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It has been raining all night and the wood is thoroughly wet. I want to screw on the ceiling plates (and apply the epdm on it). It doesn't seem like a good idea to my, because wood expands when it is wet and when the wood is dry again and shrunken a bit, there will be margin between the beams and the plates right? It's Douglas wood.

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  • Is the EDPM to be glued down or ballusted? Is there an insulation layer? This question may be better addressed in the DIY forum. – Ashlar Jun 30 '16 at 12:47
  • The question is not really about the epdm but more about the timber joining while the frame is wet. I'll put the epdm part of the sentence between parenthesis. – Christiaan Westerbeek Jun 30 '16 at 14:35
  • This question might get more (and more specifically experienced) answers if moved to the Home Improvement area. (They do carpentry; we do woodwork; the two overlap sometimes but differ significantly.) – keshlam Jul 9 '16 at 8:38
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There is no real harm in proceeding with the deck. The wood is a bit wet, but will dry out from air movement in short order with no real risk of mold or other damage occurring. This type of structure is quite flexible and will easily absorb any movement from swelling or shrinkage (which will be very minor anyways). Wood framed homes and other structures often get wet during construction and the work recommences as soon as the rain stops.

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I wouldn't if you can wait. It would be better to let the wood dry out before you work on the roof further.

You shouldn't worry too much about the wood itself as wood won't normally get damaged by being wet like this over a limited timeframe. And you don't have to be overly concerned about the structure, although ideally you protect any part-built wooden structure with tarpaulins or plastic sheeting in case of rain it's very common for roof framing to get wet during building work in any wet climate. It doesn't seem to affect the strength of the finished roofs, at least not enough for it to be a problem.

It doesn't seem like a good idea to my, because wood expands when it is wet and when the wood is dry again and shrunken a bit, there will be margin between the beams and the plates right?

Wood expands and contracts across the grain, there's virtually zero movement along the length of a board.

The reason not to do this is ideally you shouldn't drive fasteners into wet wood, particularly nails.

  • @ graphus Your point on nail grip strength is interesting. I assume the decking will be sheething of some sort and ring shank nails are recommended. This should significantly reduce loss of holding power. OF course any kind of screw attachment will not be affected. – Ashlar Jun 30 '16 at 18:48
  • @Graphus Nails driven into green wood (i.e. wood with high moisture content) will require less force to withdraw when the wood is seasoned or dried. The withdrawal strength of fasteners driven into seasoned wood which has simply been temporarily wet on its surface will not be affected. – Ast Pace Jul 1 '16 at 4:45
  • @AstPace, I realise that caution centres around driving into green wood that then seasons, but I've salvaged a fair amount of softwood in a wet climate and it can be far more than merely surface wet after being rained on, so I thought caution should be advised just in case. If he's using something more than your basic bright-finish wire nails it doesn't really apply either...... ideally I'd want to have known the fastener type before posting but there's limited scope for real-time exchange in the SE format. – Graphus Jul 1 '16 at 7:05
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    OP mentioned screws in his first sentence.:) – Ast Pace Jul 1 '16 at 20:01
  • @AstPace, I think I'll do an edit to de-emphasise that point. Thanks! – Graphus Jul 2 '16 at 6:41

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