deck building 101

I'm going to put a 27x12 foot deck on the lower level of our home. It's at grade level and would be protected by the screen porch and deck above.

I was planning on attaching the ledger board to the poured foundation wall, which would mean drilling holes and using expansion anchors. And then lagging the outside beam to the 6x6 posts that support the deck above.

While this seems like it would be the simplest and soundest solution, I've also read there are advantages to keeping the deck separated from the structure, and it would be relatively easy to build this on post pads with a few short 4x4 or 5x7 posts supporting the framing structure.

Does anyone who knows this area have any guidance for me here?

Thanks in advance for your help. I always appreciate the opportunity to run my projects past this crowd!

Mike

drewmo said:

Any building codes in MI that apply to your city/town? Decks can be a tricky issue.

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I agree that lots of decks are dangerously constructed and violate universal building codes. I would follow these parameters: http://www.ewashtenaw.org/government/departments/building_inspection/bi_deck_standardsupdated.pdf

I think the decision to attach to the existing foundation wall or build free-standing is probably subjective preference (at least in this case where I have a solid poured wall to connect to; in other cases that might be the only option). I was just wondering if folks here with more experience had any thoughts on the issue.

Thanks.

"Post pads" are just precast concrete circles 8" (dia) x 4" thick. They go at the bottom of the hole and the post sits on top of them. This is all sand on top of a hill so drainage is great and risk of heave is minimal. If I attach the ledger to the poured foundation wall, I'm assuming the frost issue is nil.

What I was really wondering about was drilling into the foundation wall and using those expansion anchors. It looks like the code says they go in 2.5" and would need to be spaced about 18". For a 27 foot ledger, that means I've got to put in about 20 of them. I'm guessing that's going to take a while to drill them (I've got a hammer drill), but is there any concern about putting all those holes in the foundation wall? No worries about cracking along that line, or creating any sort of instability?

Thanks to you both for responding to my post.

Warm_in_NH said:

No worries on drilling the foundation. Use 6" bolts, lay out your ledger and attach it with a few hilt concrete nails. Then drill a hole center of every bay one near the top next near the bottom staggered. (Over kill but it'll meet/exceed code)
Should be an 8" foundation wall, your 3-4" holes staggered every 16" won't affect it.
I really like Hilti products when it comes to expansion anchors. Seem to work most of the time. Just put the nut and washer on before hammering it into the hole.

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Whoa, this is exactly what I was looking for. Thanks for the specific suggestions!

semipro said:

You could also set some thread stainless studs using epoxy made for tying into concrete.
I recently installed some guard posts this way and cut threaded SS rod to length.

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bsruther said:

I used anchoring epoxy to mount my fireplace mantel, that stuff is unbelievable.

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Are you talking about gluing the ledger to the foundation wall with epoxy? This sounds too easy. I've never heard of this before and wasn't able to find anything in a web-search about it. Do you have a specific product name I could look at?

Thanks for all the help here.

semipro said:

I'm suggesting that as an alternative to anchors you could epoxy thread rod into the foundation wall and attach the ledger to those with washers and nuts.

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So you'd still drill the holes into the foundation wall and glue the rod into the wall? Is there an advantage to this over the anchors?

semipro said:

Yes. It may be less expensive. Some of the better anchors are pretty pricey. I also prefer stainless when there is contact with ACQ treated wood.

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johneh said:

This is what we use on all ledger board to concrete application
Just to add put a sill gasket between wood and concrete
http://www.lowes.com/pd_354677-286-862031_0__?productId=3416896

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Ok, so I drill a hole, fill it with this epoxy and then insert a threaded rod?

I guess I'm missing the advantage over just using anchors. Do I have to use fewer rods than anchors? Wouldn't stainless threaded rod mitigate that advantage over galv anchors and 6 inch lags?

Why would I use a sill gasket in this application? What is it doing for me here?

And, thanks again for all of your input.

johneh said:

Sill gasket
When wood is kept in direct contact with concrete, the moisture in the concrete will be drawn up into the wood, and after a period of time the wood will rot. A sill gasket made from a soft plastic material is designed to prevent moisture to seep from the foundation to the lumber frame.
Pressure treated lumber will slow this down but will not stop the rot from happening.

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This is great information. I've never heard this before, but it makes sense to me. Thanks, johneh!

stee6043 said:

When I added on to my deck (substantially) I chose to support the addition independently rather that tie-in to the house. I personally didn't want to swiss cheese my exterior wall any more than it already was. Likely a silly thing to be worried about if done properly but I found setting posts to be much more appealing for my application. The rental post-hole digger from Home Depot made pretty quick work of 48" deep holes.

Whatcha gonna put on this new deck addition? It's worth noting that your existing 6x6's may or may not have substantial reserves of load carrying capacity. If you're long term plan is something like a hot tub or other heavy device you may want more carefully consider using those 6x6's in your new deck plan. You don't want to compromise the safety of the room above if there is anything marginal in the existing design.

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Thanks, stee6043. That's a good consideration, but I think this is going to just be a deck to sit on, and probably string a hammock off of. It's also a way to get up off of the sand in the back and hopefully cut back on all the sand and grit that is tracked in through the back patio door.

Thanks again.

Ah, got it. Thanks for clarifying. I think the anchors will likely be my solution. I was at Lowe's looking at this stuff tonight and they had Red Head, Hilti and Tapcon anchors. The Tapcons looked the simplest (no expansion component to lock them into and you can take them back out if need be), but they are also the most expensive.

Thanks again.

It says you are tapping a thread into the predrilled hole. Maybe it's not approved for this application -- I wasn't looking that closely.

The Red Heads are about half the price anyway!

Thank you, semipro. Figure 15 is exactly where it's at for me.

I just talked with the designer of the original structure who said there will be no problem attaching to the 6x6s that are holding up the upper structures. From the guide you provided, with joists @16", it looks like I can cover the 12 foot span without any additional support.

Thanks again to everyone for their input!