Hi

I am trying to make a good decision between I-joist and 2x10's for an underfloor system using heat transfer plates. Framing wise I could go either way, both framing systems have their pros and cons. In an underfloor system it would seem difficult to insulate the odd joist bay widths between I-joists (@16" o/c). With 2x10's I could use formeldahide free fiberglass or rockwool etc. (I am also trying to avoid off gassing foam boards etc.) Those batt type insulations could be held in place with baling wire stapled across the bay (done). I have also seen XPS curl up badly when heated to 140degrees(?). I realize underfloor system shouldn't get that hot but after seeing it happen its food for thought.

Anyway I was looking for input on floor joist and insulation systems.

Thanks

John

before committing to a staple up I would have 1 more look a floor panel system on the surface. The delivered water temp can be considerably less and thus be more efficient than a staple up. If you use a condensing boiler or geothermal you can stay in a lowest possible delivery temp for the in floor H2O. That said If you are doing a staple up an I joist system is easier to drill, you will need to drill a lot of holes. use a spade / paddle or forstner (sp) bit 1 3/8" place insulators in holes to capture pipe.
Dan

I don't like pipe insulators. joist systems should allow the pipes to move.

we are using I-joists in our shop and insulating the cavity with friction fit EPS foam over heated space. two layers of 1 or 1.5" thick goes up pretty easy. thicker and it takes some doing.

Too labor intensive for this old guy. Glass is the better value if you have to pay for the labor.

as long as you don't care about it actually doing a good job insulating, I agree.

I have had no issues with glass over conditioned spaces. I usually reserve board for exterior applications.

We are getting off topic but i have heard about insulators/bushings to place in joist holes. Are these really necessary? does the pipe move that much that its going to wear out and leak?

(I've got two hole hawgs and self feed drill bits so 2x10 won't get in my way!)

John

I would only recommend them for jagged holes and I would always recommend oversizing to avoid holding the pipe 'tight-ish'. I say that because they don't usually hold very tight, so tight the tubing can't move, and so I believe they increase noise risk if they are trying to hold tight and the tubing can slip through.

with low temperature design this should be a total non-issue, but with some higher temp systems and regular pex, tubing can chew itself up on sharp edges (including staples) over time. reason 6,355 to avoid high temp systems

Pipe insulators,
It is common for a new to the trade or DYI to drill holes only slightly above pipe OD. now there is more work to feed, and make the pipe move through the structure of the building. Industry standard for small diameter pipes is drill a 1 3/8 hole, now there is surplus room for your pipe. Also industry standard also pipe insulators sized to fit the 1 3/8 " hole, If you want to oversize fine, use the 3/4 insulator for your 1/2 pipe. point is that you have created a bushing of plastic to prevent chafing against the raw edge of wood. When purchased by the bag of 50 these are cheep (10 us bucks), multi functional and make for clean work.
Another thing often over looked in the mechanical room is unistrut and cushioned clamps. Again professional and convenient as these will hold your copper work in place while you build out the system. Leaving a clean and well fastened mechanical room.
Dan

Posted By Blueridgecompany.com on 13 Feb 2010 12:08 PM
Pipe insulators,
It is common for a new to the trade or DYI to drill holes only slightly above pipe OD. now there is more work to feed, and make the pipe move through the structure of the building. Industry standard for small diameter pipes is drill a 1 3/8 hole, now there is surplus room for your pipe. Also industry standard also pipe insulators sized to fit the 1 3/8 " hole, If you want to oversize fine, use the 3/4 insulator for your 1/2 pipe. point is that you have created a bushing of plastic to prevent chafing against the raw edge of wood. When purchased by the bag of 50 these are cheep (10 us bucks), multi functional and make for clean work.
Another thing often over looked in the mechanical room is unistrut and cushioned clamps. Again professional and convenient as these will hold your copper work in place while you build out the system. Leaving a clean and well fastened mechanical room.
Dan

Dan

Who makes those 1-3/8" insulators?

We've used unistrut for electrical work but never plumbing. I presume the cushioned clamps avoid dissimilar metal corrosion. Do you have a brand on the cushy clamps? 

John

Hi John,
The ones we sell are made by Sioux Chief, http://www.blueridgecompany.com/radiant/hydronic/339/sioux-chief-pipe-insulators . You can also find an OATY brand, not sure about there price.
Cushioned insulators are great! You need to be careful on diameter though, 3/4 copper needs a 7/8 clamp, 1 inch copper = 1 1/8 inch clamp, We sell Hydrazorb, but cush clamp also makes a fine product. Dan