I need to cover 3 large windows in a sliding door every winter. I want to be able to use the same mounting holes every year. The outside of the door seems to be aluminium with wood between.

Tee nuts are one possibility but are there better options?

  • Do you expect the doors to slide with the addition? What sort of door covers are in use?
    – wallyk
    Sep 28, 2018 at 23:00

5 Answers 5


Threaded inserts are often used where repeated removal is needed.

threaded insert

They come in a variety of types, sizes and materials. The door core is likely softwood, and stainless or brass fittings are probably needed for exterior use. Some inserts come in a kit with drill bit and insertion tool.

Images and links are illustrative only, not an endorsement of goods or sources


There are two fasteners that ought to work for you. One is an expanding screw anchor

screw anchor 1

These are quick and easy to install, but if the door has a solid wood core, it will not permit the anchor to expand.

screw anchor 2

The other product that may work for you is a rivet nut

rivet nut 1

even if the door has a solid core, it will probably allow the rivet nut to expand.

rivet nut 2


I just so happen to work at a Window and Door manufacturer and I would recommend locating a set of shop drawings (cross sections) of your door if they are available. Why I bring this up is because in the frame and mullion members (the vertical members between the glass) may be constructed in a few ways.

Depending on the material used, those members may be: solid (i.e. wood or composite); hollow with multiple little chambers (with or without metal reinforcement) (i.e. PVC or composite); or hollow with thick walls (i.e. PVC). At times, especially with the multi-chamber config, you may inadvertently screw into a weak point that can crack/damage the patio door frame/members or compromise the door's drainage path or weather resistance.

You should also consider how deep the glazing cavity is as well or, depending on where you install your fasteners, you might screw into the glass itself at the risk of cracking or shattering it.

With shop drawings from either the supplier or manufacturer, you can better determine what the door is made out of, where best to screw into, and what type of screw will be best suited for your needs.

Best of luck!


While threaded inserts, T-nuts, or expanding anchors may be the most aesthetically pleasing solutions, they are not the strongest, easiest, or cheapest.

There are two main problems with putting the nut part of the nut and bolt in the door.

  1. This requires the removal of a lot of material, probably a hole that is 1/2" to 3/4".
  2. The insert could pull out of the door.

Drilling into a glass sliding door is pretty sketchy. Minimizing drill bit diameter is going to maximize probability of success. Using a bolts will maximize strength and minimize hole size. Viewed from the side it would look like this:

(inside) Bolt --> Sliding Door --> Plywood Cover --> Nut (outside)

Using this solution, four bolt heads would be visible on the inside of the door, and four bolt ends capped with nuts would be visible on the outside of the door.

  • 3
    This was my first thought as well. I'd suggest, however reversing the order and using a Carriage Bolt (image link) on the outside with the nut on the inside as this would significantly increase the difficulty in removing the panel without permission.
    – FreeMan
    Sep 28, 2018 at 12:13
  • Thinking about it some more, though... This method leaves a complete through-hole in the door panel that will let insects in and air-conditioning out during the summer months when the panels are not installed. Some sort of summer-time plug for the holes would be recommend.
    – FreeMan
    Sep 28, 2018 at 16:31

I don't know if this is practical in your instance, but wouldn't it be better to attach covers to the frame of the door or the soffit/roof joists and deck or patio?

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