Retrofitting staple-up under existing hardwood - NAILS NAILS NAILS!

[heppm01]

I'm planning on installing 1/2" PEX with transfer plates in two rooms with existing hardwood floors. The problem is that there are hundreds and hundreds of nails poking through the subfloor, and I'll need to address that before I get very far. (I'm not at all interested in a suspended-tube setup - I'm not planning on any high-temp water).

The two solutions I've thought of so far are to snip them flush with the subfloor using a pincer-type snip, or take an angle grinder to them. Even after I do this though I think I'm still running a danger of puncture/abrasion (all it takes is one nail sticking out just a little too far). I guess the best way around that is to use an extruded plate like the Wirsbro Joist Trak, but I was hoping to go with a cheaper plate.

I'm sure someone must have done this before. Any advice or tips?

Thanks,

Matt

 

[DaveBP]

Have you tried cutting any of these off? Some of those 'whammer' type flooring nails are heat treated and they are going to cut hard. You would need a Knipex brand cutter or some other high quality tool to get through many of them. But they may just be soft steel and easy to cut with regular quality flush cutters.

Even if you cut them off I'd be inclined to grind them slightly below flush so they couldn't contact the aluminum plates. Just the thought of the possible nail-on-chalkboard screeching that could come from a few nails dragging across the plates as they expand and contract with temp changes would make my teeth hurt.

You could do a "find" on the subject of nails on this very good forum specializing in radiant systems and the headaches that can pertain to them.

(broken link removed)

In fact anybody that is contemplating doing radiant heat should lurk around that forum and scan through the old posts for interesting items. Very helpful forum. Full of questions like this post answered by some very experienced pros and DIYers, too.

 

[muleman51]

We had the same thing in our house. We just took a bfh and flatted them over making sure they were all tipped over or you will find them with some part of your body. We put the Al plates up and snapped in the tubing, works great just wish I had it in all of the house, maybe someday. Good Luck with you project. Jim

 

[EatenByLimestone]

What about putting in a layer of hardboard in between the pex and the cut off nails?

 

[Dune]

Muleman has it right. I have installed many systems and there are always nails. Bend them over.

 

[jbird]

I'm working on the same project right now. Ended up cutting off several hundred (possibly into the thousands) nails with a 4 1/2" grinder. I tried nipping some of them with nail cutters but that still left a sharp bit sticking up and still had to use the grinder. I wanted a perfectly flat surface for the plates to attach. It was time consuming and done an hour here and there but it's done now.
The plates and 3/8" tubing are from Watts Radiant.

 

[in hot water]

of all the various methods I have tried the air powered die grinder works by far the best.
Very high 22,000 RPM, much faster than an angle grinder.
Use a thin muffler cutting disc. They remove very little metal with each cut.
You can get it right against the flooring. And the thing never gets too hot to hold
With a good air supply, you will cut them as fast as you can place the tool!

I've had a die grinder on my truck for years. great for sharpening drill bits, chisels, cutting padlocks etc.

Good safety protection, hood, face shield, fire extinquisher, etc. As the sparks really fly at that speed.

I've found those flat tapered hardwood flooring nails (cleats) really don't bend over so well. I've had some push back up in the process and bump up the flooring, be careful with the nail bending process. It's tough to drive them into the subflooring flush.

I've yet to find a clipper that cuts completely flush??

Don't add another layer of hardboard if you can help. It's hard to get a good conduction transfer if it doesn't touch the flooring. Plus the extra r-value concern.

It is an ugly thankless job, but grinding really is the best method.

hr

 

[atlarge54]

When I encountered hardwood flooring nails I simply squeezed the homemade alum (flashing) transfer plates to hold the tubing below them. Wouldn't the nails act as heat transfer devices? You'll hear some noise on heat and cool cycles. Doesn't matter to me, floor only provides base load with water to air HX handling temp variations. Once temps drop to freezing my floor pump is switched on and stays on until the weather moderates. No leaks in five years.

 

[in hot water]

the very best heat transfer is conduction. The plate really wants to be in solid contact with the floor to best move the energy. The heavy extruded plates do move the heat to the outer edges of the plate much better. They also have a tighter tube to channel fit to eliminate expansion noise between the tube wall and plate. Flashing gauge plates tend to warp and create noise when they expand and contract. You could see a wear point after a few years if the plates rub on the nail points? The tube and thin plates do move quite a bit, especially if you run higher operating temperatures required when you don't have a tight connection to the floor.

Suspended tube with a product like UltraFin would be a choice if you have a lot of nails you don't want to deal with. It is mainly convection transfer and a joist bay warming system. It does the same job but much higher operating temperatures are required.

Just depends on what you are comfortable with, they all work to a degree.

hr

 

[DaveBP]

The pneumatic die grinder is the ultimate tool for this. We use them all the time to cut off temporary welds and bolts that inconveniently stick through farther than we like.

But check out Hot Rod's safety caveats. When I do any overhead grinding now, I use a full face respirator. You won't believe how much obnoxious dust will fly. At the very least a ball cap with visor, goggles and regular respirator. One fragment of steel in your eye is an emergency room experience. Let's not go into how I know.

Lots of cheap chinese die grinders out there for sale. But they are real air hogs, even the good ones. Look at their CFM requirements and compare it to the CFM rating of your compressor. Your typical air nailer compressor isn't going to give you much of a duty cycle.

Electric die grinders or angle grinders will work, too, but slower as he says. If your compressor won't run a pneumatic you can get one of the little electrics for less than $100. They're also noticeably heavier for overhead work.

 

[heppm01]

Thanks for the tips, guys.

As much as I love the simplicity of the brute force method (and who doesn't love beating things with a hammer!), I'll probably cut them off. I have an air-powered mini die grinder that should do the trick. I'm aiming to have the plates as flush against the surface as possible and the only way to effectively do that is to remove the exposed part of the nails.

 

[oldmilwaukee]

Thought I'd catch up on some old threads, and I came across this one and couldn't help but chime in. Nails sure are a pain. I did a blog entry on this several months back. I guess the brute force method was all I could think of at the time.

The most tedious aspect of attaching the pex to the subfloor was dodging all of the flooring nails. The subfloor beneath the rooms with parquet and herringbone floors was peppered with thousands of sharp flooring nails sticking out everywhere. Fortunately, the flooring nails (technically they're called cleats) are made of crappy metal that breaks off just inside the plywood if bent back and forth a few times. After a full day of breaking off nails and stapling up aluminum plates, my neck was sore.

Fired up my Tarm up for the first time this season last week. Working great. I'm firing it about once every three days for hot water and to heat the home. (Nights are in the 40's and days are in the 60's). After the house gets to 74 and the super-stor is full of hot water, I dump the full output of the boiler into the basement slab and this allows me to coast without firing the boiler for 2 more days. I know I'll be running flat-out later this winter, but for now the wood burning pace is almost relaxing.

 

[rkusek]

Thought I'd catch up on some old threads, and I came across this one and couldn't help but chime in. Nails sure are a pain. I did a blog entry on this several months back. I guess the brute force method was all I could think of at the time.

The most tedious aspect of attaching the pex to the subfloor was dodging all of the flooring nails. The subfloor beneath the rooms with parquet and herringbone floors was peppered with thousands of sharp flooring nails sticking out everywhere. Fortunately, the flooring nails (technically they're called cleats) are made of crappy metal that breaks off just inside the plywood if bent back and forth a few times. After a full day of breaking off nails and stapling up aluminum plates, my neck was sore.

Fired up my Tarm up for the first time this season last week. Working great. I'm firing it about once every three days for hot water and to heat the home. (Nights are in the 40's and days are in the 60's). After the house gets to 74 and the super-stor is full of hot water, I dump the full output of the boiler into the basement slab and this allows me to coast without firing the boiler for 2 more days. I know I'll be running flat-out later this winter, but for now the wood burning pace is almost relaxing.

Wow! You have quite a system. Your GSHP must have both an air handler with vents throughout house as well as the ability to feed your radiant & dhw with hot water if you didn't build the fire. I'm surprised you even need the Tarm unless your electric rates are high. The wells were I live are poor and couldn't support a pump and dump setup which effectively doubles the price if it has to be a closed system with the 5 holes punched in the ground. You will enjoy your system.

 

[oldmilwaukee]

Our GSHP only works through the ductwork, and the Tarm only works through the radiant floors. The only place they come close to meeting is at the Superstor water tank. The GSHP _could_ heat the whole house most of the time, except we are off the grid and in the winter, we don't have much sunlight available to run it very often. It's primarily for air conditioning in the summer when the solar resource is greater. That's OK - having warm floors is a nice motivator to fire up the Tarm.

Found some more pictures of my staple-up floor plates, dodging the nails where I didn't break them off...

 

[Jim K in PA]

Tom - the house is looking great. Sorry I have not stopped by your blog lately.