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-   -   Blown Insulation after all - quick q's (I think) (http://www.diychatroom.com/f103/blown-insulation-after-all-quick-qs-i-think-163287/)

forcedreno2012 11-14-2012 12:21 AM

Blown Insulation after all - quick q's (I think)
 
Okay went to another local supplier and he was able to drop the price on the blown FG for us so it would be the same price as batts and still give the R-30 we need :thumbup: Looking at this option now. Will be happy to do it but a few quick questions before I pull the trigger.

Based on what I have read...

1 We need to install vents every second joist bay to let the house breathe but how do you stop this stuff from going over the edge near the soffit vents? Is there some type of guard they install?

2 How do you determine the thickness for R-30 is there a magic formula they use or is there a standard measurement? ie x inches = R-30

3 We can cover all lights/cans, junction boxes etc with this stuff but to take pics of the attic before they blow it in to keep track of where everything is at.

4 Is it okay to put down a plank for a walkway over the top of this?

5 How much settling occurs and what timeframe, ie do you need to top this stuff up every x years or so?

6 Can we do the just the heated and cooled part of the house and leave the garage as batts if we want to to save some $$.

okay maybe more than a few questions :whistling2: and I thank you for advance for your insight.

Robyn

Windows on Wash 11-14-2012 08:58 AM

Quote:

Originally Posted by forcedreno2012 (Post 1051761)
Okay went to another local supplier and he was able to drop the price on the blown FG for us so it would be the same price as batts and still give the R-30 we need :thumbup: Looking at this option now. Will be happy to do it but a few quick questions before I pull the trigger.

Based on what I have read...

1 We need to install vents every second joist bay to let the house breathe but how do you stop this stuff from going over the edge near the soffit vents? Is there some type of guard they install?

Baffles. They should be in every rafter/truss bay.

2 How do you determine the thickness for R-30 is there a magic formula they use or is there a standard measurement? ie x inches = R-30

R-Value divided by 3.2-3.4 = insulation depth.

3 We can cover all lights/cans, junction boxes etc with this stuff but to take pics of the attic before they blow it in to keep track of where everything is at.

You should box out and air seal all the can lights and any penetrations prior to blowing over the top. We usually put marker flags on them for future reference.

4 Is it okay to put down a plank for a walkway over the top of this?

Yes if you are talking about for the installation. No if you are talking about leaving it up there.

5 How much settling occurs and what timeframe, ie do you need to top this stuff up every x years or so?

Once it is up there, its up there. Settling doesn't happen much in blown in FG but even the settling that does happen in cellulose doesn't really impact the R-Value.

6 Can we do the just the heated and cooled part of the house and leave the garage as batts if we want to to save some $$.

No need to insulate over and unconditioned space unless you want to.

okay maybe more than a few questions :whistling2: and I thank you for advance for your insight.

Robyn

Google and read threads on this board about air sealing first before you do anything and I would also highly recommend cellulose over blown in fiberglass. Cellulose is a much, much better option.

forcedreno2012 11-14-2012 09:42 PM

Thanks WOW,

If you would be so kind, have a few follow on questions

So if we are paying a specialist to do this do they typically install the baffles?

Based on your fomula we should see about 6" of insulation up there?

Good idea for the boxes and the flags (might save m from kicking them up there lol) do the boxes have to be wooden or can they just be made of sheet rock or ductboard (got lots of that left over)?

We were actually warned away from celulose because it is made primarily of paper materials. I am all for green but we are down in ms where it does get humid and apparently this is not a good climate for celulose? Can you provide some insight?

Thanks

jklingel 11-14-2012 10:22 PM

So if we are paying a specialist to do this do they typically install the baffles? Ask them, and make sure they do not overfill anyway.

Based on your fomula we should see about 6" of insulation up there? 30/3.2 = 9+ inches.

We were actually warned away from celulose because it is made primarily of paper materials. I am all for green but we are down in ms where it does get humid and apparently this is not a good climate for celulose? Check with a local, unbiased and knowledgable individual. The "paper" is treated w/ borates to deter bugs and to resist moisture and fire. Unless cellulose is, in fact, susceptible to humidity (I doubt it, but check locally), I'd use it over loose FG, which is not dense enough for my interests. Blown FG is better suited for dense packing into walls than open to air currents.

forcedreno2012 11-14-2012 11:01 PM

WHOOPS I thought the below was

R-Value divided by 3.2-3.4 = insulation depth.

as in R-30 divided by 3.2 and then minus 3.4 (this is why I hate math lol) I'll go with the 9 inches then and not the 6.

jklingel 11-14-2012 11:28 PM

close. the r value varies between 3.2 and 3.4 per inch. i chose the smaller number to be safe. more insulation, if you have room, is better than less. remember: numbers are your friends. they don't lie, or stretch.

Windows on Wash 11-15-2012 06:17 AM

+1 to jklingel's comments.

Cellulose is better than FG every time and the insulator should be installing the baffles.

forcedreno2012 11-16-2012 05:54 PM

I talked with the blown ins guy today and he agreed that yes celulose is a better option but due to the humididty down here on the coast he said it would loose half its height within a year so it looks like it will be fiberglass afterall.....but at least its blown in fg. They will also install the baffles and insulate around them while the ceilings are open then come back and blow it in. meeting with him monday so hopefully get things on track.

Windows on Wash 11-16-2012 10:26 PM

All loose fill cellulose settles. That should not be a disqualifier and it does just fine in humid areas. Bulk moisture is a no-no but that goes for any fiberglass, cellulose, or batt insulation.

jklingel 11-17-2012 01:08 AM

When loose fill cellulose settles, it apparently "skins", or "crusts" (I have not crawled up into my attic to verify this), which is good. The skin makes it even more air-impervious. It also increases the density a tad, which is also good; to a point, higher density is higher r value. Dense packed into walls gives a higher r value for both materials. If you are worried about settling, blow in 10% more. Bugs, fire, and mold like cellulose less than fg. Either way, you'll probably be fine if you air seal well.

forcedreno2012 11-17-2012 01:48 AM

Thanks again guys. I will discuss it with them on monday. I'm not partial to either one personally, so unless he really pushes back on the humidity thing I will get the cellulose.

Windows on Wash 11-17-2012 04:11 AM

Quote:

Originally Posted by jklingel (Post 1054010)
When loose fill cellulose settles, it apparently "skins", or "crusts" (I have not crawled up into my attic to verify this), which is good. The skin makes it even more air-impervious. It also increases the density a tad, which is also good; to a point, higher density is higher r value. Dense packed into walls gives a higher r value for both materials. If you are worried about settling, blow in 10% more. Bugs, fire, and mold like cellulose less than fg. Either way, you'll probably be fine if you air seal well.

Sure does.

Almost a bit of a dense packing effect.

:thumbsup:

forcedreno2012 11-20-2012 11:59 PM

met with the insulation company and its our choice He said we would do either so we are going to go with the celulose. After seeing the roofline he is uber happy that we are holding off on the drywall to allow them to put the baffles in so I am glad I stopped the work to get that done.

Again, thanks for the input and steering us in the right direction.

Gary in WA 11-21-2012 09:17 PM

They know their stuff; not on the Coast; http://books.google.com/books?id=7Hl...page&q&f=false


http://www.greenfiber.com/step_one_-...o_install.html

Gary


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