i need to fiqure out the total sq. foot of my house.

do i measure each room or measure the Length x width of the house?

Length X Width for a single floor, do same calculation for a 2nd or 3rd floor then add them up..

Ray

Depending, accurately, you'd need to add up each room individually. Lots of dead space in many homes, which is bad if you're looking to pay for something by the square foot. The dead space doesn't count for the remodel, but the remodeler would love to charge you for it!

its to determine heater size

What you need is more than just square footage, as there are a lot of factors that go into it. The pro's use a thing called a "Manual-J" that takes into account sq. footage, ceiling height, insulation, your quality of windows and doors, and so forth...

If you go to HeatingHelp.com they have a free program put out by the boiler company "SlantFin" that will let you figure all that stuff into it, and come up with an exact number. It is billed as a :sick: Windows program, but it will run on Linux under WINE.

Gooserider

On that note, aren't all those programs just a quick way to use Q= U*A*(delta T)? I believe I have compared my "old way" calcs to using a program and the numbers were pretty similar. I don't see how they could be different, frankly. So, if a program doesn't work, crunch the numbers yourself. There are tons of insulation manuals that explain how to fill in the equation, and it is not that complicated. For the most part, you only have a limited type of heat loss.... then figure in normal infiltration, doors being left open, etc....