Floor Joist not 16" on center

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Posts: 11
Joined: Sat Sep 22, 2012 12:05 pm

Wed Oct 10, 2012 1:21 pm

was doing some measuring for insulations between my floor joists and noticed that the joist are not 16" on center or 14.5" between the joist. My joist are 16.5" between each other. this could cause an issue when i install the insulation in the next few weeks as i will have a gap to try and fill. Any one else have this issue and what did you do to solve it. My MH is a '73 hawthorn. Thanks


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Posts: 5685
Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

Wed Oct 10, 2012 4:42 pm

That was part why HUD got involved. Your home is a PreHUD home and there were really no standards to the way they were built some were built far above standards some way below. I personally feel that is in part the reason for the negativity towards Mobile Homes.

As far as it effecting the FLOOR insulation, you want the insulation to hang below the joists to create an dead air space under the floor where the pipes run.

"If I can't fix it, I can screw it up so bad no one else can either."

Posts: 11
Joined: Sat Sep 22, 2012 12:05 pm

Sat Oct 13, 2012 10:03 am

So that i am clear; i don't want to stuff the insulation between the joist? I want to create a blanket to hang below the joist? not sure i understand what i need to do.

Posts: 383
Joined: Mon Oct 25, 2010 9:53 pm
Location: Steuben County, NY

Sat Oct 13, 2012 11:09 am

You want to create a space below the floor joists so that heat from the furnace ducts can keep the plumbing from freezing. You will use what is called belly wrap, or in a pinch tyvek, fastened to the rim joists on the perimeter of the home to lay the insulation on to create an air space under the floor joists to enclose the underbelly.
Now, if you live in a climate where you don't have to be concerned about freezing, you could get away with insulating between the joists, but you would still need to provide a way to keep critters from moving in to the insulation.

Posts: 58
Joined: Mon Apr 23, 2012 1:14 pm

Sat Oct 13, 2012 12:03 pm

Mine and most others around here (Canada, so cold) come with insulation between the joists, and then some under if needed for plumbing. I.e. I had a bulge in the belly canvas down the centre of the home where there's an additional layer of insulation under some pipes. If all of your plumbing is inside you wouldn't need this. Older mobiles with furnaces and duct work differ though, the insulation hangs below.

So if your plan is to insulate between the joists, I'd just cut the insulation batts cross-wise, i.e. cut strips of it 16.5" long and lay it sideways. Otherwise you'd have to try to cut a 2" strip somehow to make the 14.5" wide batts the correct width, which probably wouldn't work out. You should still put up Tyvek or belly canvas or whatever you're going to use underneath, stapled to the joists. Mind you, it probably depends on how your was built. If it was built with insulation under the joists and pipes & ducts between them, I'd continue with that plan, so it wouldn't matter how far apart your joists were.

Posts: 11
Joined: Sat Sep 22, 2012 12:05 pm

Sat Oct 13, 2012 12:17 pm

Ok i got it, since im in michigan i will create the blanket using the Tyvek and insulation to protect the pipes. Thanks for the help everyone.