I'm replacing my 2" deck floor boards with 5/4". How do I shim them so they are the same height as before?

Answer 1

I am going to assume that the thickness of the old lumber is 1 1/2 and not 2". Full 2" lumber is rare now days.
5/4 measures 1 1/4, so there really is only a difference of 1/4".
If you really need it to be 1 1/2 or even a full 2" you could rip down (cut length wise) treated lumber to the thickness that you need. Rip 1/4" strips and glue nail them down to the old joists and then put the 5/4 on top of that to make 1 1/2"
or rip down treated lumber to 3/4" to get a full 2"

Answer 2

OK, your 2" material is really 1-1/2", the 5/4 is really 1" material. If your are going to be converting to 5/4 decking, you should rent a table saw(if you do not already have one) and cut some firing strips to add the extra 1/2" that you need. When installing the firing strips you should pre-drill the holes that you are either going to nail or screw. You need to do that because you "Will" crack the strips if you don't. If you think this is a lot of work, you might want to look at a material called "Pro-Deck" same shape as the 5/4 but the same dimensions at your current 2x6 product. Either one is a great product.

Answer 3

I have a thought or two. With all due respect and not knowing at all why you want to go thinner?

First thought is determine the difference between the two in measuring. Assume that a 2x isn't 2 inches, and 5/4 is approximately 9/16th.

My first thought would be treated lattice boards as shims on every Deck Stud/joist their entire length, then install the 5/4 over.

Certainly the test is take samples to a lumber supplier to judge the thickness similaritiies.

Replacing? SOME??? Or ALL??? or is this a situation where you may eventually replace all the 2 x . and in that case why, still, go thinner stock? OR might it be that you have to achieve a height up to a door threshold? OR steps?

In any case individual shims at the multiple contact points is NOT a good idea.

Steven Wolf

Answer 4

Maybe I just haven't been around the construction business enough, but I don't really know what 5/4 is. I will guess it means 1 1/4". If that is the case, you will need a 3/4" shim to bring them up to flush with the 2".

Answer 5

You can buy 1x stock at your local lumber yard and rip them to 11/2''. If it's a full 2'' floor board. Attach them to the joist and that should compensate for the thickness......Hope you understand what I'm saying,,,,,,

Answer 6

PEB is on target. You need some 1/4" treated strips to attach to your framing, but I don't understand why it has to be the same level.