How can I prepare my old deck for new composite deck and railing ?


Old 06-02-19, 03:49 PM
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How can I prepare my old deck for new composite deck and railing ?

I have an 18 yrs old deck just attached to the back of the house and supported by 2 5"x5" posts and 13 beams across (see attached photo Img 6585) The wooden railing top is rotting and splitting & deck board is not in the shape I'd like to see. To reduce maintenance. I'm planning to replace it with composite decking and railing. Upon examination of the deck under structure, I found that it was built with PT wood as I can see there are some greenish color on the wood and in good condition. The 2 post is not sure if it is PT wood but I see crack (splitting/checks) on both posts (see attached photo Img 6591.)

PS: I have not check the base of the 2 post yet and preliminary examination looks solid and good.

Due to the fact that compote deck board and railing are heavier than regular PT or Cedar wood. Wonder if the 2 posts are good enough to continue to use it or I need to add more post or replace them in order to support the composite deck board and railing ?
If they are good, can I use some material to patch up those split/crack holes on the posts ? or do nothing about it ?
What can I buy to stain/seal both the support beams and post to keep it in better condition ?

Thanks in advance for all your advice
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Old 06-02-19, 04:25 PM
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Congratulations on the decision to use composite, I'm a huge fan of this material and if interested here is a post I added earlier this year regarding my composite deck, a great investment!

Oh, and the comment about wanting to do maintenance, and plastic feel were never anything that I ever considered, but to each their own!

Yes it is heavier but normal deck construction is more than sufficient.

It's difficult to say from just a couple pictures but you really need to check out your headers, joists and beams, 18 years is getting up there but cracking is common!
Old 06-02-19, 04:27 PM
Join Date: Mar 2019
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I did the same thing a few years ago and from the looks of it it was the same size as yours, and also off the 2nd story. My support posts were a similar setup, too. I don't recall the Trex being heavier than wood. It was thinner and actually seemed lighter, but I didn't research that at the time.

what I did run into was the joist spacing. The Trex I used had more flex and needed closer joist spacing. I was going to add joists in between existing ones, but some of them were showing signs of rot so I just replaced them all, spacing them per manufacturers specs for the decking.

I'll leave it to those with more knowledge to address your post concerns.
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