Insulating the crawl spaces and basement with Batt insulation

drewdin said:

Nice job with the insulation, I put unfaced batts in the floor joists and now im going to put 2" closed cell foil faced foam board on the walls using the fire block suggestion above. Only half done but crawling on the floor in 2 feet of space is my favorite!

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Thanks.

I assume that you do not have your HVAC unit in the crawlspace? You got a 'Boiler"? not exactly sure how that works but I assume it heats water and runs it through a piping system and radiators through the house? Maybe there is a way to add a radiator in the crawlspace for winter?
BTW it would seem that boiler noise would be sort of impossible to abate because the noise will just go through all that piping and water, but I don't know never been in a house with a boiler.

If you did then you would be much better off NOT putting the batting in the floor joist, just insulate the walls.
The reason the old owner had his insulation fall out is because he did not put down a vapor barrier on the ground, thus the insulation became soaking wet and falls down like a horror movie.
The batting is held in place with just a straight piece of wire called Wire Insulation Stays that you bend and stick in between the joist with the bend going up.
But if the batting gets wet it doesn't matter what you do its going to fall out in chunks of wet moldy mess.
Plus the R19 turns into about R1 once wet.
Its also a mouse and varment haven.

You probably would have been better off spending the money you spent on the floor joist insulation just adding it to the wall insulation to get higher R-value foil covered polyiso rigid foam board.
But whatever you do, make sure that the Polyethylene sheeting you put on the ground is sealed everywhere so that you have less humidity up under there, if not then your batting insulation will be crap within 2 years.

Also you might wish to get a Radon test done just for the hell of it if you haven't already.
I just ordered two from our local State Radon Program so was only $10.68 for two test.
You can find them here IF your state has any.
If not then they are still only about $15 each and if you are in either Worcester, Middlesex or Essex counties then chances are good that you might have high radon levels.

http://www.epa.gov/radon/states/massachusetts.html

I am in a "Orange" zone so odds are pretty good ours might be high also, I will find out in a few weeks.

Good luck.

I have a oil hot water and heater, forced hot water with baseboard. The pipes do run through the crawl spaces, three total. two 10'x10' and one in the middle thats 8'x8'.

Right now I insulated the rim joists, i do plan on insulating the walls with closed cell foil faced foam board. Thats my project this weekend.

the three crawl spaces only have the old window openings as access's but they do not have any openings to each other. There humid and stinky. I have read that since they all have access to the basement but do not have any way for air to circulate, thats why its humid and stinks.

I drilled a few 4" holes between the spaces and i planned on putting some computer fans to circulate the air between them.

Any other suggestions? thanks!

So you have 3 "Separate" crawl spaces? Never heard of such a thing.

Ah, so just the "Rim joist" the little box end is all the joist part you have insulated then? Thats good, although frankly the rigid foam sealed with the spray fire foam would have done better for you I believe.
You ripped down all that manure, old batting and drywall that was seen in the one picture you posted?

It is humid and stinks because warm humid air is allowed to enter OR is created by the boiler and condense.

What did you drill through to open up the 4" holes between spaces? What kind of wall is it? Does it even need to have these walls between the spaces?
I am having a hard time trying to picture your crawlspace and why its built that way.
I assume this is probably a really old house, like maybe 75+ years?

Best thing I can tell you without being able to see the situation is to just make sure that you use very high quality polyethylene on the ground and seal it tight to the walls and anything else to keep down the water vapor as much as 6mil can manage.
Insulate the walls as best you can, including these "windows" of which I guess is your entrance to each one.
Since you do not have any kind of air circulation under there at all that is kind of a problem.
You are in "Boston" right?

Just how humid is it in Boston? In your area I would think it would not be nearly the same as down here in the south where the humidity is insane most of the time.
But since you have zero air circulation even IN your house because you have a boiler that just radiates heat and I guess does the same from those pipes in the crawlspace then you have kind of a strange situation.
It would be nice to get some kind of air circulation under there but in your case it would have to come from outside and if you do that then you completely defeat the reason to insulate the walls of the crawlspace because you are literally pumping in cold or hot air at exactly the wrong time, meaning pumping in cold in the winter and hot in the summer and none of it conditioned air.

Your best bet "might" be to seal everything up tight as you can, insulate best you can on the walls and then install a "Dehumidifier" in the crawlspace and open up the walls in between the 3 spaces as much as possible.
IF the 3 pipes of the boiler heat the crawl space in the winter then NOT insulating your floor joist should be fine, IF there is zero heat coming from it then you are going to get coldarse floors probably.
I would think that this boiler has GOT to put out some heat though, but also since it is heating WATER its also probably creating its own humidity.
Thus the dehumidifier may be necessary to keep the space dry.

In my crawlspace it stays between 68 to 72, period, I was under there yesterday morning and it was 32 degrees outside and was warm, toasty and dry under there because our furnace was running.

nunyabiz1 said:

I would think that this boiler has GOT to put out some heat though, but also since it is heating WATER its also probably creating its own humidity.
Thus the dehumidifier may be necessary to keep the space dry.

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great advice, let me just add this, The water boiler is a closed system and will not cause condensation issues when it is used in the winter,,, cuz there is usually no humidity in the air when the boiler is being used because there is no vapor created by the boiler.. it's all contained in copper pipes..It actually helps dries things out in the winter too much sometimes. Boston can be a humid area along the ocean in the summer, but never in the winter.
This sounds like you have water vapor from somewhere , and it needs to be controlled. The DeHumidifier that Nun suggested also needs to be sized to keep up with your space in the summer months. I'm sure there is a chart around here somewhere... good luck!

inspectorD said:

great advice, let me just add this, The water boiler is a closed system and will not cause condensation issues when it is used in the winter,,, cuz there is usually no humidity in the air when the boiler is being used because there is no vapor created by the boiler.. it's all contained in copper pipes..It actually helps dries things out in the winter too much sometimes. Boston can be a humid area along the ocean in the summer, but never in the winter.
This sounds like you have water vapor from somewhere , and it needs to be controlled. The DeHumidifier that Nun suggested also needs to be sized to keep up with your space in the summer months. I'm sure there is a chart around here somewhere... good luck!

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Thats good, I had no idea about a boiler, in my 55 years I have never laid eyes on one let alone lived in a house with a boiler. So it is totally "closed" system then at the boiler itself?
If those pipes in the crawlspace both heat and dry out the space then he should be golden at least in the winter.
Might need a dehumidifier in the summer though.

We were fortunate that both our heating and AC are in the crawlspace so heating, cooling, conditioning the air was as simple as cutting a single hole in the plenum and installing a self closing flapper vent.

Don't forget that you need combustion air for the boiler. Don't seal it so tight that you can't keep it lit.

slownsteady said:

Don't forget that you need combustion air for the boiler. Don't seal it so tight that you can't keep it lit.

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Yep, forgot about that, our crawlspace is HUGE so way more than enough combustible air for our furnace, plus I do have one small opening where the dryer vent exits to allow for some air both in or out which ever it needs.

nunyabiz1 said:

Yep, forgot about that, our crawlspace is HUGE so way more than enough combustible air for our furnace, plus I do have one small opening where the dryer vent exits to allow for some air both in or out which ever it needs.

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Your combustion air should have it's own vent and duct to close to the furnace and it should not be close to the dryer vent as it will pull that moisture that you don't want.

nealtw said:

Your combustion air should have it's own vent and duct to close to the furnace and it should not be close to the dryer vent as it will pull that moisture that you don't want.

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Yeah the outgoing vent for the furnace goes through the wall and is sealed tight.
The dryer vent is at least 20 feet away and about 10 feet above where the Furnace gets its combustible air from.
It gets that air from the crawlspace not from a incoming vent from outside.
But our crawlspace is unusually large, it is approx 9360 Cubic Feet of air and our Furnace which is a 93,000BTUh 92AFLUE which requires 4650 cubic feet of combustible air.
So basically it has almost exactly double what it needs.

So it meets the "Unconfined Space" requirement with no problem.
The other is the "Unusually tight construction" that is somewhat iffy because it IS sealed tight as a drum, all the crawlspace vents sealed tight, every tiny orifice where plumbing or electrical or ducts go up through the floor are all sealed with spray fire foam, 12Mil Polyethylene on the ground and 2+ feet up the walls plus 2" thick Polyiso foam insulation tightly sealed to the walls.

All except for ONE opening that is at the top of the about 10 foot high wall in the back corner where the dryer vent exits, (that is about 4"x9" with the dryer vent taking up much of that space) plus about 4 inches below that opening was one of the small size about 12"x6" or whatever that small size crawlspace vent size is, on that one small vent I do have a "Removable" piece of 2" thick rigid foam insulation that I can if needed remove in the winter to allow more Combustible air to enter if needed.

That I would think would negate that "Unusually tight construction" which is everywhere else, I mean if air starts to be used and a negative pressure starts then it should just pull the needed air in through that opening around the dryer vent. Although that should never happen because when the furnace is running it is blowing air INTO the crawlspace in order to heat and condition it, so I do not think its even possible to have negative pressure if anything it might be slightly positive.

Also in the winter we pretty much keep our house in the mid 60s, both my wife and I prefer the house quite cool.
Our furnace hardly ever runs until it gets in the 20s outside.

I know technically we probably "should" go ahead and install a incoming air vent, but I do not think it is really necessary with such a large cubic foot space that does have some air able to come in.

What do you think?

One of the problems with a sealed crawlspace is the chance that if ever you get enough to start mold growth or even rust on metal objects is that oxigen can be used up, so in the dead of winter, if the furnace quits leave the door open for a few before you charge in there.
Keep in mind that when a new house is built they are very tight these days, a fresh air vent is installed to a centrel hallway to allow air to be replaced as it is being used up by people, plants, and exhaust fans.

Your crawlspace sounds more like a well sealed and insulated basement.
On the other side, you have done a great job of firestopping the house from the crawspace.

Im going to post a drawing or picture of the three crawl spaces so you guys can see what I'm working with. I purchased the 2" polyiso foil face board this AM so my project for Saturday is ready.

We got 1" of snow today, not that bad but its expected to be 10 degrees next week and keep getting colder. Winter has begun!

drewdin said:

Im going to post a drawing or picture of the three crawl spaces so you guys can see what I'm working with. I purchased the 2" polyiso foil face board this AM so my project for Saturday is ready.

We got 1" of snow today, not that bad but its expected to be 10 degrees next week and keep getting colder. Winter has begun!

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Cool.
What are the walls of your crawlspace made of that you are installing the rigid foam insulation on?
If it is cinder blocks, bricks, stone etc then you should use Tapcons with large stainless fender washers.
you will need a hammer drill to drill those holes as a regular drill is utterly worthless drilling masonry, will take about 10+ minutes per hole and by the time you done the hole is useless because it is so wallowed out.
Hammer drill takes about 2-3 seconds and hole is perfect.

Also what I did was to liberally spread Boric Acid powder and Diatomaceous Earth all over the walls as much as I could to stick into every little crack in order to kill, deter whatever bug might decide to try to take up residence behind those boards.
Then put a bead of fire foam about an inch or two inside the outer edge of the top and both left and right sides leaving the bottom open then put the board on and screw in the Tapcons to hold it tight then the foam expands to usually past the edge and seals top and sides tight. I go around the top with an extra bead of fire foam after all of them are in place.
Also not sure about Boston but here in my area code requirement is you must leave a 3" gap at the top between the insulation and the joist band for termite inspection, also leave about 3" or so gap at the bottom plus I used quality foil tape to seal all exposed foam edges and the seams between boards.
I leave the bottom open, not sealed with spray foam just in case any moisture gets behind there it will be not be trapped will just drip out the bottom and under the polyethylene.

Thanks for the suggestions, I followed them to a T.

The crawl spaces have cinderblock walls, I did make one mistake buring the process, hopefully its not a big deal. Since its dark in the crawl space and I only had a head light on, when i put the foam board up i had it reversed in two sections before i realized it was backwards. I had the metal foil facing the cinderblock and the plastic facing the inside of the space. It was too late to reverse them as they were glued and screwed.

I hope this isn't a big mistake, but one i realized after i had it done. How big of a deal do you think this is?

Thanks

drewdin said:

Thanks for the suggestions, I followed them to a T.

The crawl spaces have cinderblock walls, I did make one mistake buring the process, hopefully its not a big deal. Since its dark in the crawl space and I only had a head light on, when i put the foam board up i had it reversed in two sections before i realized it was backwards. I had the metal foil facing the cinderblock and the plastic facing the inside of the space. It was too late to reverse them as they were glued and screwed.

I hope this isn't a big mistake, but one i realized after i had it done. How big of a deal do you think this is?

Thanks

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Well it certainly isn't optimal, but really shouldn't make any real difference.
The only difference it would make would be code wise to an observant home inspector and that would only be IF your crawlspace is considered "conditioned" (which yours is NOT unless I am mistaken) which would mean it would need a 15 minute Thermal Barrier and that is IF the Polyiso insulation you bought has a 15 min thermal barrier on the foil side.
A few do have the thermal barrier, most do not.

The particular insulation I bought was the Rmax TSX8500 which does have at least a 15 minute thermal barrier on one side.
Not sure what is available now but 1 year ago there were only 2 such foam insulation sheets that passed the ASTM C 1289 requirements and those were Dow Thermax and Rmax TSX8500.
Here is a memo to building inspectors from the fire marshall in Maine which is probably pretty much the same in most states.
Stating that these two materials met the 15 minute thermal barrier.

http://www.mboia.org/documents/2013/Rigidfoamletter.pdf

If your crawlspace does not need a thermal barrier by code then shouldn't really make any difference I would assume.

If that's a problem just add a couple sheets overtop of those two. Maybe

its 35 bucks for a 4x8 sheet, that's the only problem of covering it up a second time. I have noticed a big difference in the past few days, temp wise