When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I had witnessed a contractor pouring concrete over a plastic film once and he poked holes through the plastic. He explained that it would take forever to set up in order to finish it and he did not want to be up all night doing that.
Be there when he is pouring and don't let that happen to you.
Also, draw a tight string across the forms before the pour to make sure that the thickness is correct.
Last edited by Roger Walling; 03-12-2019 at 02:11 PM.
I had witnessed a contractor pouring concrete over a plastic film once and he poked holes through the plastic. He explained that it would take forever to set up in order to finish it and he did not want to be up all night doing that.
Be there when he is pouring and don't let that happen to you.
Also, draw a tight string across the forms before the pour to make sure that the thickness is correct.
I just used 2" Dow foam insulation, no plastic barrier, and my floor stays nice and dry. Unless you're in a flood zone the a dense foam insulation will keep it perfectly dry.
Right on that 10 mil poly under the concrete...and don't let them punch holes in it....also use rebar, not the wire mesh. I wont have a two post lift.....my slab is 5" thick over the 10 mil which is over aggregate. Also have them spray foundation moisture barrier (like a super thick undercoating) on the outside of the foundation/blocks. Have fun!
I was straight slab on grade. 42x78 at 4" thick on a 10x14 section along the south wall we centered a 6" slab to allow for a two post lift someday. So far the four post has done just fine. May never get to a two post. Thinking of just getting a scissor lift for wheels and brakes.
On the plastic front, in the old garage beside the new one, same elevation, same soil. High and dry above any water table, but on clay, after one winter in that garage I saw mild pitting and oxidation on aluminum parts on my then current collectibles. I was told it was the lack of vapor barrier under the old concrete. Wasn't sure if I believed it, but put down the 10mil in the new one. The guy was right. Not a spec of moisture in 4 years in the new one. Don't see any signs on the cars or parts.
Aside from the in-floor heat, a ground vapor barrier is the only thing that I knew I couldn't fix later. Passed on the heated floor as the shop is 500 back of the house and doesn't have running water. I did go with a dual stage radiant heater - was hard to find a contractor who understood what that was - but mounted 45 degrees against the wall it has done a remarkable job of keeping a large space warm. I don't miss the heated floor at all, but then, I'm never on the floor!
Hey Guys, good thread.
I'm having a new garage built also. I know I want radiant heat, but it's too late to put it in the floors. Has anyone of you used this style that is mounted to the ceiling?
That sort of radiant heat works well and is often used in repair shops. The idea here is to heat the objects in the room rather than the air. Under floor heat is superior, especially from the point of view of efficiency, but these units will certainly do the job and might be better than a "hot-dog" or other forced air furnance.
When I stick built my garage with 12' ceilings, I put 1/2" plywood on the walls to strengthen them up. I also did a 6" floor, fiber reinforced, with screen, and definitely poly under the floor. Helps keep the floor guys honest and not do a soupy pour. Concrete is very cheap, in the scheme of the entire build, and it is nice to have more, than not enough. Also the thicker the slab, the better the moisture barrier, and it isn't so cold in cold climates. With the larger size garages, stress cut the floor to control the cracking during shrinkage.I also doubled up on the footings and placed 4" steel posts in the walls and did a 12x22 steel I beam running the length down the center to eliminate the need for support columns. I use the I beam for a trolley lift. Put a drain in if your codes allow. I've got hot and cold water also, and went the Modine Hot Dawg gas style blower up high. I also did recessed lights and a second floor to store parts and such.Try to not do a mono pour (this is where they pour the walls and floor at the same time). If you do the walls and separate floor approach, you can drive your truck or car back and forth to really compress the dirt before the concrete floor gets poured. Also drive a ground rod into the dirt before you pour the floor. If you are going to run a subpanel in your garage from a main panel in your house, make sure you run a conduit for the main wire, and another conduit for hot and cold water and a phone/internet cord would be great also. I'm sure you'll get lots of points of view, this is mine, and best luck with your garage!
When I stick built my garage with 12' ceilings, I put 1/2" plywood on the walls to strengthen them up. I also did a 6" floor, fiber reinforced, with screen, and definitely poly under the floor. Helps keep the floor guys honest and not do a soupy pour. Concrete is very cheap, in the scheme of the entire build, and it is nice to have more, than not enough. Also the thicker the slab, the better the moisture barrier, and it isn't so cold in cold climates. With the larger size garages, stress cut the floor to control the cracking during shrinkage.I also doubled up on the footings and placed 4" steel posts in the walls and did a 12x22 steel I beam running the length down the center to eliminate the need for support columns. I use the I beam for a trolley lift. Put a drain in if your codes allow. I've got hot and cold water also, and went the Modine Hot Dawg gas style blower up high. I also did recessed lights and a second floor to store parts and such.Try to not do a mono pour (this is where they pour the walls and floor at the same time). If you do the walls and separate floor approach, you can drive your truck or car back and forth to really compress the dirt before the concrete floor gets poured. Also drive a ground rod into the dirt before you pour the floor. If you are going to run a subpanel in your garage from a main panel in your house, make sure you run a conduit for the main wire, and another conduit for hot and cold water and a phone/internet cord would be great also. I'm sure you'll get lots of points of view, this is mine, and best luck with your garage!
I agree with nearly everything on your list, but after doing all that, pouring and insulating the new slab you forgo radiant underfloor heat and install a forced air furnace, up high, where heat rises? That's a head scratcher.
I agree with nearly everything on your list, but after doing all that, pouring and insulating the new slab you forgo radiant underfloor heat and install a forced air furnace, up high, where heat rises? That's a head scratcher.
Dan
I did the same thing and I'm in the Northeast where winters are pretty cold. Sometimes you have to work within your budget and determine what's the most cost effective. I'm glad I put the savings elsewhere.
The heat works terrific and I have a lift so at 65 I never crawl around on the floor anymore. But I put 2" Dow insulation under the poured concrete so it really isn't very cold even on the coldest of days and I'm in a high water table area. I had to have a sump pump in the basement of my house which is right next to the garage.
I understand budgets and cold. I'm in Western MA. Once you prep and insulate for a slab, the additional cost of the tubing and a small boiler is in my view very small, especially when factoring in the cost of a Hot Dog, electrical & gas/flue piping. The difference between the two is immeasurable in terms of cost to operate and comfort.
I understand it makes no sense for an existing building, but to build new in a cold climate and not do underfloor heat seems a shame.
This is not meant to make the poster regret what he did, he seems happy. My comments are for those thinking about it and are planning a new garage. If you are going to build a garage in a cold climate and you plan to permanently heat it, put in the radiant heat.
Treat the outside of the foundation and the soil surrounding it with the strongest long-lasting insecticide you can obtain. I treated mine with a solution unobtainable since 1986 and to this day have had no indication of termites or other insects of any kind.
When I built my garage, the cost for radiant heat was expensive, not really mainstream, not a lot of information for a DIYer and no one could answer the question how long the pipes would last before they needed replacement due to corrosion or other issues (pinhole leaks) in a slab. In my eyes, a leak is not a question of if, it is a question of when.These two factors did not give me a warm and fuzzy going with this approach.
The Modine (largest BTU) was $800 total and installation was an hour. My logic was that if it messes up and I can remove and replace in a couple of hours. If I get a radiant pipe leak, I am unable to R&R a pipe leak in the same amount of time. The thoughts of needing to rip up a slab does not sit well with me. Especially when my garage is full, and a lift is installed. Maybe I'm a little paranoid, but I was unable to get data at the time of construction. It isn't like putting coils under a floor in a house where you can get access by pulling a couple of sheets of sheetrock.
As you can see each person has their opinions, logic and reasons, and as technology changes options/standard of approach changes with it.
Originally Posted by dplotkin
I agree with nearly everything on your list, but after doing all that, pouring and insulating the new slab you forgo radiant underfloor heat and install a forced air furnace, up high, where heat rises? That's a head scratcher.
Dan
Last edited by playzwithcars; 04-13-2019 at 08:58 AM.
Reason: errors
On the subject of using an in garage heater V/S in floor heating, I prefer a hot air heater that is 8' above the floor.
I have the intake ducted down to 12" above the floor to draw in the cold air on the floor.
I use a ceiling fan with the rotation that forces the heat up and to the corners of the room for even heat.
What I like about it is that because it is over sized, it quickly brings the garage up to comfortable temps, And I can lower it to 45 degrees when I am not there to save money.
On the subject of using an in garage heater V/S in floor heating, I prefer a hot air heater that is 8' above the floor.
I have the intake ducted down to 12" above the floor to draw in the cold air on the floor.
I use a ceiling fan with the rotation that forces the heat up and to the corners of the room for even heat.
What I like about it is that because it is over sized, it quickly brings the garage up to comfortable temps, And I can lower it to 45 degrees when I am not there to save money.
I agree, I keep my shop at 45 but with the Hot Dawg heater it will heat up vert quickly. That doesn't happen with forced hot water. It can take quite a while unless you leave it at a high temp all the time.
I'm using a mini split for heat and cooling. It works very well down to 0f. Only take 30 min or so in extreme cold to heat the garage.
Also did air/240/120 every 4 feet, concrete work bench 11/2 story and scissors trusses they give you approx 1/3 the span open in the center of the truss. spray in foam insulation
03-12-2019, 02:09 PM
