Sealing garage sill

[KillerIsMe]

What the heck...I may as well ask this question here.

We moved our garage last year onto a concrete slab that is quite a bit bigger than the garage, so the garage is kind of sitting on an island of concrete. Unfortunately the guys who moved the garage did not use a sill seal and instead caulked all the way around the inside and outside of the sill. Well the silicon caulk does not work all that well.

It's only the garage so it's not life and death but I'd really like to stop the water from coming in under the sill. Anybody have any good ideas? Lifting the garage and laying in sill seal is surely the best solution but it's not exactly a one-man job. I've given thought to mortar mix, roofing cement, flashing, even Eternabond. I'm going to tackle this when (if) winter ends.

[DMRGMC]

The problem with mortar mix or a masonry product is that temperature differentials between the concrete and the garage structure as well as any frost or freeze thaw cycle would crack the mortar mix and it will not last. If you cover it with a water proof membrane it would certainly make it last longer but it would eventually fail.
Roofing sealant usually cracks right where it shouldn’t again due to weather, exposure to the suns ultraviolet rays etc. Not sure what is on the exterior wall but I would try a water proofing membrane either liquid or tape form and then cover it with a flashing to prevent breakdown from the ultraviolet rays.
There are a number of different products by a company called Stonemason that sells a liquid crack filler for concrete that is water based. It is essentially a water based rubber product you can add water to thin it out and paint with a brush. I use it around the garage doors on the concrete to prevent freeze thaw and salt damage. Stonemason is a Henry Co that makes a few product lines like Blue Skin and Blue Seal. Blue Skin is like eternabond in larger formats, 6”, 9”, 12”. Its a lot stickier though but needs to have the ultraviolet protection. Blue Seal is a paint on type of product.
Also polyurethane caulking is a very good product usually used by siding contractors and comes in lots of colours. It can be smoothed with your fingers as you apply, before it’s skins over use a small container of soap & water to dip your finger in and manipulate the caulking. It is very malleable unlike silicone. It has more body and can be shaped easier. That way you can be more precise and it is more forgiving. The soap and water makes it easier to smooth and prevents it from sticking to your fingers. Cut the nozzle of the caulking tube straight, not at an angle and it is much easier to apply and control the flow.
Hope some of this helps.

[kiknads]

It's going to be very hard to keep the garage from leaking mostly due to the fact that there will be water sitting against the foundation. Most sealants have a hard time sealing against standing water for an extended period of time

[KillerIsMe]

Thanks guys. I knew this wouldn't be an easy fix. I live so far from civilization and there's so few people around here to consult, which is why I asked on here.