Looking at your pictures I see no beams as you mention. Are you confussing joist with beams? What is the depth of your deck?

Dave

I think that what Brian is talking about is the beam(double 2x) that spans the posts and the joists are hung from(1st pic). Generally, this 'beam' is sized larger than the joists.

Brian,
Let's clear up the terminology first, to make sure we all understand this the same.

The boards that support the deck floor are joists. The joists hang on a ledger at the house end, and on a header at the outer end. The header is supported by the 6 x 6 posts and is supported somehow at the house corner.

Now, were you supposed to have all 2 x 12 joists, ledger, and header, or just a 2 x 12 header? How long are the joists? In the picture they look short enough that 2 x 8 should be plenty sufficient. Is the header a single 2 x 8, or a double 2 x 8?

Is it the header what your engineer wants you to put a 2 x 12 under? I think it would be. Give a picture of how the header is connected to the house, or is it just fastened to the end of the joist that is against the wall?

A 2 x 12 under the header hanging on the posts would like kind of ????? in my opinion because it would hang so low. Or is he suggesting you fasten it alongside the 2 x 8 header? If that, then you have the ends of the deck planks to do something with.  I'm sure we can come up with a better idea. Give us a few more pics. OK?

Actually, I think my preferred fix would be temporarily support the joists from underneath, remove the header, even if you have to cut it into pieces, rip the hangers from the joists, notch out the posts, slip a 2 x 12 header in place, and reconnect the joists to the header.

Is there any way you can get to framer to own up to not following instructions and make him do the fix? Was the deck detailed on drawings, or was this all verbal?

Mac

Oops, I just looked at the pictures again. I see it is a double 2 x 8 and of course the deck planks run parallel so there are no ends to deal with. Can you remove the outer 2 x 8 and replace it with a 2 x 12? If you glue and screw that sucker into the 2 x 8 the joists are connected to, I would think that should be enough. Lean on your engineer a little more to reevaluate this. You aren't building this deck to support a crowd of 40 300# guests are you?

Or, add a 2 x 12 to the outside of the 2 x 8 ledger and replace the outside deck plank with a wider one.

In my opinion there's no glory in building something hell for stout when heck for stout is good enough!

MAC,

   It sounds like you understand my situation. There's 9 40" x 96" commercial double-hung windows sitting on the outside edge of the deck that are really heavy. That's why I am worried.

 

Maybe I could add 2 2x8's to the outside end and move the 6x6 posts so they are suppored by it. Or I could support the joists from the middle, take the hangars off at the ends, cut 3" from the inside of each joist, and slip in 2 2x8's.

I also don't like the 2x12's underneath.

Brian

For strength and stiffness the 2 x 12 is better. The strength of a beam is directly proportional to the cube of the depth. In other words, a beam 2' deep is 8 times as strong as beam 1' deep. The cube of 11.25", the actual width of a 2 x 12, is 1143. The cube of 7.5 is 422. Therefore a 2 x 12 is 2.7 times as strong as 1 2 x 8, or 1.35 times as strong as 2 2 x 8's side by side.

Discuss this with your engineer and see what will work. The 2 2 x 8's may be enough.

In line with the comment above a 1 x 6 on edge is twice as stiff as a 2 x 4 on edge! Of course, there are other considerations such as the tendency to twist that have to factored in, but you get the idea.

Mac

So, the deck is enclosed? You didn't mention that little detail. I'd erect a temp support, and replace the 2x8 beam with a 2x12 beam. Simple, effective, and it won't look like a hack.

It looks to me in your bottom photo, like your header board is attached to the outside of the foam wall sheeting of the ICF wall. Thus the "J" bolts, or what ever anchors you have in the concrete core inside the ICF wall, are in a potential bending moment. The foam is potentially crushable from the weight and varying load of the enclosed structure/occupants that will be on the finished floor.

FYI: We build our ICF wall panels with the header board integrated into the wall panel, (instead of foam) with "J" bolts already in place. Double nutted inside and out, with a full width strip of poly glued on the inside of the header board. That way, after filling, the header board is attached directly against the concrete core with a moisture barrier. This makes for a solid header board and there is no possibility of a bending moment being applied to the attachment bolts. Just like you'd do if there was a formed bare concrete wall. It also saves the labor of adding a header board at the job site. Something to consider for your next ICF project.

I would also recommend you discuss the vertical supports with your structural engineer. I would propose to your engineer at least 8 x 8 posts or a cluster of about (6) 2 x 8's bolted together. Because you are enclosing the "porch" or "deck" with walls and windows plus you'll have people utilizing the space. 4x4's or 6x6's would be adequate for a deck, but you're building an enclosed room. I recommend you discuss these details extensively with your structural engineer(s).

Solution to consider: You can take a hot knife or bread knife and simply slice away the foam where the header board will be mounted to reveal the bare concrete core. If it is a waffle core product, I would trowel a cement product (such as a product with a poly additive for greater strength, like "thin set") over the irregular concrete surface to make it smooth and vertical. I assume the "J" bolts/studs are deep in the concrete core. Next apply a moisture barrier. Then install the new 2 x 12 header board and tighten the screws. Now the header board will be tight against the solid concrete wall core, the bolts will be in tension and shear. I believe this method is stronger and long term structurally superior to having 2 inches or more foam between the header board and the concrete core.

Remember, a house is a big piece of structure. It moves, it changes shape, the earth beneath it moves and changes shape over time. We tend to think that these things are rigid, but they are not. I'm sure if we instrumented a home we'd see it also moves in a storm. Those forces and influences over time are how foundations sometimes crack, old stone foundations collapse, houses settle, etc. The foam will likely change in thickness... it may also simply deteriorate over time....not enough to cease being an effective insulation, but enough that the header board could sag on the 2 inch or more stuck out "J" bolts or anchor bolts.

It looks like your header board is only about 15 or 20 feet long, so, we're not talking a lot of foam to cut away. Doing it As I outlined entails the opportunity of adding new 2x12 floor joists in between the inadequate 2 x 8's. Another alternative is to leave the existing header board intact and instead add 2x12 beams with vertical support posts against the ICF wall, just like at the outside end opposite, as your letter says your engineer recommended. That way the floor is structurally self supported and just bolted against the ICF wall.

It is an interesting situation, good luck with your project. Overall I'm sure you'll be very satisfied with the finished ICF home ! ! And I'd highly recommend adding a solar system and/or wind turbines, depending on your days of sunshine or prevailing winds or a combination. Include the cost in your mortgage, the monthly savings should easily exceed the small additional mortgage increase. That will give you and your family more discretionary income, you'll help contribute to less dependence on foreign oil and less CO2 being exhausted into the atmosphere by the power plant serving your community. A potential triple win situation.

Good Luck.

P.S. You could add a larger solar/wind generating system, buy a plug-in hybrid, (assuming you have a car payment anyway, like most of us) and use the electrical credits your system will generate during the day to charge the electric car batteries at night....adding the savings of not buying gasoline for most of your driving.

If you personally don't like hybrids or electric cars, I'll bet your wife would love not having to stop at the dirty, stinky gas station. And you can use the savings to buy a Corvette or a Hummer for yourself ! ! Take a moment to calculate the savings of virtually no electric utility bill and no gasoline for 75% to 90% of your (or your wife's) driving. Remember that is after-tax savings. How much of a raise at your job, or more revenue at your business, would you have to get to equal that much cash savings? A full up Zero Energy Lifestyle home WILL partially pay you to live in it.

Don,

  Thanks for all of the info. I thought about wind and solar but the house isn't really positioned well for that and the subdivision is very strict about what they allow.

 

Attached is a picture of the foam behind the ledger. The ICF contractors cut 6" holes before the pour so our carriage bolts would have solid concrete to attach to.

 

 

He really does need to discuss this with his engineer. I doubt there's any need to go to 8 x 8's. An 8' tall structural grade 6 x 6 will support something close to 25,000 lbs. If the deck is 12 x 25 and supported only on two posts, you'd have to have 150 psf load to come close to that. That's ignoring the support provided by the connection to the wall. The end support strength of a post is a lot!