Seems like one app would suffice but you need to call roundup people to ask how long b4 seeding. I think its 21 days b4 roundup is no longer toxic but unsure

Scalping will suffice (that's all I did), and this is the one time it might make sense to bag it. I didn't want all that lawn trash sitting on the soil surface when I seeded, and there was a lot of it.

You can certainly take a rake to the lawn if you like, but it's overkill. I did it in one or two very thick areas and can't say I noticed any real difference when done. Certainly the seeding went the same way there as anywhere else.

While Round Up is not technically recommended too close to planting or seeding, I did some touching up just before seeding (literally, put down the sprayer and pick up the grass seed). Seed isn't susceptible to Round Up, and by the time it sprouts the stuff is already deactivated in the soil. RU's root activity is limited, and usually requires that it ran off or you spilled a little, which then got diluted. Even so, a few days sees that soil-bound.

I'm presuming you're going to Round Up a second time (if necessary), let it work, scalp again, then plant. That won't be an issue.

Bossy - I think I can seed within a day or two using RoundUp. I'm using that basic stuff, not the one with pre-emergent.

Morpheus - thanks. When you did your renovation, after you seeded, did you follow up with rolling and/or mulching with pest moss or compost? I did this in the backyard when I was seeding overtop plain soil. Nothing existed there before. However, this time my front yard, there will surely be some dead crowns and root systems still there from the dead lawn, even after scalping. I feel that these would provide the same benefit thst mulching would (preventing dry out/providing cover). Would rolling and/or mulching the seedbed be overkill?

Either rolling or mulching (or even both) is great, as each improves the seed-soil contact. I dropped 1/4" of peat moss (closer to an eighth or even less in areas that weren't dry and didn't sit in blazing sun).

I didn't roll; a partially full roller weighs almost what I do, although even an empty roller would have helped a bit, I'm sure.

Owlnsr, you are right. I found this

Here's how to use Roundup® Weed & Grass Killer to kill an unwanted lawn and weeds for a clean start. If soil is dry, water before application and 2 to 3 days after application. If green patches remain after 7 days, reapply. Wait (at least) 3 days after last application to rake, till or replant with seed or sod.

OK so everything is nice and dead.

Ive scalped it down to 0.75 inches and bagged everything up.

I made some minor adjustments to my irrigation system (hey, why not?)

I've been watering lightly all week, 5 minutes per zone, 2-3 times per day. It's been significantly hot around here...

So far, I haven't seen any weed action. None of the usual suspects in my lawn are showing up (lespedeza, clover, oxalis, crabgrass).

I kind of feel disappointed that I can't get any weeds to grow when I want them to grow. :-P.

If I don't see any signs of life by Saturday, should I go ahead and seed? Or should I give the weeds more time to germinate?