Monthly Archives: February 2011

Bathroom basics

Figuring out the basement bathroom layout happened pretty early on in our project. We needed to know how to route the new sewer system and what drains to put where.

We also learned during the deconstruction process that moisture and water leaks can become a real headache. Bathrooms, in building science terms, are considered wet rooms. There is a whole laundry list of moisture management strategies for bathrooms (or wet rooms) that we researched and wrote about.

Moisture that is not properly managed or contained can lead to sever durability issues and indoor air quality (IAQ) issues, such as mold growth.

One wet room recommendation was to include a floor drain. We actually have two. And no, we don’t have a second one because I am German, but because we opted for a walk-in shower. The concrete floor is already sloped toward the shower drain and floor drain.

Tiles and grout are a good idea on the floor and in the shower area, but they are not water proof. To actually create a water proof environment, it is recommended to use a waterproofing membrane under/behind the tile.

The logical place to start is on the bathroom floor. Whatever membrane we use, we will have to fold it up by a few inches on the walls – walls that are not in place yet.

Well, maybe I should get started on those walls …

Moisture management is often connected to indoor air quality (IAQ). Another moisture management recommendation for wet rooms that helps with the long term IAQ  is to use cement board instead of paperbacked gypsum board (or drywall). Cement board is much more water resistant and less prone to mold growth as it lacks the paper backing component.

The installation involves some puzzling. I have to measure in and cut out holes and openings for the plumbing connections. That took some time, but we got all the openings to fit.

For now I just installed the cement board around the bottom so that we can get started with the water proofing membrane.


Bath tub plumbing

One problem with our open house was that we could not offer a functioning bathroom to our visitors. This is something we would like to change. And of course, it would be nice to have it for our own use so we no longer have to rely on our neighbors and the local fast-food place for our bio breaks.

Everything in the bathroom is still bare-bones with a hole in the concrete floor for the bath tub connection. That seemed to be a logical starting point. I called Mariusz who sent his crew out to install the plumbing connection for us.

As with most things, one runs into glitches when starting on a new task. In this case it was about the location for the connection. We took the dimensions from the old salvaged claw foot bath tub and realized that we had to break up some of the concrete floor to get the plumbing to the right location.

Boy, am I glad that I took some pictures of the PEX tubing in the floor. That took the guess work out and reduced the risk of damaging the PEX loops while grinding and chiseling away.


Once the plumbing connection was in place, I could fill the hole by building up the floor section again, starting with some aggregate. The gravel is followed by rigid insulation and the concrete patch.

Great!  With the hole gone, we can begin to think about waterproofing the bathroom floor.


1st Open house

Cathy and I have been giving impromptu project tours on occasion. We decided a while back to step it up a notch, to stage an open house, or better yet a green rehab tour. The question was, when to do so?

With the last layer of insulation installed we were about to close up the walls and ceiling. Because the thermal envelope assembly is such an important component of our green rehab, we decided that now was the perfect time to send out invitations.

Other items that show well are the heating system, plumbing and drain water heat recovery unit.

We were not sure what attendance to expect. We were surprised with the turnout … very surprised.

Cathy and I were busy non-stop, showing a constant stream of visitors around. Because it was so busy I had difficulties keeping track of the visitor numbers. I counted 45 but am sure that I missed a few.

We are looking forward to a repeat a few months down the road. That time, we will be better prepared!

If you missed the open house, but would have liked to attend the next time, leave a comment. I will make sure I put you on our e-mail list for the next open house announcement.


3rd layer – rock wool insulation

I shared our experience with the 1st and 2nd layer of insulation in recent posts.

We originally intended to use spray foam for the entire wall section, but decided after some more research to add another material, or a third layer: a rock wool batt product.


What is rock wool? It was first discovered as a byproduct of volcanic activity, where lava came into contact with air and cooled into fibers. Modern manufacturing processes spin molten rock into thin fibers. The process is said to look like cotton candy production.

After adding a binder to the fibers and letting it cure, the batts get cut into the required dimensions and are ready for packaging.


The rock wool option subtly slipped into the picture for a number of reasons:

  • It has the thermal resistance we are looking for.
  • Unlike spray polyurethane foam (SPF), rock wool is not a petroleum based product.
  • It has a high recycled content.
  • Because rock wool is made out of stone and slag, it won’t burn.
  • It is a very economic insulation material (typically around $0.16 per board foot), more economic than SPF or recycled cotton batts.
  • Rock wool is very easy to handle and install.

I found two rock wool manufacturers (Roxul and Thermafiber) that distribute their products in Chicago. The Roxul Comfort Batt was sold for a price that fit our budget at the Chicago Green Depot, where I placed my order and picked up the material.


The batts are very light and dimensioned to fit between 16 inches on center wall framing or floor joists. Due to their somewhat soft nature, we could squeeze the batt, slide it between the framing and let go. Right away it expands back to its original size and firmly sits between the studs or floor joists.

We appreciated the ease with which rock wool can be cut. A long, serrated bread knife was the perfect tool to trim the batts to the required length or fit them around outlets and light switches.

The heat has been on for a few weeks and with all three insulation layers in the walls (an R-value of 25 to 27), we should be able to keep that heat where we need it.