Lazer lines and popped lines. The tape measure and lazer, will be your friends.

thanks for the quick response floorguy! I assume you mean using one of the lazer level products and using that to "paint" a line that continues my line from one room to another using a line existing from already installed floorboards?

thanks very much!

and again, any comments or suggestions on layout are most welcome, e.g., I feel like the lines should be layed down perpindicular to the door but, since the living/dining room not really divided much that is going to be one long room with horizontal boards in it...?

VP,
I think you should run the flooring all the same direction. Using diagram # 2, just run everything front to back (top to bottom). I don't see any reason for the direction change. As for T-molds in doorways, we don't use them for the following reasons.
1) People consider them a trip hazard and basically don't like them.
2) They are not needed IF you maintain a reasonable humidity and temp range ALL YEAR ROUND. 45 to 50% humidity and 65 to 75 degrees F.
Your floors will move very little IF you keep the environment the same.
AS far as your subfloor is concerned, try to avoid subfloor seams in doorways. At least, tie the areas together. In other words, if the bottom layer has a seam in a doorway, make sure top layer spans that seam. You must never marry seams together on a floating subfloor OR your hardwood floor WILL separate. Better yet (and this is more work), lay your subfloor at 45 degrees to your wood floor install. This way, you will never have a wood floor joint over a subfloor seam. Seam overlaps should be a minimum of 1', preferably greater for more strength. You don't need to kerf the plywood and keep the subflooring away from ALL verticle obstructions by 3/4"; including jambs. This will prevent your subfloor from buckling. The wood flooring can and must extend over the subfloor in places. This is not a problem. Keeping your subfloor flat while you are attaching them together will be one of your greater challenges . Good luck. Let us know how it turns out!

Just wanted to let everyone know how it is going on my naildown over plywood and slab project… Slicing old carpet and pad into 3' wide strips and then rolling was a great idea (from "How To" article on this site). Flatening the slab took longer than anticipated. There were several cracks where there was slight heaving. Ground down these and then used thin set to flatten slab in places where it was low. A couple places took two passes with the thinset. The self leveling stuff would be nice but wow would that be expensive on 2800 feet of floor! Am now putting in the plywood underlayment over the 10 mil poly. Found 2x8 sheets easy to work with. Fitting bathroom corners was a pain. Put bottom layer at 45 degree and then top layer at 90 to anticipated floor alignment. Both layers at 45 was going to be ALOT of work. This way I get the benefits of not having overlapping joints but it is a little quicker. Glue and screw layers together. 3 ply ½" plywood works ok but you have to be careful to weight down stack as you use it. That way it stays as flat as possible before use. I imagine 5 ply would be better but it is an extra $4 per sheet here in Phoenix. Home Depot cut 160 sheets into 2x8 panels for $20. This is a great labor saver. Am picking it up in 20 sheet batches as needed. So far, have half the house done with the poly and plywood. My prefinished flooring supplier slipped their forcast delivery date so am taking my time with the plywood install. Should have it all done by the time the flooring arrives. I like the slightly soft feel of the two layers of 1/2" plywood. With the 3/4" nail down on top it should be very nice. I do check the top layer of plywood as I go to make sure it is securely glued and screwed to bottom layer. Add screws where it feels mushy. For those concerned with moisture, using 10 mil poly under the plywood up the wall slightly and forming a "pan" over your concrete together with "floating" the plywood and keeping everything spaced from the walls – should all but elimate moisture concerns even in a wet climate (which mine is not). Will be removing about a 150 sq ft of glue down next week and that should be interesting! Hope my pogo stick power scraper works as advertised. Well, thanks again everyone for the help and advice. Back to work!

VP, Glad to hear things are going well. Keep us up to date and take some photos! Gary

Am now putting in the plywood underlayment over the 10 mil poly. Found 2x8 sheets easy to work with. Fitting bathroom corners was a pain. Put bottom layer at 45 degree and then top layer at 90 to anticipated floor alignment. Both layers at 45 was going to be ALOT of work. This way I get the benefits of not having overlapping joints but it is a little quicker. Glue and screw layers together. 3 ply ½" plywood works ok but you have to be careful to weight down stack as you use it. That way it stays as flat as possible before use. I imagine 5 ply would be better but it is an extra $4 per sheet here in Phoenix. Home Depot cut 160 sheets into 2x8 panels for $20. This is a great labor saver. Am picking it up in 20 sheet batches as needed. So far, have half the house done with the poly and plywood. My prefinished flooring supplier slipped their forcast delivery date so am taking my time with the plywood install. Should have it all done by the time the flooring arrives. I like the slightly soft feel of the two layers of 1/2" plywood. With the 3/4" nail down on top it should be very nice. I do check the top layer of plywood as I go to make sure it is securely glued and screwed to bottom layer. [/quote]

Hi VP,

I saw you're post on the Hardwoodinstaller.com site. I'm planning to lay hardwoods on my slab here in Atlanta. Read many of your post and it looks like I'll be using the same technique as you did.

How did you're project work out? Are you happy with the floating subfloor with regards to feel and sound? Would you do anything differently? I have only 900 sq ft to do and I'll be using unfinished hardwoods.

I've already installed hardwoods upstairs and that went very well, as I had joist to nail into to.

Anyway, any feedback you could provide would be appreciated.

Best...Stan in Atlanta