So when I moved back down to North Carolina a couple years ago, I bought a house built in 1957. And they had a bedroom/bathroom/laundry room addition out over the carport. Been through two winters now and when it gets down to about 20 the floors in the addition are about 37 and the waterlines running to the washer freeze. Strangely enough, the bathroom is another five or 6 feet farther along out into the addition and the waterlines there don’t freeze. I think it’s just the branches that cut out to the washer. I used a hole saw to check this summer and there’s really old moldy fiberglass insulation just laying on top of the the plywood that’s the roof of the carport. The rest is open air.

Contemplating trying to find someone to pull the wood and put either spray insulation or something like rock wool up in there so I have a chance of it not freezing. I’ve reached out to a couple insulation places and they won’t even respond to come and give a quote so I’m wondering do I need to get a general contractor? I’ve never really dealt with any of this stuff. If I was a little younger and not working about 60 hours a week, I’d probably consider doing it myself, but I don’t really know what I’m doing. I’d be reading stuff on the Internet and doing that. If I had to do it myself it would probably be foam board sealed right up against the wood floor and then rockwool for the rest of the area between the joist, filling up the rest of the cavity between the floor of the addition and the ceiling of the carport. I could probably get it done in a couple of weekends if I’m not being lazy and as long as I’m being careful because I’d have to have a sheet rock jack to get the plywood back up there.

After tearing my bicep last December, I’m a little more nervous about just doing things on my own all the time.

Kinda looking for suggestions. And wondering if maybe there’s a different kind of contractor I should be reaching out to for this. What do you guys think?

R value is what you need to look at
Rock wool-23
3M foam board-8
Owen Corning’s pink-depends on thickness-R13 for 2x4
Closed cell sprayed (2x4)-R22-32

You could also add those heated wires that run next to plumbing lines, then insulate.

This is a common problem with an unconditioned space below.

The best solution is to tear out the ceiling and have a spray foam contractor spray the underside of the floor above. At the same time also completely cover any exposed water lines (both supply and drain) then install a new ceiling.

The void space between your existing insulation resting on the ceiling and the underside of the floor above is the issue since it is unheated.

You might have to get a remodeling contractor to do it since the ceiling demo and reconstruction is usually not something an insulation contractor does. If you have a local building supply house nearby (not a big box store) go to their contractor sales department and ask them for recommendations. They are usually pretty helpful.

Open cell foam is fine in this application and code requires R-19 in this application in NC

with the moldy insulation sounds best to have it all taken out, cleaned and reinsulated, you could tape up the water lines and use foam pipe insulation round the pipes and foam seal the area

We had an overhang on our first house in Ohio, and the master tube drain would freeze in really cold weather, they didn't insulate it properly when the house was built, We had the contractor come back out in the spring and fix that up.

Or you could just close up the carport with block walls and a garage door

Since you have moldy insulation due to moisture intrusion, you will want to address that as well while you're reinsulating.

Rockwool/mineral wool insulation is mold proof (and rodent resistant too), so may be a better option in this application.

smisig posted what I'd do and it'll make a big difference.

I appreciate the suggestions. I had a feeling I wasn’t getting responses because I was reaching out to the wrong folks.

one more recommendation for what smisig posted. An insulation contractor will not do the required carpentry work. That is why you will need to hire a renovation contractor.

Also, can you enclose the carport? Yes, it would cost more but you would gain a wind break and have secure storage available.

Enclosing the carport is not an easy fix as you may still need to get into the cavity to check for moisture (mold source) and make sure the interstitial exterior walls are well insulated

Well, I have tomorrow off I’ve got a couple guys coming to discuss options and maybe get some quotes started. Fingers crossed