Foundation insulation is usually placed on the outside of a basement wall so unless the plumber knows otherwise, the pipes would be placed as close as possible to the wall

If you add rigid foam on the inside of the wall, a "thermal barrier" (usually 1/2" drywall) would have to be installed to protect it from fire.

We had exterior foundation insulation installed.. The plan for the interior is to do 2inch rigid foam, then 2x4 framing.. Inside the 2x4 framing will be r11 batt insulation once we run electrical and ready to close.. From all the sites I have found online this is the ideal setup.. They also state this can be left as is.. I have found many who do just this setup (rigid foam / framing) until they are ready to completely finish with drywall and flooring and such..

But my point still remains.. As far as the builder is concerned there is a high likely hood that we were going to accept the quote and have them finish the basement.. So why have the plumber run the pipes as shown? If we say yes to their quote then in essence they would have to remove the piping and rework it.. I just don't see the point in running it wrong the first time with the knowledge that we are planning to finish..

I am not sure there is a right answer here. All in all, they may have calculated the cost of having the plumber redo it is cheaper than having the plumber wait. As crazy as that may sound it is really not that unusual. Someone didn't get you the price before the plumber was scheduled so they let him go ahead. Moving those pipes you have shown will actually cost very little. The contractor's mistake is not getting you the price faster - Once the plumber is on site and ready to work the contractor has to weigh the definite cost of making the guy come back another day vs. the possible cost of replacement.

Sanford - Thanks for the input. I was unaware of the code that it must be covered.. I was going off of multiple "do it yourselfers" that I have seen insulating basements as well as the companies that post videos.. We were considering leaving it with a "semi finished" look in just having the rigid foam and framing.. I guess at this point we will have to reconsider.. They originally quoted 8k to do perimeter wall framing and electrical with no insulation.. I am going to assume it will double that amount if we have them go all the way to the sheetrock stage.. Thanks again for the info..

This kind of interior insulation approach for basement walls is usually in lieu of exterior insulation in your climate zone. Exterior foam board insulation should be enough unless it is not possible to continue it above grade to the top of the foundation wall.

If the R-value of the basement wall will be over 30, would the above grade walls be R-50?

Most likely, they called in the plumber, and may or may not have mentioned the possibility of framing the basement to him. And he's gone ahead and done what he *always* does, without a care of how that will affect future plans.

Sanford - We currently have exterior foundation insulation at 1 inch thick.. This is from the top of the footing to grade.. This was tied in with the waterproofing and delta drain that we installed.. Due to the grading of the property the left side of house has approximately 18 inches of uninsulated foundation wall that comes above grade.. This works its way up to the right side which has approximately 30 inches of above grade uninsulated foundation..

My plan was to add in the 2inch rigid foam board to interior walls which would have given r10 value and use the foam board w/ spray foam to seal rim joists.. This would leave us with r10 above grade and r15 below grade (2 inch interior and 1 inch exterior foam board below grade).. We then figured we would add in batt insulation that is basement rated with an rvalue of 11.. This would have given us an r value of 26 below grade and 21 above grade.. The other option was to build the 2x4 wall on top of the 2inch rigid board and then "cut to fit" 1inch rigid foam board and place inside cavity.. This would have left us with r20 below grade and r15 above grade..

The first and second floor are having r21 batt placed inside wall cavity of exterior walls.. We figured that since basements tend to be cooler we should go with equal or slightly higher insulation.. Based on the numbers we would have a range of r21 to r26 in basement going with combo of rigid foam and batt or r15-r20 doing all rigid foam..

We were following the idea off of the buildingscience.com website..

@ amberm145 - You may well be right - but had he told the plumber of the plan, nothing would be different. I have personally been involved with plumbing an entire hotel knowing that we were going to have to redo a significant portion of it. The math is almost never in favor of delay.

I will throw the math out to make it simpler: You have three options (1) have him do nothing, and come back later to do the whole thing (2) have him do all but this spot (3) have him do it all and just ask for a repair.

Option 1 is never good - It costs a lot more and puts too much power in the hands of the plumber to delay your entire project.

Option 2: lets say that the additional cost for having him come out a different day after the decision made is $500.

Option 3: You still have to pay the previous $500 but now you also have parts that are going to be needed for the repair - lets say $100 (that is high, but round).

Now let's guess there is a 50% chance that the new wall, that requires a shift in plumbing, will be chosen. That means that you have a 50% chance of spending an extra $100 vs. a 50% chance of saving $500.

By and large when your skilled trades are there to work, you let them work, if there is any way you can.

No, what I mean is, they told the plumber, "add an extra 2 inches here for future insulation." The plumber ignored it and put the pipe wherever the hell he wanted to, and it's the insulation guy's problem.

But maybe I'm jaded because my plumber is an ass.

amberm145 - I am thinking this is on the builders decision.. After all they knew well in advance of the possibility.. My guess is the builder never brought it up and just let the subs go to work.. They did the same thing when I had the framing issues.. They never told the framer that I was switching a window location and closing off the upstairs loft.. So the framers went to work and did it as per plan and were never told of the revisions.. My builders are great guys, but I am finding that they lack the proper oversight of the subs on scene.. They don't discuss the modifications in advance and just let the subs do things with the plans they have.. It really means nothing to me as any work that needs to be done over will be on the builder, although I am sure they will make up for it when some kind of overage somewhere else.. I just get annoyed that they are constantly doing things one way KNOWING that it will need to be done over.. For example.. They closed up the entire garage knowing I was putting in a side door.. They claim they do all their doors like this.. Only recently did they cut out the framing and install a header.. I guess we will see..

Bry911 - My only issue with your idea is that the wall he did the piping on was 100% being framed.. That was on the plans to be done.. The insulation was an "add-on" but regardless the wall was supposed to be framed.. Maybe I am asking too much here.. Afterall they have the entire house framed, wrapped, etc and the slabs in basement and garage are still not poured.. Perhaps that is why they just let the plumber do his thing..

"Since basements tend to be cooler"

That is a perception based on poorly insulated and/or poorly heated basements. Compared to the above-grade outside temperature, the temperature below grade will be warmer in the winter and cooler in the summer. Unfortunately, that is also true for the floor. If you want to keep the basement as comfortable as the spaces above it, you should insulate the floor (as shown in the drawing above) rather than triple insulating the walls.

Sanford - Thanks for the info.. I will have to look into this a little more and discuss with builder..

As for the original topic in regards to the plumbing location.. The project manager said that the framing goes in front of all the plumbing and they make access panels to get to it.. He said framing cannot go directly against the concrete.. I told him that I was aware of this, however I had not heard of needing a 4 inches of space.. He seems to say that "this is the way it is supposed to be".. I am just trying to figure out why they cannot do the 2inch rigid foam and 2x4 framing and then drop the pvc in front and soffit it off.. I am just concerned because that wall is part of the future bathroom and the laundry room.. So if you pull the wall out 4 inches to accomodate the pvc and then add a 2x4 you are already eliminating 7-8 inches from the room.. The future bathroom is only 6.5- 7ft at its widest point.. add in the 8 inches from the framing/pvc and then another 4 for other wall and you just lost 1ft of space and bathroom is now 5.5-6ft at wides point.. I mean it should be fine, but I just feel that they could build a soffit to run the pvc at the top end of the wall and put the pvc in front of the framing.. That is unless there is a code violation in doing that.. Plus if we ever have a problem we would have to tear open walls/framing vs opening a soffit.. The pvc piping will be about 8ft above slab so it is out of the way for headroom..

SandfordW said:

"All plastic foam insulation must have a thermal barrier or an intumescent coating. It cannot be left exposed because of the dense toxic smoke it produces in a fire."

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Not quite so.

While "most" foam insulation products require a thermal or ignition barrier....not "all" do.

For example, Dow Thermax rigid insulation foam boards are listed for use without a thermal or ignition barrier....and Thermax is the only rigid foam board on the market that has been approved for use without a thermal or ignition barrier to my knowledge. If you use this system, however, you must also use Thermax joint tape and Dow's special adhesive. This makes it quite pricey. But Thermax does not require drywall, coatings or anything else to make this foam board 'fireproof'. So all told it is usually cheaper than using other types or brands, having to frame a stud wall in front of thes foam insulation, then cover with drywall. Thermax is designed for use and installation 'as is' and kind of resembles the Corning basement wall finishing system. It comes in at least 2 color schemes.

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Superior Walls foundation systems are also listed to be used without a thermal or ignition barrier over its fully exposed Dow foam board. The 'system' is tested and approved for use without.

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Several spray foam insulations are also available that do not require thermal or ignition barriers. They contain fire suppressant chemicals or inert materials like pulverized stone to make them non-flammable or very low flammable.

Just FYI. Carry on.

Good topic. :)

The design the OP is proposing uses extruded polystyrene foam board on the interior side of a CMU foundation wall that has already been built. It will need a thermal barrier.

Dow Thermax has foil facers that create a vapor barrier so it is not an option for this kind of wall design. The Owens Corning basement wall system is nothing like Thermax foam board; it uses panels of rigid fiberglass board that are vapor permeable.

Had Superior Walls been used, additional XPS would have been added to the inside and a thermal barrier would have been required.

To better understand the proper design of insulated masonry foundation walls read the Building Science guide the OP referenced.

Now I am getting very confused.. I met with project manager again, and now he has a different "plan" but is still throwing a curve ball.. He is now claiming that the pvc is "pitched" and that we cannot do the 2inch rigid insulation behind it because it will alter the pitch if we pull it out.. So I tell him that if they did the 2inch rigid foam first then the pvc would have been attached through the foam board.. He said that the foam board would not have allowed the pvc to get attached strong enough and it could have moved around.. At this point I am really not buying it because it seems like he is just making stuff up as he goes along.. I think the real problem is that he realized that the holes that were cut in the first floor will not line up if they move pipe and they don't want to pay to have it redone.. So he said they will run the 2inch foam board up the pvc and then cut it and continue after the pipe..

He also is now saying they are going to run the 2x4 framing under the pvc and then bump it out when it gets to the top to make the soffit so that we maximize floor space.. This guy has me so confused its not even funny.. A lot of this just doesn't sound right.. I think they messed up by not accounting for the foam board and framing and at this point are just trying to do what is cost effective for them..

The only pipe in that photo that needs to be pitched is the "horizontal" one. And it doesn't need to be pitched AWAY from the wall. I agree, they screwed up and are giving you a story.