When too insulate

[APG]

When should you insulate the floor joists?  Appears some insulate before the subfloor goes down.  Others wait.  I'd thinl it would be easier to insulate right after the floor joists are in.  

[John_M]

The only concern is will the insulation get wet before you are done with the rest of the structure and the roof?  I would think that most people would put it in after their building is weather tight!  Foundation issues are also a factor as you may not be ablt to get to the joists after the subfloor is on.

If you can wait..then wait.....just my opinion.

[borgdog]

Any plans for plumbing, wiring, etc in that space?

[MountainDon]

When to insulate floor?  :-? Good question. As pointed out by Johm_M already that partly depends on whether or nor the floor will be made weathertight, whether or not there's potential for the insulation getting wet. You didn't state whether or not there was a crawlspace to provide easy access, or reasonably easy access from the bottom. That's one concern as well. Also mentioned by Dan is whether or not there's any electrical, plumbing, or HVAC needs that have to be addressed. You have to take all that into account.

My own plan is to get the piers in place. Position and secure the beams, then install the joists, on top of the beams. At that point I need a couple days, hopefully less, of highly probable clear skies, no rain. My plan is to install ventilated sheathing under the joists. I don't want to share my pink fibreglass with the mice, call me selfish.  Then install the insulation from the topside. Next install the T&G floor sheathing with plastic roll sheeting under it. Cover it at that point with tarps if necessary.

When I get to this building, Late May - beginning of June, I do have the advantage/luxury of being able to work on my project non stop. Or at leasy as non stop as I can stand, as I will be off work thru mid August. As well the months of May and June generally have little precipitation. Now that I've said that the monsoons will come a month early.  :'(

[glenn-k]

If there was a bunch of rain and the tarps blew off would the water sit on top the plastic below the t&g?  Seems it might still create problems for fiberglass.

Quite a few of our members had tarp problems last year.  

[MountainDon]

Good comment... gives me second thoughts. Anyone know how to get in touch with the rain god?

[MountainDon]

I just had a brainstorm; or maybe a brain fart.  :-/  First, remember I'm talking about a smallish cabin, 14 x 26. What if the floor was built as I suggested and a layer of the synthetic roofing membrane was laid over top the T&G. I know, there's still a chance of this being damaged during the rest of the construction, but it would help a lot in the case of a rain. After the shell is weather tight it could be cutaway and possibly be reused on one of the small outbuilding that will go up sometime later.

The manufacturers of RV's used to (don't know if they continue) install the interior carpeting, then cover it with a protective sheet before installing the interior cabinets, fixtures etc. That way they eliminated having to cut carpet around everyhting and the carpet was protected (mainly from soiling).

[peg_688]

The [highlight]ONLY time [/highlight]to insulate right after joist are rolled is [highlight]IF it is a trapped floor system , meaning zip zero nada access except from above . [/highlight] Meaning removal of the subfloor. A raised wood floor over slab on grade , basement / garage remodel would be examples .


Main reasons wiring / plumbing / heating / venting / keeping it dry for weather /etc.

One added reason is moisture in the joist's and subfloor itself , if trapped because insulation was installed before this is allowed to dry out some what  ,  mold could be in your future.

So if at all possible insulate later in the job , after all the above things have been completed and that moisture has time to go away.  

[glenn-k]

From the dude who knows.  Thanks, PEG --- lots more reasons to delay.

[peg_688]

--- lots more reasons to delay.

 I'd procrastinate about it but I don't have time right now , I'll think on it

[glenn-k]

I helped my uncle procrastinate his young bulls one time-- cowboy work is hard. :-/

Wait a minute-- that's not what it was.  Gotta look that big word PEG used up....

[peg_688]

You should look it up but heck I'd just put it off till later Yup have ole Will Catchitlater do it on pickup That guy sure is busy He's always got somethin ta do!

[MountainDon]

Thanks guys, You've convinced me to have my son crawl under there and put it up later  

[glenn-k]

There you go, Mountain Don.

Avoid the whole unpleasant situation.

And they say nothing comes from going off topic.  We just taught Mountain Don how to procrastinate and avoid playing with fiberglass.