Are there any advantages to securing a subfloor to concrete by pre-drilling and using Tapcon concrete screws as opposed to using a power activated nailer to secure the subfloor to the slab? My slab is about 15 years old and, from the test I've preformed, there are no signs of moisture. I have heard that the older concrete gets very hard. Sometimes so that is nail from a power gun will bounce off the off the concrete. Any thoughts on this?

Best...Stan

Never had a problem with it bounching. If you find that it does not drive it all the way down you can get a heavyier load.I have never seen a floor that a #5 cant drive through. The thing to remember with powder is longer is not always better with concrete. You only want to drive about ½ to ¾ into the concrete any more and you run the risk of busting up the concrete rather than grabbing it.

Tapcons will hold better and won't loose their hold over the years, like nails sometimes can. But Tapcons will be slow and expensive. I prefer to both glue and nail.

Thanks, Gary,

I too heard that Tapcons are pricey but I found a link for online purchase here. http://www.confast.com/products/tapcon- ... escrew.asp About 100 screws at around $10.00. I'll most likely use the screws to secure the CDX to the concrete and use "KLS" tip of using roofing caulk in the pilot holes for added sealing.

Regard the Tapcons. Do I need to pre-drill pilot holes in the CDX and concrete first?

Absolutely! Those tapcons will screw themselves into the concrete but you MUST predrill. Tapcon makes a drill bit assembly that you should consider getting. Different size screws require different drill bits. You must also predrill to the proper depth as well. This is why it takes so long. Hope you have a good electric drill

Like gary mentioned, you'll need a good hammer drill..If you dont have on e then RENT one. even the best non hammer drill will take twice as long. A good heavy duty hammer drill will make it a lot easier, try to use one for drilling and another drill for driving the tapcons. Phillips also make a good Tapcon style screw, I forget the name but they sell them at Lowes, they have a better head than the tapcons and they hardly ever strip (as tapcons sometimes can if you dont really lean into the drill when setting them).

Oh, and if you use a hammer drill get some ear phones, they can really scream!

why not use these http://www.confast.com/products/split-drive-anchor.asp -- at least you do not have to screw them in, just hammer?
still bugger of a job, but works

You still have to predrill with those. I don't think the screwing part is really the issue/time waster. I will be going with the concrete screws.

I agree. The more I think about it and reflect on Gary's tips, I think screw are the way to go. How many screws per 4x8 or 2x8 boards would per appropiate? Regarding the hammer drill, how many volts should I get? The range is from 14 up to 28 volts. http://www.coastaltool.com/cgi-bin/Soft ... E+coastest

I'll try to rent one instead of purchase. Don't have much need a hammer drill on a daily basis unless I can use it for general projects around the house?

Thanks again to everyone for their input.

Best...Stan

One other question on the concrete screws. 3/16" or 1/4" and what lenth? 1 1/2"?

Thanks...Stan

Just rent a good "corded" hammer drill. Like you said, if you dont have a need for a hammer drill then its kind of a waste to buy one.

3/16" X 1 1/2" is what you need. They only need to sit about 3/4" into the concrete. Buy a few extra tapcon 5/32" masonary bits too. Sometimes they can burn out quickly. Its better to have an extra right there instead of having to stop and run to the depot!.

The thing with tapcons for me is that BR-111 requires one fastener per sq ft. no matter if it is nail or tapcon. 32 tapcons per sheet of plywood is a lot of tapcons and a lot of work. A trade off is to do 9 tapcons per sheet and shoot the others. Other manufacturers are not so stringent on the amount used, but BR-111 is pretty set on 1 per sq.

We are not floating the 3/4 inch plywood because......

...visions of PERGO dance in my head.

I suppose 3/4" oak is a much different animal and the overall weight of the flooring, combined with the stoutness of the 3/4" CDX and furniture on top of that would keep the floor stable. But I just don't know. I just think that the whole project should be as secure as possible.

There was a guy on this list about a year ago that layed down to layers of 1/2", (at Gary's suggestion) and he's been satisfied with the results.

With that said, SK, what are you suggesting?

Thanks...Stan

Redi-Drive is the best anchor available at any price. A spunky, little feller named Portland J Frango turned me onto them.

Tapcons will work in a pinch, but there is not really all that much holding them there. They can come loose. I saw it happen back in 'Nam.

Seriously, though. Tapcons at 1 inch imbedment are rated at less than 400 pounds pullout. Redi-drives are rated at almost 1700 pounds pullout. That is the better part of a ton, peeples!

CHU

p.s. They are cheaper than Tapcons, too. 1-5/8 redi-drives can be had for around 7 bucks per 100.