DIY Basement Workout Room Step 2: Insulating the Walls

Who knew that one of the most time consuming tasks in finishing the basement would be figuring out how to construct the walls. I agonized over the approach I would take, knowing that the wrong decision could cause me to tear down everything and start over. I hope my story here will help you make a good decision too.

The Walls I’m Working With
My house was built in 2005. We chose the particular lot we are on because it seemed like high ground with respect to other homes in the neighborhood. The walls are constructed of 12 courses of cement block which, despite my location, get saturated in different areas during heavy rains. I was shocked that a brand new basement could be so porous to water. I don’t get streams, but I would not say the basement is bone dry either. If we run a dehumidifier on high after a few days of dry weather the walls will dry out.

Last year I called EverDry in frustration, hoping that they could diagnose the water problem and propose a remedy. After the doom and gloom sales pitch of the dangers of deadly mold and crumbling foundations, their solution came out to a cool $17,000. It involved digging out around the outside of the foundation, trenching the interior perimeter of the basement and installing an industrial dehumidifier. This would guarantee dry block and also $17k less in my bank account. I decided to finish the walls without the massive expense, but the specter of water made my decision making far more stressful.

The Vapor Barrier Decision
The builder had originally planted the seed that putting a vapor barrier against the block walls (even if damp) leaving an airspace, and installing 2×4 studs would be a suitable way to finish the walls. I had a ton of questions about EXACTLY what to do though.

• What kind of plastic should I use?
• How far away from the walls should the studs be?
• Should I install fiberglass insulation between the studs?
• Do I need a pressure treated floor plate?
• The most nagging of all questions: Will the walls get wet on the inside if I use this approach?

To answer my questions I followed Google to this great forum entry on how to vapor barrier a basement. There were some differing opinions, but THE BEST resource was referenced; Building Science Corporation’s Basement Insulation Systems Guide. Hallelujah! This is the advice given to builders on how to insulate/finish a basement. It has detailed pictures of the effects of what my builder had suggested (putting up a plastic vapor barrier and insulation)…it retains water and mold. MY solution was found on page 13 of the guide which explains the use of extruded polystyrene insulation and furring strips.

The Dow Styrofoam Solution
With a solution in mind I went looking for where I could find this extruded polystyrene (EPS). Lowes saved the day again. I found 2″ thick EPS sheets in either 4×8′ or 2×8′ tongue and groove sheets. Then I wanted to know how to install the stuff. Lo and behold the Dow website has this very thorough Dow Styrofoam Wallmate XPS Installation Guide. It gave me the plan I needed to purchase the rest of my materials, which included 1×3 furring strips for every 2′ and plenty of Tapcon screws.

A Special Note on the Tapcon Screws
For my project thickness the right size Tapcon screw was the 1/4″ x 3 3/4″ HEX head Tapcon screws. First, they are the thick ones to prevent any chance of them snapping on me when I installed them. Secondly, you MUST use the hex head for ease of screwing it into concrete. Don’t even think of using a Phillips head or flat head. Finally, buy a LOT of them, and NOT at Lowes. Tapcon screws are insanely expensive there, and these big ones run out of stock. I probably used 6-8 boxes of 25 screws each to do my single room. Buy them online in bulk if you can.

The Right Mix of Tools and Technique
It took me a couple of nights to get into a rhythm of how to best install the stuff. Let’s start with tools because they mean the difference between extremely slow, and super efficient. You’ll need:

• Tape measure
• Drywall square
• Permanent marker
• Utility knife
• Spare 2×4′ board
• High power CORDED hammer drill for drilling concrete
• High quality masonry drill bit
• Another electric drill for drilling countersink
• Cordless drill/driver for installing Tapcon screws
• Hand ratchet for finishing off stubborn Tapcon screws
• Chop saw for cutting furring strips to length
• Level to ensure furring strips and styrofoam are plumb
• Ear protection
• Work gloves

A menagerie of Craftsman tools helped me efficiently install the insulation

Working from one corner of the room, you begin by cutting the styrofoam to the height of the block wall so that it fits underneath the floor joists. To cut the material I marked a line with a framing square and permanent marker, then scored the line with a utility knife. The final step was to break the styrofoam over a spare 2×4 as shown below.

Once a couple of pieces of styrofoam are dry-fit into place, you then cut a furring strip to cover the seem between them. Using a level I made sure that the furring strip was vertical, and had my trusty assistant hold it while I went for the hammer drill…

A Special Note on Hammer Drills and Bits
Not all hammer drills are made alike, and neither are masonry drill bits. Trust me. The first rig I used was my Craftsman 19.2V Cordless with the 3/16″ bit provided in the screw box by Tapcon. That was slow and painful. Then I thought I’d try my dad’s Black and Decker corded hammer drill from the 1980s thinking the electric power would help. Nope. I nearly burned out the drill. Check out the lean and grimace I’ve got trying to use that sorry rig.

So, I went to Kmart and bought a reasonably priced Craftsman corded hammer drill, and I went to Lowes and bought the toughest sounding 3/16″ masonry bit they had - the Bosch Blue Granite 6″ long Hammer drill bit. This combination cut through concrete like butta, and made this portion of the project take days not weeks!

Drilling and Screwing With Protection
I’m obliged to warn you that I used protection when hammer drilling and screwing. Muffs for the ears and gloves for the hands (padded for my pleasure). The sound reverbed throughout the basement and could have spread a WTD (Work Transmitted Disease). Without gloves, my hands would have developed some nasty sores. OK, enough with the stupid jokes…

1. I drilled into the concrete
2. I countersunk the hole
3. I drove in the Tapcon with the cordless drill and hex driver
4. I finished off the screw with a ratchet when needed

The end result is a securely fastened piece of Styrofoam insulation with Tapcon screws that are flush on the front so that drywall can be installed directly onto the furring strips without obstruction.

Closeup of furring strip with countersunk Tapcon screw

The insulated basement wall completed

This portion of the project took about 5 days, and the end result was actually really fulfilling. I could have very easily left the basement looking like this. It is now insulated, and the blue looks much better than block. Unfortunately I think there is some code that says you need to cover over the Styrofoamwith wall board for fire protection. Well…that and we can’t have Tricia’s clients working out in a half-finished room, now can we?

Next up…how I installed the electricity and painted the ceiling with a Wagner Power Painter.

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DIY Basement Workout Room: Step 1 | Step 2 | Step 3 | Step 4 | Step 5