Sliding Glass Door Rough Opening Shims

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bottom-lip-slider-door I wrote this morning about the first steps in a sliding glass door replacement: preparing the slider rough opening. In addition to ensuring that the rough opening is right sized, you must also ensure that the bottom of the rough opening is 100% flat (both front to back, and from left to right). If the bottom of the opening isn’t flat, the sliding door will likely struggle to open or close, and may be structurally unsound.

While our door is flat from left to right, you can see in the picture at the right that our bottom opening was not flat from front to back. The tongue from the plywood ends mid-way through the door opening. In order to fix this, we purchased 1/2″ pine slats from the local big box store and used shims to raise the height of the 1/2″ pine board. But first, we cut out the plywood tongue.

Cutting out the Plywood Tongue

Cutting out the plywood tongue was a pretty simple task and we employed our Skil 18V Circular Saw. Simply set the depth on the circular saw shave off the tongue without going through the board beneath and run the saw the full length of the door frame. For areas close to the left and right sides were the circular saw wouldn’t fit, we used a simple wood chisel to remove the tongue. We used a handheld grinder to create a smooth surface.

Shimming the Bottom of the Rough Opening

After the tongue was removed, we used shims and out 1/2″ pine to level the opening. We ripped the pine down to size using a light duty table saw, and fastened the pine and shims to the floor boards using construction adhesive and finish nails.

bottom-board-shims-patio-door

When finished, the bottom opening of our rough opening is 100% flat and ready for the patio door to be installed.

Shimming for Left to Right Uneven Openings

If your door has an uneven bottom from left to right, you have two options: if you have the space, you can shim appropriately and add 1/4 plywood over the threshhold. If you don’t have the room in the rough opening, you can shim underneath the door directly but it can be challenging to get this perfect.