Hey guys, I am fast aproaching the delivery date for my SIPS and could use some help. I dont explain these things to well so i will attach the plans for ref. Basement is installed and i have 7/8 pex 300 ft in a 5-7 inch slab over 1 and 2 in foamboard. The middle floor trusses and decking are installed and I hope to pour the 1 and 1/2 inch slab with two, 250ft loops totaling 500ft for the middle floor. To keep on schedule i will need to order the loft trusses within a week so they arive before the panels on dec 11-15 . Since the loft will gain alot of heat from the two lower floors i am considering just doing the bathroom, possible with staple up pex. We like to sleep in the cool in the winter so low 60's is fine. I would like everyones opinion. Second, I have been given mixed instruction on wether to place 10 mil poly on top of the Advantec before pouring the slab or letting the slab stick to the decking. The Sips walls are 6 inch r 23 and the roof is 10 inch r 38. One last question. Here in central carolina near charlotte what would be the best choices for hot water/radiant combo? I hope to add solar DHW in the future, no natural gas and fairly cheap electric. power does go out several days a year so we will have a small gen set for the well and sewage pump. The house will have a mini split or heat pump for A/c so the radiant is a luxury for us. Thanks for any help. michael

in your case skipping the loft is probably fine.

you need about 30% more pipe (9" o.c. or tighter) on the 1st floor to avoid heat striping and to keep your water temps down. I would do 6" o.c. in the main cathedral area if I didn't have a load calc to tell me otherwise.

combine that with heavy plate staple up in the bath, which looks to have a significantly lower load, and it should match up ok. I will stress the *should*.

Rob, Thank you for the help. Would you place the poly between the concrete and the subfloor? Its not light weight just beefed up concrete with smaller agraget. Thanks again. Michael