Slc – Doesn't Fit In

July 25, 2010

Information I Should Have Known About Gypcrete Before Having It Installed

I installed self leveling concrete in the master bathroom (about 7 by 8 feet). It did not come out good with the primary issue being that it was not completely level. I had calculated how much of the SLC I needed to do the job but some of it seeped through holes in the concrete. I did my best to fill all of the holes but SLC will find it’s way through the smallest of holes. I had a situation where the SLC was draining through holes as it was drying, leaving some sloping in places.

For the master bedroom I decided to contract the install of self leveling concrete to third party. I choose to have Koch Mechanical install Gypcrete. Gypcrete is not the same as the concrete product I bought at Lowes for bathroom, some would argue it’s not a concrete product at all. There are a number of things I should have understood about Gypcrete before I had it installed, thankfully non of it’s issues would prevent me from using it.

Gypcrete is a brand name belonging to the Maxxon company. Although proprietary, the name of the product should indicated that it contains a large amount of gypsum. According to the Manufacturer it is superior at dissipating heat vs normal concrete. Thus, the company that installed it for me specializes is installing gypcrete over radiant floor heating.

Gypcrete is installed in a liquid form and can be walked on in few hours, and is completely dries in 30 days. It doesn’t cure like concrete, it just dries. The finished product is like having a floor made of solid chalk. It can be scraped and dented with sharp objects. I don’t know for sure, but it seems like it could be busted up and re-liquified.

Gypecrete absorbs water easily and might react with concrete products. It also isn’t a structural product and can crack easily. For these reason the manufacturer recommends some sort of anti-fracture membrane or barrier between the Gypcrete and thinset. Since I had it installed over a very solid concrete floor (as opposed to a more flexible wood floor) I wasn’t worried about cracks.

Although the thinset I used stated it was ok to use on top of Gypsum, I felt it was a good idea to put some kind of barrier. I put down RedGuard, which is an expensive waterproofing liquid plastic that is rolled on like paint.

I’m happy to report the tile has been installed and there have been no issues with the tile, thinset or gypcrete.

June 2, 2009

Installing Self-Leveling Concrete In The Master Bathroom

Another milestone is complete in the ongoing (3.5 year) master bathroom project as the self-leveling concrete was installed on top of the radiant floor heating. The process wasn’t exactly what I expected and the results weren’t perfect but the floor did come out level.

The manufacturer of the concrete product recommends not to install it when the heater is running and when the humidity is low otherwise cracking could occur. That meant I needed to wait until summer when the heater didn’t need to run and the evaporative cooler could be running. I didn’t need the cooler, it was installed on one of the rainiest days of May and the humidity in the house was over 75%.

Prior to pouring the concrete I made a riser out of aluminum flashing to extend the height of the air duct in the bathroom. I held the riser in with some cardboard and sealed it to the old duct with some concrete sealant. I did the same for the area around the toilet.

The entire house has an expansion joint around the perimeter and one wall of the bathroom has part of this expansion joint. The self-leveling concrete cannot go into the expansion joint or bridge it or it will crack. I sealed the joint with concrete caulking and put foam under the drywall so it sticks out over the joint.

I had scheduled 3 friends to come over to help (although only two showed up), one who had worked with self-leveling concrete before. It takes at least three people: 1 to mike the concrete with the drill, 1 to pour water and concrete into the 5 gallon bucket and 1 to pour the floor. My $88 corded Dewalt drill had a tough time with the concrete mixture. Luckily I had an old heavy duty single speed craftsmen drill that tore through the concrete without a single complaint.

The only problem we found during the pourig of the floor is there wasn’t enough water in the concrete and it wasn’t quite liquid enough. This made some rough spots where the different pours came together. it work in our advantage since one area where I had sealed the expansion joint gave in and started filling with self-leveling concrete and I completely missed a small crack in the concrete slab near another wall. The self-leveling concrete set too quickly for this to impact the level of the floor. Had it been more liquid the entire floor could have drained down these cracks.

It took four bags of self-leveling concrete and I ended up with a 3/4 inch floor, I will have to recheck my calculations as I expected a 1/2 floor. It cost about $50 in supplies and a few beers.

I was a bit hesitant about doing this pour myself and considered hiring someone. I’m glad I did this small area first and I’m confident I can do the master bathroom with enough people. I may have to have a pour-party and get about 10 people together to have a constant flow of self-leveling concrete then bar-b-que when we’re done. I had meant to take more pictures but I was too busy working on the project, the pictures I did take can be viewed on flickr.

The next step is to install the Schulter Kerdi waterproofing material and to finish up the shower stall before laying tile. This will be a non traditional installation of a shower floor. I’m not sure if I will start this during the summer as I plan to spend my time working on outdoor projects as much as I can.

January 31, 2009

Radiant Floor Heating Elements Installed

This was a long work week. 4 x 12 hour shifts and workouts afterwards meant I had little energy left at the end of the day to work on the master bathroom. With the weekend here I finally was able to complete the installation of the heating elements.

The first step was cleaning the living piss out of the floor. I’m installing an insulating layer, which the manufacture of the heating system says will improve heat transfer. It’s not required but I would like to try to use this as the primary heating system for the house. (One Project Closer did this same project and there’s some debate in the comments on whether or not insulation is needed. They went without the insulation.)

The insulating materials is a dense closed cell foam that’s about 1/8″ think. It has a black plastic mat on the under side and attaches to the floor like contact paper. I have to first put a tacky glue on the floor and let it set for about 20 minutes.

If I was experienced at this, I could have cut the mat in one or two sections and applied it all at once. But I’m not so I cut it into small pieces and applied it to the floor a little at a time. It was much easier that way.

Installing the heating elements was a little more involved. Not only did I need to cut it, I had to do some manual wire layout where the floor was not square in front of the shower.

Since I will be embedding the elements in self leveling concrete, it’s important that they are anchored onto the floor so they don’t float up in the SLC.

The heating element is sewn onto the green mat but the round edges are not. They can easily stick out and have to be glued down. The manufacturer recommends using hot glue, a procedure I tried. After about a half hour and when I ran out of glue I thought there had to be a better way. There’s no way I can do this when I do the much larger master bedroom.

I found double-sided carpet tape at Lowes. I taped the green mat to the floor then taped the rounded edges to the mat. Not only does the double sided tape do a better job of holding down the mat it’s a lot faster and easier to put down.

Next up is to lay the self-leveling concrete. Concrete is still kind of magic to me and SLC is just that much more of magic. I will definitely need help with this part.