Basement Floor Insulation

[toughguy]

Has anyone done it? I'm talking about the blueboard stuff on the concrete with plywood on top of that than carpet. I see it more often on TV DIY shows. In the last basement I finished I didn't do it ant it got pretty cold down there in the winter. I did my own HVAC too and I don't think I put enough vents in. Does it really help keep the floor that much warmer? I'm planning on putting in a gas fireplace so that should take care of the cold once it's been on for a half hour or so. Once it's finished I'll probably use it nearly every day so I want it to be comfortable. I just want to be sure it's worth the time and $ to do it.

[LightningBG]

I've never used it, or even heard of it being used.

What comes to mind for me is, how do you attach the plywood so that it stays put? Personally, I'd hate to have to nail into the concrete that much, and glue seems like it would be a lot of work.

In my basements, I've just put somewhat thick carpet over a nice thick pad and have never had an issues with the floor being cold. And then the installers did all the work and I didn't have to worry about it at all.

[CAMAN]

I did it in a laundry room I had at my last house and it worked great. Luckily it was only a 5x7 foot room, but it was a room that didn't get much airflow through so it was bitterly cold. I Glued and screwed a treated 2x2 frame I built with "joists" 12" OC. Then layed 1.5" pink foam between everything and layed 1/2" plywood on top. The temperature difference was night and day, and I was actually able to walk in there with bare feet afterwards.

I wouldn't do it if you have water issues unless you lay a riser sheet (similar to DryCore but without the plywood) between the floor and foam to allow for drainage.

[toughguy]

Man I was hoping I wouldn't get good review on it. I plan on being in this house for quite a while and I want to do it right but I'm sure it's going to get fairly expensive. I'll run some estimates. I'm guessing that will make up my mind for me.

[toughguy]

I found this on the web. This is kind of how it's done only you use the foamboard stuff in between the strips and apply chipboard on top of that. I think they recommend a plastic layer under all of that too.

[cavalierowner]

I did this in my 3 season porch that I wanted to heat once in a while with electric baseboard. I used treated 2x2 sleepers @ 16" o.c. glued and nailed to the concrete with a powder-actuated gun about every 24". I put the blue polystyrene between the 2x2's. Over all that I put down a 6 mil poly for a vapor retarder, then screwed 5/8" plywood over all that. I made sure all the side and end joints were over the 2x2 sleepers/blocking. Because I was putting down ceramic tile, I went over the plywood with cement board, but if you're using carpet you would probably be OK without a second layer of plywood if all your joints are over solid blocking.

This has been in place for 2-1/2 years now and is solid as a rock. No cracks in the grout joints or tile anywhere. Like the other poster said, if you do this in your basement, be sure you don't have any moisture/groundwater problems.

I should add that if you're putting in supply air vents, don't forget the return air vents too. The rule of thumb I heard years ago was minimum of 1 return per room or 1 return for every 2 supplies if you need more than 1 supply. And be sure your returns are at the floor.

[toughguy]

I think I did 1 return (near the floor) for every supply in the last house but the problem is when the supplies are in the ceiling the heat just ran right upstairs even with the pull from the return. The returns were also on the opposite side of the room from the supplies. I think my issue was not having enough both. I have a friend of a friend that's in HVAC. I think I'm going to have an expert do it for me this time.

[Tom7227]

A big issue in keeping the basement comfortable is having a door closed to keep the heat down there. If you can't close it off you're not going to keep it warm no matter what you do.