Deck Joist Flush Mount Tool
Concept
Building a deck can be rewarding, economical and add value to your home. There are many web sites and references available to guide one in the design and building of a wooden deck. One of the first steps in the fabrication of a deck is the positioning and attachment of the main ledger board. This is the main horizontal board that is attached to the outside of the house. The rim and common joists will be attached perpendicular to this ledger board.
The joists are usually held in place with galvanized joist hangers. When building a deck alone it would be nice to mark out your joist spacing and install all joist hangers first. This would allow you to slip one end of your joist into the hanger and free you to line up and attach the other end. Unfortunately, pressure treated lumber of the same size does not have consistent dimensions. The width of standardized pressure treated lumber can vary greatly. For this reason, joist hangers should not be installed on the ledger board first. A photo of this process is shown above.
No matter what the width of the joist is, the key is to make sure the joist is flush or even with the top of the ledger board. When working alone, this can be a difficult task. A common aid is to attach a flat scrap piece of wood or metal to the top of the joist with one end hinging out past the edge of the joist. Two or three deck screws are used to hold the scrap wood in place temporarily. The extended end of the scrap piece of wood or metal will rest on the top of the ledger board and keep both boards flush. Once the joist is secured, the deck screws are backed out to remove the scrap piece of wood or metal. This process can be time consuming and tedious with a lot of joists to install on your deck.
I always wondered why a quick release clamping device had not been developed to eliminate the need for constant screwing and unscrewing the scrap piece of wood. Or in my case, I was using a scrap piece of metal to screw into the top of one end of the joist.
Using some commonly found supplies I put together a prototype tool that could be quickly attached and unattached to the top end of a deck joist. This would eliminate the need to constantly screw and unscrew a scrap piece of wood or metal. I have no welding skills, so my prototype was put together with bolts and epoxy glue.
Supplies
All materials and parts needed to construct this deck joist flush mount prototype were ordered on Amazon or purchased at my local hardware store.
· (2) Heavy Duty 2 ½” Stainless Steel C-Clamps
· (2) 10mm dia. x 20mm length bolts
Local hardware store
· (2) 10mm dia. Lock washers
Local hardware store
· (1) Galvanized Slotted Steel Strut Channel
· (1) JB Weld Epoxy Glue
Local hardware store
· (1) 5mm thick plywood sheet
Local hardware store
· Phoenix Support Systems Square Washer 3/8” EG 5 pack
Local hardware store
Fabrication
1. The thick square washers I purchased were slightly larger than the channel of the strut. Using my benchtop metal bandsaw, I trimmed about ¼” from one side of the washer. Now the washer fits inside the strut channel. I repeated this step with a second washer.
2. Next, the heavy-duty C-clamps had to be attached to one end of the channel strut. I felt I needed two clamps to hold the prototype joist flush tool firmly on the deck joist.
There are two reasons I purchased these particular C-clamps. First, they were large enough to clamp around a typical pressure treated wood joist (nominal 1 ½” thick). Secondly, they came with a 10mm threaded hole already tapped in the long side of the clamp. The two C-Clamps were attached approximately 3 inches apart. The first C-Clamp was positioned close to the right side of the channel strut. A 10mm dia. bolt with a corresponding sized lock washer was placed through the square washer and slotted hole of the channel strut and threaded into the top of the C-clamp. The bolt was tightened with the C-clamp perpendicular to the long axis of the channel strut. The shortest bolt I could find was 20 mm long, which was a little too long, and will have to be trimmed.
The second C-clamp was mounted to the channel strut in a similar manner spaced approximately 3 inches from the first clamp (see the photos).
3. As mentioned, the bolts were a little too long. I shortened the first bolt with a sectioning disk, in my hand-held Dremel tool, so it was flush with the inside of the C-clamp. This was a tedious process, so I tried something different with the second C-clamp. I marked the bolt where it was flush and backed the bolt out. I secured the bolt in my bandsaw table and cut the bolt at the indicated mark. This turned out to be a much easier process. I reattached the second C-clamp with the shortened bolt and verified that it was flush with the inside of the C-clamp.
4. As the joist flush mount tool sits now, it would not work. If clamped on the deck joist, the joist would be positioned too low by the thickness of the C-clamp (5 mm). To compensate for this, I found a 5mm piece of plywood to take up this gap and make the inside surface of the prototype even. The plywood was cut to the outline of the channel strut.
To secure this plywood to the resting end of the channel strut (left side) I cut a second piece of plywood that would fit inside the channel. Epoxy glue was used to secure the two wood strips together through the slotted holes in the channel strut (see photos). The wood strips were clamped in place until the epoxy cured.
5. Once the epoxy was set, I removed the clamps and noted that the plywood spacer was secured in place to the channel strut and even with the inside of the C-clamp. The deck joist flush mount tool prototype was now complete.
Testing
The first couple of photos show the old way I was making flush the far end of a deck joist that is on the opposite end of where I am standing. Instead of using a scape piece of wood, I was using a scrape piece of metal. It was just as time consuming because I still had to screw and unscrew the metal scrap piece to each deck joist.
The next series of photos show the use of the prototype deck joist flush mount tool. I found it much easier and quicker to use. I simply tightened and untightened the prototype to one edge of each deck joist with a simple 5/8” box wrench.
Future Improvements
I already see some improvements I could make to this joist flush mount tool prototype:
1. I need to put a knob on the C-clamp tread handle top to make it easier to turn.
2. I could mount the C-clamps, so they are centered on the channel strut, when clamped around a 1 ½” thick deck joist. Right now, they are slightly off center but would still work with a thicker joist.
3. The C-clamp frame jaws could possibly be longer.
4. Someday I will have a welded prototype fabricated.