What’s the best way to fasten underlayment to the subfloor?
This application is different from most, as the underlayment will actually be 8′ long X 12″ wide rips of either 3/4″ particle board (under carpet) or 3/4″ CDX plywood (under hardwood or VCT). These strips are sleepers for a DIY radiant floor sandwich. The 3/4″ wide space between sleepers will accept channeled Al plates, which will be stapled to the sleepers and ultimately serve as channels for 1/2″ PEX. One room has a 3/4″ plywood studi-floor subfloor, the rest all have 3/4″ Advantech sublooring.
1600 sq ft of floor surface.
OVER these sleepers will be a variety, depending on the room:
1…3/4″ solid maple flooring in kitchen/dining room.
2…another layer of 5/8″ plywood topped by VCT in mudroom and laundry room
3…Cement board backer for ceramic tile in the master bath
4…3/4″ oak veneer plywood squares in bedrooms and sunroom (don’t waste time dinging me on this, I’ve already done it sucessfully in another room)
5…1/4″ pegboard topped by pad and carpet in living room
Yes, I have had a room-by-room heat loss analysis done and end up with about 25,000 BTU/hr load on a 80* design day.
So…to fasten these first sleepers down…I want to make sure they are done well, at least as well as a typical install of 4/8 sheets of underlayment, but don’t want to waste time and efforst on overkill.
PL400? Sheetrock screws? Ring shank nails? Spacing on edges versus field? (although with the strips only 12″ wide I probably should follow generally accepted practice for edge fastening) Should I take the plunge and buy an air crown stapler for this one job? I have access to a regular framing nail gun too.
Another factor is the second layer over these sleepers…for this second layer, should I plan to use fasteners long enough to go all the way through and into the subfloor, and, if so, would that affect the schedule for the sleepers?
I sure would appreciate some info here…even if it’s just the technique you use to fasten underlayment in general…I can adapt a variety based on my situation and skills/time/tool set. Thanks much
Replies
I'm bumping this up...maybe too much information.
All I really need to know is what is your typical fastening schedule (spacing on edge and field) and type/size of fastener to attach 3/4" particle board underlayment to 3/4" subfloor, part of which is advantech, and part 3/4" plywood sturdifloor.
You could use deck screws and screw it down. I would screw it ever 6" on the perimeter and every 8" in the field.
I would use deck screws at 6 or 8 " centres and maybe roll out some watered down wood glue to help bond it all together..............Rik............
Wow, such a pile of questions! Let's shake my head and see what falls out. Hope it's not snake eyes.
These pieces are not really underlayment, but shims to blcok up the real underlayment. Normally, underlay is glued and nailed with rings at 6"oc along perimeter and 8"oc in field. I would not use screws on particle baord because the heads are too likely to stand proud.
For yours, I would be likely to put down the PB with glue and nail at 6"oc along the preimeter and occasionally enough in centers to make me proud that it won't move.
I would then fasten down the real ply underlayment with glue and screws long enough to go all the way through and tie things together #### a single unit. under the VCT, I might use PB and nails, but I hate PB anyplace around moisture.
pegboard????????why do you want all those holes under the carpet? Surely you mean hardboard? Glue and nail.
Your biggest challenge will be to keep track so you don't drive a nail or scew thru one of the pex tubes. I have been known to use a can of spray paint when placing each sheet of ply over this system. Someday, someone else will be moving a wall...or the carpet layer might feel compelled to help you level out a lump....
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