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I-Joists, Fiberglass Batts, Joist Trak and Energy Star Checklist

A_Guy | Posted in General Questions on

I’m about to break ground on a 1.5 story, 2100 sf Cape Cod house on Cape Cod (lots of knee-walls). The first floor is to be heated with Wirsbo Joist Trak. Also, the large room over the garage will have an insulated floor to allow for future conditioned space(mini-split). The house will use 11 7/8 I-Joists exclusively due to the open concept design and all floor surfaces above I-Joists will be glue and screw 3/4 plywood. My building code requires I use/meet the energy star checklist.

Now for the tough stuff; my wife insisted I sell my motorcycle, use a 4 point harness when I paint my 2-decker, and spray in (foam) won’t be used (substantially) in the house.

My questions are/quandary is:

1. How to achieve Energy Star compliance for sub-floor insulation contact when a small air gap for extruded heat transfer plates promotes even floor surface heat? (current design call for R-30 9 1/2″ un-faced fiberglass batts with rim plates insulated under the 1st floor)

2. How to achieve sub-floor insulation contact compliance while using 12″ R-38 un-faced fiberglass batts in the garage/under knee wall ceilings; can an insulation installer get sufficient fit with 15″ or 16″ x 12″ in the plenum formed by 11 7/8 I-Joists 16″ on center for a 25′ x 35′ ceiling?

I’m afraid there was some misunderstanding with the HERS rater plan review during the permitting stage; he figured I would change the design during the build phase.

Oh, and increased cost is an issue…Does anyone have a winning lottery ticket they want to sell cheap?

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  1. wjrobinson | | #1

    Advice; Stop the project till the entire plan is ready, priced, on a schedule, with subs signed.

    Joe L, says insulation does NOT need to contact floor sheathing.

    Sell the motorcycle, cost benefit verses divorce.

  2. user-2890856 | | #2

    I am a Uponor certified designer / installer and have been for a very long time . The only underfloor heating application that requires an air layer is suspended tube (horrible) , PERIOD . If someone is telling you otherwise , fire them and seek qualified assistance . Uponor joist trak fastens directly to the subfloor (no gaps) and the even heat is achieved from that direct contact taking spacing , water temp , room ambient temp and all things into consideration . Insulation should be a minimum of R19 and should be right up to the sub floor . Although I am a Uponor recognized designer / installer I only use joist trak for retrofit or the occasional area where floor height is an issue . As for your knee walls , why don't you utilize them as radiant wall heat instead of the floor , heat does not rise ! Plus when your wife wants to place a wooly mammoth on the floor the heat emitter won't be compromised .

    In most new homes , again depending on design and preference . Where responsiveness and efficiency are of the utmost importance I use this product , have a look .

    In case you wonder about my qualifications you can check the "find an installer " section of Uponor North American site , my zip code is 08755 and find me at my Bluewater Mechanical space and I also design and install for Langans Plumbing and Heating , we are the real deal .

    Don't sell your scooter my friend , it does not talk back and always understands you . Putt away .

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