pressure treated 2x6 decking

[yetti462]

Will there be any issures using PT 2x6 t&g for porch roof decking? 

My original porch rooves are decked with spruce t&g.  I do not have a source for these other than special order or driving to TN.  The PT t&g are cheaper too.  Just want some feedback on your thoughts.  Thanks in advance!!

[doc henderson]

If fresh bought, they will be wet and will shrink.  they will not be as pretty assuming seen from underneath and roofing on top.  might get them and sticker to let them dry.  if they shrink enough, the T&G will not add much structural strength.

[beenthere]

yetti
Click on your user name and there you can update your profile to add information, such as location.

What is your source for pressure treated decking? SYP, or a different species? What roofing materials over the decking?

Docs good suggestion would be mine as well. Buy half again as much as you need, sticker all of it to air dry; if you have the option to return the un-used decking.  That would include all the warped pieces from air drying, as well as other reject pieces.

[yetti462]

I'm located in Southern Indiana.  

I did find what I'm looking for in Kentucky for a good price and closer drive than Tennessee.  Disregard my original question.

[Tom King]

I see the OP has found his source, but thought I'd add this in case anyone in the future is searching and finds this.

I've used a fair amount of T&G treated Pine 2x6's for porch roof sheathing.  It's kept in stock here around the lake because it's used for one style of waterfront bulkheads.

I dry it on sticks when I first get it until it's down to less than 15% moisture content.  Some of it might get a little twist, buy you can pull it down with a hand hammered toenail into above the tongue by holding it as tight as you can get it and pounding it in place.  Then they get surface fastened.

Sometimes a pipe clamp with a scrap of the groove might be needed, but once it's all in place it stays just fine.  I have it on our screened porch roof on our house that used to be a greenhouse.  The joints will open up a little bit over decades, but not objectionably.

[Joe Hillmann]

Drip edge and fascia(on the bottom and edge of the roof) is often made of aluminum.  Some types of pressure treated lumber chemically corrodes aluminum. 

I am pretty sure you can get steel drip edge and fascia.

I would also want to research how PT lumber reacts with roofing underlayment, roofing fasteners, and your choice of roofing material.

I have seen large amounts of damage done to houses caused by aluminum flashing where a pressure treated deck gets attached to homes.  The flashing rotted out by the PT wood and let water get into the walls of the house.  So it would be a good idea to see if you can find information on how each item in your roof reacts with your specific type of wood treatment.

[Tom King]

That's a good point.  Our porch has the coated metal drip edge made by the same people that roll-form roofing panels for the standing seam roof on it.  I think since the wood was dry, and stays dry, makes a difference.  I just went out and lifted an edge of it, and it looks like I just put it up this morning even though it's more than a few years old.

[sprucebunny]

They sell rolls of tape specially made for isolating flashing from PT. Or they have 4" wide rolls of the same material as "bit(hethane"... can't think of the real name.

I recently used a lot of it to redeck some joists that had too many nail holes and replace sill flashing.