We need to replace the flat roof on our balcony deck. In the process we also need to replace the balcony deck railing.

The salesman for our contractor recommended a wooden railing to match what we will be removing. But the contractor's carpenter is saying that the pressure-treated lumber he'd use will shrink over a 12 month drying period and might cause water problems around the post flashing.

Question: Is pressure-treated lumber shrinkage actually a concern in situations like this?

This has turned into a minor emergency since this unexpectedly became a game day decision.

Thank you so much!


Wood expands and contracts regardless. It shrinks when it's sunny and it expands when it rains. Any flashing should be able to accommodate that, and I assume whatever was there before did so.

That said, vinyl post sleeves aren't terribly expensive. Even if your railings are bare wood, white, beige, or brown posts could look very nice. They'd also eliminate your contractor's concerns. They're worth considering.

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