After we built the detached garage the old one was turned into a playroom. The floor was a bit of a challenge but the contractor built a subfloor, and added baseboard hot water heat connected to the existing system. We had it carpeted and all was well, for over 20 years. Four years ago we made it an exercise room and wanted a laminate floor, better to sweat on. I pulled the carpet up, screwed the squeaky parts down and put in the laminate floor. No moisture barrier was needed, the laminate pieces provided that on their own. Last year a soft spot was felt in the floor. I blamed myself, thinking there wasn't enough left for the floor to expand. And it was minor. It quickly became major so I ripped the floor out to see what happened. Here is what I saw:
Not good. After ripping out the subfloor and insulation it gor worse.
A closeup:
So what happened and what do I do so it doesn't happen again? And not that is matters but did the contractor do something wrong to cause this? I think not, since the floor looked fine when the carpet came out. The floor did have fiberglass insulation, looks like it had paper on both sides but the side on the cement did not hold up well. There was nothing like a truly moisture proof material on the cement.
Despite repeated requests, turning this back into a garage is not an option.
If that is a water pipe, it could have a leak from a nail through it. I don't think I see any protection plates above it.
Or, could it just be from condensation (if that is a water pipe)?
I'm not a carpenter by trade, but I'd be looking long and hard at the exterior wall for any water/moisture points of ingress. The rot pattern looks to be centered at the door frame. Is it possible that runoff/rainwater is somehow getting in under the floor somewhere?
Can you pressurize the system to see if there is a pin hole leak in one of the corroded areas? And as for the repair, move the hot water baseboard pipe to the wall and the sub-floor and cover the concrete directly. (If that is an option)
The pipe is for hot water to the radiators. Temp probably over 120F. The door is interior to the laundry room, any water from there would have shown up on the cement step. No nails, the area was well marked with orange paint. My theory is condensation from the pipe, which puddled on the cement or was absorbed into the wood. I think it was happening for years but the carpet allowed the moisture to just go into the room. The floor looked perfect before the laminate went in.
If there's no vapor barrier (plastic) under the slab, I's bet what you're seeing is due to moisture migration through slab. Water vapor from ground condenses within the floor cavity. With carpet it diffused and dried to the interior to some extent. If hard floor introduced a second vapor retarder you have a classic "moisture sandwich" where condensation has no where to go so accumulates within floor system.
Most garages don't have moisture barriers because they weren't intended to be living spaces.
Best fix is to prevent in the first place. Failing that, very thorough moisture control is needed to top of slab. Are you willing to pull entire floor out?
In reply to carbidetooth :
Yes I think you are correct. I suspect the worst spot, in front of the door, is a low area. The whole floor is coming out and then I can check for low spots. I am also waiting for the contractor and HVAC guy to take a look. All the copper pipe might be replaced by insulated PEX. Needless to say a better vapor barrier over the cement, would a brush on sealer help at all? Then insulation, not sure about fiberglass or an expanding foam. I want this done right, it is an exercise room now but it could be the first floor bedroom in the future.
I'm not buying the "condensation on the pipe" theory. That would be a possibility if it was a cold water pipe, but plumbing for a radiator is never going to be cooler than room temperature and usually will be far above it during heating season.
+1 on carbidetooth's theory.
carbidetooth said:
If there's no vapor barrier (plastic) under the slab, I's bet what you're seeing is due to moisture migration through slab. Water vapor from ground condenses within the floor cavity. With carpet it diffused and dried to the interior to some extent. If hard floor introduced a second vapor retarder you have a classic "moisture sandwich" where condensation has no where to go so accumulates within floor system.
Most garages don't have moisture barriers because they weren't intended to be living spaces.
Best fix is to prevent in the first place. Failing that, very thorough moisture control is needed to top of slab. Are you willing to pull entire floor out?
Total agreement, with one additional thought: The condensation/diffusion up from the concrete was bad enough with the "new" vapor barrier trapping it, but the area around the water pipe was worse because that area was noticeably hotter than the surrounding area when the heater was on, causing it to evaporate more. That means more humidity in the vicinity of the water pipe, but not because of a leak.
Are those regular sized 2x4s you are using for joists? Is there any slope to your concrete floor and the joists are ripped to fit? And, is that a foundation wall sticking into the garage? Is there a basememnt on the other side or is that a slab-on-grade house?
If there are no water leaks and it is all trapped moisture, maybe you need to insulate with ridged extruded polystyrene sitting on treated flat 2x4s that are anchored to the concrete slab. On the house side floor at one corner add 4x10 heat register to draw warm air into your floor and on the opposite cold side corner add a vacuum with a small box fan like in a radon mitigation air pump and run it out the exterior wall.
Remember your air flow in the floor is going to behave just like in an intercooler. So, you might have to just use one heat register at one corner of the warm house side floor and put the vacuum fan on the opposite corner exterior cold side of the garage.
Low spot would only be an issue with bulk water. If you can include the underfloor area within the conditioned envelope and introduce no ground moisture you're golden. Problem is, that's difficult to do after the fact. There are paint on vapor barriers, but hydrostatic pressure from below is mighty. Easy test is to tape down a 16"x16" piece of clear plastic over open, dry area and see what accumulates over a week. I'll bet it's significant.
If you can get the whole area cleaned up really well, that means slab and stem walls up a few inches, you could use a paint on barrier but it has to be 100% sealed. Any small imperfection will recreate he problem if conditions are the same. For long term peace of mind a ventilated space like volvoheretic is suggesting might be a better approach. No way I'd put fiber insulation in a situation like that. XPS foam boards are a pretty good vapor barrier, if abutting edges and perimeter are sealed.
Here's one. There are many. Google "concrete vapor barrier". Vapor Barriers for Existing Slabs - Overlay Moisture Control - Concrete Network
Do the plastic test and might as well get it all taken out if you're wanting a permanent repair. I hope contractor that's eyeballing it isn't the same one who built it initially. That's a mighty big oversight to saddle a client with. Mother nature always wins over time. Paying attention to details extends that time considerably.
It also wouldn't take much of a centrifugal fan to pull any moisture out of the floor space plumbed out to a dryer outlet flapper vent cover.
Amazon.com: small centrifugal 120 volt fan
porschenut said:
Why does that remind me of a True Crime episode I watched a couple of months ago? 
In reply to VolvoHeretic :
Thanks for the drawings to illustrate the solution. To answer your questions it is a slab, there is a small crack in the floor in front of the door. So that might explain why the damage is the worst there. I need to remove more to see where the low spots are. The floor is angled so water runoff from a parked car goes out the garage door, so the joists are either cut or shimmed to level. While we couldn't tell when it was carpeted the contractor did a terrible job on this. As soon as the laminate was in a yoga ball in the room rolled around like it was possessed.
I will be replacing the copper pipe with insulated PEX, won't fix anything but will eliminate the moisture accumulating on one area. Since there have been so many useful ideas, what about just pouring cement in and making the whole floor level? Regardless of the laminate instructions I would then put a vapor barrier in before the laminate.
carbidetooth said:
If there's no vapor barrier (plastic) under the slab, I's bet what you're seeing is due to moisture migration through slab. Water vapor from ground condenses within the floor cavity. With carpet it diffused and dried to the interior to some extent. If hard floor introduced a second vapor retarder you have a classic "moisture sandwich" where condensation has no where to go so accumulates within floor system.
Most garages don't have moisture barriers because they weren't intended to be living spaces.
Best fix is to prevent in the first place. Failing that, very thorough moisture control is needed to top of slab. Are you willing to pull entire floor out?
Came here to say this. Concrete is a big sponge that soaks up water and it evaporates to the easiest spot... the top. You need a vapor barrier between the concrete and the subfloor.
In reply to porschenut :
Thanks. I'm not a concrete guy but I can't think of why it wouldn't work to pour another layer to level it up, one with a flow additive to self level. Doesn't laminate use a thin foam backing which should also be a vapor barrier? How do they install it in concrete basements?
How do you run your PEX, in a 3" pvc pipe embedded in the new concrete or boxed-in along the wall?
In reply to VolvoHeretic :
You run the pex and pour directly over it, that's how heated floors are done.
My gut says box the pex in, just in case there is a problem in the future but ultimately I will do what makes sense and costs less.
porschenut said:
My gut says box the pex in, just in case there is a problem in the future but ultimately I will do what makes sense and costs less.
There can be no problems in the future if you pour over it, no way to leak at that point.
Curtis73 (Forum Supporter) said:
carbidetooth said:
If there's no vapor barrier (plastic) under the slab, I's bet what you're seeing is due to moisture migration through slab. Water vapor from ground condenses within the floor cavity. With carpet it diffused and dried to the interior to some extent. If hard floor introduced a second vapor retarder you have a classic "moisture sandwich" where condensation has no where to go so accumulates within floor system.
Most garages don't have moisture barriers because they weren't intended to be living spaces.
Best fix is to prevent in the first place. Failing that, very thorough moisture control is needed to top of slab. Are you willing to pull entire floor out?
Came here to say this. Concrete is a big sponge that soaks up water and it evaporates to the easiest spot... the top. You need a vapor barrier between the concrete and the subfloor.
Agree on the sponge part, but to do as you suggest, would put anything below subfloor in a condensation zone. that would include wood joists, foam boards, etc. Moisture did not evaporate, that's what caused the problem in the first place. water vapor is present in the atmosphere, what structures need is a way to dry. Depending on climate, this can be to the interior or exterior of structure.
In reply to carbidetooth :
Good points except with all of the radon news today, I definitely wouldn't want to vent the concrete surface into a living space.
Some things to consider:
Finish floor height if you pour on top of existing slab. Most concrete guys will say 1.5- 2 inches minimum thickness. If this works out put a vapor barrier on top of old and make sure drainage on exterior is away from structure.
Having been a garage floor, the surface bonding is going to be iffy without scarifying surface if you opt for paint-on waterproofing.
How much fall from back to front of garage? Most self leveling stuff I've dealt with has minimum and maximum thickness. Manufacturers know their product so I'd use their guidelines.
What part of the country are you in? Main house is slab-on-grade or framed floor system? Age of structure?
In reply to carbidetooth :
Floor is 2.5 to 5.5, cement to level. The old cement has several cracks, it has been 30 years since it was a garage and I guess I never paid attention to that stuff. No, not even going to try painting to seal the old stuff. House is in SE PA, built in the 70s.
I have 90% of the old floor out, and it looks like there are low spots in the old cement floor where the rot was the worst. Turned the heat on today(55 inside this AM) and no leaks in the corroded pipes. They will still be replaced. Need a day off this thing, working with a full respirator is no fun and I am just burned out on the project right now. But tomorrow the rest of the floor comes out and I will start scheduling contractors. Given the floor condition and what I am learning from you all cement will be my choice.
More pics tomorrow, thanks to all who posted.
If you replace the copper pipe with PEX, be sure to spec oxygen barrier pex. Regular pex is semi permeable and will allow oxygen into your heating system, which accelerates corrosion of all the ferrous parts of the system.
I get it, unplanned remodeling/reconstruction is never fun. Bulk water puddling in low spots would explain damage concentration.
I'll add a couple of things that crossed my mind eyeballing your project from over here in Idaho. When you get demo done, some detail photos would be helpful from an advice standpoint.
Given the way floor was constructed, I wonder about how the original door opening (car-sized door) was framed in. Bottom plate should have been pressure treated for sure, but given the moisture present, I'd want to inspect that closely for water damage. If you install slab on top of existing, moving bottom of that wall to top of new slab would be ideal. Outside of that, I imagine you've got house on one side and stem walls on the other three. Drainage away from structure is important.
And, just so you know, cement is an ingredient of concrete. Portland cement, water and aggregate make concrete. Add lime and you have mortar. Many other additives for different purposes. If contractors you're interviewing don't know the difference, I'd send them packing. The hard part is going to be finding someone well-versed in remediation which, unfortunately, is not your garden variety concrete contractor.
These guys make stuff that may interest you or at least give insight.
Stego Industries | Moisture Protection Solutions
