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[slimjim]

 Yes we are using bubble wrap to insulate the bays, fiberglass is better but some of the joists are only 2X6 construction and there would not be enough air space within the bay for it to properly function, the homeowner has insulated the exterior walls to below grade with 2 inch foam and is not concerned about loosing a bit of heat down there to protect his piping, besides I don't care how nice the view is it blows from under the house and I really would not like to spend my day under there unrolling and stapling up fiberglass.

[Sloppy_Snood]

Yes we are using bubble wrap to insulate the bays, fiberglass is better but some of the joists are only 2X6 construction and there would not be enough air space within the bay for it to properly function...

More questions:   .... bubblewrap to insulate the joist bays....when you insulate each of the floor joist bays contianing the UltraFins, does the bubble wrap just close the open side of the joist or does it also line the inside of the sides of the vertical portions of each floor joist?

My home has 2" x 10" and 2" x 12" floor joists and I am wondering if it would be beneficial to line each floor joist with a radiant barrier  , install the pex tubing and Ultra Fins  , and "enclose" the between joist voids with 1" or 2" foam board with radiant barrier aluminum foil .  My idea is to keep as much heat as possible in the enclosed airspace and only heating the subflooring (and not the floor joists themselves).  Feedback is appreciated! 

Am I over-thinking this?  Is it "worth" using radiant barrier lining on the joists and foam board enclosing pieces? 

[mlappin]

I think you are over thinking it Mr. Snood. I need to remodel the office next, it's right next to the bedroom. Most likely will be the same as the bedroom, remove all the old true 2" x 10"  floor joists that are on 24" centers with treated 2x12's on 16 inch centers. I did have the helps kids out and had em shovel a bunch of dirt out of the bedroom before installing the new joists but I'm pretty sure I didn't have em shovel enough out to actually crawl under there. I think part of the office and bedroom were originally much smaller then they enclosed a 8 foot porch. Had two footers on the south wall and two sill boards when we repaired the foundation. The footers were just stacked rocks with some mortar dumped over em. The floor had it's own sill board and the wall sat on another.

Anyways back on track, I think you need just enough insulation to create a dead airspace.

If you have room to work easiest would be 4x8 sheets of 1 inch foam board and use the nails with the plastic washers already on em.

When we redid the foundation we placed 2 inches of foam board outside from 3 foot up. I also had em did around the inside of the foundation and we placed 1" board around the inside of the foundation then refilled. I'm wondering if I can just do the drill the joist method in the office and not close off the under sides of the joists? Rest of that crawl space is tight. Two sides are very well insulated and the other two sides butt up against the field stone walls in the basement. On the other hand this isn't a true crawlspace to speak off, no way under it except cut a hole in the floor. So if a joint would start to leak....

[slimjim]

mlappin you are spot on, the idea is the dead air space, no need to insulate the sides of the joist Slopster as I said before, fiberglass is preferred but bubble wrap works fine. We did a garage addition  for a friend/ boiler customer about 5 years ago, it was a tire bay and 4 wheeler addition with a gym upstairs, the wife wanted the gym warm and Dave wanted a bit of heat in the tire bay so we never put anything under the plates in the floor joists of the gym and they both love it

[slimjim]

OK so Dan and I are back on the Island to finish the job, we had an uneventful trip other than popping a $165 dollar trailer tire while turning hard to get both trailers onto the deck of the barge, we will be setting the pads and boiler today and hopefully heating the water and most of the house tonight, as you can probably imagine Joe and Barb are pretty happy to have us back to finish the job, we would have been here long before now but I had no boiler to install, it's going to be very busy from this point out!

[sceptre74]

So, how is the install going?

[slimjim]

So far so good, fired the 250 last night to heat the domestic hot water only so far, Dan will be connecting most of the radiant today while I wire the mess, I'll try to get some pics later.

[slimjim]

So we got 3 of the 4 radiant loops running last night as well as hot water, I just went in to use the bathroom and the house is warm and hot water will take your skin off if you aren't careful, low temp of 39 degrees F last night here on the Island. Now the work starts, we still need to add an additional radiant loop in the back sun porch and 3 zones of baseboard upstairs, it's an old 3 season home, running the pex upstairs will be a real challenge, we also after running the extra radiant loop will need to install all the bubble wrap under the floor joists as the wind is blowing right through the dirt crawlspace, the 250 is running great with less than desirable wood.