View Full Version : Basement remodel begins this week, any feedback will be greatly appreciated

11-22-2011, 09:09 AM
I kinda hijacked an older thread so I thought I would start a new one with more specifics on my basement remodeling.

I rehabbed this 1950's ranch about four years ago in lovely Tyngsboro Ma, gutted it down to the studs and rebuilt everything, including a side foundation wall and basement floor. The wall was bowing in and had to come out along with the basement floor it was completely cracked. The space is 50x25 with only 2 columns, so its a nice open space, heres were the fun begins, the front wall and back wall are mostly original cinder block the replaced wall (10' of the front and back and 25' on side) is poured concrete and the floor was ripped out and lowered a few inches to create more headroom so now 2-3" of the original footing is visible. The other side wall is not totally an exterior wall because there is a garage on the other side this wall however is a large rock wall with a fireplace in it. But 5-7' of the rock is exterior wall. Also there are no windows in the basement at all only a door that leads to the garage.

2 years ago I had a humidity issue that caused minor mold due to the lack of ventilation, both problems have been corrected with the installation of a air to air exchange/ dehumidifier tied into the natural gas hvac and a ultraviolet light installed in the return plenam of the hvac. I now keep the humidity around 50% and never smell any musty or mildew scents in the basement. There is still a very small concern about the 60 year old concrete blocks letting water in. (a very small concern)

I am a big fan of overbuilding and really making sure I address everything to the best of my abilities. This being said I have been trolling all over the web reading and learning as much as I could over the past few years. Also waiting to see if any other moisture/humidity issues presented themselves. They have not.

My plan of attack is to clean the walls with a mold/mildew solution and then cover the walls halfway up with super thoroseal. Then secure at least 2" xps to the walls front, back and one side that is an exterior wall. Seal it all together and begin framing it in with 2x4 walls. I saw someone use a piece of trex decking with pt 2x4 as the bottom sill and I thought this would be better than just putting the pt on the floor for the walls. Then I will frame with regular lumber and insulate the 2x4 cavity with batts, there will be about an inch between the xps on the wall and the back of the batts because of the original footing that sticks out. Once all the wiring is done I will use durarock on the bottom half of the walls as an over precautionary measure, and blue board the rest. A coat of paint and walls are done.

Now for the floor. From a response I got from Dana I think I will use 6 mil poly and 1.5" xps and 0.5 plywood on the floor, half of the room will be tiled for a bar and pool table area and the other half carpeted for the theater room. Would it be ok if the xps is cut around the hvac that sits on the concrete? I really do not want to lift it. I dont have to worry about the water heater because its on the wall although I guess the same question applies, can I use xps around it?

The ceiling is already insulated with batts in the joist cavities and I would like to keep as much headroom as possible and keep it easy access to the plumbing, wiring and hvac ducting in case or future problems. So I do not want the sheetrock the ceiling I want to use .25" panel board and just cover the seams with trim. I probably will not even paint it. I figure it I leave a .75" to 1" gap between panels and use 2" trim this should be enough for expansion and contraction due to the fact that the panel will be very close to the hvac ducting although the ducting is covered in a thin layer of reflective insulation.

This is where I am kinda torn. I have enough space to put in a second household bathroom (stand up shower, no tub) should I ? The main drain pipe is halfway up the front wall so I will need a grinder and a pump. Are the failure rates on these things high enough to make them more a hassle than its worth.

Sorry this is so long but it seems there are many people here far more knowledgeable than most other forums I have visited. I am open to all thoughts and ideas, I have not started anything. All feedback is greatly appreciated.



11-22-2011, 09:11 AM
The top pic is rockwall fire place I am just gonna clean and use and the Bottom pic is the basement before plumbing and hvac ducts all the ducting is on the left side ceiling about 4 " below the I-beam

11-22-2011, 10:47 AM
Overall plan sounds good to me.

Why are you insulating around the furnace on the floor? You should create a separate room for the furnace, with 3' clearance around it, and leave the floor cement in there. insulate the walls of the furnace room, not the floor. Same thing probably applies for the water heater, I'm not sure what kind of clearances are required for a tankless, but I'd probably box out around it and insulate the box out, not the wall its mounted to. make sure you're venting/fresh air supply is not effected by this arrangement.

On a job this large, I'd consider doing your 2x framing with a gap between it and the wall of whatever you want, and having it professionally spray foamed with closed cell foam. This will give a better air tight seal. You'll have to get input from people like Dana about all the ramifications of this process as far as moisture control, as he obviously knows far more about it than I do. It should cost in the range of $1.10 per board foot (one square foot, 1" thick), but is very good at what it does. Most formulas are at or close to R7 per inch, it adds structure to a building, is completely air tight if installed correctly, and pretty moisture resistant. Again, I defer to Dana and others for the proper moisture control of this setup. Personally for a basement, I'd frame it 1" away from the wall, even if you need to notch over the footer to do so, spray that entire cavity full of foam, and then fill the 2x4 framing with R13 fiberglass and call it a day. You will get a total of about R19-R20, but its a completely air tight assembly, so it far outperforms a typical R19 fiberglass installation in 2x6 walls.

i wouldn't bother with CMU on the bottom, personally. I'd just use MR the whole way, holding it up about 1" off the floor to avoid picking up any moisture from the floor. Alternatively, if you put your 1.5 XPS on the floor right up to the footing, then frame on top of that, you wouldn't have to worry about gyp board to cement contact at all, and you'd have a tighter insulation seal. The paint texture difference between the 2 boards would be unacceptable to me if you use both CMU and gyp board. a tight seal and low humidity is all you need there.

For your ceiling, if you want the look you are describing, I would do something like what you are saying and not attach the 1/4" boards to the ceiling at all. Make your seams on a 24x24 or 16x16 pattern (something that works for your joist spacing) and only attach the trim to the joists, letting the panels float. if you want to get fancy, you could rip your 1x2's into a "T" shape, creating a notch on each side to carry the panels, and the middle unnotched part can sit directly on the wood studs. This will ensure that the panels are not sandwiched tightly against the studs by the nails holding the trim to the joists. on a table saw, this would be a quick job, just make a 3/8" deep by 1/2" wide groove along the top of each side of the 1x, allowing the panel expansion room and 1/8" of play up and down so that it can't be pinched in place. It will also reduce the thick/chunky look of the 1x trim.

The installation on a macerating toilet system is nice and quick and easy, i can't comment on their longevity. Around here, drain lines are almost always below slab, so i always plumb directly into them. I think there are some other preferred options rather than a maceration toilet, but I'll let the plumbing pros answer that one. The value/convenience added from this bathroom would be worth it in my opinion. If you can hide the equipment for this in the furnace room or something, it makes access/service easier, and looks better. Not sure what your layout looks like/if thats possible.

11-22-2011, 12:10 PM
2" XPS on the wall would be a max, not a min. At 2" it's about 0.6 perms, and given that you've had moisture issues it might be better to keep it over 1 perm (1" of XPS or up to 2" of EPS.)

Do NOT leave a gap between the foam and the batts, as that will allow convection loss performance within the batts (which require a tight air-barrier on both sides to meet rated-R), also leaving a potential unobstructed thermal bypass air currents. If you can't get the studwall any closer to the foam, use R19 batts and compress them to fit. Be sure to use sill gasket (or the floor- XPS) under the bottom plate of the studwall to eliminate capillary wicking of moisture into the wood.

Use only UNFACED batts, no interior vapor barriers, or you'll essentially have buried the studs under ground, where wood never rots or molds, right? :-) The foundation & studs need to be able to dry toward the interior via vapor diffusion- use only standard latex as the interior finish (2-3perms), and avoid vinyl or foil wallpapers, etc.

You can use duct mastic to air seal the seams of the EPS, or use housewrap tape if it's XPS, but sealing the foundation sill to the foam calls for a spray-foam solution, at which point you might as well spray-foam insulate the band joist as well. Closed cell foam is about a buck a square foot per inch of depth if doing the whole wall, but doing just the band joist & sill on a 25x50 rancher with 2x10 (9.25") joists would run ~300 board feet at 2", including sealing over the top of the wall-foam and top plate of the interior studwall. This is a DIY project using an online kit, but if you're doing it now use the "cold weather" forumulations or you'll have expansion & bonding issues. A 600 board foot kit is ~$650-700 shipped call it $750 with extra tips, tyvek suits etc. A 200 board foot kit is ~$350 shipped. A pro would probably nick you $1500 since it ties up the truck & crew for a partial-day (time is money), but if the state will give you a rebate (see masssave.com) it might be cheaper to let them do it. Call some contractors, tell them the size of the job, and ask about the state rebates.

Framing an inch or more away from the wall and spray-foaming with closed cell to fit as mtcummins suggested would work, but it's a lot more foam $ even at a 1" nominal depth. At 1" of closed cell you'd be at about 1-1.5perms which is fine, and at about R6 (also fine, from a wintertime dew-point calc point of view.) Virgin EPS is ~10cent/R/square foot, compared to closed cell spray foam @ 17cents- probably more if it's under a couple thousand board-feet (time is money, and tying up the truck for half a day costs something.) Reclaimed roofing EPS is typically about 3cents/R/square foot, and about 1-2 perms @ R10 (2.5"), (well worth a trip or two to Framingham with a pickup truck.)

Leaving a gap in the floor insulation around the heavy mechanicals is fine. As long as you have at least 1/2" of plywood or gypsum as an ignition barrier at the edge you can take it as close to the water heater as any other wall material.

11-22-2011, 12:33 PM
On a somewhat unrelated note... Dana, I was just curious what it is you do that you have such a detailed knowledge of this stuff. I'm impressed and learning a lot from you.

Thank you for sharing your knowledge on this tricky subject with us... I've seen some really awful basement renovations where there was obviously zero thought for moisture control, what a mess that can be.

11-22-2011, 01:21 PM
So let me see if I completely understand

I definitily have the issue of the original footing at least 3" from the original block wall, the back of the framed wall will not be able to begin for this distance so I would like to do as thick of a board insulation on the block wall as possible, So It seems I should use 2" EPS and R19 unfaced batts in the cavity of the new framed wall, because the R19 is 5-6' deep and will be able to press tightly up against the 2" eps...right?

I am not to keen on spray foam because I think I will need alot more than the above set up, but if I was to do foam would I still do the EPS on the wall? also would the foam be sealing in a the electrical in the wall and above it?

The part thats not getting through my thick skull is where the floor meets the stud wall. If I put 1.5" XPS right up the lip of the footing that sticks out and my bottom plate right on the edge of the XPS is it possible for the XPS to compress under the weight of the framing and cause the wall to shift? If I do XPS on the floor and put my bottom plate right on top should I use a can of great stuff to seal the inside between the EPS wall, the XPS floor and the footing lip?

As for the ceiling I am more looking for ease of access then fancy look especially because it will not be uniformly flat accross the span of the basement. I was just thinking of using 4x8 sheets 1/4" thick, I dont think I will be able to attach directly the the joists because the plumbing pipe are lower than the joists and I want to hide everything, as best as possible.

Sorry if I'm a bit thick when it comes to these things I am very new to this stuff and have always paid someone to do any major things like this but in this excellent economy were in the budget is tighter than before so I am going at it as a diy project. I cant thank you guys enough for the advice.

11-22-2011, 01:23 PM
I just make it up as I go along! :D

Facing facts, I'm just an enginerd. I design electronics for a living, but my degrees are in math & physics. I look stuff up and analyze it 6 ways when making decisions on my own retrofits. (I live in a circa 1923 bungalow in Worcester MA that was long on charm, short on insulation & heating efficiency when I took it on.) While there's a wealth of ignorance out there posing a pros on DIY sites, there's also a wealth of info on academic and DOE sites. Building Science Corp (a DOE contractor/consulting company) has tons of mostly readable less-nerd-science briefs on an number of topics, including basements (http://www.buildingscience.com/documents/reports/rr-1003-building-america-high-r-foundations-case-study-analysis). <<<Note the locations of capillary breaks before doing any of those as a retrofit- some really need the capillary breaks, whereas others are more forgiving.

It may take a bit of study to familarize yourself with the hygric-analysis, but if you can read a psychrometric chart and do simple ratios it's pretty easy to come up with reasonable numbers on foam/fiber R values that would reliably limit wintertime condensation for a particular location & climate, etc. without doing the hard-math versions. There are also some pretty good freebie energy use and moisture modeling tools out there (WUFI, DOE2/BEopt, Hot2000) depending on which aspects you're chasing. Basements are a special case, since you have both ground moisture drives (with quite a range of values) as well as wintertime condensation issues (better bounded) to contend with, but it's still possible to get reasonable good/better/most-resiliant designs out of it using basic principles.

Codes are starting to catch up, but code-inspectors & contractors are always playing catch-up- you can't count on just pulling a contractor out of the phone book and know that it'll really work. I too have seen multiple basement-buildout disasters where well intentioned and otherwise competent contractors or DIYers made critical design errors that went completely over the inspector's head, and 2 years later they're gagging on mold, debating whether to rip it out & start over, etc.

11-22-2011, 01:34 PM
Dana your in worcester if you need something to do an a sunday farm fresh steaks and ice cold beer here in tyngsboro. :)

11-22-2011, 01:39 PM
Sunday's are for soccer some seasons, skiing for others (but thanks for the offer!)

11-22-2011, 02:21 PM
Well the offers out there.

But did I understand your previous post correctly? well 2 or so posts ago.