*
Doing a new build house in London with Trus Joists and 3/4″ plywood subfloor. Have gone for a 7/8″ routed plywood thermal panel system which has a metallised factory foil face to help the pipework dissipate the heat evenly. The panels have been screwed into the subfloor and into the joists which has really stiffened up the floor very satisfactorily. The manufacturer has however allowed a 2 foot zone around the perimeter where no tubing occurs and overall the tubing layout is probably not as even as I would have liked although it is still pretty good. Question: I would rather nail a regular hardwood floor down…the pattern of the tubing is clearly marked on the panels. My gut feeling however is that the areas where there is a no tubing/tubing transition could be where the finish floor misbehaves distorts. The manufacturer says no problem will arise. I don’t like laminated flooring much due to the way the ends finish abruptly.
Any comments?
Replies
*
Daniel,
I don't know what you mean by misbehaves. Is your hardwood supplied with square butts as opposed to T&G?
Normally, there is no problems associated with installing hardwood flooring over radiant.
Gabe
*No the flooring would be standard T & G on 4 sides 3/4" and I'm still debating which to choose. Quarter sawn oak is under consideration although I don't like the grain pattern as much as flat sawn. The issue was/is really the thermal stress likely to occur over the heated,non-heated transitions due to the fact that presumably the nailed wood will be wanted to move differently on each side of the divide. I don't have prior experience of this and want to know if anybody has had problems with this.
*Daniel, the quick answer is no problem.Hope you enjoy your floor, I prefer wood as well.Gabe
*You better check the heating system specs. If you add another layer of wood floor, you insulate the radiant heating tubes. If you have any airspace under that finished floor, you will have serious impacts on the systems supply temperature (ply wood warm floor, air space, finished floor). If they have to raise the supply temp by 15 - 20 F degrees, the system may not have been sized to handle this. By raising the temp, you may compromise other structural components.The 2' no-tube radius goes against the standard practice of having more tubing closer together on the edges. I would take a second look at the design assumptions for both floor and supply temp.tedd
*PSCoincidently, I just picked up a Plumbing and Mechanical Journal article (July 17 - posted on their site 06/01/2000) by Tom Tesmar: "Don't Leave Radiant Design to Fate."I quote: "... 80% of the [in-floor radiant] heating load exists within 2 feet of the outside wall." He also talks about supply temp and the affect of flooring materials on hydronic systems.see: http://www.pmmag.com
*Thanks for the advice. The floor has been designed and I have an engineer involved in addition to the Thermal panel manufacturer. I'm not worried about the insulating value of the wood. There is only 1-1/4" of wood between pipe and and floor surface. There is no air gap beneath as 4" insulation is going to be wedged in tight between the joists. Your comments regarding the perimeter detailing is quite intriguing however, I'll take this up with the manufacturer.
*I tried accessing http://www.pmmag.com and it said that I didn't have authorised access. Sounds like a high security place! Could you perhaps post the article or explain how to access the site. There was not even a page to register on or enter a password.
*The site is definitely open to public. It has a ton of articles on radiant heating. Also, go to HeatingHelp.com and ask on the forum (called the Wall). You won't get much BS there. http://www.pmmag.com/CDA/BNPHomePage/1,2365,,00.htmlMy point about air space was not the space below the tubes, but the space above the tubes. Depends if you nail to subfloor or use sleepers, which mean a space and therefore further insulating your hydronics from the room. Since your system is embedded into the wooden floor, its unlikely your going to be able to nail into it from above without using sleepers. And, even though your not concerned with the R value of the finished floor, you should be. It is a definite heating load calculation factor and if your not being told to worry about it, then your not getting good advice. Sorry, but its a well established fact that flooring material and its R-Value and the quality of connection between tubing and finished flooring are elementary factors in design and performance. This is particularly a concern if you have no underfloor tubing within 2 feet of perimeter. That means you will be pumping up the system even higher to off-set this design flaw (and it is a flaw in the design) along with overcoming the R factor of your layers of wood floor. Laminate flooring is recommended over solid wood flooring by the way for reasons you can read about anywhere. If you have to overheat the underfloor to get more heat to surface of finished floor your risking impacts and also contradicting other benefits or RFH. But that's your business. Just don't be sold a bill of goods by your advisiors. Check with the experienced experts. You can also go to the Radiant Panel Association forum and ask there.
*tedd...I have seen the tube ply system at trade shows it is meant to nail tight to...The cost was high for it and I would go under the subfloor first. It is meant to be a carpenter friendly version of a gypcrete floor...It is well engineered and is more effective in heat transfer than underfloor staple up...i no muss, no fuss, just saw dust... Maybe I should be in marketing...near the stream,aj
*Your right, AJ, I don't know the actual product so perhaps its designed resolutions to the issues I outlined (nailing tight for example). Still doesn't resolve the 2' perimeter gap and the fact that a finished floor will add R value: both of these points will require hotter supply water temperature to overcome.Is there some extra mass in these panels to make them an alternative to gypcrete?
*I think mass is old news...And the edge idea is to... i not... pump money, outside...It is way more thought out than you and I sparing on the web...And and...like I said...I think it is expensive.Near the stream,aj
*Thanks for the advice. I do appreciate it. The 7/8" plywood has been routed and the pipe inserted in the factory, there is a metallic foil sealing it in from below. The foil surface sits on the subfloor. They have printed the tube pattern on the topside to enable the carpenter to avoid the tubing when screwing through or toenailing. There won't be any air gaps to speak of. The manufacturer believes that due to furniture placement the perimeter is often covered anyway. I'm interested in your vote in favour of laminate flooring because there would be less surface to surface contact using a floating floor particularly if the thin foam underlay were used.
*
Doing a new build house in London with Trus Joists and 3/4" plywood subfloor. Have gone for a 7/8" routed plywood thermal panel system which has a metallised factory foil face to help the pipework dissipate the heat evenly. The panels have been screwed into the subfloor and into the joists which has really stiffened up the floor very satisfactorily. The manufacturer has however allowed a 2 foot zone around the perimeter where no tubing occurs and overall the tubing layout is probably not as even as I would have liked although it is still pretty good. Question: I would rather nail a regular hardwood floor down...the pattern of the tubing is clearly marked on the panels. My gut feeling however is that the areas where there is a no tubing/tubing transition could be where the finish floor misbehaves distorts. The manufacturer says no problem will arise. I don't like laminated flooring much due to the way the ends finish abruptly.
Any comments?