You can see how this is a real "Rube Goldberg" operation... plus you risk damaging your wall hanging, the wall itself... all for the extrication of a single set of anchor wings.

Your dime, your choice!!

The SnapToggle... a unique toggle that does less damage to your walls!

THE SNAPTOGGLE (formerly called just "The Toggler") is one of NH's favorite anchors… strong and easy to install with a REUSABLE toggle… unlike other toggle bolts!

The three big pluses are:

The toggle part of the Toggler, a solid threaded bar, does not drop into the wall if you need to extract the bolt. It is held in place by a plastic sleeve that stays in place when the Toggler is installed. The SnapToggle requires a much smaller hole than a similarly-sized standard "winged" toggle… especially important in drilling hard materials such as ceramic tile or for hanging smaller heavy or stress-prone objects such as towel bars or grab bars. Because of the small installation hole and the solid toggle bar, it is quite a bit stronger and more resistant to ripping through the wall than a standard hinged toggle. Learn about them first online... then try to find them at a local store. Be forewarned... they are not as widely available as standard toggles, but you can order them direct online at www.toggler.com!

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naturalhandyman.com - You Can Hang ALMOST Anything With Wall Anchors

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