Replies

1. 
   BossHog | Feb 17, 2004 04:07pm | #1

   I know of no way to insulate floor trusses than to use loose blown in insulation. No one makes anything for this situation.

   I would definitely cover the ceiling with 5/8 FC drywall. If you're in an area with building codes, they may have specific requirements.

   Have you bought the trusses already? No way would I EVER use such shallow trusses on that span. Whoever called those out ought to be slapped upside the head. I hope that was a typo.

   It may be a small world, but I'd sure hate to paint it.

1. 
   we3beach | Feb 17, 2004 04:42pm | #2

   Boss, Thanks for the reply, I have NOT ordered the trusses yet, I'm still in planning stages of this project. The building supplier told me the 13's could span up to 24ft. according to there manufactures specs.  If it's even questionable though, I'd rather spend the extra doe and deal with the changes in elavation than have any regrets later.

   Regards.

1. 
   BossHog | Feb 17, 2004 04:48pm | #3

   I would NEVER recommend spanning 24' with anything less than 16" deep. Use a wider spacing (19.2" maybe) and you probably won't end up spending any extra money. It might actually be cheaper.

   I can't believe they would recommend 13" deep. They must have only used a 30# live load. (Allowed for 2nd floor sleeping roms) I've never seen a span chart that shows 13" trusses going 24' with conventional 40# loading.

   I did a thread a while back about Floor Vibration which explains my concerns with long span shallow floors.

   Sometimes you're the bug and sometimes you're the windshield.

1. 
   we3beach | Feb 17, 2004 11:50pm | #4

   I like to know your opinion on wet insulation as an optional way to insulate between the open trusses,  the dry blown insulation and rock would more than likely be exposed to the outside world for some time.  My guess is the sub floor would have to be put down first before insulation could be installed............  This one's got me worried.

   thanks in advance

1. 
   BossHog | Feb 18, 2004 03:16am | #5

   I know very little about insulation, and would prefer not to venture an opinion on wet vs. dry.

   My only suggestion would be to close in the structure, then put up the drywall ceiling. After that, drill some holes in the subfloor and blow insulation in that way. Don't know how hard it would be to make that work, though.

   Anybody with some more insulation experience wanna jump in ???Vote Democrat - It's easier than working

2. 
   we3beach | Feb 18, 2004 05:51am | #6

   Thanks BH, I'll stay tuned for other suggestions as well. 

3. 
   xMikeSmith | Feb 18, 2004 06:25am | #7

   i'm  a big fan of cellulose.. but a 16" webbed floor truss is not going to allow good distribution or compaction..

    also...if you put one post in the middle.. you can run a beam and break your span in half.. then you can use conventional 2x10.. and that will lend it self to dens-pak cellulose..

    if you stick with the webbed truss.. i think you're limited to sprayed -in-place foam..

   i wouldn't even consider fiberglass , either blown or batts...

   if you go with a TJI.. then that would be easier to insulate alsoMike Smith   Rhode Island : Design / Build / Repair / Restore

4. 
   jonblakemore | Feb 18, 2004 06:37am | #8

   Mike,

   I understand your concerns about distribution, but would compaction be as important?  If the guy goes with 16" deep trusses as per Boss, than even if the cell settles a good bit he will still have a pretty thick blanket.

     I guess the cells could lose >1.5" and an airspace below the top chords could form.  Is lateral convection going to hurt this floor that much?  Am I missing something else? 

   Jon Blakemore

5. 
   xMikeSmith | Feb 18, 2004 07:00am | #10

   floor over garage wants to have the insulation in contact with the floor... especially if there is any plumbing in there.. but even without the plumbing...

   suppose you blow it... either from slots .. or by boring the band  at teh end of each bay.. those webs are going to play hell with the distribution and the settling...

    and you're very likely to have big convections and moving air in the space ..

   if it's an i-joist you get dens-pak...

   but like i said.. i think free span floors are overrated and try to avoid them ...in this case one post in the middle solves the whole problemMike Smith   Rhode Island : Design / Build / Repair / Restore

6. 
   Scottiebrink | Feb 18, 2004 04:20pm | #11

   I saw only one mention of the spray in place foam, but have to speak up, this stuff is great.  Yes, it's expensive, but as soon as you have you're trusses in and sub-floor down, you could insulate, and leave it exposed until you get to the garage ceiling.  This stuff forms a great vapor barrier as well, so you'll eliminate drafts from the cold space below, and any possibility of Carbon Monoxide getting into the apartment if people are warming up cars, even with the garage door open.

   Scott

7. 
   we3beach | Feb 18, 2004 08:37pm | #17

   Thanks Scott,  The spray foam idea I think is a good one.  You bring up a good point.  Warming up the car in the garage, with doors open of course, will probably happen. If sealing off Carbon Monxide fumes with the spray foam is the most effective, and assuming I can get the R-value required, then it may be the way to go. Do other types of insulation offer a barrier from theses fumes once they pass through the sheet rock??? Poly under the sub floor?  Even being the cheapest man on the planet, I would have to air on the side of caution.......maybe.

8. 
   we3beach | Feb 18, 2004 07:50pm | #15

   Thanks Mike........

   I'm tryin to avoid thoses dreadful posts in the middle of the garage.  I have a bad case of wanting my cake and eating it too !!  There are some good ideas floating around out there and I'll continue to look at the pros and cons of each . Cost being one of them.  I may have to bag the free span idea at some point, ........but I'm not there yet. :>)

9. 
   BossHog | Feb 18, 2004 09:19pm | #18

   "I'm tryin to avoid thoses dreadful posts in the middle of the garage."

   So would I. Can't imagine why anyone would want to put up with one.

   I certainly wouldn't give it up over something as minor as insulation.In some cultures, what I do would be considered normal.

10. 
    we3beach | Feb 19, 2004 01:02am | #20

    ......momentary lapse of sanity BH. Got my head screwed back on right.

     thanks.

11. 
    0002steve | Feb 18, 2004 11:10pm | #19

    How about a beam under the floor joist at mid span

12. 
    we3beach | Feb 19, 2004 01:08am | #21

    Steve, I'd still need a post to support that beam, no?  I'd like a single door entry with no center column.

13. 
    xMikeSmith | Feb 19, 2004 03:32am | #22

    single door as in 7x16 ?.. i prefer (2)  7 x 9's... they last longer, operate better.. you don't have to negotiate 2 vehicles into a 16' space... and you only have to open half the garage to get things in and outMike Smith   Rhode Island : Design / Build / Repair / Restore

14. 
    Scottiebrink | Feb 19, 2004 04:40am | #24

    We3Beach,

    In response to the few questions you posted to me in your reply regarding spray foam:

    I'm sure you'll get the R-value you want, usually icynene (the brand of spray foam I had put into our house) I think is 3-4 per inch.  You wouldn't even have to count on filling your hole truss space. 

    This is helpfull if you are going to run any wiring/plumbing through the truss space too, although it'd be more work, you could apply nailers to the sides of the trusses, with a bottom edge say at 10 inches from the bottom of the truss.  To the bottom of these nailers you install rips of 2.0" thick High-R polyisocyanurate rigid foam insul. board (r7 per inch=R 14), this leaves 8 inches for spray foam (min. R 3 per inch yields R 24).  Now you have truss bays above your insulation that are open, and 6" deep for any mechanical runs you need.  Not that I'd recommend your plumbing here if you have better places to run it, I'm over in Vermont, and hate to see pipes freeze.

    The selling factor for me for spray foam was that you're much more assured to obtain the R value spec'd, because if doesn't get compressed around wires, get caught on things keeping it from lofting, nor does it settle, I think the only comparable product for these reasons is dense pack celulose.  If you do select a product other than spray foam, I would certainly stay detail oriented on whatever vapor barrier you do put in.  Plastic under your subfloor would be tricky to put in, but I'd also add a bead of polyurethane caulk on top of every truss.  It's around the edges you'll really have to be carefull.

    Just sharing my thoughts, good luck to you.

    Scott

15. 
    BigRick | Feb 19, 2004 04:06pm | #26

    Scary thing about cellulose is that it burns very very very rapidly.  I'm a firefighter / paramedic and we have neighborhood in our first-in district where every house has cellulose insulation.  We shudder every time we have to go to a fire over there.  The stuff is really nasty. 

    My first experience with the stuff was when I was a rookie and was sent up into an attic to check for fire spread.  I got up into the attic and was looking around for a minute or so when the fire broke through the ceiling and touched off the cellulose (on the opposite side of the house).  I was completely engulfed in a fire ball in less than 10 seconds.  The cellulose fire didn't last long but, we did have to get a hose line in the attic because of fire spread caused by the cellulose.  Ended up doing a lot more water / smoke damage than we would have had to do with any other type of insulation.  Seen it numerous times since.  Other insulation types will burn, but not with the ferocity of blown cellulose.  I'm told that blown cellulose is cheaper, but I would never have it in my home. 

    Just my $0.02

    Rick

    Rome wasn't built in a day, take your time and do it right the first time.

    Edited 2/19/2004 8:08:46 AM ET by Big Rick

16. 
    UncleDunc | Feb 19, 2004 04:21pm | #27

    How long ago was that?

17. 
    BigRick | Feb 19, 2004 04:30pm | #28

    First happened to me in the early nineties. The homes were built 60's/70's.Rome wasn't built in a day, take your time and do it right the first time.

18. 
    xMikeSmith | Feb 19, 2004 04:43pm | #29

    big rick... why would you say that?... it's bunk... i've been associated with the testing of cellulose since  1979..

    i can line up fire personnel from here to timbuktoo that will attest to the safety of cellulose compared to fiberglass, foam, or even uninsulated structures..

    i willl scoop up a handfull of cellulose in my bare hands, put a penny in it , and heat the penny to cherry red with a blow torch..

    i have been to many fire scenes where the only protion of the house left standing was the parts insulated with cellulose.. the walls would have the paper burned off the drywall.. but the studs would be untouched....

    cellulose insulation is mfr'd to CPSC HH-I-515E; 16CFR 1209,   & meets ASTM C739-97 , and is rated as a Class1 building material..

    cellulose insulation makes a house  or building safer .... you experienced something other than cellulose insulation ... it will NOT ignite into a fireball..

     the biggest problem you have with fighting fires with cellulose is if you are trying to ventilate the roof.. cellulose will not let the air past the ceiling.. it will not burn and it will not melt..so the fire can't get thru

    Mike Smith   Rhode Island : Design / Build / Repair / Restore

19. 
    BigRick | Feb 20, 2004 05:00am | #38

    Mike,

    From your reply, we are obviously talking about two different animals.  The stuff that we call "cellulose" is blown, gray, and (supposedly) made from recycled newsprint & glue.  Looks like large round confetti with tattered edges.  It is definitely paper and it does burn very quickly.  It burns so quick that it's not going to kill a fire fighter unless it startles him and he falls through the ceiling landing on his head.  It does get pretty warm when you are engulfed in the stuff but its not like a flashover.  Imagine shedded news paper with an accerlant and that is how this stuff burns.  Very quick, but with relatively low heat.  We call this stuff cellulose because A) we are not GC's, we're FF's.  B) That's what the Captain called it.  C) The Captain called it that because the Arson investigators called it that.  I didn't see the Arson Investigator last night to ask him why yet.

    So, give me some info to take back to the station...  If this stuff is not cellulose, what is it?  Rome wasn't built in a day, take your time and do it right the first time.

20. 
    reinvent | Feb 20, 2004 07:06am | #41

    I have a therory that both Big Rick and Mike Smith are right and heres why. I read some where that back in the 70's with energy costs going thru the roof, all sorts of insulation manufactures started springing up. Some were out to make a quick buck and skimped on the additives used in the manufacture of cellulose. Some of that cellulose got moldy and some was less flame resistant than it could have been. Mayby Big Rick was exposed to some of that 70's era stuff that was not up to spec.

21. 
    dIrishInMe | Feb 19, 2004 05:04pm | #30

    Rick:

    I gotta wonder if when they first started using cells, it had less (no?) fire resistant treating.

    BTW - welcome to BT.  Yours is an interesting perspective that we have not had a lot of here at BT.  For example, we had a discussion regarding the fire resistance - or lack there of I-joists:   http://forums.taunton.com/tp-breaktime/messages?msg=37987.1  As far as I remember, the discussion was based largely on conjecture, and little if any was based on actual experience with house fires.  Do you know if there have been actual studies on the actual performance of various building materials in house fires that are published on the internet.  Looking at ASTM flame spread and smoke development ratings is one thing, but seeing what actually happens when a house catches fire could well be something entirely different. 

    What's your thoughts on the performance of foam insulation in house fires - rigid and/or spray in place.  I bet you have had some specific training in this area.  Are you a full-time Firefighter/paramedic?  BTW, as I am sure you know, there are probably 10 distinctly different types of foam insulation, so lets not fall into the trap of lumping them all together.   I believe that some emit highly caustic and poisonous gas that will kill a human with only a few good whiffs, where as others emit gas/smoke that is no more poisonous than a wood fire, which is poisonous too, but I think we all know the danger is more limited.  Matt

22. 
    BigRick | Feb 20, 2004 05:15am | #39

    Matt,

    I go both ways regarding the firefighting...  I am a professional firefighter / paramedic with the city of Houston (24 hrs on the engine, 14 off, 24 hrs on the 'bambulance, 5 days off).  On my days off, I volunteer with the local fire department (I live just past the 'burbs). 

    As far as web information on building materials in structure fires, a guy by the name of Frank Brannigan is the authority on the subject from the fire service perspective.  He frequently write articles for Firehouse.com.  Here's a link to his Firehouse.com bio page.  Be sure to explore the archives.  The ones you are looking for are the "Know Your Enemy" series.

    RickRome wasn't built in a day, take your time and do it right the first time.

23. 
    xMikeSmith | Feb 20, 2004 05:42am | #40

    rick... you've got it right... it's cellulose insulataion... made from ground up newspaper and borate or boric acid..

     and it's the closest thing to  a fireproof material you can find in a house.. also the most benign...

     the borates  ( or boric acid ) is what makes it imflamable... if you take a torch to it , it will char.. you may see some small embers .. but as soon as you remove the flame , the embers die... the borates extinguish it..

     it does not give off toxic fumes, it doesn't melt.. and it will protect anything  between it and the flame...

    another advantage to it... vermin can't stand it.. mice will not burrow in it.. termites and ants can't live in it.... even racoons will give it a wide berth.. they don't like the borates..

     back in 1979,  the fiberglass insulation mfrs . tried to  kill the competition... they got 60 Minutes to do a big story on it... the story featured a lot of film of houses burnign  that had supposedly been insulated with cellulose insulation.. ..

     cellulose fought back and did their own testing.. here in RI my boss's company sponsored a burn with 3  (4x4 ) buildings .. uninsulated, insulated with fiberglass, and insulated with cellulose...... the first two were just a pile of ash after two hours.. the last lost it's roof because the flames from the accelerant  burned thru the joint  where the rafters met the plate and got into the attic.. the walls were untouched.

    a month later he invited all the Fire Departments in RI to the "Big Burn" and we repeated the show and the results with 3 (8'x8' ) buildings... he made a video that was distributed nationally ..

     the red hot penny test became a staple at home shows across the United States..

    if you have some cellulose that burns, it is something that wasn't manufactured to meet those specs i sited ..

    Cellulose Insulation mfr'd to those specs WILL NOT BURN.. if a house burns to the ground that is insulated with cellulose... the only thing left besides the concrete foundation will be the cellulose.... but ,it probably will not burn to the ground because the cellulose insulation will protect the framing....

     most of the mfr's i've seen have their product tested by Factory Mutual or UL..

     here is an excellent report on the flame  characteristics of Cellulose Insualtion..

     this is by Regal Industries ..

    http://www.regalind.com/fireretardregal.htm

    really , the firefighters i know are very enthusiastic about using cellulose insulation in homes... it gives them time for first response....Mike Smith   Rhode Island : Design / Build / Repair / Restore

24. 
    BigRick | Feb 20, 2004 07:22am | #43

    S#!t  I forgot to paste the link.  Sorry guys here it is...

    http://cms.firehouse.com/content/contributor/bio.jsp?id=29Rome wasn't built in a day, take your time and do it right the first time.

25. 
    BillHartmann | Feb 18, 2004 05:28pm | #12

    Mike

    "i wouldn't even consider fiberglass , either blown or batts."

    What about BIBS. I don't really know that much about it, but it if it could build up to 6-8" the bottom of a horizontal surface it wouldn't it work.

26. 
    xMikeSmith | Feb 18, 2004 05:41pm | #13

    don't know...it's still fiberglass... but if that's what you want, i'd get a  BIBS contractor out to talk to me.... the webbed truss is just a tough act to insulateMike Smith   Rhode Island : Design / Build / Repair / Restore

27. 
    BowBear | Feb 18, 2004 05:49pm | #14

    I recently insulated my attic by putting up the dry wall ceiling and then spraying foam on top of it. Would it be reasonable to build the structure leaving out the sub floor over the garage. After the structure is closed in, install 5/8 DW ceiling, blow in the cells then put down the sub floor?An ex-boat builder treading water!

28. 
    xMikeSmith | Feb 18, 2004 08:24pm | #16

    bob..... long answer..... NO!

    hah,hah, hah.... sorry devil made me say thatMike Smith   Rhode Island : Design / Build / Repair / Restore

29. 
    cutnnail | Feb 19, 2004 05:59pm | #33

    I think BIBS would work fine here. The insulation guy will staple up his netting and fill your open webs as full as desired. This system is pretty much standard fare with the good builders around here.

30. 
    we3beach | Feb 19, 2004 11:34pm | #37

    Looking into this option, however, this is for over a garage so I'll need to find out what kind of vapor barrier it creates.

2. 
   dIrishInMe | Feb 18, 2004 06:44am | #9

   I used to work for a company that used webbed trusses over crawl spaces.  They were nearly impossible to insulate properly.  Finally, after me suggesting it about 10 times, the boss had a great idea - said he could actually save money by going with I-joists!  The I-joists are much easier to insulate.

   Regardless of what type of joists you do use, never exceed about 2/3s to 3/4s of the max span - this I have learned the hard way. There are span charts for most every kind of joist on the web, although you may have to depend on the manufacturer for web truss joist spans. 

   BTW - don't think any of the above folks said it explicitly, but the reason for the 5/8 drywall between the garage and the living space is to meet fire code.   The drywall gives the occupants about an extra 15 minutes to get out of a burning building.  Codes vary from place to place, but if the garage is going to have any kind of inspection at all, I'd be the drywall (or something similar) would be required.
    

   Matt
3. 
   WorkshopJon | Feb 19, 2004 04:26am | #23

   "I'm Installing 13 inch, open joist floor trusses to clear span a 24 foot garage.  There will be a heated apartment above"

   Beach,

   I have no advice for you, but reading through this thread, can't picture what type of structure you are trying to build. ie. something like a 1 1/2 story garage w/t loft or a true two story structure?

   More info = better answers.

   Jon

1. 
   we3beach | Feb 19, 2004 07:48pm | #34

   True 2 story structure . Plan is for a studio apartment above Garage with full shed dormers on front and back sides. It will be heated with FHW on a seperate zone fed from existing house.

1. 
   BossHog | Feb 19, 2004 09:33pm | #35

   "True 2 story structure...with full shed dormers on front and back sides. "

   Back the horse up a minute here.

   A "True 2 story structure" to means that the walls go straight up from the first floor, then the roof is on top of that.

   If you've got dormers, that makes it a 1.5 story structure. If that's the case, the roof has to be self supporting. Or the floor sustem has to be beefed up to handle the extra loads.I've been thinking about a sex change. Specifically, I could start having some.

1. 
   we3beach | Feb 19, 2004 09:53pm | #36

   O.K. B.H. Cats out of the bag...I'm not a carpenter by trade.  Garage/ceiling/trusses/subfloor/apartment with dormers above.  That's it!  :>)

4. 
   artacoma | Feb 19, 2004 07:24am | #25

   Just did a similar setup ,25' x 24' with 12" I joists on 16" centers with a triple 1 3/4" x 18" LVL beam down the centre. Used regular batt insulation sized for steel studs. It's plenty stiff and the beam only hangs down 6".

   ............Rik...........

5. 
   dIrishInMe | Feb 19, 2004 05:21pm | #31

   As stated above, I'm for putting a 24' flush beam down the center and running the joists the length of the building.  When I say "flush beam", I mean flush with the top of the joists.  You did not tell us how long the building is.   Assuming it is a good bit shorter than 48', you may likely be able to go with 12" I joists.  If the "garage" is 48' or more long - you may be a rich redneck ;-))

   BTW - all spray in place foam insulation is not the same, and I believe that only the closed cell types are a vapor barrier.  I believe that Icyene (sp?) is an open cell foam.  If you get interested in going the foam route, check the price of installed spray in place foam before you get too committed.   I may be wrong, but I believe that a floor of a 24'x30' building with a 5" layer could start at ~$3600 - but that's just a wild guess.
    

   Matt
1. 
   we3beach | Feb 19, 2004 05:58pm | #32

   Redneck?.......ahh...maybe?  Orginally from CT., so technically I could be called flatlanderin'redneck, rich, far from it!  36 Big ones would put me out of the game if that proofs to be true.  I'll be looking into priceing for my area soon.

   W3B

6. 
   Nivek | Feb 20, 2004 07:09am | #42

   I have used two different methods for insulating garage ceilings over living spaces.

   The first and most expensive is sprayed in place foam. This works very well, it never moves, keeps everything tight but if you are trying to cover water pipes they will have to be placed dangerously close to your floor for them to be covered enough for freezing.

   The other I use more often is blown in cellulose. Once all framing and utilities are finish in the ceiling I cover the garage ceiling with 6mm plastic and hold it up with 1x3 strapping at 16 center.  The insulation guy then punctures the plastic with his hose and files up the space. This works great because he can see what he is doing and he pokes as many holes as neccesary. The 5/8 gyps are fastened to the strapping. One the guy is done the cellulose is very dense and there is, in your case, 13" of insulation.

1. 
   we3beach | Feb 20, 2004 06:25pm | #44

   Kev,

   This sounds like a good recommendation, however, in an earlier response it was suggested that in order for the insulation to be up to it's rated R-value it would have to be in contact with the subfloor above. I guess my questions now would be...........

   1.) How much settling would there be with the cellulose over time ,if any?  

   2.) How will it effect the overall R-value I'm trying to obtain?   

   I known that the foam or BIBS would eliminate this problem, however, the cost factor does come into play.   Any thoughts?  

1. 
   Nivek | Feb 20, 2004 07:39pm | #45

   if done right, when the cellulose is blown in it is very well packed. it is hard to push it up with your hands because it is so well packed! I do not think it would settle when it is done so dense.  I am thinking that the only place the insulation has to touch the floor is around the outside edge of your floor joists(the rim joist). If there is a small airspace under the floor then the insulation it should not effect the warmth as long as the cold is not comming in from the sides. Alot of times when I get the basement shot with foam I also do the rim joists at the same time because the are very hard to apply a good vapor barrier to. Maybe you can foam the outside perimeter than cellulose the middle. The only thing with that is that the foam guy has a minumum price which may be more than the actual price of doing the rim joist that is why I do it when I have the basement walls done.

   kev