How to Install Mull Bars

Ascertain which side of the window will be attached to the mull bar. Score the fins with a chisel and peel away from the side of the window. Mirror the step with the "J" leg.

Drill the anchor clip to the mull bar with the power drill. Fasten the left and the right end of the mull bar using two screws of the same size.

Pre-drill the holes for the screws that will join each jamb. Raise your window from the bottom by 3 inches. Drill a 3/8 inch diameter hole on the first layer of the window only. Raise the window from the top by 3 inches and drill another 3/8 inch hole.

Drill another hole from the bottom end of the window by measuring up to 9 inches. Repeat this step until 9 inches or less of space remains from the center. Repeat for the top end of the windows.

Fasten and lock the sash for one window. Repeat for the other window.

Squeeze silicon caulk down the lengths of one window in a vertical motion. You may start at the top or the bottom. Distribute silicon caulk on the other window as well.

Center the mull with the jamb of the window. Tighten the mull and the jamb with screws. Repeat this procedure for all pre-drilled holes and the other window.

Apply an inward pressure to seat the mull cap to the grove. Repeat. Apply a similar amount of pressure on the other side.

Apply silicon caulk along all the crevices and the cuts of the mull cap. Distribute silicon caulk along window head and window sill of the mull.

Attach the anchor clip to the sill plate after other pieces are finished being built. Tighten screws in the center. Repeat to adjoin the top anchor clip to the header.