Finished Basement

Many homes have finished basements. There seems to be some confusion about what to enter for a finished basement that will be conditioned. Here’s some tips on what data you should enter in the room Data Screen.

First in the Room Data Screen select the down arrow in the Floor Material section.  Choose the Basement Floor tab (number 21).basement 1

21 A is a concrete floor with no insulation below the concrete. 21B has R-3 or higher insulation below the concrete.

In the lower section find the appropriate length for the shortest side.

The smallest length is 20′. What do you do if the shortest side is 16′? That’s really very simple with a little bit of easy  math.

Look at the U-Values. There is a .002 difference between a 20 and a 24′ length.  And there is a a 4′ difference between 20 and 24 and a 4′ difference between 20′ and 16′. So we can simply add .002 to the U-Value of the 20′ wide selection (21A-20) to give us a U-Value of .029. or you can add .003 which is the difference between the 24′ and the 28′.

For the purest among you, you can be more precise. But in reality the affect is so small that it isn’t really necessary.

basement 2Once the floor material is entered, click on the down arrow in the Wall Material section.

The number 15 tab is the Basement wall material.

There are a lot of selections available so take some time to review all your options.

We will, for this example use 15A – Concrete Block.

Now look at all the additional options; there are a lot.  If we scroll down through these options there are selections describing the finish.   This will take some explanation:



basement 3


Arrow 1:  the insulation between the basement wall and the sheet rock finished wall.

Arrow 2: how much of the wall is finished (sill to floor).

Arrow 3: the size of the studs.

Arrow 4: is the block in the outside walls hollow or solid?

Arrow 5: is there board insulation against the outside wall?

Arrow 6: what type of studs – metal or wood?

Arrow 7: the depth from the soil line outside to the basement floor.

The real trick to calculating the load for the finished basement is to spend time reviewing all the construction materials available in RHVAC.

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