I'll take a stab at it but it's really hard to give specific recommendations w/o seeing where and how the water is coming into the garage.
There are a number of things to look at before you do anything. Does the garage have gutters and downspouts? If not, get them. If so, are they 'working' properly? If not, in the next heavy/steady rain, put on a raincoat and boots, and grab an umbrella (watch out for lightening), and see if the gutters are overflowing or leaking. See if the downspouts are leaking or are blocked. Repair and/or adjust the gutters and downspouts so the water is 'flowing' like it should. The same applies to the house.
THEN, for the house and garage, 'look' where the water goes when it exits the downspouts. Does it run BACK towards the garage? Does it pool and not drain? If so, there are options. Extend the downspouts far enough away from the garage to stop the negative draining. (Go underground with the piping if you have to.) Re-landscape around the foundation of the house and garage so that water is kept AWAY from it. If your landscape dirt is up against the block itself, it acts like a 'sponge' and will draw moisture/water into itself, thus, possibly contributing to your problem.
I could go on and on but if you want to e-mail me more info on the landscape setup and the gutter/downspout 'situation' I can give more specific info on what to do. Depending, you may or may not have to do certain things. For example, all you may need to do is re-grade. Maybe all you need to do is 'fix' the gutters/downspouts. Maybe all you need to do is extend your downspouts. Maybe all you need to do is install a french drain. I'd stop the construction until you have a remedy that works. Remember, your homeowners may NOT cover you if there's damage. (That's worth looking into ...)