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Is there a building code on deck board spacing?

Julia Ko | Posted in Building Code Questions on

I have a flat roof and my contractor built a cedar board floating deck. the area is 16’x20′ range and he made into 4 section, 16’x5′ each. the boards are tight fit(no space) and also tight fit to the edge wood board( the wood board sit on top is metal capping). the nails are all sunken under the wood surface. One winter with snow/rain, I had to shelve the snow off the roof since the ice/water sit on the cedar boards. there was a leak(this roof did not have leak before the new deck). I tried to find out where the leak was, but the boards were all frozen together, like a big ice block. Everyone I know said it is built wrong–should have space. and my roofer refuse to touch to avoid any claim. my builder insist he did it properly. I do not know what to do. the contractor finally came to break the edge of board from edge of roof wood and remove 2 sections. but insist what he did is totally correct. the fact I am unable to remove the deck is my problem, not his. I find this attitude wrong. but there does not seem to be any code of construction.

is there any association or building code for deck? any bureau for me to call who really can offer professional opinion?

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  1. GBA Editor
    Martin Holladay | | #1

    The building code requires (in Section R502.2.2.4 of the 2009 IRC) that "Wood/plastic composite deck boards shall be installed in accordance with the manufacturer's instructions."

    Whether this applies in your case depends on whether your deck boards came with manufacturer's instructions. Some do. For example, Tamko deck board installation instructions state, "When installing decking, side-to-side spacing must be a minimum of 1/8" between adjacent boards."

  2. David Meiland | | #2

    Julia, I don't know if code applies, but in my opinion, your deck problems are the result of an inexperienced carpenter. Deck boards should be spaced well apart, 1/8" is the minimum and I would go wider, usually 3/8". Without that gap you get stuff accumulating between the boards that you can't easily clean out. Find another carpenter--a good one--to fix your deck.

  3. Julia Ko | | #3

    thank you for both Martin Holladay and David Meiland! I really appreciate. I think I should fix before next winter. but I find it wrong that a GC who took the job refuse to fix. claiming industry standard. and when I check around, everyone said to have Gap. It seems that a simple word is the golden rule and he can get away doing bad job for other people.

  4. Julia Ko | | #4

    I checked with the supplier, the boards came in w/o manufacturer instruction. and I call the stores, the answer is experienced contractor should know it is always space with gap. to redo the entire deck to space properly, we have to take out the current ones, but nobody wants to do because all the nails were sunken under the wood and too close spaced. the suggestion: cheaper to re-do the entire deck. Is there another code for NO Manufacturer code?

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