Ipe- a few question about joist span, and ventillation needed


Old 09-24-05, 07:31 PM
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Question Ipe- a few question about joist span, and ventillation needed

I'm resurfacing my deck, and am thinking about/strongly leaning towards Ipe with the Ipe Clips. (Looks beautiful)
My deck does not have great clearance underneath. (5-6 inches below the Joists to ground)
I'm concerned that the lack of ventillation will cause the board to cup. The deck does get some sun, but not all day long due to neighbors trees.

Does anyone have experience with 5/4" x 6" ipe cupping?
Would I be better off with 5/4" x 4"?
What about 1" x 6" or 1" x 4" as cost savings?
Are screws better than the clips at stopping the cupping? (I have my doubts about that, but the dealer tells me they are).

The other question is about joist span. I'm putting the boards on 45 degree to the joists Which are on 16" centers, and 14" centers in newer part.

If I go with the 1" x 4" (which is actually 3/4" x 3.5"), will it feel like a trampoline?

I know, lots of questions, but thanks for any help!
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Old 09-26-05, 06:52 AM
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The limited ventilation will cause the framing to rot, as well as tend to make the deck boards cup.

Screws rather than clips. Screws won't stop the cupping if the board decides to cup, but they will delay it from occuring.

Put an additional joist between those that are 16" O.C. if you are going to run the decking diagonally.Otherwise, you are overspanning the deck boards and they will 'bounce'. Where the joists are 14" O.C., either put an additional joist between them or sister a joist to one side of the existing.
Old 09-26-05, 06:09 PM
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agree with lefty on one item, not the other

Left is right. IPE needs ventilation. Otherwise, it will "move" which includes cupping or warping. You should have a foot or so free air movement under the decking.

On the span issue, I will disagree with lefty. 1x6 IPE can span 24" and maybe more. There is a small deck to the lumber yard where i work. The deck part is 16" OC. That's not because IPE needed it, but because something else was there before the IPE was installed.

On the steps, the stair stringers are 24" apart. Here is a test I have done. I sorta jump off the top landing and land stiff legged on both heels on the next step in the middle of the 24" span. When I land with all my weight (which is considerable), it jars my teeth. The boards do not bow or spring. It's like jumping on cement.

I've heard that 1x IPE can span greater than 24" and I believe it.

On clips versus screws, the clips are a lot more work and you definitely need several pairs of hands to force subsequent boards into the clips which hold down the previous board. You off course need a biscuit cutter (unless you have the wood grooved) and that is more work. Long boards can really cause a problem unless you have plenty 3-4 helpers to allign and force the boards in.
Old 09-26-05, 10:28 PM
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No choice on deck hight, now what are my best options?

Thanks to both Lefty and Jay.
I don't have much of an option with the clearance under the deck. The existing deck has been there for at least 6-8 years, and it is quite solid! In fact I had a heck of a time pulling the 2x6 PT deck boards with nails off with a 3 foot pry bar.

I layed out 3 boards on top of two 4 x 4's 24" apart and jumped on them, solid! and I weigh in at 240, not so solid! ha!!!

As for movement, do you really think that the 4 inch (3.5 inch actual measurement) wide boards will cup? I'm with you that if the wood wants to cup, it will no mater whether its screwed in or fastened with clips. Do you think I'd be better off with standard PT, Please don't suggest composite, as Im not a fan.
What if I seal the wood on the bottom before I lay it down? would that help, and if so, do you suggest a product?

Thanks again for all your valuable input. this is a great forum and you two guys seem to keep it going!

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