(structural) filler for door threshold

[tff]

My builder installed an entry door and a French door on the side of my garage, and the slab that the doors rest on is slightly sloped from the rear of the garage to the front (as it should be). Due to general incompetence in my opinion, they didn't support the doors' thresholds in any permanent way as now one side of the door rests on the slab and the other side of the door has maybe a 1/4" gap or so under the threshold.
I'm trying to come up with the best way to fill the gap to 1) support the threshold and 2) seal the gap.
My plan right now is to support the threshold with shims every 6" or so and then seal the gap with foam or caulk/sealer.
Does anyone have a more elegant solution for this? e.g. drill and fill into the gap from the top with some sore of epoxy/concrete stuff (after sealing the inside and outside edge with caulk)...
Thanks.

 

[LegacyIndustrial]

"Plastic Wood" is pretty rigid once cured.

 

[bullnerd]

Can you see the gap? Or does it just flex?

Rip a piece of matching plastic and slide it in there?

Old piece of plastic decking is what I would use.

I try to use as little caulk/glue as possible for stuff like this.

 

[tff]

Can you see the gap? Or does it just flex?

Rip a piece of matching plastic and slide it in there?

Old piece of plastic decking is what I would use.

I try to use as little caulk/glue as possible for stuff like this.

So there is a gap. But the gap is zero at one end and ~1/4" at the other end since the slab is slightly sloped. If it was a consistent gap I'd add a piece of something in there, I agree. The variable gap from one end to the other is giving me the trouble.

 

[bullnerd]

Ahhh, bummer.

Yeah, something you can squirt under there would be nice.

I like your idea of drilling and filling, but you'll probably need so little, and have to buy so much.

 

[nh_yota]

Stick some composite shims every 8-12" and fill in the rest with spray foam.

 

[The Cobbler]

I would think mix up some mortar and work it underneath . clean off square & when dried run a bead of caulk ( or not)

 

[tff]

I would think mix up some mortar and work it underneath . clean off square & when dried run a bead of caulk ( or not)

Thought about this method. I'm not experienced with 'mortar' or cement... any particular type that I should use for this application?... namely working it underneath, compressive strength... thanks.

 

[The Cobbler]

any brick mortar or a concrete topping bond cement .
mix it up and work it in with any tool that you can push it underneath . they make narrow trowels for this but you can improvise
https://www.amazon.ca/dp/B000FK1UEA/?tag=atomicindus04-20

 

[bullnerd]

Spray foam, the sign of a true craftsman! lol!

How about self leveling compound? That stuff can be mixed pretty thin.

 

[Major Woody]

Use structural grout and squirt it in there with a grout bag.
You can get both at a masonry supply place.

 

[FJ4FUN]

Wolverine Coatings' TrowelEase 1162 would be up to the task...

http://www.alphagarage.com/repairing-damaged-concrete/

 

[Carford]

)) ok

 

[lakeroadster]

Can you see the gap? Or does it just flex?

Rip a piece of matching plastic and slide it in there?

Old piece of plastic decking is what I would use.

I try to use as little caulk/glue as possible for stuff like this.

So there is a gap. But the gap is zero at one end and ~1/4" at the other end since the slab is slightly sloped. If it was a consistent gap I'd add a piece of something in there, I agree. The variable gap from one end to the other is giving me the trouble.

Ahhh, bummer.

Yeah, something you can squirt under there would be nice.

I like your idea of drilling and filling, but you'll probably need so little, and have to buy so much.

Not a bummer at all. I'd stick with this concept, using some composite decking. Then follow up with some window & door spray foam to seal everything up.

 

[tff]

Getting back to this thread... Here's what I ended up doing. After sealing (caulking) the gap on the inside of each door's threshold I patiently pushed in 'Top 'n Bond Concrete Patcher'. It was kinda challenging (sort of like putting toothpaste back in the tube), but with the right tools I was able to push in the patcher and fill the gap. (I did insert aluminum spacers first every foot or so to support the threshold). Thanks for everyone's input.