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Deck over deck

4670 Views 30 Replies 17 Participants Last post by  dnconstruction
How can I put a new deck 5/4 XLM over existing 2x4 PT deck??
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You can't.

But the bigger question is why would you want to?
Remove the 2x4 decking...
Mike, your kidding, right?
Zinc coated Fascia nails.
Everybody knows this!

I thought you knew how to build decks, til this question.

Robert all ready gave you the answer, but I couldn't help the smart arse reply. No hard feelings eh?
What exactly would happen if this were done? Mold, mildew & rot of Biblical proportions?:laughing:
now I remember why I put you on ignore the first time...

now I remember why I put you on ignore the first time...

My neighbor had his "carpenter" son do this last spring.(April-ish) 2x6 PT over existing 2x6 PT. He shot 4 ringshank nails through the face on every joist (16" oc). Damn planks were curling up by August. :no:
Lots of glue. And it will be Timbertech's fault when it goes bad. Mike I assume you got this question from a HO?
Here's what I have. The orginal deck was over 15 years old very sound 2x4 PT. A deck that was built over that the orginal us cedar 2x6 nailed with 12Galv into joist, but a 1/2" furring strip was installed between deck surfaces. I removed cedar and strips installed new strips and install XLM hidden fasteners. I belive this will last as long as the cedar did or longer. I don't see why not.
The only hope for you is my brother lives in NJ so showing Major restraint I will not even hint about your install being total foolish. J.
In a perfect world with out working for for any landscaping General Contractors and knowing that a deck was hiding under those 2x6 cedar boards. I would have included the removal in my original agreement. But this world is far from perfect. Once we discovered the mystery deck it would have been hard for me to sell the idea of me charging the landscaping General Contractor who would have to pass that on to the owner an additional cost for something that had not been a problem for over 15 years. Maybe it was the 1/2" furring sleepers that separated the two surfaces, and allowed for good damage that saved this deck from disaster. But in any case I thought it would have been useless to attempt to bill anyone for the removal. Just didn't feel that was the hill I wanted to die on. I did manage to submit a bill for installing new furring / sleeper strips and longer screws for decking.
Except for a couple of misinformed issues. Most of the time the info I get from this site is RIGHT ON RIGHT and after all, I do have an advanage. I'm the only one here that had the privilege of visiting the site to access.
Don't be so quick to to condemn maybe an Innocent man. (The world is not flat)C. Columbus
Let's hope there are no problems but generally this type of install is trouble waiting to happen. From Timbertech's website:
XLM Plank, Earthwood Plank, DockSider Plank, TwinFinish Plank and ValuPlank

There must be a minimum of a 2" (nominal) sleeper system supported by and connected to the substructure over which the deck is to be built.
maybe that doesn't apply so much as the ''under decking''? is spaced

i have a hard time believing nobody here ever deviated from man.recommendations before
The one thing that we do know is who will be under the gun, if it fails.

In cases like this, it is imperative that the contractor let the GC or homeowner know that they are going against the manufacture's guidelines, and to get a release.
When doing work properly the number of issues that can pop up and cause us grief is high. Now add to that a condition that the manufacturer does not recomend and you have the makings of a potential Monster headache. That being said this installation may be fine, may give them many years of good service, and they saved on demo and carting, who knows, GMOD.
Thanks for all the help and warnings on this matter. I'm not worried do to the prior performance, and may I add I do have my big boy pants on.
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