Connecting 4x8 HSS to Cement Wall and Two Piles

On rough guess, I think the L6x6 is heavier than needed, but the other pieces are too light. What is the spacing of the 3x2's? What is the design live load (dead ≈ 60 psf already)? Can you make the pilings 25' between, with 5' cantilever at each end?

Sorry the spacing on the 3x2's would be roughly 2' C to C....If they are two light I can go 4x2....That would lessen the amount of concrete in the slab. As I would prefer to fill in the rectangle with concrete. Basically have a steel rim around the perimeter and flush to the top with concrete.

I would prefer to keep the pilings on the edge as there are "windows with a view" on the walkout basment.

Sorry, I meant "I have a design that I would like to use". I want to use a low profile with an ascetically pleasing look. That is why I would prefer to use HSS instead of "I" beam.

I just want to go into the Home builder with some ideas/research done as they don't normally deal with this type of construction. Although using your rough figures I would need something around 16 to 18" in depth....That might be a little bigger and interfere with the windows in the basement. So I might have to compromise and move the piles together; I don't want to, but it might be the best compromise.

I also have to attach the slab and steel to the home. That is why I was thinking about either the L6x6x.375 or make a ledge out of concrete. I think it will be easier to attach it to the side of the home on the angle, but I just wanted some opinions.

ok, thanks for the comments....

This is a new home, it is still in the design stage. Yes I live in the snow belt. I guess I was not clear in my question. I am looking for ideas on how to anchor this deck to the home. When I spoke to the SE, he said he was unfamiliar with attaching an "industrial" type deck to a personal home. He said it would be easy to do if I was prepared to have a framework and posts all around, but to me that is just duplication. The cement used for the basement walls is usually either 25,000 or 30,000 Kpa. Even if I have to increase the cement in the basement from a standard of 6" thick to 8" or 12" (or more if required) it will still look better (IMO), then having a framework underneath. Admittedly I am not a SE, but I wasn't considering anchor bolts. I would have drilled the holes right through the wall and used a significant backing plate and bolted it through.

The corner posts will be piled into the ground and then continue up as posts to the deck frame. When completed they will be covered with decorative stone. If I end up requiring a 16" beam across the slab(or larger from all of your unanimous comments), I will happily increase the Joist size. The original thought and something I am trying to get across to the SE doing my home is I want to keep the depth as low as possible. I was going to either weld the steel joists at site once the 35' beam was set in place or get a bolted design done. IMO if the 6x6x.375 angle (or larger/smaller) bolted through the home would work it would be a simple to weld the steel joists on to the angle.

I tried to mention that I would like to have a small sight line....I don't want a massive Rail Road type structure. Obviously I am not going to sacrifice safety for aesthetics, if it needs to be thicker, well so be it. But I would rather pay more $$$ up front for more expensive HSS instead of Channel or "I" beam if it means I can get a shorter/smaller depth of the deck.

Again, sorry if I did not come across clear. I am looking for some ideas to attach this to my home....At $150 an hour I am being charged, I am just looking for suggestions where if we come to a road block I can say "Hey, what about this?". It will be stamped by an SE, I might lay the Q deck and rebar myself, but otherwise I have to pay someone to do this.

Thanks for you comments, I appreciate the responses!

Funny I just got an email from the SE involved with building my home; he works for my homebuilder. I don't know him personally nor his experience. But looks like they want to install the HAMBRO system now. I live in Canada, Calgary, Alberta.

The only stone we were thinking of would have been on the vertical cement columns and MAYBE across the vertical face of the 35' beam.

If a bolted system were built I was going to cost out Galvanizing and/or powder coating to protect the steel. I have worked with Aluminum/Steel for decades and I am much more comfortable around steel/aluminum then wood.

Normally the only rebar required in bsmt wall is over the windows, but again that wasn't the point of my topic. But I will check into it, I know they need to build up the footings on the home to support the slab.

I appreciate all your responses, it has really opened up my eyes. I guess I am the client that makes you pull your hair out and bald prematurely jk. I will see what they say about the HAMBRO system, and if this turns out to be a white elephant, I will have to consider something else.

Again thanks for the replies!

You're very welcome, and good luck with the house project!

[now, it's time for me to head off to Philly Cheesesteak land! Therefore I'll be off the forum yet again for a few days! Okay, everybody be good and play nice, okay?! LOL]

letssled,

Moosie and Passington are not kidding around. This 35' span will fail before you get half the wet concrete poured. It might fail before you get all the decking on if you have a bunch of guys up there standing around waiting for the mud pumper.

Let me make a suggestion - don't attach to the house. Is your primary objective to have the largest clear span possible under the deck, or have the strongest deck?

You mention that you want the deck to be "low profile", but I don't see any sketches of railings in your drawings. Are you planning infinite edge glass for the railing? You can't use that with the design you have sketched out. I'm going to assume you will have to have some railings since this is 9' off the ground. There are a lot of different ways you can design code-compliant railings that can minimize the aesthetic weight of the deck floor in contrast to the railings.

Unless you go to four or five columns, you are never going to get a concrete & steel framing profile six inches thick on that 35' span. You'll need a "16 x something" beam to make that span. A center post cuts that to 9-10 inches. Three columns on the quarter marks gets you down to 8, but does nothing to solve your corner problem where the 14' beam off the house ties to the 9' cantilever off the first post on the 35' side. That will never, ever, never, hold up unless you intentionally want something that looks like a mini Oakland or Northridge training station.

If you have lots of money for the project, how about considering doing a cantilever, or center row of columns properly spaced, so that there are no columns at all at the outside corners? This way you could have your thinner outside edge profile you want, but the deck would be thicker in the middle to carry the perimeter loads. 6 inches at the outside edge, no steel exposed at all, and 10-12 inches thick through the middle with substantial columns to support the load? Yes, lots of money. Yes, tons and tons more weight. Have you asked about doing a precast deck and having it placed on top of piers that are properly constructed to support the 40,425 pound load of the concrete slab?

Maybe this is why 99 percent of decks in the ice and snow area are built with wood and have slots between the boards to let the water out.

Now, if you have a proper budget, my gang would be thrilled and could fabricate this thing for you in aluminum, and you could have a 3" edge profile, glass railings, and the center would be about 10" thick, and the bottom would be convex curved almost like an inverted aeroplane wing. NOW you are talking sexy deck. Get your check book warmed up... it'll be close to $105 a sq ft plus engineering and columns and earth work, but it won't rust and you'll have the sexiest deck on the block, I guarantee it. For a "bit extra", we will anodize the whole thing and build in warmers so it won't collect snow and ice.

When shall we start?

As I said previously, I will not compromise safety for aesthetics.

Agreed, this may not work or it may be to costly. My wife and I have had extensive discussions from the responses on this forum. From what you describe I agree the aluminum would be pretty sweet. Although the polishing would be pretty intensive if it were not anodized.

I am looking for a clear span/view under the deck as well as on top. The walkout basement will be used for entertaining and large gatherings. It has large windows and 9' ceilings so that is why I prefer no posts or columns blocking the view. The 2nd story looking out over the deck will be my Kitchen, as we spend a fair amount of time there as a family, I would prefer a clear view as well(within reason).

It will have an aluminum railing with glass inserts and LED under-rail lighting that I will be making myself and it will meet all local codes.

Tyrone

Thank You very much for this excellent information!!!! I will add this to my bank of questions.

It has been asked, and wood was suggested, but this guy is a glutton for punishment, because he had an idea he fell in love with and will not let go...

Could a wood or composite deck on top of this steel frame solve the problem? besides solving load issues, it would be possible to replace the deck surface in 15 years or as needed.

Or maybe this guy has a dream of using this concrete deck as the base for an enclosed addition in the future... LOL

I want concrete because:

I can be aggressive as I want with my snow shovel.

I prefer the finish of concrete compared to wood.

zero maintenance.

my kids don't get slivers in there feet.

I prefer the look.

I find it has better traction under all conditions(we use our deck extensively in all seasons).

At $3.34 a lineal foot I just don't see value in composite decking.

etc,etc,etc

I had an elevated concrete deck at my old house. But it was only raised 2' off the ground and was 16' x 14'.

Tyrone

so it really comes down to concrete vs. composite as far as functionality, but you are preferring to sink your extra $$$ (as you said) in concrete and the associated extra costs and headaches, rather than the 'more expensive' but fool-proof simple composite. I wonder what a true cost comparison between the two solutions would yield.

I've been there and I know what you are going through, in terms of having a vision and staying with it as the costs and problems start mounting; but it is your $$$ and you are fully entitled to do this!

Hey all,

I just wanted to sincerely thank you all for you comments and suggestions. After taking a step back and reviewing the comments. I am going to take your advice and move towards a traditional design (although POSSIBLY a steel beam over the 35' run), 1x6 pressure treated or composite deck boards, 2x10 or 2x12 Pressure treated Joists.

When pretty much 100% of the expects on here comment:

"You can do this, but it is going to cost you a poop pile of money that most others will not see value in".

So again, thanks for all you help! My homebuilder has priced out a Strucutral Slab, that I will at least hear the price, but we are heavily leaning now to a more traditional deck.

Thanks!

letssled

Now this is beginning to make some more sense, but I am still of the opinion that you will need an additional steel or wooden column between the corner ones, thus reducing the two spans down to 17.5 feet each, give or take. A 35-foot span is way too long and will result in a very beefy steel beam + very expensive.

Take my advice on the abovementioned comments as I've been a Structural Engineer for 35 years now.

Good luck with your project!

the slab must have enough re-inforcing to support it's own weight and live loads after it's cured. wet concrete is exstremely heavy. a strong falsework system is critical until the concrete has set. approx. a week.

the weight of wet concrete per yard x the yards needed should give you an idea of the strenght of the falsework needed. the weight of wet concrete may suprize you. contact your concrete supplyer as to weight per yard before design the falsework.

the falsework should remain for at least a week. cover the pad with plastic and be sure that the slab remains moist.

if it's done correctly, the slab will support it's self and transfer the weight of the slab to the columns

as a p.s: i've always used scaffling for the falsework. you should be able to rent it by the week.

Typically, the concrete weight for design of forms is 150 pcf, plus you add in an extra 25 psf allowance for bodies and construction equipment, etc., + include an impact factor (20% increase) for unforeseen live loadings, especially for concrete dropped (a no-no) a distance.

pcf = pounds per Cubic Foot (a 6-inch thick slab weight = 75 psf)

psf = pounds per square foot.