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Deck addition and changing boards

Hi everyone,

I am having to replace my 2 x 6 decking due to some rot issues (bad pressure treating) I think. The current deck boards abutt my raised concrete screen room on one side and are flush with the brick edging that surrounds the concrete. Since I am at it I want to add on to the deck for a bigger footprint which will extend on the other open side of the screen room. Here is the kicker: I don't want to go back with 2 x 6 decking, I want to use 5/4 x 6.
The NEW framing on the addition will be raised 1/2" to compensate for the thickness difference. How should I go about getting the extra 1/2" needed on the OLD deck framing to bring the new boards flush ?



Re: Deck addition and changing boards

Since you will be losing 1/4" (not 1/2" as you stated), you will have to raise the joists by 1/4" so that the top of the boards will be in the same exact place as the old boards.

I'm pretty sure it would be impossible to raise the joists, therefore my suggestion is to install sister joists that are 1/4" above the original joists.

The new boards will be attached to these raised sister joists. Use deck screws.

Re: Deck addition and changing boards

ripping PT lumber is a bad idea as the inside of PT lumber is often not PT all the way through. You might get away with redwood or cedar ripped to the right thickness, but sistering will make the deck stronger.

Re: Deck addition and changing boards

The easiest thing to do is lay a piece of your 5/4 down to set the space and install 2X4 pt on the side of the joists and lift until 5/4 in position. Onec 2X4's are installed caulk the top joint between the 2X4 and the 2X6 so water can't get between them. Install the decking on the 2X4's.


Re: Deck addition and changing boards


I thought 5/4 boards are actually 1" finished thickness?

Re: Deck addition and changing boards

Let me rephrase it: not all deck boards created equal. Wood and composite may have some variations, so you will need to measure the boards you buy and then compensate accordingly.

Re: Deck addition and changing boards

Personally I'd rather have the 1 1/2" (2X dimensional)vs the 1"(5/4 dimensional) decking anyway. But if you must, I just don't see that the 1/2" difference will be enough of an issue to cause any real problem.

What concerns me most is that you have pressure-treated wood that is rotting. I have replaced quite a bit of the newer ACQ decking due to rot and do not recommend it anymore. It doesn't seem to have the rot resistance of the old (now banned) CCA wood, which I've seen last 20 years in the same environment that killed ACQ in as little as 2 years. If you must use ACQ then seal it and maintain it well or you might be replacing it sooner than you'd like.

Look into the newer composite deckings. They are one of the few newer materials I truly like because I don't have to go back and fix them- ever!


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