Subfloor and Underlayment Questions for Staple up Application

The_Zimmer_House

Hello All,



I recently purchased an 110 year old wood frame house in the NYC area and I am in the process of a reno that includes converting from a 40 year old oil fired hot air system to a hot water on-demand wall hung unit. My reno work so far has included A LOT of insulting in the walls and ceiling that were until now non-insulated. I'd say I have insulated about 70% of the home at this point with R15 Walls, R19 Ceilings, and R49 in the Attic. I plan to insulate the rest of the wall spaces with a blown in product at some point hopefully before the winter sets in.



I think I have pretty much narrowed down the system I'd want to install ( but am still open to suggestions) to a Laars Mascot II with 2 Zones of Baseboard Radiant (2nd floor bedrooms and Bathrooms, and Attic Bedrooms), and 1 zone of staple up radiant from the basement joists to heat the whole first floor approx. 800 Sq Ft.



My primary question and concern is will get the heat I need from this application, and what is the best solution for conducting or spreading the heat from the PEX across the floor evenly.



It was suggested that I use a foil type paper insulator directly under the PEX, then standard fiberglass batts w/ R15 value or os, and then finally finish the ceiling as normal, with 5/8 Sheetrock.



Joist track and or the Ultra Fins would likely be a difficult install in this application, and likely why there were not suggested. I am wondering if there are any other options.



My second question in regards to this application pertains to the flooring. The existing floor is 3/4 hardwood over a 3/4 plank sub-floor. Since the 3/4 hardwood is not really salvageable as a finished floor my plan was to go right over it with new 3/4 Oak, not removing the existing hard wood as it would likely be the best base for the new floor.



Can anyone share some advice on this.



Will the 3 layers of 3/4 wood be too much to penetrate to offer efficient and comfortable heating ?



What type of underlayment if any should i consider, just Red Rosin Paper ? 15LB Felt? Will the QuietWalk noise reducing material be a bad idea ?



Any advice would be greatly appreciated.



Thank You In Advance,

Dave

icesailor

Underlayment/olf finish floor.:

If at all possible, I would remove the old finish floor. If you do not, you will find all kinds of glitches. You will need to cut 3/4" off the bottom of every. The bottom stair step will be a "Shorty" that can seriously screw someone up. The new floor will stand proud of your old kitchen floor making a foot thumper. If you raise up the kitchen floor, you need to replace your cabinets or raise the counter-top. If you just raise the counter-top, you will not be able to remove the dishwasher. If you remove the dishwasher and run the new floor under the counter-top, you won't be able to get  the dishwasher back. If there is a cabinet over your refrigerator, make sure that the refrigerator will go back without interference.

Among Other Things.

And 3/4" of wood has a good insulation factor. Enough to compromise the heat output of the floor.

The_Zimmer_House

Underlayment/old finish floor

Thanks. Good point and def. something to consider. However I peeled away 4 layers of other old flooring to get to this orig. finished floor, so i have one uniform level of flooring across the whole 1st floor of the house. based on all my measuring and observations cabinets, doors, steps, etc. should all be good and play nice with the additional 3/4 f new hardwood.

NRT_Rob

questions

what is "baseboard radiant". you mean baseboard-style radiators, like Runtal?



staple up without plates with 3 layers of wood won't even get to 20 BTUs/sq ft. your questions cannot be answered without a good room by room heat load calculation.



Watts has a "flex plate" made of graphite now that can be handy in situations where you have lots of nails to work around. it's pricey, but seems to be a good performer.

The_Zimmer_House

Subfloor and Underlayment Questions for Staple up Application

Tx. Rob.



Yes sorry, just standard Slant-fin 15 Baseboard. I'll look into the Watts Flex Plate.

I have the head load calc somewhere for the space. I'll have to pull that up and i'll post it.



Much appreciated.



Dave

Kestrel

Watts Flex Plate

Has anyone had any experience with this product yet?

I was looking at the install instructions - it goes up after the pex, like the cheap stamped aluminum stuff that is pretty widely dismissed around here - it certainly doesn't have the 'snap in' or otherwise tight hold between the tubing and the transfer plate.

They claim however, that it's performance is better than beefier extruded aluminum.



I'd love to consider this product - I have a floor of joist bays filled with protruding nails from the hardwood above that I've been dreading nipping/grinding in preparation for the transfer plate install.  The install info says you can just puncture the FlexPlate with the nails and go on your merry way.  Wow, if true.



Any advice highly welcome!

Mark Eatherton

Doubtful...

In order for ANY heat transmission plate to work correctly (exception being Ultrafin which is a different method of heat transfer) the plate MUST have a good surface bond with sub floor. Having porcupines in your joist bay is going to complicate this matter, because the protruding nails are most probably going in random directions. Even if they were all coming from the same direction, spearing the carbon fiber with nails is going to effect the required intimate surface to surface contact.



I know that Watts has done some infrared photo comparisons. I plan on trying some of these at my radiant demonstration project in the mountains, but won't be able to give any actual data until this coming fall or winter.



As for dealing with the porcupines in the joist bays, ya just have to bite the bullet, and get in there and get'er done. Mini grinders like a Dremel tool will make the task a little easier. It is a good idea to keep a spray bottle of water available to douse any micro fires that could result from the sparks flying in the grinding process, especially if there is any lint, or spider webs involved. 



The alternative is to use Ultrafin, which is more of a convective heater in the primary stages. It does require a hotter water temperature, which is not conducive to condensing equipment, but it can be made to work. I know Hot Rod Rohr has done some infrared testing of this product early on, and saw some good data from it as it peratins to even floor temperatures.



Good luck in your endeavors.



ME

NRT_Rob

the watts plate

has better contact that most lightweights (not all) because the pipe pushes the flex groove in a bit. so less gapping. but no omega awesomeness.



I would consider them equal to extruded plates in overall capacity. and if all it does is mean that you only need to grind nails in two 3" wide strips instead of the whole joist bay, that might be nice.



I do prefer extruded plates though.

Kestrel

Thanks guys

I was figuring that that was the case.  You know what they say about things being too good to be true...

Yup - bullet meet teeth.

Do you guys nip them off, and then grind smooth, or just grind straight away; either way, what sort of tools do you use for this?

In any case, I'm seeing bigger allowance payments to the teenage, and fitting him out with hand and eye protection...

NRT_Rob

grinder

with cutting wheel attachment.



have a spray bottle on hand, can get hot. and sparky.

Gordy

Oscillating tools

 Give a power oscillating tool a try. No sparks, not as dangerous in close quarters as a grinder with a cut off wheel.

Kestrel

Oscillating Tool

Like a Fein MultiMaster?  I've had it suggested to me by a contractor friend that one of these could be invaluable, and I'm thinking of investing in one.

CMadatMe

Will I get Heat

If you are heating a space radiantly as a primary heat source then plates are a must. Can you heat without them? If the heat loss and design says I can, yes. Keep in mind that you give up even floors surface temps, quick response time and lower water temp. All factors that lead to comfort. So if comfort is what your looking for then go plates.



Fixed many of systems without plates and the difference is night and day. Ask someone that had to live with a system without plates and then had it fixed.

The_Zimmer_House

Plates

Thanks for the straight and clear advice Chris. Much appreciated.

NRT_Rob

usually true

but in low load areas, using suspended tube, the only trade off is response time, which isn't much of a design consideration IMHO.



Plates are necessary in most cases in cold climates, but low water temps are not what lead to comfort. appropriate water temps for your load/installation method and good control is.

Charlie from wmass

Low water temps are required

to get energy ( read money) savings by keeping the mod con boiler in condensing mode.

NRT_Rob

that's a few percent

true, but the double digit savings come from being sealed combustion and modulating.



I'm not arguing FOR high temp systems... just saying in the correct application suspended tube works.