decking boards

[curly]

Our deck is 5 years old . the boards have been treated , stained , waterproofed. Now...I want to place new treated boards on top without removing the original decking boards. They were screwed down... some short boards and some long. I want to place the proper length

5/4x6x16 and 5/4x6x10 over the others. The small boards 3' have started to buckle down , I will again waterproof the bottom boards .Should I remove all existing decking boards..........would it be safe to place new over the old.   

[wjohnston]

buffalo ny: subject to your climate, removal will allow you to inspect for hidden damage. get an expert opinion as to whether the deck support is properly constructed for support, pitched, anchored, and flashed against the house. spacing of replacement boards to allow for drainage may be needed. overlapping new deck boards is inviting problems of trapped moisture damage and more warping. subject to local codes: the size of the deck and related neighbor property setback boundaries.

[Jim Elbrecht]

Safe? I suppose. But you're inviting all sorts of problems to avoid what should be a pretty easy job- unscrewing a bunch of decking.

If you're not into it- put an ad on Craigslist- 'Free pt deck boards- you unscrew and take away.'

I'm dismantling a 20 yr old deck [pt 2x6's by a pool & sealed every

3-4 yrs] and have been just unscrewing 95% of the screws. A few have broken and needed to be pried- then I grab the end with a pair of vicegrips and turn them out. If the right screws were used a 5yr old deck should be a piece of cake. And if the wrong screws were used- then you want them all out of there anyway.

Jim

[ransley]

What do you mean buckle down, sag? Run extra supports if thats the case.Two decks will trap dirt and water and some new PT is not as good as old CCA.

[aemeijers]

What he said. And where are you? 5 YO deck boards would be an upgrade, for me.

-- aem sends...

[trader4]

And why does a 5 year old deck surface that has been treated, stained, waterproofed, etc need to be replaced? If there is significant buckling, I would definitely remove the existing would instead of looking for more trouble in the future. And figure out what went wrong to cause it to fail so soon.

[Phisherman]

Not sure how putting the new over old would not be "safe," but I would remove the old boards. My PT (stained with semi-transparent Cabots decking stain) deck is now 20 years old and no rot yet, in e.TN. I would think moisture getting between the boards may not dry out as quickly when boards are sandwiched together, plus this may offer hiding places for insects. I am curious why you want new boards on top, when you already have relatively new deck? Decks are high maintenance, why make it more difficult than you need?

[Jimw]

"Safe" is not the issue....... What you want to do is stupid. Assuming this is an outside deck exposed to weather, you are going to have moisture trapped between the two layers constantly. This moisture will lead to mold growth (a health issue), warped boards, and wood decay (even on treated wood). Remove the old boards before you put on new ones. Or save yourself some money and just replace the bad boards.