Measure the height of your threshold and use this measurement to position the fence on your table saw, keeping it that distance from the blade. Raise the blade to be 1 1/2-inches above the table. Run each board through the table saw so the width of the board equals the measurement of the threshold.
Draw a line on each board from corner to corner using your straight edge. Cut each board in half diagonally so you have 16 equal-sized triangular pieces of wood.
Position two boards against each other so the ends are flush and the longest sides are aligned. Screw these two boards together using two screws spaced 20 inches apart, so each screw is 5 inches away from the ends of the boards. Position another board against these two so all of the edges are flush. Screw the third board to the first two using two screws. Alternate the positions of the screws by 1 inch so you do not run into the first pair.
Screw the rest of the boards to the first three following the same process. You will have a 24-inch wide ramp that is 30-inches long. Position the tallest part of this ramp against your threshold for moving dollies or other equipment in and out of your house.