Basement Finishing

In an earlier post, I talked about a basement finish job that I was bidding. This originally included adding a basement egress window with window well enclosure by Bilco and was to have a bath.

The  job was downsized to an basement office. This sketchUp drawing is showing the components that explain the building science involved to make this a warm and dry space to work. To get a closer view, click on drawing.

Basements in Northern Michigan are typically cold in the winter and damp in the summer. Generally the soil is sandy with good drainage. We have to keep these things in mind when designing systems to make this space a pleasure to use.

1. A 2 x 6 sill plate on a 8" block wall allows air flow from inside of block cores into basement space cooling floors above the block and the basement as a whole. I glue in 2"cuts of 1" foam on top of block. I then glue  4 x 8 sheets of 1" ESP foam (R-4) on the block surface. The reason I use ESP is it allows the walls to dry to the inside. It costs about $4.-5.00 a sheet ($1.00 per R factor rating). 1" EXP foam is R-5 and is quite pricey. Up north, it is difficult to get EXP without the moisture retarding skin and that would not allow the walls to dry out. All seams are caulked (as is the perimeter) and taped.
   
2. 2x4 stud wall on 2' centers goes up next. Use a treated plate. This is needed for running electrical and heat runs easily. 
3. Run heat runs in stud bays as close to floor as possible. Make sure you add cold-air returns equivalent to heat.
4. Insulate stud bays with R-13 insulation.
5. NO VAPOR BARRIER.
6. Drywall lifted off concrete slab. This prevents any wicking of moisture from floor. Caulk bottom gap.
7. Prime and paint with latex paint (NOT OIL). This will allow the walls to breathe and continue to dry to the inside.
8. Flooring is next. Because of the dampness of basements in the summer, the flooring choices are limited. Carpet gets musty and damp in summer. Glueing wood to cement is not a good choice. Tile is about the only good choice but would be cold in winter. We put DriCore panels down after it was painted. It was amazing the difference your feet felt between the concrete slab and the DriCore surface. DriCore claims about a 6 degree difference. Well worth the $5.00 per panel cost.