Finishing a Basement

[soldoncass]

Just a fyi....I've seen more moisture problems on south and east walls of basements, than on north or west. I think it has to do with the sun's warmth, causing condensation against the poly. Poly is ALWAYS put on the WARM SIDE(inside) of a wall,because moisture moves from warm (holds more moisture)toward cold (holds less moisture), and it is trying to equalize itself. Now if the sun warms the outside warmer than the inside....that moisture is going the wrong way, and getting stopped by the inside poly. Of course this is my 2 cents opinion, based on YEARS of service work on problems we encountered.

[amateurfishing]

so if there is moisture behind poly, it is from the treated bottom plate? should there also be signs of the mold starting on the bottom as well? this is definitely not the case, the spots are kinda everywhere with no real high concentration spots anywhere

as far as water to garage, no drain but well sloped floor

[soldoncass]

If you use water out there with a sloped floor, the water runs to the garage door and freezes it down. That is why I personally wouldn't put water out there, unless the garage was built for it....floor drain, insulated, and heated. Up to you though.

All the new wood has about 19% moisture in it, treated usually more. The moisture is just trapped in that space, and can't get out, mold can form anywhere in there. If there are big problems , the insulation is usually wet on the bottom.

[amateurfishing]

Just a fyi....I've seen more moisture problems on south and east walls of basements, than on north or west. I think it has to do with the sun's warmth, causing condensation against the poly. Poly is ALWAYS put on the WARM SIDE(inside) of a wall,because moisture moves from warm (holds more moisture)toward cold (holds less moisture), and it is trying to equalize itself. Now if the sun warms the outside warmer than the inside....that moisture is going the wrong way, and getting stopped by the inside poly. Of course this is my 2 cents opinion, based on YEARS of service work on problems we encountered.

U hit nail on head, the only place this stuff is is on south and east facing walls, so do i need to assume its mold? and completely redo insulation on walkout wall (east) and south stepdown wall? if so, with what?

...& with the framing i already have done against the blocks, do i need to assume that will have to be pulled out for the foil line insulation behind it or does it just go inbetween framing studs? thx so much for your info & help.....if u r ever in elk river area, i invite u to stop by for a cold one.

[soldoncass]

My gut feeling is you have to only change the poly....that would eliminate the mold, and I believe the wood has dried out, so the cause should be gone. If you feel moisture in the insulation, most likely on the bottom, that may show other problems. FUN to figure out sometimes...not.

As far as the foil board goes, you want it covering ALL the block and taped, joints, corners, top. If there isn't enough room between framing and blocks, for that,you'll have to move it.

Just think of a cold drink glass on a hot summer day.....it gets wet on the WARM SIDE...right? It is the temp differential that causes it...not a leak. So to keep it from happenning in our house walls etc., we have to make sure HOT and COLD don't meet. Just like using an insullated cup in the summer...put enough insulation between HOT and COLD areas, so condensation can't occur. SIMPLE

Good luck in your venture.

[amateurfishing]

k, so in theory, its the poly thats the problem (minus any possible moisture in the boards) right? guess i will have to research some foil lined insulation....and take off poly very carefully as to not disturb/disperse mold spores

i have made a couple small slits and there is coloring on the insullation, does that mean it automatically has to go?

[soldoncass]

The poly is where the mold grew (by it's appearance anyway), so I would take that off ....but I would also wait til it is warmer outside. When you take the old poly off, the moisture in the house will try to get out, and may condense/ frost on the outside sheeting pretty quickly.Let the outside air get closer to the inside temp, so you have more time. It won't hurt to keep investigating, cut some slits to check it all out...just tape them back up afterwards.

Just discoloring doesn't prove mold. Before all outlets had to be taped/sealed, we used to remodel houses....the insulation was ALWAYS discolored around the outlets. All that meant then was, there was air movement through there sometime.

[K_Josh87]

soldoncass has given you pretty wise advice on the situation... I would check in out and follow manners to correct he has advised, of course its really hard to know without looking it it ourselves... But seams very likely to be the scenario.. goo dluck

[amateurfishing]

does anyone have any knowledge, experience, info, or feedback on dricore subfloor, wondering if this would be a nice moisture/heat barrier for on concrete in basement.

[amateurfishing]

city inspector said all is fine, start doing whatever we want

we have r5 insulation on outside of house foundation, any good reason to double up insulation and do some on inside against cinder block as well?

also, any recommendations/experience/knowledge of dri core subfloor?

thx for all the info

[soldoncass]

I don't know anything about that dri-core subfloor, so I can't help you there.

The r-5 on the outside of the block explains no insulation on the inside of the blocks....I wondered how they got away with that. I knew it was legal outside, but it was rarely done, because it needs to be covered with something to protect it. That also creates siding issues, because of the thickness. Because your inspector o.k.ed it, I'll assume it was done properly.

I think r-5 is minimum code still, but r-10 would be better for the heating bill, for you. Can you slide 1/2- 3/4 inch foil-faced THERMAX board between the block and framing? I'd probably go that route.

[amateurfishing]

I don't know anything about that dri-core subfloor, so I can't help you there.

The r-5 on the outside of the block explains no insulation on the inside of the blocks....I wondered how they got away with that. I knew it was legal outside, but it was rarely done, because it needs to be covered with something to protect it. That also creates siding issues, because of the thickness. Because your inspector o.k.ed it, I'll assume it was done properly.

I think r-5 is minimum code still, but r-10 would be better for the heating bill, for you. Can you slide 1/2- 3/4 inch foil-faced THERMAX board between the block and framing? I'd probably go that route.

that goes between the block & framing, NOT inbetween studs INSIDE framing?

[amateurfishing]

i already have plastic poly down agains the block, does that need to be removed for this thermax?

any subfloor needed on basement foundation?

[soldoncass]

I would put it right on the blocks, tape all joints and top. Taped thermax is considered a vapor barrier, so poly isn't needed or recommended behind it. The thing about the insulation on the outside....I believe code only requires it above ground level(if my memory is right), so I wonder where it stops???

[soldoncass]

subfloor on concrete?? I've only seen it done once, by a do-it-yourselfer, it is definitely NOT a common practice. For that reason I say no.

[amateurfishing]

thx, already have poly over cinderblocks inside, just got back from store and like city inspector said no more insulation is required and if any more is added, the benefit may be minimal at most (personally i dont know). sounds like if we do anything with insulation it will be just adding fiberglass or denim in frame next to poly coverd blocks, feel free to chime in if that is a worthwhile benefit or not. thanks again.

[soldoncass]

Putting fiberglass in the framing will work, with poly on the WARM(inside)side, but because of all the problems I alluded to before with poly on BOTH sides of fiberglass, I would't go that way. Before all the codes changed to the new international code, basement walls had to have r-11 in them, with poly on both sides. Now the new code requires r-5,and they use thermax on the blocks, just to eliminate the moisture problems created by 2 polys. You can probably guess what I think about the r-value change. It was blending several codes together into one...so there was some give and take there.

[amateurfishing]

if poly has to be on the warm side or inside and that is already down, maybe just better off going with hard foam insulation inside the poly that is alrady against the block.

[walleye vision]

Was just talking about this with my neighbors as all of us are planning on finishing our basements. I did a little research and found this product: insofast (insofast dot com). It seems like pretty cool stuff and no worry about mold.

The research I did do seemed to suggest never to use fiberglass insulation and a vapor barrier against concrete or block walls. The theory is that concrete will always wick moisture from the ground and the moisture will eventually contact the fiberglass, the poly holds the moisture in the space and then mold will start. Closed cell foams seemed to be the way to go (spray or panels). It makes sense about the fiberglass and mold, but maybe I'm wrong.

So is this idea right? And, has anyone used the InSoFast product?

[soldoncass]

I have not seen that product before. Just like any product out there, there are pros and cons...in spite of all the positive HYPE in the brochures. I googled it and here's my first thoughts: plastic studs to fasten drywall and trim, etc to? ....in order to put required electric outlets in the wall, they would have to cut holes in the foam for the boxes(no insulation behind the box then)....even with channels molded in for wiring, I can't imagine an electrician liking that, compared to wood studs.....it only takes 2 inches out of the room ,per wall, instead of 4-5 .....anytime a company advertises their product as faster,instead of better,there is a trade-off somewhere.....codes require most foams to be covered with sheetrock, because of the fumes they give off in case of fire, thermax is excluded(check with your inspector).

You are right about the fiberglass.....

[soldoncass]

I don't think that would be a problem, except glueing it on would be tough.

[hanson]

Quite honestly, there are a variety of different ways to finish off a basement, and a variety of different costs associated with those different methods.

If I've got the money and I'm doing my house, I'm spraying the insulation. Build the stud walls 1" +/- from the block, run all your wiring, bring in the spray foam crew and let them work. The insulation will get behind the studs forming a complete vapor barrier around the perimeter.

You can do a couple inch thick coat and then fill the remaining stud cavities with batt insulation as a compromise to doing full thickness spray insulation.

If spray foam insulation is not in the budget, I'd adhere polyiso rigid insulation (pink, blue, yellow, etc depending on brand) to the block, tape all seams, then put up my stud wall inside of that. Rigid insulation fully taped is a vapor barrier in itself.

If moisture is a concern, the place to correct that is outside the house with foundation waterproofing, NOT inside. A sheet of poly is not going to solve moisture problems. If correcting it outside is not an option, there are ways of installing drain tile inside the footings, drilling holes in the block cells, and creating a cavity to allow weeping of the moisture to the tile but thats a different topic. Bottom line... get your moisture control under control before finishing a basement.

With all that said, check with your cities building department/official first. In the Cities, here... most cities have published guidelines that they will look for during inspections.

[amateurfishing]

ive been told that with the r5 surrounding the foudation on the outside, adding any extra insulation inside the block is all extra and unnecessary, my big question is it really worth it to add more insulation on the inside of the block that is already painted & sealed? if so, then what? if not, great!

[soldoncass]

amateur....,

The inspector MAY be correct, about the small gain realized by adding more insulation inside, but.......here's my concern with the whole thing.

R-5 is Not MUCH, between the outside air temp. and the 70 degrees you want inside. Between the 55 degree thawed ground and the inside, it might be o.k., but between the frost line and up to the framing r-5 isn't much. Maybe the best thing to do ,would be to check the temperature of the block inside. If it is consistently 60-65 I'd be comfortable with it....but if it is 50-60, I'd add some. The theory with putting insulation outside, is that it lets your block hold and radiate the inside heat into the room. It does do that(like heating rocks, they stay warm a long time), but if they are cold...they stay cold a long time also.

In the outside framing wall, you have to have r-20....why is that NOT required from the framing down to the frost line????

Any way to tell exactly what insulation is outside and how far down it goes? We used to have to insulate down to frost line with at least an r-10 foam on walk-out foundations, to protect it from frost.

[amateurfishing]

amateur....,

The inspector MAY be correct, about the small gain realized by adding more insulation inside, but.......here's my concern with the whole thing.

R-5 is Not MUCH, between the outside air temp. and the 70 degrees you want inside. Between the 55 degree thawed ground and the inside, it might be o.k., but between the frost line and up to the framing r-5 isn't much. Maybe the best thing to do ,would be to check the temperature of the block inside. If it is consistently 60-65 I'd be comfortable with it....but if it is 50-60, I'd add some. The theory with putting insulation outside, is that it lets your block hold and radiate the inside heat into the room. It does do that(like heating rocks, they stay warm a long time), but if they are cold...they stay cold a long time also.

In the outside framing wall, you have to have r-20....why is that NOT required from the framing down to the frost line????

Any way to tell exactly what insulation is outside and how far down it goes? We used to have to insulate down to frost line with at least an r-10 foam on walk-out foundations, to protect it from frost.

when u say outside insulation, are u referring to behind the siding or against the block?

the rest of your info on ur last post is absoultely the best info i was looking for, how to determine if i need more insullation or not. thank you very much, i will start placing thermomoters in different areas.