Fastening Wood Posts To Concrete
Believe it or not it is sometimes easier to drill a hole in concrete than it is to do the same thing in wood. The general misconception is that concrete is difficult, if not impossible, to work with. This is unfortunate because otherwise easy tasks are simply not considered by many folks – because “working with concrete will be too hard”. OK, concrete is heavy, so if you have to remove some prepare for heavy lifting. OK, concrete is hard to finish, so if you want to pour a slab hire a finisher. However, adding features to a concrete patio can be a cake-walk if you know what you are doing.
Let’s say you want to add a handrail or trellis and you want to attach one or both to your existing concrete patio. If you know your choices, and how to easily accomplish them, you’ll discover that “will be too hard” is an old wives tale.
Most attachments to concrete are made with lag bolts that fit into an expanding sleeve known as a wedge anchor or “anchor”. A hole is drilled into the concrete, the wedge anchor is placed in the hole and a screw or bolt is screwed into the anchor causing it to “spread out” and firmly hold everything in place that gets between the bolt head and the concrete. Anchoring systems include:
- Lead shield anchors
- Steel sleeve anchors
- Plastic anchors
- Just plain hardened screws
- Concrete nails
- Powder actuated pins (concrete nails shot from a gun)
Although concrete nails and powder actuated pins are commonly used in construction, lagged anchors are safer to use and hold better. So, anchors it is. By the way, plastic anchors are OK for light tasks like hanging pictures, etc., but the big jobs like patio covers, trellises, awnings and handrails need a bit more power to insure a permanent connection.
Lead-shielded and steel-sleeved anchors are the strong ones. These puppies can be purchased along with specifications that relate their structural integrity (how much they can hold). In any event, if you want to mount a column to support a patio cover you will want to use a fastener that won’t be pulled out when a heavy wind swoops under the cover in an attempt to “blow it away”. And don’t be afraid when the store person tells you that you will have to drill the hole 4 inches deep (or more). It really is easy to do. Just make sure to clean all of the concrete powder out of the hole before attempting to insert the sleeve.
Granted, working with concrete requires special tools and fasteners, but they aren’t that difficult to learn to use. In fact, except for the type of drill bit, drilling a hole in concrete is exactly the same as drilling a hole in wood. Some wood is harder and some concrete is harder. The harder the material the longer it takes to get through it. However, hardness only slows the process – it doesn’t prevent it. To drill or cut wood use a wood bit or a wood blade. For steel use a metal bit or a metal blade and for concrete use a masonry bit or a masonry blade. It’s that simple. Now, when cutting large areas of concrete it is wise to rent heavy equipment, but the same holds true with any task and any heavy weight construction medium (wood, metal, stone or concrete).
There is one very important factor that you should keep in mind: You can use a really cheap drill bit to drill through most types of wood, but trying to save money on a masonry bit usually backfires. It is easy to drill into concrete if your masonry bit is sharp, but a cheap bit quickly dulls and that’s where a lot of the bad rap about working with concrete and stone comes from. So, even if cheaper bits and blades work well for your wood working projects be sure to step the quality up a notch when moving to stone or concrete.
If you don’t like the idea of drilling you still have the option of using a 2 lb. hammer and case hardened concrete nails, however we recommend drilling. Once you try it you’ll never go back to nails.
By the way, we didn’t mean to underrate the value of plastic anchors. They do have value beyond hanging pictures. They also are great for mounting power or irrigation panels, conduits and other pipes to all types of concrete or stone walls – inside or outside. And, that’s all there is to it.