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Installing insulation between Metal Floor joists in crawlspace

Installing insulation between Metal Floor joists in crawlspace

Old 10-08-21, 03:18 PM
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Thumbs up Installing insulation between Metal Floor joists in crawlspace

I recently had to flip insulation in a crawlspace that has metal floor joists that are spaced 24 inches on center. As you know if you have installed insulation before with wood floor joists, the metal straps are 23 1/2 inches long and do hold ok with wood floor joists. With metal floor joists, it is much different, nothing for the metal straps to hold on to and the straps are not long enough to hold. So after looking through the internet for ideas, nothing came up, so I had to get creative and make something work. Well the answer was 1/2 inch plastic drip tube that is used for landscaping irrigation for plants. I went to the local home improvement store and looked around for material that was 1) strong enough to hold insulation in place 2) not expensive for the amount I needed and 3) would last forever in a crawlspace with the conditions of it. I found the plastic drip tube in the plumbing section at a length of 500 feet for a price of $40.00, YES $40.00!!! That is a bargain when you think about the price of the metal straps ($18 a box of 100). The metal joists have holes already in them for plumbing and electrical lines/wires to pass through, so I used the holes to install the drip tube. The holes are 1in dia., the drip tube is 1/2 inch dia. The spacing between the joists is 24 inches on center so you cut the drip tube at a length of at least 28-30 inches. I used a pair of siding cutters to cut the tub, you can also use a PVC pipe cutter or a razor knife. You cut it long so you have enough length to have them hold together. You first will install one side under the insulation to hold it up, in the next joist bay, you install the next tube into the same hole where the first tube is installed, this will lock the tubes into place so they won't slip out, they will fit, they are only 1/2 inch dia each. Keep doing this on the rest of the floor joists. You can turn the tubes so the curve of the tube pushes up on the insulation, it's not so much to compress the insulation, just more support.
The good thing about using this material is that they will never rust, rot, or corrode. They will also not bend and get damaged, they will stay flexible to a point, but stiff enough to hold the insulation in place.
This technique saved me tons of time and aggravation trying to figure a way to keep the insulation in place. The only reason I had to do this was due to the previous home owner or contractor installing the insulation with the paper side down and they stapled the insulation in place to the subfloor. This is not the proper way to install insulation. The paper also states that it is flammable, don't leave exposed to heat source, and you always install the vapor barrier toward the warm side of the house. In most states it is toward the living space.
Hopefully this will help someone out when they run into this issue. I know I will use it again if I come across these metal joists again.
I have attached photos of the tubes used and the technique.

Tubes holding up the insulation

Tubes locked together through the 1 inch holes in the floor joists

Metal joists and spacing of 24 inches, holes already in them.

Old 10-08-21, 03:57 PM
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Nothing more satisfying than finding common items to solve uncommon problems!

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