Even in an unconditioned crawl, the ceiling should not be insulated in the first place, only the walls. And certainly not with moisture sensitive materials.

Here is a link that might be useful: Building Science Corp. on crawlspace Insulation

This post was edited by worthy on Thu, Aug 8, 13 at 15:40

Duplicate

This post was edited by worthy on Thu, Aug 8, 13 at 15:46

wow, interesting reading. (I even went over other articles in there)

if it was my house, first I'd tear it down and rebuild. but it's not.
It's a rental (cheap falling apart cottage in a high end neighborhood) SF Bay Area

The cottage was built in the late 20's. it has a crumbly cement foundation around the sides, and pier/posts in the middle.or cinder blocks holding it up. The wood is totally eaten --termite heaven. I don't know if any "fresh" wood left. The outside is redwood lath siding. (It's probably in the best shape!) the house inside is lath and plaster. no insulation in attic, ANY walls (exterior or interior) and of course no insulation under house in the crawlspace which is vented at 4 locations plus the cellar doors are opened now and then. (their size is 1/5 of house side, so lots of light and air come in when opened.) plus the old floor furnace access is down there.
I can see the floor joists, the subfloor (more wood), I remember seeing the skinny original wood floor (or I hope that wasn't the sub floor!!!) when the carpet was changed.-so new pad and new carpet. and yes the kitchen is linoleum. very uneven as well. the floor rolls...so it will get some floating on it before another layer goes down next year.

The landlord loves me (my folks live right down the street who I take care of) so he's trying to help me enjoy the cottage more.
He got me more amps. He only rewired to romex in a very few areas. Blew in attic insulation (the access to the attic was for a skinny person with a tall ladder!) i got new dual pane windows. vents were put in bathroom and kitchen.
He IS going to blow in insulation in outside walls all around the house in a month or so. (and under windows too since blown in can't get there.)
but my feet freeeeeeeze each winter for our 2 months of "cold" here and I decided to put this insulation under the floor. He -landlord- is reimbursing me for batts and wire clips.(I would have died if i was breathing fiberglass) I just don't want to be miserable. I want to live here at least another 5 years, maybe more.
the weather in the SF bay area is sort of boring. no major cold, no major hot. and lately these past few years, no major rain.almost no humidity. the temp under the house is cool, and the same all year round, literally.and yes it does "smell" musty....as I crawled from corner to corner painstakingly slow (so i wouldn't lose my head or arm..) I saw no bugs, no webs, no peeks of outside light except the 4 vents. the dirt was just cool, lots of light dirt that would go everywhere if i blew on it.

so..... did I totally waste my time and energy on this project?

should I start saving for a small house built on wheels?

thanks guys. so just tell me like it is...i can handle it-I hope.
cindy

The whole conditioned crawl route is the best approach, as you now understand. But, as you say, it's not your house or your call.

Since discomfort from the "cold" floor in "winter" is the issue, you could treat the crawl as if it were in a flood zone or a house on piers.

As per the suggestions (and here) of Green Building Advisor's Martin Holladay:

Insulate between the joists with whatever you have--take the denim batts from the crawl wall. Then run a layer of foam board across the bottom of the joists. Finally, protect it with a layer of ply or light metal.

you still working on that place Cindy?

finish the floors with batts & wires to hold them in place.
are you filling the joist bay completely with insulation?
what size joists & what R-value or depth of batts?

for instance if the floor joists are 2x6 then insulation would be at minimum R-19 to completely fill joist bay. once insulation is installed then nail foam board as worthy says
across bottom of josts. use button cap nails, tape all seams
& caulk at peremiter of house. this will keep insulation in contact with floor, and stop any moisture or air from crawlspace from entering floor joists.

use a lightweight metal flashing to seal large plumbing access under tub. cut flashing to cover opening, caulk it in place then screw the flashing into the floor.

you should be sealing any air gaps into the house as you insulate. then once inside continue caulking. caulk is a good investment that lasts a long time.
insulation doesn't stop air movement..it only slows it,
so caulk & seal...then insulate. good diy stuff.
use a clear caulk with a long life Alex brand Dap is what I use..25-35 year life.

congrats of getting it done, I know you've been working towards improving your place for a while.

best of luck.

yep still working on it.....
filling the space between joists FULLY with the denim batts. r19 (16" wide batts) and nice thick, it fills up the area just about. I just finished TODAY putting up the last bit of insulation but it figures I need 1 more strip (not the package) so I'm not buying more of that stuff. maybe my landlord/contractor has a wee bit of fiberglass stuff.

I've been plugging up every hole i see into the house looking up, with expanding foam and letting it cure first.
I caulk smaller cracks.

The foam board sounds like a good idea, but that means I'm back under the house AGAIN???? ugggg. I don't know if there's space for the boards, then tape? Lots of wires I went under/around/over...you know what I mean. a longgggg process for such a small house. I swear I'm living here till I die.

The one thing I have noticed since I've installed this stuff is the crawl space stinks. dusty as hell but just smells. fiberglass has a smell too. how long till this goes away? should i leave the cellar doors open?

thank god landlord is spraying in insulation in the side walls. the interior walls have nothing but thats ok right?

he even "hinted" at taking out that scary floor furnace and putting in central heat, 7 or 8 small ducts/vent covers needed at most and the return air vent already there where grate is for floor furnace, plus already vented to outside. (didn't insulate around that pipe--i want HIM to do that or whatever it takes.

so aside from insulation (ceiling "could use" a bit more, but that knob-n-tube..... I could use a new toilet, a kitchen redo LOL and I'm set for life --unless he raises my rent double --he wouldn't dare...he loves me. I've turned this pit into a jewel. I will post pictures I promise. Waiting for patio cushions (I got ORANGE instead of the green i ordered. great if you're a SF giants fan (I am...but seriously--orange??)

cindy

Covering the denim batts with foam and then light metal or OSB/ply is not just a good idea. Without the foam and protection for the foam, you're creating perfect conditions for mould growth. Not to mention a comfy home for all sorts of adorable rodents.

BTW, Article 394.12 of the National Electrical Code prohibits covering k&t wiring with insulation.

yup..... that I found out worthy... (hate k&t wiring) that's why the ceiling has loose fill around the wires, not covering them at all. and seems "not enough" :(

thankfully he (landlord/contractor) did rewire one side for high tech equipment, etc. with the romex.

I'm sure as soon as he hears I've finished this part, he will mention the foam board etc. haven't told him I'm done yet..gotta put the bill together!!

worthy !! plz need more advice

now you know I'm sort of clueless at this.
I'm reading LOTS of articles on this. all say different things where you live.

just to make it clear on me. I live in San Jose,CA area. no freeze, very little humidity. OLD cottage built 1930's has eh, some rotted wood, some termites (EVERY home here does), no varmints under the house. neighbors get skunks YUCK. foundation around perimeter is cement and up to above dirt grade, well thats a given.
it is a rental (so no heavy money put into this, just want it to last with low maintenance) landlord very very cool with me, just likes to do things RIGHT. -he's anal like me and a contractor (with many licenses ) who's very busy so I do the dirty work.
house has no insulation except blown in the attic,not covering any k&t. wish more could go up there, but have to closely look into that.
just put in that new style batts, ultra soft touch shredded denim -no way I could put in fiberglass, the joists are literally touching my face in areas) there is an old floor furnace down there (shockingly they recently stopped making them LOL--hate the thing) it is vented with 4 vents. house is approx 30x30' at most. cellar doors open to go down to crawl space, able to stand and walk about the area of 8x10'. since insulating, the place stinks of the stuff (expected) and can also smell thru the vents.(always smelled a bit "musty". remember I just finished putting it all in there the other day (took about 7 days total - 6+ hrs per day so you can see it is thin crawl space. no k&t under house. small holes were filled with expanding foam. oh and one more thing, this house is grandfathered, so not required to be like "new" up to code in certain not redone areas-obviously. it is with whatever gets fixed. my landlord is GOOD! He has not tried the new denim expensive batts and wondered if I looked into them (which I did)
so.............
need honest opinion what else to do -( I know you've already said stuff, but I am getting different answers-at least I'm stupid to read into them. **help**
and I'm not trying to be nosey, but since you know codes etc so well, I'm assuming you are a contractor ,or ?? by trade.

so plz help me so I can talk to him. plzzzzzz
I'm waiting to do anything else before I get some details what and why from you. (and others!) THANK you soooo much for your knowledge !!

cindy
I do plan to live here till I die! -only 53. :) (in less than 2 weeks ) feel like 29!

oh and a few more things IF they even matter on this (I am just trying to stay warm/cool comfortable year round.
new dual pane windows were put in entire house. 12 total some very small. new carpet pad and carpet. new linoleum in small bathroom, a ceiling to outside vent in bathroom. I think that's it. (yes house needs a vent in the kitchen-every window in house gets wet when closed up in winter and stovetop cooking LOL. kitchen does have 4 windows and a door to back yard with a screen door as well. water heater in kitchen in vented closet door. just LOVE those. (yes you can see I am into decorating.) :)
can't afford to buy, never in this area and family needs me nearby. so as mentioned earlier -hope to live here LONGGG time -I'll sh*t when and if they decide to sell property. but life will go on.
cindy

sorry guys, just realized i just wrote/repeated everything I had mentioned in earlier posts. I'm braindead from yesterday long day at work, so I'm going to go by what you said already. I obviously want to get this crawl space done.
hope the smell will go away.
I've also looked at other threads reading blown in insulation on outside walls (from the outside drilling holes) cellulose the best? and most homes I am finding out of this age and wood siding have cross boards that cut the wall in half, so you need to drill holes and blow from top AND bottom? remember my walls are like a freezer in winter (oh and made a mistake, no vent in kitchen as I just said in last "summary" i had said earlier there was one. but not. I think that will have to be done soon. (landlord will wring my neck on that one LOL--we are good friends, and I just keep coming up with a "honey-do list" his wife just shakes her head. he spends more time on this rental than their house which also has lots to redo! (I love him tho!!!)
**my little jewel** as I call it. :)
where would you put a kitchen vent if someday down the road you redo the kitchen. like just relocate some appliances.?? it is VERY strangely laid out right now, but this is NOT a priority. maybe in 5 years.............. he has put SO much work into this rental.

One tip: Check your walls to make sure there is an air gap before hiring a service to blow in insulation.

Many years ago we lived in Marin County, Calif. and remodeled a home that had once been a summer cabin. We found we had a plank house.....a method of framing used in the early 1900's. Once the walls were open we discovered 1 x 12" boards (12" side nailed to the sill) and the electrical wiring running thru the gaps between the boards. Of course, we ended up gutting the place.

If your home has this type of framing, then I'm not surprised the walls are cold!
Check out the link below......scroll down to the discussion re: Plank construction.

Here is a link that might be useful: Plank houses

With the insulation in place, you need two things now for your project to be complete. One is a vapor barrier to keep any moisture from getting into the insulation and being held against the wood and rotting it. The second thing you need is a barrier to pests.

The thinnest thing that I can think of that would accomplish both tasks would be the galvanized material sold to create your own ducting. If you nailed it to the joists with roofing nails (caulked) and then used metal tape for the seams, that would provide a pretty rat proof protection for your insulation. A wholesale HVAC supplier will probably have it cheaper than a box store, but it won't be all that cheap to do. But, it's better than the insulation rotting out what the termites haven't eaten, and the rats getting into the rest of it. :)

A point that wasn't mentioned earlier: if the crawlspace floor is soil, not concrete, it should be covered in a heavy polyethylene groundcover to keep the rising damp at bay.

Having seen what termites do to houses here, I'm surprised you find their presence amusing. I would insist on termite treatment before everything else.

A former girlfriend didn't realize her house was infested until a door fell off and a forgotten book under her bed was half-eaten by the cute little critters.

(Yes I am an occasional licenced homebuilder.)

Foam (assuming it has a proper vapor retarder level) across the bottom of the floor joists is fine.

Foil faced ISO works well in this case and make sure, regardless of it be ISO or XPS, that it has sealed seams.

Definitely, conditioned or unconditioned, get a vapor barrier across the floor and sealed at the stem wall.