Sunday, April 12, 2015

How To Properly Frame a Floor Using TGI’s and Sheeting

How to properly frame a floor using TGI’s and Sheeting

When you are planning to frame a floor and the floor is made out of TGI’s (wood I’s) you will have to do it after the concrete walls have been poured, stripped and the interior posts and steel beams have been installed. Without these you will not be able to successfully install the sub-floor. These beams and posts are part of the engineering that works with the TGI joist system to make up your floor.

First you have to install the plate on the top of the concrete walls; this is done by attaching it to the anchor bolts that are embedded in the concrete wall when it is poured. Under the plate which is usually a 2x6 must be a piece of foam gasket, this will help stop the plate from rotting from the moisture in the concrete and will also give a better air seal.

Once your sill plate is installed then you can layout the floor joist by marking them on the newly installed sill plate.

To layout out the floor properly you will have to refer to the floor layout that is supplied by the floor manufacturer. This layout will tell you where each floor joist goes, where the beams are to be placed, the nailing pattern that must be used on the beams and the size and shape of the hangers that need to be used for the area’s that require hangers to hold the floor joist.

Once you have successfully marked out the location of the joist and beams on the sill plate then it is time to install the rim joist.

The rim joist is installed at the outside edge of the sill plate, it should be placed flush with the sill plate. The rim joist material is a different material then the floor joist and is supplied for this reason.

You should install all the beams for the stairwell or load bearing walls before you start on the TGI’s, this way none of the TGI’s will end up in the way of the beams.

Once you have it installed and nailed the beams properly you can start to install the TGI’s. These TGI’s can be installed starting at one side of the building and working your way to the other. You must nail the TGI’s into the sill plate and the rim joist at the ends where the TGI’s come in contact with it. Anywhere there isn’t enough room for the TGI’s to sit on top of a beam or the sill plate you will need to install a hanger to hold it. All hangers need to be installed with approved hanger nails, this goes for when they are nailed to the rim joist or beams/headers and also for fastening the TGI’s to the hanger.

Once you have installed all the rim joist, beams/headers and TGI’s then you can start installing the sheeting on top of them.

To install the plywood sheeting you have to start at one end of the building. Measure the depth of a sheet of plywood from the edge of the floor in, this should be 4 ft. Measure this from both ends of the building and chalk a line, this line will be where you set your first row of sheeting down, this will help keep it straight for installing every other row across the house.

The plywood sheeting should be placed with the tongue to the outside and the groove to the line that you chalked. Before you lay a sheet down you must cover the top of every TGI that the plywood will cover with a sub-floor adhesive, the amount of adhesive should be at least a ¼ inch thick and be a consistent bead everywhere. Then place the sheet on top of the area, position the sheet so that it lines up with your chalk line and is square to the edges of the building, then install screws every 8 inches throughout the entire sheet into the TGI’s below.

Install the entire first row this way all the way across the building with them lining up with your chalk line. Once this is done, then go back to where you started to start the next row of sheeting.

You should stagger the next row with a half lap, this means that you should cut the 8 ft sheet of
plywood in half so that it is only 4ft. Cover the TGI's that the sheet will cover with your adhesive and place the sheet on top. You should place the sheet so that it is facing the same way as the one before it with the grooves away and the tongue toward the first row of sheeting.

The installation of the rest of the floor can be done with you working on the sheeting that you have already installed. This is the safest way to install the floor sheeting and it also keeps you from walking on top of the adhesive that you applied to the floor joist.

Take a 2x4 and place it on the open end of the plywood sheeting so that it is butted up against the groove, now that you have the sheeting listing against one another you have to force the tongue and groove together. To do this you stand on top of the sheet and hit the 2x4 that you placed at the edge of the plywood with a sledge hammer, you hit the 2x4 and the sheet of plywood until the tongue and groove of the two sheets of plywood are tight together. Then you screw the sheet down like you did the first row.

Proceed to install the entire floor this way until the whole area is covered in sheeting.

Trims the edges so they don’t overhang the rim joist and you are done.

Rob Abbott
Village Builders Inc

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