When a bench needs to be fastened to concrete, brick or block, there are a nu
mber
of different considerations to take into account before starting the
job. These critical decisions include: selection of the proper type of
anchor, anchor material as well as the diameter and length of the
anchor. These will impact the success of the fastening application.
The first consideration is whether or not the bench will be
placed outdoors or indoors. This will include whether or not the
environment has moisture or chemicals present. If the bench is outdoors
in a moist environment or where chemicals are an issue, then a stainless
steel anchor should be used. Anchors made from stainless steel are rust
resistant and will retain its appearance and holding values for its
life span. If the bench is going to be placed indoors and in a dry
environment, then a standard zinc plated concrete anchor will work. Many
times, benches are placed outdoors using these standard zinc plated
anchors and after several years, the fasteners become rusted out. This
causes two major problems. 1) The rusted anchors look unattractive 2)
their holding values deteriorate. Rusted out concrete anchors are unable to hold the loads originially intended.
Another consideration is whether the bench is made from pressure
treated wood. If the bench is, then the anchor will need to be made of
stainless steel or hot-dipped galvanized. Standard zinc placed anchors
shouldn't be used to fasten pressure treated wood because these will
erode quickly. The only way to prevent erosion ois to use a stainless
steel concrete fastener or to use one that is hot-dipped galvanized.
Wedge anchors are the only concrete anchor that is manufactured using
this galvanized process. If any other anchor needs to be used, it must
be made of stainless steel.
If this bench is going to have to be removed and replaced on a
regular basis, then a female type anchor should be considered. This type
of anchor will allow for a flush surface after the bench is removed and
can also be bolted and unbolted as many times as needed without the
deterioration of the anchor's holding values. If the bench will remain
once put in place, then a wedge anchor should be used.
The third consideration when anchoring a bench to concrete is the
diameter of anchor that should be used. The larger the bench, the
larger the anchor is going to need to be. The main determine factor will
be the size of the hole in the footplate of the bench. It is important
to note that a 1/2" diameter wedge anchor will not fit into a predrilled
hole that is 1/2". The next smaller wedge anchor diameter will need to
be used. If female anchors are used, then the hole must be spotted
because the designated diameter is equal to the inside diameter of the
female anchor. For example, a 3/8" drop in ancor will need a 1/2" hole
to be drilled.
The base material will also need to be considered. If the bench
will be placed on concrete then certain anchors should be used. If the
bench is to be placed on a brick surface, the application will require
the use of different anchors. It is imperative to determine which type
of anchors will work best in the base material at hand.
The last consideration is the anchor length that needs to be
used. The length of the anchor is determined by the type of anchor used,
the diameter of the anchor and the thickness of the material being
fastened. Each anchor has a minimum embedment depth for placement of the
anchor into the base material that will allow for proper holding
values.
Types of Concrete Anchors & How To Use Them to Fasten a Bench
Wedge Anchors
Wedge anchors are commonly used for fastening benches to
concrete. They are available in zinc plated, hot-dipped galvanized and
stainless steel. They can be used in both indoor and outdoor
applications. If the bench is made from treated lumber, then a wedge
anchor can be used. Both stainless steel and hot-dipped galvanized wedge
anchors are deemed acceptable for use in treated lumber. Wedge anchors
are male type anchors meaning that the threads will be sticking out
above the surface of the concrete. The bench can be removed by loosening
the nut and lifting the bench over the threaded part of the anchor. If
the bench needs to removed permanently and the hole was drilled 2x the
length of the anchor, then the wedge anchor can be pounded into the
concrete until level with the surface of the concrete. Wedge anchors
have excellent holding values in concrete. The minimum length of the
wedge anchor that needs to be used is determined by adding the thickness
of the material to be fastened plus the minimum embedment.
Sleeve Anchors
Sleeve anchors can be used when an application requires that a
bench be attached to concrete, brick or block base material. Sleeve
anchors are available in zinc plated and stainless steel. Zinc sleeve
anchors can be used in indoor applications and stainless steel sleeve
anchors can be used in outdoor applications and with treated lumber
benches. Sleeve anchors are male type anchors so the stud will protrude
above the surface of the base material. Taking the nut and washer off
and lifting the bench over the stud will remove the bench. If the bench
will need to be removed, drill the hole 2x of the length of the anchor
so it can be hammered into the hole in concrete after removal. The
length of sleeve anchor needed is determined by adding the thickness of
the material to be fastened plus the minimum embedment of the anchor
being used. Adding the thickness of the nut and washer is not necessary
because the designated length of sleeve anchors are measured from under
the nut and washer.
Drop-in Anchors
Drop in anchors are commonly used for attaching benches to
concrete and for applications when the bench will be removed and
replaced repeatedly in the same location. Zinc plated drop in anchors
are available for indoor usage and stainless steel anchors are available
for outdoor usage. Stainless steel drop-ins can also be used with
treated lumber. The bench can easily be moved by removing the bolt that
is inserted through the bench and into the drop in anchor. Drop-in
anchors have excellent holding values in concrete but are not designed
for use in brick or block. The length of bolt that will be needed can be
found by adding the thickness of the material to be fasteneed to the
length of the internal threads of the anchor. Space must be added to
this length if any type of washers will be used.
Before installing and anchoring a bench to a concrete, brick or
block base material- it is essential to consider many things including
environment in which the bench will be placed, the base material and
length of anchor needed amoung others. Before starting your project,
taking all of these considerations into account will help the project
proceed smoothly and help prevent problems after installation.
As with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications. This article is meant to serve only as a basic explanation of concrete fasteners. Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.
Article Written By:
Bob Carlisle, President of Concrete Fasteners
Concrete Fasteners, Inc. has over 40 years of experience selling concrete fasteners. We can ship out one box or a whole pallet of concrete anchors. Our products are of the highest quality... "your satisfaction is guaranteed". We ship all orders the same day the order is received.