I am installing radiant heat in my home. According to the instalation instructions for a basement slab I have to put down 1 inch foam insulation first on the dirt floor. Do I have to do this. I am on a tight budget and this will cost an extra $850.00. Are there any alternatives?
No. If you don't insulate the dirt, you'll be pumping heat into it, and would have to double the amount of radiant to compensate. Then your next post will be "the radiant heat I installed under my basement floor w/o insulating first isn't heating my basement too well, and my utility bills are out of this world. What can I do to raise the temperature and lower my bills?"
What's ironic about your question is that you've got the money to heat your basement at ALL - but you claim a "tight budget."
If you think about it, is there ever a person who says "Money is no object, I don't care what it costs...go ahead". You'd know that person by the line of contractors at his house stretching around the block.
Cost is always a concern, but I agree that being penny wise and pound foolish at this stage is a not a good idea. I'd bet 2" of foam would be even better, but that's where you get into cost/benefit analysis. $850 is probably chump change for the total cost of the project.....don't go cheap now.