Half Basement Family Room and Bath - Planning and Rework

[John_7951]

Hi, I'm in the planning stages for remodeling my family room in the half-basement. I want to create an in-law suite including a barrier free bathroom/shower and a furnace room. This is following a major renovation and room addition in the rest of the house. Following construction, the original family room, utility room and power room were, essentially, trashed - but I expected that. I planned to finish this part of the house as "phase 2".

The original power room was pretty useless. I want to build a new bath with a roll-in shower & linear drain. The laundry was relocated to an upper level but I want to anticipate putting in a stackable washer/dryer in the new bathroom. Two furnaces were put side-by-side in the basement. They are loud and I need to enclose them.

The construction that supported the first renovation pretty much used the basement without much thought. One result is that the DWV and supply lines for the floor above consumed a lot of head room that I would like to get back. I also need to relocate the water heater to put a water softener in where I want it.

Right now, I'm just planning things out. I think I have a workable plan, but that remains to be seen. I need to do some prep work first to get things situated better before any real construction can begin.

So ... I will have a bunch of questions ...

To start this off, I want to upload some design pictures and then deal with a couple specific DWV rework efforts to help me get my head room back in the proposed location for the new bath.

Here's what the basement looks like now and my proposed designs.


Here is the first question on re-working the DWV ... Can I move the drain pipe for the upstairs bathroom that runs overhead, across & under the joists? I want to route it so it ties into another stack that is next to the furnace. Please see these photos in the next post ...

 

[John_7951]

I want to move the 1.5" drain pipe for the upstairs bathroom that runs overhead, across & under the joists. I want to route it so it ties into another stack that is next to the furnace - five feet to the west, and 7 feet to the south. Please see these photos ...

 

[Sponsor]

 

[Jadziedzic]

Not DVW but I noticed ...

Your high-efficiency furnaces are drawing intake air from the basement; is there a reason the intakes were not piped to the outside? If you close the furnaces (and water heater) in a small room you'll definitely need to provide an exterior air supply to the furnaces, and perhaps to the water heater as well - particularly if the house is moderately air tight.

 

[John_7951]

Thanks - and good point. That is another re-work item. I have enough clear joist spaces to run intakes from the outside to the proposed furnace room. I need an intake duct for the water heater, so whether I make separate runs for the furnaces too, is something I have to work out. The county will probably have a required duct size for the WH. I can accommodate 8" round without any problem, I think. I'm thinking that covers the furnaces too but I'm not going to assume.

 

[Dana]

Anwering some questions not asked...

The batts on the exterior walls don't look like they're full depth, nor are they correctly installed. The amount of dust on the exposed fiberglass on the edge of the batts in picture 5/7 indicates significant air infiltration/exfiltration in that stud bay. Pulling the batts and caulking the sheathing to the framing on all four sides, then installing full-depth higher density batts (R15/2x4 or R21/2x6 if fiberglass R15 or R23 if rock wool) would be advisable before installing a finish wall.

There appears to be no foundation insulation. IRC 2012 code min for US climate zone 5 (northern IL) would be R15 continuous foam, or R19 in 2x6 framing up against the concrete. Installing studs in contact with below grade concrete is universally bad practice. Equivalent or slightly better performance can be had with 1" foil-faced polyiso up against concrete (seams taped with foil tape, edges can-foamed air tight) with a non-structural 2x4 studwall w/ unfaced or kraft faced (but not foil-faced) R13s, and no interior side vapor barrier. If you're going to cheat that, 2" of foil faced polyiso held in place with 1x furring through-screwed to the foundation with TapCons 16-24" o.c. would get you nearly as good performance, taking up less space than a 2x4 stud. The finish wallboard can then be hung on the furring.

On the band-joist it's worth using cut'n'cobbled 1-2" polyiso directly on the wood, and the foundation sill as well (and any exposed foundation-top), then trimming batts carefully to fit on the interior side there as well.

If there is headroom, it's worth insulating the slab with at least R4 (1" EPS) under any new subfloor & finish floor. This will limit the mold potential of anything resting on the floor, which is fairly high in summer in your location. Your deep subsoil temps are in the low 50s, but your summertime outdoor dew points average north of 60F. The result is when you put anything with any insulating value (a rug, for instance) the temperature and relative humidity on the underside of that object is well within the mold zone. With as little as R4 the temp of the materials on top of insulation will track the average room temp, which will always be above the dew point.

Uninsulated basement walls & slabs are the primary cause of basement mold & musty smells. If turning it into a usable living space, it's worth turning it into a NICE, healthy & pleasant space, not just a prettified still-clammy space that smells like a dungeon in summer with frosty-cold walls in winter.

If moving and cutting into drains that close to the water heater, it's the right time to think about whether a drainwater heat exchanger has any value to you (other than scrap copper). A 3" x 60" or a 4" x 48" would return more than 50% of the heat going down the drain during a shower directly into the hot water tank a (and the cold feed to the bathroom, if done optimally). If your fuel is natural gas this would have a very long payback time in energy cost terms, but it effectively makes a standard gas fired tank into an "endless shower" water heater- it can keep up with back-to-back showers all day & night, if need be. It does nothing for tub fills, since the heat can only be recovered & delivered when both the drain & potable sides of the heat exchanger are flowing. If you open an account at EFI (with a credit card over the phone) you can get 'em for cheaper than retail, which improves the payback economics considerably.

 

[Reach4]

I don't know about the drains, but I was struck by the furnace combustion air intake pipes in the middle picture. I wonder why these intake pipes are not run outdoors.

 

[John_7951]

Wow Dana! Thanks for the very thoughtful and detailed information. You raise many points that I had not considered yet - and quite frankly, wasn't even aware of.

What you are seeing is the gutted space after the first construction effort ended. I removed the 2x2" furring and insulation from the foundation. What you see of the insulation may be left over from 1968 when the house was built. Or, it might be from the early 90's when I think the prior owner built out the family room.

Thank you for the recommendations on insulation. I will definitely apply them to the design. they may also have an impact on my DWV design. I had thought to minimize the depth of the framing/insulation of the foundation. If I do a full 2x6 frame out, that may change some of the DWV rework in the concrete. I can maybe reduce the amount of concrete cutting. I had wanted to avoid thick walls in front of the foundation and making the windows look set back too far.

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Headroom and floor space, in general, are concerns. I want to keep as much floor space as I can since the in-laws suite is a consideration for my handicapped father-in-law. ADA compliance is not mandated, but the design is already tight as it is. He is using a wheel chair now - for convenience while in his home but not when he goes outside.

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I have one question about the insulation over the slab regarding the suitability with water intrusion - vs condensation? I have done some work on the perimeter drain tile and I have seen improvement. Prior to that, there had been some minimal water coming in thru two foundation cracks and the slab was damp in the rainy spring pretty much every year. So, there is more drain tile work I need to do (and/or pay $8k+ for interior drain tile). Would you recommend insulating the slab floor without doing that other remediation first?

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I had never heard about drain water heat exchangers. There are a couple things that might play into that decision. The house is now a quad-level. All the upstairs DWV drains with gravity to the septic tank. Only the basement is serviced by the ejector pit. As an in-law suite, I don't know how may showers there might be in a week. Probably not one a day. If not used an in-law suite, the showers would be very infrequent. Would a heat exchanger for the upper floors make sense? Other than my father-in-law, it would be two showers a day for me and my wife. I will research a little and look to see what the payback might be.

OTOH, a BIG concern is the amount of water I will be flushing down the drain every day to get hot water up to the fourth-level shower. I have planned from the start to install a circulation pump configuration of some kind to get hot water up there. It takes over a minute to get hot water flowing. That may be a consideration/advantage when considering a drain water heat exchanger?

Thanks!!!

 

[John_7951]

Hi all - regarding the air intake for the furnaces - I don't remember my builder ever asking me what I wanted, but it was my plan from the start to remodel the family room as a second phase to the construction. I am guessing that somebody (HVAC guy?) decided to do it this way. The basement is now considered unfinished by the county so using intake air from the house is OK.

The inspector did say that the intakes would have to meet code if I were to build the furnace room - and that could be dedicated intakes for each furnace or a common intake duct. He did not tell me the specific requirement but said they follow the manufacturer's specifications. So, I would probably opt to run dedicated intakes for each furnace - one, to remove any doubt about them and, two, to reduce the size of the intake duct needed for the water heater.

Running the 2" PVC should be pretty easy but I will be reducing my open joist cavities which are precious commodities. I have dryer vents to accommodate too.

 

[Dana]

Drainwater heat exchangers work on a gravity film principle, and have to be installed vertically to work. (The water coming down a vertical drain clings to the inteiror surface of the drain pipe and spreads out for a larger heat exchange surface area.) It has to be on a section of vertical drain downstream from the upstairs showers to get any benefit. The ejector pit pump would not be running continuously while showering, and would recoup very little heat from that shower.

But drainwater heat exchangers work just fine on hot water heaters with a recirculation loops- it's feeding the COLD side of the water heater & shower with tepid water (typically room temp, or slightly above), and tee-in in just ahead of the hot water heater is not a problem. Sometimes it's easier to just have the output of the heat exchanger feeding the entire cold-water distribution network of the house, since then it's automatically feeding both the hot water heater and the cold side of the shower for maximum efficiency. The worst that happens in that configuration is that someone in another bathroom might end up brushing their teeth with room-temperature water instead of something colder.

The bulk water intrusion issues need to be dealt with before ANY finish floor gets put down, insulated or not. But when you insulate, a layer of 6'mil polyethylene between the insulation and the new subfloor would mitgate against minor groundwater issues that occur under the foam. As long as you use EPS or XPS (and NOT polyisocyanurate) for the floor foam, it'll be fine. With a history of water incursion it's worth extending the floor foam and polyethylene sheeting all way to the foundation wall, with the sheeting going up the wall several inches, and installing the wall-foam on the interior side, where the bottom edge of the wall foam is resting on polyethylene, and not the EPS/XPS. This is most important if the wall foam is polyisocyanurate, which can wick & store moisture. If it's EPS or XPS it'll tolerate it, but you still want to keep the subfloor & stud/plates away from any moisture seepage.

There is no need to do a full 2x6 frame-out inside the foundation- it's one of the worst/riskiest possible ways to insulate a foundation from mold & rot hazard perspective. Performance-wise A 2x6/R19 wall only comes in at about R13-R14 "whole-wall" after factoring in the thermal bridging of the studs (which is why continuous R15 is a code specified alternative). T The same or better performance can be had with an inch of foam and a 2x4/R11-R13 studwall, or 2-3" of foam mounted with furring. Foil-faced polyiso runs about R12 @ 2", but with the foil facer facing a 3/4" air gap the low-E facer boosts the performance a bit, so it's really close to R19/2x6 performance even though it doesn't meet the letter of code.

To figure out what to do where lower part the wall is foundation, with a ponywall above, if you extend the plane of the interior surface of the concrete up to the stud wall above, what is the distance from the exterior sheathing to the concrete plane? (Measure the depth ledge of concrete on top of the foundation and add 3.5" for a 2x4 stud depth.)

And what type of exterior siding is on the framed wall?