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Discussion Forum

Finish 2 sides of Mahogany T&G decking?

dockelly | Posted in General Discussion on April 7, 2008 09:38am

Just picked up the stair steps for the porch, beautiful 5/4 x 12 Phillipine Mahogany. As I was paying for it the salesman asked if I needed anything else and suggested the penetrating oil they sell, $35.00 per gallon, 400-500 ft coverage. Told him I had a 350 sq ft porch, he figured I needed two. Said the T&G decking needs to be finished on both sides, Mahogany requires this or it will absorb moisture on the underneath. Since the stuff is already installed, I’d have to crawl under the porch to apply, not a big deal, about40″ space.

Does this sound right to you guys, both top and bottom need penetrating oil finish?

Kevin

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Replies

  1. john | Apr 07, 2008 10:02pm | #1

    Absolutely right, carry out the same treatment to both sides to reduce the danger of the material warping

    John

    If my baby don't love me no more, I know her sister will.
  2. rnsykes | Apr 07, 2008 10:31pm | #2

    yeah, thats correct.  if not, the bottom will absorb moisture faster than the top resulting in cupping of the boards.

  3. frenchy | Apr 08, 2008 12:49am | #3

    dockelly

       Oil isn't a durable finish. it needs refinishing periodically. If you intend on using it on the top I would definately use a Varnish on the bottom side.. myself I would tend to finish all Mahogany off with Varnish show off the beauty of the wood .

     Of all varnishes out there the most durable has proven to be marine spar varnish.. Helmsman is about the least durable and Epiphanes is the most durable  (also many times more expensive)  Interlux is right in the middle   

    1. dockelly | Apr 08, 2008 01:24am | #4

      I'll look into it, I don't mind applying the oil once a year, it's only 350 sq ft of porch, I don't want it to look like an interior floor, definitely don't want it to be shiny. I wet some of the steps I bought and they didn't get dark at all, I will have to experiment to try and get the two, decking and steps, to match. Maybe when the decking is sanded down they'll both be at the same starting point and will match better following whatever I do.

      1. DougU | Apr 08, 2008 02:25am | #5

        doc

        I'd be careful varnishing the floors, might be a little slick when wet or snow on them.

        And yes, oil the underside! Get a sprayer, hell it dont have to look nice.

        Doug

        1. dockelly | Apr 08, 2008 02:52am | #6

          Say I went with the oil, and later deciced I didn't like all the maintenance, wouldn't it be easier to aplly a varnish then? 

          In other words, once you varnish, to try applying oil a year later would require more prep than vice versa.

           

          Good point about spraying the underside, as you say, it doesn't have to look pretty.  Maybe apply in several thin coats, 2-3 maybe.  Unless can says keep a wet edge, than all at once?

          1. Piffin | Apr 08, 2008 03:23am | #7

            A wet edge refers to brushing, not spraying. you would have a hard time spraying slow enough that it dried somewhat from one pass to the next. For under a deck, you can even use a pump up garden sprayer. Spraying can use more than brusing typically, but no other way to do it under there, IMOPenofin the Brand? Best there is!You have not been reading enough here at BT tho. You missed the part about doing this before applying the decking, so you can get all six sides. But with a roof over it, you shouldn't get too much water soaking into the T&G joint to cause early rot. 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          2. dockelly | Apr 08, 2008 05:06am | #10

            two things:

             

            1.  "Haven't been reading here long enough", sometimes I feel like this is all I read.

             

            2. "early rot", this is mahogany, I thought this stuff would last forever!

             

            With regard to spraying, I figured I'd do it all from beginning to end and than reapply.  If it can't completely dry between coats, I'd do each bay twice or three times before starting next bay.

             

            PS Penofin is what they sell, guy I bought the stair threads from, 34.99 per gallon, good price I thought for 400-500 coverage.

             

            Thanks, as always

            Edited 4/7/2008 10:10 pm ET by dockelly

          3. Piffin | Apr 08, 2008 05:54am | #11

            oil is not something that layers up in 'coats' like poly or varnish.spray or roll it on, then rubb it in, removing the excess while working it into the crevices where water would want to hide. One coat is probably enough now, then again in the fall, then every year or two.Doing two coats right on top of each other could leave you with a tacky finish. 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          4. dockelly | Apr 09, 2008 05:38pm | #16

            I think I know the answer to this but I'll ask anyway. Since the wood got wet, should I wait for several days, 3-4, of no rain prior to applying oil so it, (the decking), dries completely?

            Edited 4/9/2008 3:01 pm ET by dockelly

          5. Piffin | Apr 10, 2008 01:02am | #17

            definitely 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          6. John @ SoloSider | Apr 08, 2008 05:57pm | #12

            Doc, we have been trying to figure out this whole mahogany deck thing also,we had a 36' boat made out of mahogany it was painted and maintained and full of rot from the rain water. Every time we hear about a deck made with this we wonder if we are missing something?

                                                                     Thanks Cathy

          7. frenchy | Apr 08, 2008 07:00pm | #13

            John,

               Mahogany isn't mahogany.. Chris crafts used to use Phillipine mahogany which as you are aware of rots easily.. There is also African Mahogany and several south American Mahogany's   The really desireable Mahogany used to all come from Cuba but that has long since been harvested commercially to near extinction.  Today similar wood comes from Honduras and other central American countries..

             Extremely valuable and unlikely to be affordable for decks..

          8. John @ SoloSider | Apr 09, 2008 05:17am | #15

            Thanks Frenchy, that makes some sense and yes it was philippine mahogany - rot city-

                                             Thanks Cathy

          9. dockelly | Apr 08, 2008 08:44pm | #14

            Yikes, hopefully I'll have better luck, porch has a roof.

          10. dockelly | Apr 16, 2008 03:57pm | #18

            Hey Piffin, I'd appreciate your thoughts on this:
            http://forums.taunton.com/tp-breaktime/messages?msg=103495.1
            Thanks
            Kevin

            Edited 4/16/2008 8:58 am ET by dockelly

          11. DougU | Apr 08, 2008 04:20am | #8

            Say I went with the oil, and later deciced I didn't like all the maintenance, wouldn't it be easier to aplly a varnish then? 

            In other words, once you varnish, to try applying oil a year later would require more prep than vice versa.

            Yes! I wouldnt want to try to take off varnish and go with oil, much better to do the other way around.

            Doug

          12. Piffin | Apr 08, 2008 05:04am | #9

            And all the congregation said "Amen!" 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

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