Exterior door on slab

[BK777]

I'm currently downsizing a garage door (pics here) so I can install a small prehung door next to it. The door will sit directly on the slab. While I have some experience installing doors, I've never done an exterior door. Since the garage door itself is obviously exposed to the weather, do I need to be that concerned with the prehung door? Specifically, do I need to use a sill?

Under certain wind conditions, we can get a little water under the garage door. Not a big deal -- but I do want to avoid trapping water under the threshold of this new door. I had intended to put some kind of sealant underneath, I just don't know whether the sill would be overkill or not. Any thoughts?

 

[Toolfool]

Should always have a weathertight sill on an exterior door. If you get windblown rain I'd go for an outswing door.

 

[CraigStu]

In my previous house the walkout door was one of the pre-hung assemblies. There was an aluminum sill plate. The brick molding and a little of the main jam rotted and had to be replaced by splicing in new wood the bottom 9 inches or so. I had to remove the sill plate to do that and re-installed it w/ a couple of screws into the concrete. I sealed the outside by squirting under the edge w/ foam. I suppose you could skip a sill plate but then need some kind of hanging seal at the bottom of the door. That seal will be dragging on the floor for the entire swing of the door. I don't think you would like that much.

 

[yeldogt]

Get a pre-hung unit w/ sill. Ideally one with synthetic jams. This way the door will properly seal all the way around. It's no different vs a typical residential situation -- the inside will be a bit higher so the door clears the inside floor. I have a small commercial carpet inside of mine for winter mess.

Good sealant under the sill

 

[Kaizen]

I got a metal Pre hung fire door from Home Depot. Had plastic under the sill. I did not use any caulking under the door but did on the inside. Used pvc for the surround. No water blowing in and if any does it can dry but really nothing to rot anyway.
The door has a nice flange all the way around it for good security


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[BK777]

Thanks for the responses -- the door has already been purchased. It's inswing and has no sill so I'm kind of stuck with all that. Outswing would be dangerous because of the wind here & I really don't need a closer for this application, but could add one if it comes to that.

I think I'm going to go with something like this -- since I have the flashing and flashing tape. Those sill kits are ridiculously expensive -- I'd get one if this was going on the house.

 

[yeldogt]

You basically want a replacement sill/threshold -- sits between the jams ... I don;t remember them be all that expensive $30-40 bucks ... it's just as you have pictured.

The really nice frames have the full jams on the threshold -- so nothing is sitting on the end grain of the jam.

 

[BK777]

I was referring to something like this, which costs about 1/3 the price of the entire door. For my purpose it seems easy enough to mimic this with flashing and tape. I'll look around to see if I can find a combo unit, though the door I have has a pretty nice threshold already.

Again I would be a lot more paranoid about this if I was installing on a subfloor or had any kind of flooring on the slab.

 

[yeldogt]

In the garage -- mine sits right on the slab. You don't need anything under it. The concrete does not need any protection.

The AL threshold is sitting on the slab -- adjustable wood strip on threshold adjusts to seal rubber weatherstrip to the door bottom. I like these vs the ones with the 'U" shaped rubber on the door bottom.

The other would be for wood construction

 

[jetnow1]

In the garage -- mine sits right on the slab. You don't need anything under it. The concrete does not need any protection.

The AL threshold is sitting on the slab -- adjustable wood strip on threshold adjusts to seal rubber weatherstrip to the door bottom. I like these vs the ones with the 'U" shaped rubber on the door bottom.

The other would be for wood construction

It may not need any protection but sealing it prevents water intrusion as well as insect entry. Cheaper to do it right the first time.

 

[yeldogt]

It may not need any protection but sealing it prevents water intrusion as well as insect entry. Cheaper to do it right the first time.

I did a thick line of Sika sealant under it -- since the whole bottom is Al .. it's not a moisture concern. Any stray water is wicked into the slab anyway.