Porch Floor - Tongue and Groove versus 2x6 Boards Pros and Cons

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Porch Floor - Tongue and Groove versus 2x6 Boards Pros and Cons

by brian
(st louis)

QUESTION:I have a porch I need to redo. The deck is currently built out of tongue and groove 2x6's and is rotting in areas. I feel it's because it is made of tongue and groove because the water can't flow off the deck as freely. What are the advantages and disadvantages of tongue and groove and the same for just straight 2x6's?

ANSWER: Brian, thanks for visiting our site; we really appreciate it.

The main purpose of tongue and groove, whether it be a floor or ceiling, is that it provides a solid surface area. The “tongues” allow the boards to move (all wood expands and contracts) yet still maintain its solidity. A board floor of 2x6s, much like that on a deck will have the noticeable spaces between the boards. No matter how tight you place the boards beside each other, they will eventually dry and contract thereby creating the spaces.

Most wood porch or deck flooring actually degrades from the bottom up. Unless you have standing water on your porch floor most of the time, it should normally dry through evaporation. So in your case, no matter what option you choose, you need to take precautions under the porch. As a minimum, I would lay heavy plastic over the soil completely under your porch and ensure the porch is well vented so that air can move underneath. The more air that can move under your porch the longer your flooring will last.

If you choose to use 2x6s, do the same as discussed above. 2x6s will allow water to drain more quickly but you will have gaps between the boards.

If your issue is that you floor is so flat that water tends to stay on it for long periods, you may want to slope it slightly if you replace the entire floor.

Typically, tongue and groove wood flooring is used for most porches and I recommend it also. If you elect to go that way, treat the boards prior to putting them down. That way, you can treat the “tongues” and “grooves” and also the bottom of the boards. I recommend using a product from Sikkens. You can find it at paint stores (I don’t think Home Depot or Lowes carry it). It costs a little more but I’ve had excellent results from using it.

Remember that wood degrades over time but if you prepare it properly, it should last quite a while. Do everything you can to reduce moisture and increase air flow!

You may also enjoy a couple other questions we have been asked about tongue and groove flooring.