Hollow Wall Anchors
on June 21 2013
When it comes to hanging items such as an antique mirror, beautiful painting or heavy bookshelf on a hollow wall, a simple screw won't do the trick. Since drywall is constructed of lightweight materials that are not designed to support heavier wall hangings, standard fasteners can easily pull right out of the wall. To solve this problem, you'll want to use an anchor. Anchors come in a number of different styles, ranging from light-duty plastic wall plugs to heavy-duty toggle bolts. Which one you choose depends on what type of wall you have, how thick it is and how heavy the load is. Consider the following questions as you determine which one is right for your task:
• What types of anchors are available?
• What applications are they best suited for?
• How is each type inserted?
• How can anchors be safely removed?
• Are there any special features you'd like to have?
Applications, Types, Insertion and Removal
An anchor is a fastener, just like a screw, nail or staple. Where it differs is in how it's used. Anchors are best suited for very hard surfaces, such as concrete and masonry, or hollow surfaces, such as those found on doors, walls and ceilings. Anchors give you the ability to hang pictures, mirrors, plants and more, even if there's no stud in the spot where you wish to locate the item. One important point to remember is that no matter how much weight a given anchor is rated to hold, if the wall itself is not able to withstand the weight, whatever you're hanging will not hold. Anchors are secured into the wall, and a screw is then inserted into them to hold the object. Depending on the anchor you choose, the best methods for insertion and safe removal may differ somewhat. Applications and Usage:
Anchors can be used for a wide range of applications. Use them to secure electrical or telephone fixtures, mirrors, paintings, shelves, smoke detectors, curtain and towel rods, clocks and more. When anchors are installed, they're subject to two types of pull - the force of gravity, which pulls objects down, and the weight of objects, which pulls them outward away from the wall. Each anchor is rated to hold a specified amount of weight, but it's best to leave yourself some margin for error. A good rule of thumb is to assume that anchors will hold 1/4 of their stated load without any problem. To secure an object, simply use a number of anchors whose total load is equal to or greater than the weight of the object when added up and divided by four.
• Thicker walls will be able to support more weight, and larger anchors that accept bigger screws are
generally more secure
• Wall strength and material must be taken into account along with anchor load when determining whether
or not an object can be hung
• Even though an anchor may feel strong once secured, it may not hold over time if it cannot handle the
weight of the object it's supporting
• Drywall, plaster, lath, brick and concrete all have different densities and, as a result, can bear different
There are many different types of hollow wall anchors available. The chart below lists some of the more commonly used types, what applications they are best suited for and a few points of consideration.
Insertion and Removal:
Points to Consider
|Cement Board Screw
||Well suited for exterior use or use in moist areas, such as bathrooms.
||• Nibbed, bugle head countersinks itself
• Features a dual-depth thread that provides strong
||Used in solid materials like concrete, brick, mortar and more.
||• Spread open once anchored to provide a stronger
|Hollow Wall Anchor
||Medium- to heavy-duty applications, including paintings or solid shelving.
||• Also referred to as "molly bolts"
• Expand as screw is tightened to provide a more
• May be inserted with either a hammer or a drill
• Available for use with various wall thicknesses
• Strength increases with larger spreads
|Plastic Hollow Wall Plug
||Light-duty applications in drywall or plaster where it's not possible to anchor to a beam.
||• Require a pilot hole
• Inserting a screw causes plug to expand and lock
||Medium-duty applications, such as anchoring open shelving units like closet organizer kits.
||• Easy to install
• May be made of plastic, nylon or zinc-coated,
• May be removed and reused
• Threads cut deeply to provide a secure hold and
||Heavy items, such as mirrors and shelves. Can be used to hang items from ceilings.
||• Available in both square and slot-drive
• Require a pilot hole
• Feature wings that lock into place behind wall for
strong holding power
• Sized by both the length and diameter of the
|Winged Plastic Anchor
||Medium-duty applications, such as hanging towel bars and toilet paper holders.
||• Require a pilot hole
• A special tool is used to expand the wings once it's
Each type of anchor is inserted in a slightly different way. A toggle bolt requires a pilot hole that's just slightly larger than its folded wings to be drilled prior to insertion, after which the screw is inserted into the wings. Collapse the wings and slide the toggle into the hole. Once it's in place, pull the wings until they lock into place against the back of the drywall and then tighten the screw. To install a threaded drywall anchor, create a small hole by using an awl and then screw the anchor in with a screwdriver. Don't worry if the surface of the drywall tears or distorts slightly, as this is natural. Removing anchors is not a simple task. The easiest and most common way of dealing with them, if you are not planning to hang anything in the same spot, is to simply knock the anchor back through the wall and then close up the hole with spackle or patching compound.
• Consult manufacturer's instructions to ensure proper insertion and removal
• Insertion tools include drills, screwdrivers, awls and hammers
• Plastic wall plugs, hollow wall plugs, threaded anchors and winged plastic anchors require a pilot hole
to be drilled prior to insertion
• Other anchors can be hammered into place without the need to drill a pilot hole
• Some anchors can be removed by using a screwdriver to draw them back out
Some manufacturers make it easy to differentiate at a glance between different-sized anchors of the same type by color coordinating them, a system of classification that can make it easy to choose the appropriate corresponding screw. Molly Setter:
A molly setter is a tool, similar to a pliers, that allows you to expand threaded anchors, or molly bolts, after they have been inserted without having to make use of a screwdriver. Antirotation Fins:
This feature prevents anchors from spinning while they are being inserted, which strengthens their hold once inside the wall.