insulating a marble floor in unheated kitchen
 

Hi --

Former owners installed a marble floor in the kitchen, and removed the old hot-water rad in the room to make space for a pantry cupboard.

Looks nice, but in Toronto, the winters are cold! and the kitchen floor, and air temp., are freezing.

I'm considering getting kickspace heaters installed. If I do, electric is the way to go (even though power rates are sky-high here) because the cost of hooking hot water kickspace heaters into our old boiler system is in the many thousands, and I have surplus heavy duty outlets in the kitchen that could be converted to provide power for heaters.

Even so, it's not worth installing heaters without insulating the floor from underneath.

What is the easiest, most cost-effective material and method?

I've thought about stapling that shiny foil bubble-wrap stuff to the exposed floor joists.

Another option: fibreglass batts shoved up in between joists -- but would I need a moisture barrier? Would I need to cover up the batts with cheap tile or something, to ensure the insulation doesn't get dirty (it's an old, unfinished and unheated basement) or fall down?

Yet another option: spray foam insulation, but I've heard it's really, really pricey. Also might necessitate moving wiring -- you can't spray over power supply, right?

Last option: rigid foam panel insulation, cut to fit between joists -- which I think I've heard has low R value and is also expensive.

Also, should I do kitchen first, then do rest of underside of first floor (which is hardwood in other places) as time and money permit?

Will it make a big diff. to heat bills?

Thanks for input on costs, and ease of installation for various insulation methods.

I am going to bet using unfaced fiberglass batts are going to be your best option. Moisture barrier if any would go against the bottom of the floor according to the insulation sites. You have to be somewhat careful about what you cover the insulation with, it has to be non flammable which rules all the real cheap options out. You may want to just leave it exposed. The batts are held up with thin wires you wedge between the joists.

Spray foam is best if you can afford it. It seals all the holes up and is sprayed directly over just about anything even wires. There are some light fixtures that you have to watch out for. There are diy systems but even those cost more than a dollar per sq ft only a inch deep for closed cell foam. You get r6 per inch which is better than almost anything else but to get say r24 you would be paying $4 sq foot.

Cutting foam board is a pain when you have anything at all in the joist bay and you quickly find that nothing is straight and even the width of the bay will vary from the top to the bottom. You will never get a good tight seal.

And in most cases building codes require you to cover these insulation product with a non flammable surface, there are complex rules related to what the space is used for.

Are you on a crawl space or basement?

basement type
 

Full basement, made with very thick fieldstone and rubble walls, which are not airtight.

House is 100 years old, so there are ways for cold air to seep in everywhere.

I try to seal up cracks in stucco-type wash on inside of basement walls, but its hard to keep up.

So, there's easy access to work, but the basement is chilly.

Do you know what type of hot water boiler you have? Is it a converted gravity feed or monoflo system? I'm asking because I wonder why it would be "in the many thousands" to add a loop to your kitchen? So many things you can do with hot water heat. Hate to see you go to an inferior system because someone gave you bad info

Exactly. You have a full basement woth access to floor joists- I think ki plate electric heat should be your last option. Insulate the walls of the basement, foam board or even fiberglass batt, and your basement will be 68 degrees f. all year, so floor above will be much more comfortable. Even if you just seal around the rim joist area with caulk, expanding foam, or insulation as listed above, it will likely make a difference. Or you have several options of under floor heating, since you have easy access.

enough about the underfloor heating, already!
 

I did quite a bit of research on options/costs/efficiency of heating methods prior to posting here, and am confident kick-plates are the best here.

I do very much appreciate your suggestions about sealing and insulating rim joist, however.

Thanks!

Butterscotch

I'm curious why the kick-plates are your best choice. Is it because of the ease/cost of installing them is so much better? I had similar problem in NJ, ceramic tile over crawl. Underfloor heating was too expensive for me to install, but the electricity is too expensive here for kick-plate heaters. Sealing the exterior of the crawl helped. The floor doesn't feel "heated" of course, but there is a huge difference now that the crawl is always about 68-70 degrees f., and there is no more cold draft from the rim joists. So if you do that, hopefully you have as much luck as I did...

http://www.beacon-morris.com/html/ki...t_twin_flo.asp

Here's an example of the hydronic version, instead of electric.