John Hinckley-Garage Floor Questions

[Grant M.]

John,

I'm in the process of having a new home built and have been in discussion with the builder re: underlayment for the garage floor to help prevent moisture and frost problems. I've read one or two of your posts relating to what was done for your garage a few years ago (some kind of vinyl moisture barrier followed by high density rigid foam with foil on both sides, then re-bar and mesh). When I inquired about having this done for mine, the builder's concrete contractor said he'd do the foam (they use out to four feet either side of all footings), but has never used foil-backed foam nor the vinyl sheeting and therefore was unwilling to do or warranty something he had no experience with. Could you explain why each layer is used so that I can try and convince him, or better yet, perhaps give me a contact number/e-mail for the concrete contractor you used so that maybe I can get the two to talk?

Sorry this isn't strictly Corvette related, but thanks!

grant

[Kevin M.]

Re: John Hinckley-Garage Floor Questions

It's called a vapor barried out here in So Cal. It's code along with the mesh, we don't worry to much on the insulation side.

Kevin

[Clem Z.]

Re: John Hinckley-Garage Floor Questions

the cement guys do not like the vapor barrier,plastic sheet, under the cement because it takes to long to dry as the water keeps coming to the surface instead of being sucked up by the fill underneath. the guys that did my house with the plastic sheet were there for hours waiting for the cement to "set up" so they could finish it. the fiberglass strans added to the cement to make for different strengths should also be discussed

[Kent K.]

Re: John Hinckley-Garage Floor Questions

Grant ----

All the model codes (Southern Standard, BOCA, UBC, etc.) require a vapor barrier under slabs on grade. We have been using 6 mil polyethelene vapor barrier, sometimes refered to as "visqueen", for ever since I started practicing architecture about 38 years ago. The purpose of it is to retard the curing rate of the concrete, thereby increasing its strength and lessen chances of cracking.

Fiber reinforced concrete (FRC) is not recommended because it may grow hairs very much like a fiberglass bodied car if left outside, or exposed to the elements, without being painted. We, and our structurel engineer, recommend using steel reinforcing where necessary and, at least, one layer of 6x6-#10/10 welded wire fabric in the slab. Also, FRC is more difficult, if not impossible, to finish if you are planning an epoxy floor finishing system in the garage, shop or any where else the concrete slab will be exposed and perhaps sealed.

When it comes to insulating a slab, recommendations vary depending upon where you live. For example, in Alaska, the entire slab would have insulation under the vapor barrier. In most northern states, under-slab rigid insulation may need to extend 24" or 48" in from the slab edge including the stem wall or bell edge foundation. In Florida, southern California and most of many southern states, that insulation is a waste of time and money but the vapor barrier is necessary.

You might try surfing the internet for construction industry norms in your local. If your builder has a problem with these standards or your request to exceed the minimums recommended by the building code applicable in your vicinity, talk to people at your municipal's building and zoning department about his reluctance and/or find out what they require for inspections.

If you have any further questions that I may assist with, email me.

Regards,
Kent #6201

[John H.]

Re: John Hinckley-Garage Floor Questions

Grant -

After discussing my requirements (zero moisture migration and good insulation) with my architect, we used a 10-mil poly (Visqueen) barrier on the tamped soil, then covered that with 5/8"-thick 4'x8' sheets of high-density closed-cell foam with heavy foil on both sides, then set up the mesh on top of that and poured the slab (no fiberglass reinforcement in the concrete). Let it cure for four months, then had Home Pro Floors (www.homeprofloors.com) do the epoxy floor with their "Classic System" (steel shot-blast and two separate coats of 2-part industrial epoxy, with the second coat tinted the color I wanted). It's indestructible, easy to clean, dry, and warm, and six years later still looks like it was coated yesterday; worth every penny ($1.92/sq. ft. six years ago, turnkey job).

[Grant M.]

Re: John Hinckley-Garage Floor Questions

Kevin,

Thanks. Wish I lived in So Cal where insulation's not needed; unfortunately, it's Ottawa, Canada where it can get a bit chilly in mid-winter.

grant

[Grant M.]

Re: John Hinckley-Garage Floor Questions

Clem,

Thanks for that info re: the plastic sheet. Now I can understand part of the concern (time is money$).

grant

[Grant M.]

Re: John Hinckley-Garage Floor Questions

Kent,

Thanks very much for the comprehensive and expert response. We're closer to Alaska's requirements here in Ottawa, so the foam is definitely needed. I noted that the builder uses foam under all of the footings and basement walls, extended four feet out either side.

It doesn't seem to be a code issue with this contractor, merely one of his not having used these materials before.

Thanks again!

grant

[Grant M.]

Re: John Hinckley-Garage Floor Questions

John,

Thanks for your reply. As you and others have mentioned, it's a matter of insulation AND moisture barrier. I've checked out the Home Pro Floors website and there's no mention of any Canadian franchisees, so I'm not sure how I'll proceed with coating the floor. I think I recall from one of yours or someone else's earlier posts that their material is true epoxy rather than some of the other coatings available.

The house won't be built until next summer, but we're in the negotiation and specification process right now, so I want to get this all straightened out before we sign the check.

Thanks again for your help!

grant

[Dennis R.]

Re: John Hinckley-Garage Floor Questions

Grant--I know this is a liitle off the path, but if you are going to heat your new home with hot water, consider heating your garage with floor heat. The hot water piping attaches right to the mesh, and your entire garage floor becomes the "heater". For cold weather climates, it is the perfect heat system. Imagine working on your Corvette on a sub-zero Ottawa night while standing on a warm floor. This really isn't that expensive--about $1.40 a square foot. I did it in my shop, and it was the best money I've ever invested.

[george romano]

Re: John Hinckley-Garage Floor Questions

Call a local waterproofing company and see if they install Preprufe floor mambrane. It installs UNDER the slab, and after the pour it will actually bond to the cement through chemical reaction and will not leak if installed correctly. Floorprufe is a cheaper alternative.

George

[Gerard F.]

The real purpose of a vapor barrier

Grant,

is to prevent moisture migration, due to a heat differential, from the ground to the interior.
If you heat the space above the slab, moisture from the ground will tend to migrate from cold to hot. If you live in the tundra, you will always have wet floors in heated space unless you have a vapor barrier. A good vapor barrier is 6 to 10 mil visqueen over 3-4" pea gravel to break the vapor action. They also use a inch or so of sand, over the visqueen, to hold the visqueen down and improve the finishing (the excess moisture from the pour has a place to go).

Foiled insulation is a good idea in cold county. It bounces back the heat from whence it came. A radiant heat system in conjunction with foil insulation, as suggested. is a good idea for a garage.

The best slab (what we use in Fire Stations) is a 6" slab with #4 rebar at 12" centers both ways. With a vapor barrier, 3" pea gravel under (and insulation in the tundra) this slab would be bulletproof.

Jerry Fuccillo
#42179

[Clem Z.]

i removed the fiberglass hair from my floor

by using a comercial floor polisher with a scotch brite pad on it and also i used the wire renforcement,overkill i guess. the concrete is hard as hell when you try to drill it

[Alan Drake]

Re: Warm garage!

Have a heated garage floor - GGGreat! Floor area stays warm and upper does not over heat, cost is also low.

Did the 6mil over top cover of sand, 2" of DOW ridged foar, sheets of wire mesh, then used 1X1X1 section of ridged foam to space hot water piping off the wire mesh.

Mark and measure (pictures too) the layout of all piping and save - this assures you will never need to drill anywhere in floor or lets you drill without hitting a pipe.

If you are going to add a lift make sure that area is 6" of cement. Also leave a larger area for bolting wihtout piping.

[Grant M.]

Re: The real purpose of a vapor barrier

Jerry and all,

Thanks for the detailed explanations and suggestions. I live north, but not quite in the "tundra" which is an area with perma-frost below the surface. In fact, our new house will be built on the granite of the formation known as the "Canadian Shield" which surrounds James and Hudson's Bay.

Since we're buying in a developer-owned subdivision, my challenge will be to convince the concrete contractor used by the developer to do the floor as suggested. Our climatic conditions are not too dissimilar from those faced by John Hinckley in Michigan, although it gets a little colder here in winter. I'm inclined to press the contractor to use the vapour barrier and foil-foam-foil layer below the re-bar and mesh.

Thanks again to all for the replies!

grant