Deck Framing Enough Support?

builditright

I am a plumber by trade but i have done alot of everything else on my own house. I am building a deck over a one story flat roof. The roof slopes down 10 inches from the high point (where the ledger board is attached) to the low point. Coming up through the roof from the foundation of the structure are four 6"x6" PT posts. I did this when i built the extension to have a place to attach the new deck so not to have anything sit on the roof surface.

So now i have a 25'x 15' deck to build. The four posts and a ledger board at the main house will be the vertical support. So here is the problem. I built the one story extension a bit to high. I wanted more ceiling height inside. So now the window that i will make a door leading out the the new deck is going to be very short and i can't change the lintel. To minimize the screw up i framed the substructure with something less than i would have if i had the room. I used double 2"x10" PT beams running between the 6"x6" posts (a span of 15'-0") then i ran only 2"x8" PT joists between the beams and the ledger board. There are two bays of these joist which span 11'-6" each which makes up the total length of the deck that is 25 feet. All these spans are good with all the span charts i have looked at but now i want to use IPE for the decking and at nearly 6 pounds per lin. foot. I am concerned this thing is going to sag in the centers and eventually touch the roof. The bottom of the joists at the high point of the roof is only 1 inch off the roof. Again this was to keep things a low as possible.

So my questions....

Is 11'-6" too much of a span for 2"x8" PT?

Are the double 2"x10" PT beams sufficient for the 15 foot span?

Do you beef up substructure when using heavy stuff like ipe?

Do i have to bite the bullet and just use Azek deck which is one fourth the weight of ipe?

I have a perfect photo of the framing but it is too big to post on this site. I can email it to anyone that can help me with my dilema.

thanks for any help

nick

genecarp

sounds ok . hard to say for sure without a visual, why cant you alter the window header? is the cieling done in the room below? if not you may be able to double up some rafters and pick up some weight. ipe is fine, weight is ok, also place solid blocking in between bays

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deckman22

You're over spanning both the beam & the joist. Add a 2x12 to the outside of the beam if you can, or peel off one 2x10 add a flitch plate then add the 2x10 back on. To help out the joist area you could add another joist between each existing joist then run a couple of rows of bridging blocks. BTW, you can use 1x6 ipe for the flooring, it weighs about 2 lbs. per linear ft.

Al

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Deckman
www.alscustomdecks.com

Stewy

I would go 3 and maybe even 4 2x10 on the beams and your 2x8 would be ok on 12" centers, blocking over beams and a row of bridging in each joist section.

builditright

Thanks men,

I don't have the room in height for the 2"x12" and no i cannot alter the lintel.

So what i have understood from all of you is i am laking on the beams more than the joists. I have plenty of room to add three more 2"x10" so the beams would then be 8" or even 10"x10" spanning between the posts. Then as for the joists i can either double them or add solid blocking in between.

I sure wish i could send a photo of this. It would make it all clear.

BTW.... Ipe is 2 pounds per lin. foot??? How is that possible. Its the heaviest decking there is and PT is about that weight. The lumber yard told me its three times the weight of PT.

Nick

neolitic

With 10" of fall you do have room for
a double or triple 2X12 beam, just
hang the joist off the beam.

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(Sorry....it seems there really are dumb questions)

RobertCDF

Both your beams are lacking... But you center beam is lacking the most. It carries twice the weight that your outer beam does. The middle beam needs either more posts and/or more members/bigger members. Your outside one should be fine as a quad. But the center one has a lot of weight. I would run it by an engineer.

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Robert Shaw
Colorado Springs Custom Decks
Colorado Custom Decks
Custom Composite Decks

deckman22

I sold ipe for a year, mainly to out of state customers so I had to calculate the weight for trucking purposes. 1x6 ipe is 2 lbs per linear ft. which is the same as 2x6 treated pine. That means it's exactly 2 times heavier than treated pine, but you can use 1x material instead of 2x so the weight would be the same unless you use 5/4 material. 5/4x6 is 2.5 lbs. per linear ft. It takes 2.2 linear ft. of 5 1/2" material to cover a sq. ft.

The boys at your lumber yard obviously haven't sold much ipe.

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Deckman
www.alscustomdecks.com

ChillaWatt

Here's an image resizer I use to resize my digital camera uploads. http://download.microsoft.com/downlo...ertoySetup.exe

For an example, turns a 4.93 MB image file into a 52.7 KB one.