I live in a 120ish year old pier and beam home that was stripped to the studs and remodeled inside and out in 2012. However, there are some items that need addressing and some improvements that could be made.

The plumbing is all PVC and I caught hell during the freeze a few years ago. I want to have someone like Repipe Specialists come out and replace all of the water lines with Pex, but I don't necessarily want/need them to go up into the interior walls and cut holes so they can replace the feeds to the two showers and water heater. Per the owner who remodeled, he left the original shiplap under the sheet rock and I don't want to damage any of it in the event I want to remodel in the future. In my mind, there's enough heat radiating through interior walls to keep the pipes behind them from freezing. Any thought/opinions on doing it this way?

Once plumbing is done, I want to get the underside of the house spray foamed. The old batt insulation is falling down in spots and it's a mess. I'd rather do it right and be done with it. How does foaming work with plumbing? I'd imagine they can work around most of it, but what about the areas where supply lines run through the floor? Do they sleeve them or anything, or is that just a downside of foam, assuming you have to do plumbing work in the future?

If you foam the underside of the joists it'll leave whatever pipes are down there more or less alone. They will also be uninsulated with less heat radiating down from the house above into the crawlspace in extreme cold so you'll probably need to find a way to wrap them somehow.

Pex is freeze resistant, whether it's insulated or not. My house is P&B with zero insulation under it. I had no problems at all when it was below freezing for 40 hours and got down to 12 degrees.

The only issue I could foresee is if you need to access the plumbing for any reason you'd have to go pulling out insulation to try to find it. My suggestion would be to not spray foam any bay that has plumbing in it. Put batt insulation in those bays, secure it by screwing 1/2" rigid foam to the joists beneath it, and mark the rigid foam with the plumbing locations and what they service. This way it's easier to know where the plumbing is and you can drop the insulation easily if you need to.

Ryan the Temp said:

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Pex is freeze resistant, whether it's insulated or not. My house is P&B with zero insulation under it. I had no problems at all when it was below freezing for 40 hours and got down to 12 degrees.

The only issue I could foresee is if you need to access the plumbing for any reason you'd have to go pulling out insulation to try to find it. My suggestion would be to not spray foam any bay that has plumbing in it. Put batt insulation in those bays, secure it by screwing 1/2" rigid foam to the joists beneath it, and mark the rigid foam with the plumbing locations and what they service. This way it's easier to know where the plumbing is and you can drop the insulation easily if you need to.

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Excellent idea. It's a tiny 1100sqft 2/2, so plumbing is limited. There would only be a handful of spots to fill with batts.

I've had pex freeze in two different houses and it just expanded with the water/ice, then shrunk back down to size once thawed. I had it installed with a manabloc when I custom built in 2007. No idea why the guy who remodeled this place didn't have pex installed when he remodeled this place. It would have been so much quicker and easier.

If you spray under the house, use open cell and not closed cell. I made the mistake and used closed cell and condensation has caused all of my floors in a double wide trailer house I have as a rental to move and buckle. Part of the problem is that the subfloor is mdf and not plywood but it would be the same issue with plywood just probably less severe. I was told replacing the falling down batt with spray foam would make the insulation better and while it did do that now I am looking at having to rip up all of the floors and insulation to replace the floors and then going back with open cell. Wish I would have stayed with batt insulation. What a mess all because the spray foam installer thinks closed cell does everything.

Good advice. Thanks.

You still always have to control condensation. Its strange that the floor was still cold enough to make moisture condense.

Using open cell isn't necessarily going to solve a moisture problem.

I suspect the floors are still cold because the ductwork for the house is run under the floor and then comes out in floor vents. perhaps the floors would have been fine if the duct was coming through the attic like in a traditional home even with closed cell but with a doublewide and floor vents this has been a major problem.

cowtown ag02 said:

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I suspect the floors are still cold because the ductwork for the house is run under the floor and then comes out in floor vents. perhaps the floors would have been fine if the duct was coming through the attic like in a traditional home even with closed cell but with a doublewide and floor vents this has been a major problem.

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I think the better option for a pier and beam house (non-manufactured) would be an encapsulated crawl space.

It may even work for permanently placed manufactured homes.

Bob Vila on Encapsulated Crawlspaces.

Keep the moisture out of the crawl space entirely and if you insulate the walls, it should naturally end up at a temperature between the exterior temperature and the interior temperature, but closer to the ground temperature.

We had the our 1050 sq ft P&B home sprayed underneath with closed-cell foam.

My memory might be wrong, but I believe our wood flooring is laid on top of 2x6 (I think?) going diagonally across the home and then wood 2.25" on top.

The expansion/contraction seemed to actually get a tiny bit better with the closed-cell for us.

Agreed with the suggestion of encapsulating the crawl space, but the foam was a $1400 repair.