Insulating a Garage Floor


JimReed

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I am starting from scratch in a new 900 sq ft insulated and heated garage with a concrete slab floor. I want to insulate the floor and put down a wood floor. I am looking for the optimal solution. Thoughts include 1.5" board insulation between 2x4's face down on 24" centers. Then a 3/4" T & G plywood floor either painted or with a laminate floor. I have no clue whether this is the right way to go if there is a better/cheaper/easier solution that I have yet to consider. So OK experts, what would you suggest if you could start from scratch?

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Do you ever experience water getting in if there is heavy rain? I am very interested in doing what you are doing but it's not in the budget just yet. I will definitely be following this thread, hope you get some good responses!

Very warm on the east cost, for now, but that wont last all winter.

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You may also want to take a look at cork flooring. Soft on the feet, has sound and thermal insulation qualities, and can go over the concrete with a moisture barrier. Wears alright, but can be slippery. You can pull and replace damaged panels with extra left over stock.

If you put in a sub floor (pls use pressure treated with a moisture barrier), you can run electrics thru conduit for more equipment location flexibility.

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I am starting from scratch in a new 900 sq ft insulated and heated garage with a concrete slab floor. I want to insulate the floor and put down a wood floor. I am looking for the optimal solution. Thoughts include 1.5" board insulation between 2x4's face down on 24" centers. Then a 3/4" T & G plywood floor either painted or with a laminate floor. I have no clue whether this is the right way to go if there is a better/cheaper/easier solution that I have yet to consider. So OK experts, what would you suggest if you could start from scratch?

This is pretty much exactly what I did to my two-car garage shop (~480 sq ft). I love it so far. I even ran some circuits beneath it.

My biggest advice would be to let that assembly float - don't anchor it to the concrete.

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I researched a few different WW forums on this, went with 2" PolyIso,(free from CraigsList) 2x4' PT (flat) (with a 5/8" thick 3" wide plywood shim), no plastic, (I have a little leaking occasionally), and I used Advantech. Advantech is a T&G type of underlayment that can get wet at a new home site in rain and not have the type of damage as flake board. I left the floor to float, and have enough gaps that it can breath under the Adevantech.

In the past, the floor got cold, and stayed cold all winter, now with a solid wood floor it is comfortable and much better on warming up the whole shop (24x40'/ 2 stories) when I put the heat on.

If you can't get to the job right away, I liked using stall mats on thge concrete prior to changing. They are about 3/4" thick, and I found a bunch of smaller pieces from a girl that changed horse trailers, she had cut her mats into smaller pieces, 3x5, 2x6, 1x6, etc, I bought her whole pile for $20 off craigslist. I screwed the floor, so I could get at it if need be, no nails, no glue.

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@davidrn-- just a few followup questions. I loved what you did and have heard good things about AdvanTech-- did you paint your floor and if so what kind of paint did you use? Also, I would love to avoid shimming-- does anyone know where you can get 1.5" board insulation so I can avoid shimming?

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@davidrn-- just a few followup questions. I loved what you did and have heard good things about AdvanTech-- did you paint your floor and if so what kind of paint did you use? Also, I would love to avoid shimming-- does anyone know where you can get 1.5" board insulation so I can avoid shimming?

I am a huge fan of Karma and Craigslist plays into that system of coming upon a deal thats too good to pass up. I check materials and tools daily, I found a contractor giving away PolyIso, I emailed him, he told me I was third on his list, and would get back to me. Turns out he was restoring a 18th century building, and had piled all the PolyIso on the second floor in a huge pile, but you had to get it down from the second floor. The first two responders to the ad weren't willing to do the work of bringing it down, so I got it. I rented a large enclosed uhaul trailer, and spent 3 hours filling it, the pieces were not uniform in size, a prior owner of the building got odd pieces and put them in the ceiling.

I ended up with 40% more than I needed, sold it for $50, the cost of the trailer.

You can buy any size thickness PolyIso, but if its free, cutting up old 5/8" plywood for shims is a simple thing to pl;ace over the 2x4's. I did not paint the floor, left it open to breath, and no plastic, agaian so it wouldn't retain water any longer than needed to dry up.

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I would love a wood floor in my garage, but how do you transition at the end where the garage door comes into play?

In my case, my shop is dual purpose, I park a sports car over the winter, and usually work in their if the weather is bad year round on the cars. So I left a 10x 20' space open from the barn door back, I am considering paint vs a thin pad or garage tiles. My barn door is sliding on the inside, so I had to leave a 12" gap between the end of the floor and the wall, so I used a 12' 2x6 PT and beveled the edge, and then the flooring holds it in place. I would think if you did the same at a car edge, a bevel ging you about a 1/2" at the leading edge would not fall apart with a car driving over it slowly. I did not glue or secure the PT sleepers to the floor.

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I would love a wood floor in my garage, but how do you transition at the end where the garage door comes into play?

For my floor, it is currently "open" - meaning you can see the 2x4 frame beneath the OSB I put over it. At some point, I plan on buying some 1x6s or 2x6s and "edging" those exposed edges.

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  • 3 months later...

I thought about it, but then thought otherwise cause of where I live.

In Texas during the summer, the floor tends to be cooler than the air temp in my shop. So it helps cool my shop. In the winter, the floor is TONS colder than the air in my shop, but Texas 'winter' isnt bad at all. I feel comfy in the winter with tshirt and jeans.

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  • 2 weeks later...

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