Hi!

I tried doing a search and just got contractor results, not info. (Maybe I need to read the welcome info posts?).  Anyway, want to do my first radiant floor heat, avid DIY'er and licensed electrician. 

1930's cape cod w/ a 3 season back porch additon in the 60's.  Existing slab foundation, new 8' slider door southern exposure in Michigan.  Stripped exterior walls & flat roof, added much insulation and want to install a passive solar tiled floor w/ radiant heat for occassional use (not sure how I will use this porch/mud room during winter, but great for summer cooling breezes in the summer from nearby lake).  18' X 8' area so first thought was electric vs hot water., But.....

Also on south side is the mstr bath & mstr bed  addition, 1954, over crawl that I may also heat w/ radiant floor vs existing nat. gas forced air running under floor joists.

Questions:  1.  Back porch, existing slab---easily have 1.5"+ area to raise floor so thinking pour a thin suspended slab over existing slab w/ 1/2" foil foam board, then add non glazed tiling.  Room heats up nicely from solar when we do have winter sun.

                    2.   Mstr bath/bed--plywood sub over floor joists, 16" c-----keep installation ABOVE subfloor on sleepers (maybe sand base).  I want to remove/avoid any systems in crawl (i.e. electrical, heat ducts, etc).  I only want to go into that crawl space once and that would be for removal. Finish floor optional, whatever will work best.  These 2 rooms are currently demo'd/stripped down, prepared to raise thresholds, etc.

       ?One system or two different types for these 3 rooms?  Bulk of house will remain nat. gas forced air heat. 1 yr ago, replaced old elect. wtr htr w/ a 40 gal elect htr.  1900 sq ' but I live alone, 2 bths.

I apologize if this is too many questions/details or too vague.   Just trying to start gathering the info.

Thank you for your time and info you can give me.

Sparkie

Since my original post, I have decided:  for initial job, back porch/solarium...electric heat, either cables or mat.  This area is small (14' X 8') and will not need to be heated constantily. 

I am thinking I need to install a thermal break above existing cold slab.  I'd like to keep the total height of insulation and 'crete'-set to 1.5".

Any recommendations for system/brand, insulation?

Thanks Again

Hi Sparkie:

You can use "The Barrier" insulation. It is XPS 3/8" with a vapor barrier attached above and below. Their site is "nofp.com". Depending on what your finished floor is and which electric source you use for heat, you'll work up from there with either backer board or plywood.

Sorry for the delay and thanks for suggestion about "the barrier".  I looked at site but looks to be suggested for UNDER slab.  Can I use it ABOVE existing slab?

Thanks again.

P.s.  Even tho not best, I plan to use electric radiant heat vs water for the several rooms I am converting from nat gas forced air.

We've used it just as I mentioned; on top of the slab and under either backer or plywood. It worked beautifully in both cases when compared to no insulation at all and looking for minimal floor height buildup.

We do a lot of work in NYC where the existing structures are concrete and have little or no room for buildup. We install it wherever we can. We tested it in our warehouse in the exact application they did on their site and got almost exactly the same results.

Take a look at using Redwell Radiant heating panels on the walls or ceiling. They are more cost effective than putting in boilers etc. Operating costs are on par with natural gas.
Andy
www.redwell.ca

I ALWAYS compare the cost per therm of available fuel sources. Claims that electric heat is somehow more efficient or easier or less costly or safer or you get the idea, are often exaggerated beyond reason. Doing the math quickly dispels hyperbole and may save money for decades.

MA