Insulating ideas for basement bathroom

[thefed]

i'm finishing a new bathroom which is built in a basement garage. It is sectioned off with 2x4's and drywall in the rear corner...right outside the door is a hallway at the bottom of the steps going to the stairs as well as another door to the basement area itself (heated...stays 65 while upstairs is 69).

Well, I have an ice cold slab in the new bath and for some reason opted out of heated floors. Instead,I have 2 "teed" ducts leading into this 70 sf bathroom...probably a total of one full registers worth of hot air. All walls except the one touching the block wall separating the heated basement area were insulated with r-13 fiberglass. The one exterior block wall also has a layer of r4 styrofoam on the block. The ceiling has new r-13 I put in as well.

as it is, the garage dips to 50 at night....the bath might stay at 60....very chilly still. The heater doesnt run too much so not much heat gets blown in there (our upstairs is insulated to the gills). Would it we worth it (4,5,6 degrees diff?) to add another layer of r-13 to the walls meeting the coooold garage? I can do this before I seal up that side of the walls with more drywall if so desired.

In addition, I'm thinking of adding a piece of weatherstripping to the bottom of the porcelain toilet as a thermal barrier...but is it worth it? Wonder if it'll help at ALL? The floor temp must be 15 degrees less than that of the room...or more...its COLD. The toiled is sealed and pumps UP so it wont interfere with a wax ring or anything


I did install a 1500w in-wall electric heater...but dont want to run it continuous duty...hoping I can insulate this small room enough to stay usable

any ideas, experience, or input?

 

[jazz4cash]

Mr Project:
How about an infrared heat lamp with a timer? The wall insulation probably wont help much, but it would be cheap and easy to add while the wall is open, so why not...might help as sound barrier also.

 

[thefed]

Didn't plan for an infared, so no wires run and drywall is done overhead.

Another idea I had is tyvek or similar plastic wrap around the exposed walls....cant hurt....

I think a heated toilet seat would be ideal, but the saniflo toilet i bought has a wierd bolt pattern....6 1/2" or so and most toilets around here use a 5.5" bolt spacing to attach the seat. Any idea where to find one?

 

[samclem]

i'm finishing a new bathroom which is built in a basement garage. It is sectioned off with 2x4's and drywall in the rear corner...right outside the door is a hallway at the bottom of the steps going to the stairs as well as another door to the basement area itself (heated...stays 65 while upstairs is 69).

Well, I have an ice cold slab in the new bath and for some reason opted out of heated floors. Instead,I have 2 "teed" ducts leading into this 70 sf bathroom...probably a total of one full registers worth of hot air. All walls except the one touching the block wall separating the heated basement area were insulated with r-13 fiberglass. The one exterior block wall also has a layer of r4 styrofoam on the block. The ceiling has new r-13 I put in as well.

as it is, the garage dips to 50 at night....the bath might stay at 60....very chilly still. The heater doesnt run too much so not much heat gets blown in there (our upstairs is insulated to the gills). Would it we worth it (4,5,6 degrees diff?) to add another layer of r-13 to the walls meeting the coooold garage? I can do this before I seal up that side of the walls with more drywall if so desired.

In addition, I'm thinking of adding a piece of weatherstripping to the bottom of the porcelain toilet as a thermal barrier...but is it worth it? Wonder if it'll help at ALL? The floor temp must be 15 degrees less than that of the room...or more...its COLD. The toiled is sealed and pumps UP so it wont interfere with a wax ring or anything


I did install a 1500w in-wall electric heater...but dont want to run it continuous duty...hoping I can insulate this small room enough to stay usable

any ideas, experience, or input?

I'm having a little trouble visualizing this.

1) What is over this basement bathroom? If it is the liveable area of the house, why did you insulate it? The heat flow from a heated space (even above it) would be beneficial in this room)

2) Are you thinking about/able to do more work on the walls? If the bl;ock walls insulated at the R-4 level are exterior walls (or separate the bathroom from a cold garage), that's where I'd start: make them R-8 (2" of XPS foam) or R-12 (3" would be even better. Also, if the other (non block) walls are opened up, you might consider some other insulation choice rather than fiberglass due to the high expected moisture int hat room and the low temps on the outside wals: Moisture and mold problems are a real possibility with this combination.

3) The only way to make that floor actually warmer is to install hydronic or electric heating elements in re-poured slab or to add a new wood floor on sleepers and insulation over the existing concrete slab floor. There's no way I would recommend doing any of that--it's a giant, expensive PITA, and a concrete slab is a very good choice for a bathroom at any rate. Water is going to leak after all, and you've got the perfect floor now for the day that happens. Make the slab look nice and put some throw rugs/bath mats on the floor and call the job done. Really. The problem with the slab is not so much it's temperature as it's heat capacity--the concrete is dense and makes bare or stocking feet feel very cold when in contact with it. A rug will be the same physical temp, but heat flow out of the feet will be much reduced.

4) Heating: You've got plenty of physical register size for a room that big. If the existing ducts leading to the bathroom are going through unconditioned spaces, be sure they are insulated. Also, be sure there is a return air path out of the bathroom so that the air will go in. It sounds like the basic problem is that this room has higher heat loss per cubic foot than the rest of the basement (because it is in a corner and therefore has a lot of outside wall area), so it gets colder faster. Increasing the heat flow to the room (e.g. with a booster fan, etc) is unlikely to be very successful, since it will only bring in more warmth for the limited time that the furnace is on. You'll probably get more bang for the buck by insulating if you can. BTW: What type of electric heater is in there now--fan forced air/convection or radiant heat? A radiant heater will warm the occupants a lot faster than a convection or fan-forced heater will--they'll feel the heat within a few seconds after turning on the switch. That may be a more effective answer than trying to keep the room toasty 24/7.

5) Toilet: Maybe inserting something between the toilet and the slab might help it stay a little closer to the room temp rather than the slab temp. If you decide to go this route, it needs to be something that can take a lot of weight without deforming. Any "give" as people move about on the throne wil eventually wreak havok with the pipes you've got installed at the back. I don't have any great suggestions. They do make high-density foam sheets, but these aren't commonly stocked in hardware stores, and I don't know if they'd be up to the task. 1/4" cork gasket material might work okay, with caulk around the outside to dress it up.

6) If it weren't a bathroom, I'd suggest possibly having some mechanical ventilation between this room and a warmer part of the house (maybe upstairs). That won't work here. BTW, is the room properly vented tothe outside? You'll want to get that hot, moist air fom the shower removed from your cool basement before it condenses on those walls down there.

 

[samclem]

Another idea I had is tyvek or similar plastic wrap around the exposed walls....cant hurt....

Be sure you've figured all these vapor issues out--plastic causes many more problems than it solves. Tyvek is a different thing than plastic--water vapor flows through it freely, but it blocks liquid water and the flow of air. Plastic (polyethylene, etc) blocks the flow of water vapor and can cause bad mold/moisture problems if it is not installed in the right place/way. Your situation (cold walls in a room where warm water vapor is introduced into the air) is a textbook case for mold formation, so it needs to be done right.

Regarding the drywall: This is a room that is very likely to get wet. The "greenboard" that is traditionally used in such places is not much better than standard gypsum board. Consider cement board and tile for areas that will be getting splashed by water. At the very least, use the mold-resistant drywall in this room for walls (and ceiling, if you re-do it) that won't be directly exposed to liquid water. It is similar to regular drywall, but it has a fine fiberglass mesh on the faces rather than paper. Cellulose (what paper is made of) is what most mold eats, which is why you see it living on drywall often. As this room is a trouble spot, invest a few more bucks for DenseArmor or other mold-resistant drywall.

 

[thefed]

samclem...thanks for the post. above this new bathroom room is a liveable space...yes. But moreso important than keeping this bathroom warm is keeping the floor of the room above it warm....being that most of it is above said garage which gets chilly. i insulated to keep that upstairs heat up-there.

2)to clarify the original post, the one exterior basement block wall has r4 xps AND r13 fiberglass. Everything has vapor barriers up, and siliconed. Moisture shouldn't pose too much a problem, but we'll see.

4)I have a convection heater in there now, but can likely track down radiant.thanks for the suggestion

6) I have a nice 130 cfm fan in there vented outside for shower moisture. your mention of mechanical ventilation....can you elaborate? Ironically,there is a laundry shoot I could likely tap into 3 feet away from the new bathroom....we don;t use it. It runs from our bedroom (the hottest room of the house) to the basement. Maybe a fan in there or something...but what about noise?


Thanks!

 

[thefed]

on your other post:

i did use greenboard for the bathroom,and cement board for the shower stall and backslash behind sink in same room. actually not greenboard....but paperless drywall treated somehow... i think we'll be okay....

 

[samclem]

to clarify the original post, the one exterior basement block wall has r4 xps AND r13 fiberglass. Everything has vapor barriers up, and siliconed. Moisture shouldn't pose too much a problem, but we'll see.

Just a=out of curiosity, where did you put the vapor barrier? As you know, the cement blocks pass water vapor from the moist soil outside very readily, and 1" of XPS (perm approx 1.5 IIRC) will retard vapor but isn't a barrier. Many codes call for plastic against the block. OTOH, many sources recommend a vapor barrier on the warm side of wall structures, which would be right behind your drywall. When the room isn't full of warm, moist airm it will behave like any other basement room and water will be trying to come through that wall and dry to the inside. When it is moist inside, the gradient will be reversed. I'd be afraid of trapping water in there with any impermeable barrier. What did you wind up doing?

your mention of mechanical ventilation....can you elaborate? Ironically,there is a laundry shoot I could likely tap into 3 feet away from the new bathroom....we don;t use it. It runs from our bedroom (the hottest room of the house) to the basement. Maybe a fan in there or something...but what about noise?

Good job on installing the exhaust fan--I still need to put them in my bathroom. I don't think mechanical ventilation will likely work here--though it is tempting to give it a shot. Just a small, quiet fan (like one in a desktop computer's chasis) might be effective in bringing in enough warmwer air to raise the temp a few degree if you could bring the air from a considerably warmer room. It would be more of an experiment than a sure thing, but you could give it a go. The noise issue could be reduced with a baffle box with foam baffles. It would also be important find a way to disperse the air so that it doesn't create a breeze in the bathroom-any air movement will make the room feel much colder and negate the few degrees of temp rise you'd get from the piping in the warmer air.

 

[thefed]

well,i found a heated toilet seat to fit my weird toilet....so that should do the trick!

It stays about 65 in there now with a few modifications to te heat registers and filling some gaps I found. If I run the 1500w heater for a couple hours I can get it up to 88 in there....not bad considering its 48 on the other side of the wall!

 

[Martha]

We have a basement bathroom with a cold cement floor. When we use it we just run a space heater for a few minutes with the door closed. Warms it up fast.

 

[tmm99]

Alternative to heated toilet seat.. (or until you get the heated seat installed.)

WARM COVER TOILET SEAT,WASHABLE.PERFECT 4 WINTER. BROWN - eBay (item 200279642499 end time Dec-23-08 12:40:09 PST)

tmm

 

[thefed]

Alternative to heated toilet seat.. (or until you get the heated seat installed.)

WARM COVER TOILET SEAT,WASHABLE.PERFECT 4 WINTER. BROWN - eBay (item 200279642499 end time Dec-23-08 12:40:09 PST)

tmm

lmao that it's dark brown....cant beat that!

 

[Ronstar]

I have a basement bathroom as well - ceramic tile over concrete floor. One of the bathroom walls abuts the interior house side of the garage wall, so I insulated it with 3-1/2" fiberglass. The whole basement is heated with supplys/returns like the rest of the house, so the basement air feels warm. But the ceramic tile near the walkout side of the basement is extremely cold.

I would think a small baseboard electric unit would take the chill off your floor, but I'm not sure about the code for baseboard electric in a possible wet area.

 

[thefed]

I have a basement bathroom as well - ceramic tile over concrete floor. One of the bathroom walls abuts the interior house side of the garage wall, so I insulated it with 3-1/2" fiberglass. The whole basement is heated with supplys/returns like the rest of the house, so the basement air feels warm. But the ceramic tile near the walkout side of the basement is extremely cold.

I would think a small baseboard electric unit would take the chill off your floor, but I'm not sure about the code for baseboard electric in a possible wet area.

i actually have an in-wall electric heater hard-wired in this room. my goal though was to have it warm upon entering...not having to heat it up to take a dump! so that's why i think the heated toilet seat should help tremendously....only 30 watts and it stays on all the time

 

[mattgg1]

It sounds like your main complaint is the cold floor in the bathroom. If this is the case, additional insulation in the walls/ceiling will not add much comfort. Although it may not be a viable option at this point, you should inslulate the floor. This would isolate the very cold concrete basement floor slab from the heated living space.

It is a very easy process...
-put down vabor barrier on concrete slab
-lay pressure-treated "sleeper" studs on the floor
-add rigid foam insulation between the sleepers
-lay plywood/OSB on top of the sleepers

However, unless you do this to the entire basement/garage, your bathroom floor would be approximately 2" higher than the rest of the basement.

 

[samclem]

It sounds like your main complaint is the cold floor in the bathroom. If this is the case, additional insulation in the walls/ceiling will not add much comfort. Although it may not be a viable option at this point, you should inslulate the floor. This would isolate the very cold concrete basement floor slab from the heated living space.

It is a very easy process...
-put down vabor barrier on concrete slab
-lay pressure-treated "sleeper" studs on the floor
-add rigid foam insulation between the sleepers
-lay plywood/OSB on top of the sleepers

However, unless you do this to the entire basement/garage, your bathroom floor would be approximately 2" higher than the rest of the basement.

This would raise the temp of the floor, but I would not do it. If you go this route, keep the measurements of the plywood/OSB handy, as you'll need them to cut replacement pieces for these swollen sheet goods when the toilet or sink overflows.

Concrete is the right floor for a bathroom, especially one in a basement. Go with the throw rugs.

 

[mattgg1]

This would raise the temp of the floor, but I would not do it. If you go this route, keep the measurements of the plywood/OSB handy, as you'll need them to cut replacement pieces for these swollen sheet goods when the toilet or sink overflows.

Concrete is the right floor for a bathroom, especially one in a basement. Go with the throw rugs.

Apparently you didn't fully understand my post or standard building methods.

The plywood/osb is simply the SUBFLOOR, not the finished flooring material. Obviously, you would cover the plywood/osb subfloor with your choice of finish flooring (tile, linoleum, hardwood, ect.)

With the exception of homes built on slabs, virtually every home in America has a wood subfloor in every room of the house, including bathrooms and kitchens.

 

[samclem]

Apparently you didn't fully understand my post or standard building methods.

I understood your post and I understand standard building methods. I know people do build basement bathroom floors as you've suggested. And I understand how to rip out a rotted wood floor (having done it a few times) and how to replace it. And that anyone who puts a wood floor in a basement bathroom over a perfectly good concrete slab will also likely be ripping out that wood floor eventually. That's all I said.

PS--Don't forget the underlayment under the linoleum or vinyl and over that OSB. That underlayment is another layer that will need to be ripped out eventually.

 

[mattgg1]

I understood your post and I understand standard building methods. I know people do build basement bathroom floors as you've suggested. And I understand how to rip out a rotted wood floor (having done it a few times) and how to replace it. And that anyone who puts a wood floor in a basement bathroom over a perfectly good concrete slab will also likely be ripping out that wood floor eventually. That's all I said.

PS--Don't forget the underlayment under the linoleum or vinyl and over that OSB. That underlayment is another layer that will need to be ripped out eventually.

Could you elaborate on how such a subfloor would become "rotted out" in this application?

 

[ERD50]

Could you elaborate on how such a subfloor would become "rotted out" in this application?

I'm also curious. I would think the vapor barrier and the other steps listed would be OK. Unless you actually had seepage in that area, but you'd have wet rugs and you would know about it.

-ERD50

 

[travelover]

I'd be reluctant is use any wood in floors below grade, just due to Murphy's law. Even if it didn't rot, I can see it turning moldy and funky under there. I have a dry walk out basement and from time to time I find sow bugs and crickets on the carpet - not sure where they come from, but they'd love a place like that to live.

 

[samclem]

Could you elaborate on how such a subfloor would become "rotted out" in this application?

Maybe it wouldn't. But I just think the odds are against the wood floor in this situation avoiding water damage for a multi-decade period.

Factors:
-- Potential for water/water vapor leakage from outside the basement. This is reduced by adding the vapor barrier. But, the vapor barrier guarantees that any water that does get under the wood subfloor will stay there for a long time, making the RH below that subfloor 100%. That's hard on wood products.
-- Leakage from the sink (trap, overflows)
-- Condensation from toilet (very cold porcelain bowl/tank, high RH in basement=drips).
-- Toilet overflows
-- Toilet drain line leaks
-- All the toilet/sink drain "challenges" are exacerbated by the ejector pump setup needed to drain these fixtures "up" (per the OP). More fittings/seals to leak. More importantly, standing sewage in the drainpipe at all times, all depending on a check valve to stop backflow onto the low point--the wood floor.
-- Supply lines to sink and toilet with maybe a dozen total connections to leak.
-- Whatever the floor covering is, it will be only marginally effective in stopping the penetration of water to the subloor. Vinyl/caulk works sometimes to keep incidental water out of the wood system, but really is only effective against the occassional splash from the tub. It cannot be depended upon to keep 100% of standing water out of a wood flooring system that does not have the potential to drain/dry from the back side.
- Even if it is possible to prevent ANY liquid water leakage into this subfloor/insulated system, that would only be possible by making the finished flooring 100% water-tight and (probably) vapor impermeable (I'm not aware of a flooring that is 100% impermeable to liquid water and permeable to water vapor). Its virtually certain that the RH under the poly on the slab will be 100%. That means that if the perm rating of the poly (complete with the tiny holes it will get as the grit on the slab wears through the plastic under the sleepers) exceeds the perm rating of the vinyl floor on top, then the RH under the floor is guaranteed to be 100%. That's a great environment for mold and wood rot. This is a classic "double vapor barrier" situation, and that is nearly always a problem.

I've just replaced two wood floors in the bathrooms of my 50 YO home. Both had excellent drying to the back side (open joists to the basement) but both nonetheless rotted badly over the years. I'm just very conservative when it comes to these things, and I think it's prudent to give these building systems the best possible chance to succeed. You are right, people do build bathroom floors as you've described them all the time. I only said that I wouldn't do it.

 

[freebird5825]

i need to wear my glasses more...the title looked like
"INSULTING ideas for basement bathroom".
i got my mind all revved up for some fun and then.......saw it was a serious thread. carry on...

 

[thefed]

One idea to prevent the subfloor rot from RH 100% would be to either use exterior grade treated plywood or treat the the plywood with some sort of primer to effectively retard rot


But anyhoo....i'm not going down that route....just needed a heated pooper to solve my problems! i'll post a review...no pics

 

[mattgg1]

Maybe it wouldn't. But I just think the odds are against the wood floor in this situation avoiding water damage for a multi-decade period.

Factors:
-- Potential for water/water vapor leakage from outside the basement...
-- Leakage from the sink (trap, overflows)
-- Condensation from toilet (very cold porcelain bowl/tank, high RH in basement=drips).
-- Toilet overflows
-- Toilet drain line leaks
-- All the toilet/sink drain "challenges" are exacerbated by the ejector pump setup needed to drain these fixtures "up" (per the OP)....
-- Supply lines to sink and toilet with maybe a dozen total connections to leak.
-- Whatever the floor covering is, it will be only marginally effective in stopping the penetration of water to the subloor....
- Even if it is possible to prevent ANY liquid water leakage into this subfloor/insulated system, that would only be possible by making the finished flooring 100% water-tight and (probably) vapor impermeable (I'm not aware of a flooring that is 100% impermeable to liquid water and permeable to water vapor)...This is a classic "double vapor barrier" situation, and that is nearly always a problem.

I've just replaced two wood floors in the bathrooms of my 50 YO home. Both had excellent drying to the back side (open joists to the basement) but both nonetheless rotted badly over the years. I'm just very conservative when it comes to these things, and I think it's prudent to give these building systems the best possible chance to succeed. You are right, people do build bathroom floors as you've described them all the time. I only said that I wouldn't do it.

Most of the issues you listed are not specific to a basement bathroom, and apply to nearly every bathroom in America (in homes not built on a slab). Wood subfloors have been used in bathrooms for 100+ years, and even with all the modern advances in construction materials/techniques, wood subfloors in bathrooms are still the standard by which homes are built today.

While there is always a chance of rot when wood is around water, using proper building methods, care & routine maintenance will keep you from fretting over a rotted subfloor. Builders of ultra high-end homes where no expense is spared use wood subfloors in bathrooms. I assume these builders don't tell the owners to (in your words)...

"keep the measurements of the plywood/OSB handy, as you'll need them to cut replacement pieces for these swollen sheet goods when the toilet or sink overflows."

So I think we've established that possibility of water issues above the subfloor (leaks from the plumbing fixtures,ect) are not reason to abandon the use of wood subfloor materials.

The use of a good vapor barrier, pressure treated lumber and closed cell foam insulation would virtually eliminate any concern over the few remaining issues you mention.