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Old 05-26-2011, 10:36 AM   #1
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Replacing deck...questions...


My wife and I purchased this home two years ago, and two owners before us built this deck in 1997. It's weathering pretty badly, the posts are spaced inconsistently, and there's a ton of butt joints that have shrunk and curled causing lots of areas to whack your toe on (not to mention the posts are sunk IN concrete, not on them above grade). So, the plan is to rip everything out back to the ledger and start over with new holes dug in, sonotubes, and simpson ties attached to the piers. Instead of using 4x6's as are being used now, I plan to just use 6x6s. The deck is ~32'x30', but in a U shape that wraps around the house. The diagram below shows the layout looking down (the black thick lines are the current girder locations and their direction. The red lines indicate joist direction:



Now, here's a few dilema's. The diagram above, there is a 14' beam span over our patio with only 2 2x12s and the 4x6 angle bracing shown below in the photo:



According to most beam span charts, I would need 3-2x12's in SP to span this distance. Is that what I should be shooting for?

My other major dilemma I'm having is where to place my new posts, and my beams. Right now the decking is running parallel to the house on the sides, and perpendicular at the front. I plan to make the portion at the front 12' out, and ideally keeping the boards perpendicular to the house at this spot (basically the bottom of the "u" in the diagram above) would ensure NO butt joints. I was thinking of adding a small 1' cantilever to the front to attach the deck railing posts to, and then having all the main support posts set back in. Is this doable?

Using the diagram above, and looking at the photo above, where would I be be suited to place my posts and beams? Is there another method of attaching beams to post other than notching? The only reason I ask is by notching a 6x6, I can't extend it up through the deck to serve as part of the railing, so where the corner posts are concerned, I would have to setback the support posts from the railing posts (again, why I'm considering a cantilever). Lots of questions, and I'll probably have more, but any thoughts or opinions are welcomed.

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Old 05-26-2011, 11:41 AM   #2
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Replacing deck...questions...


When I built my deck, my building inspector supplied me with a copy of "Prescriptive Residential Wood Deck Construction Guide", based on the 2006 IRC. This guide supplies definitive instructions on how to size beams, joists, posts and decking, how much bracing is required, how to install stairs, rails and landings, and details for a wide range of connections. I don't know what code you operate under in PA, but I would go to the building inspector and discuss code issues with them. If they have this guide, it is excellent, lots of diagrams, and pretty thorough. If you have no building inspector, or you don't need a permit, I would order a copy of this guide anyway, if you follow the rules in the booklet you will be OK.

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Old 05-26-2011, 11:56 AM   #3
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Replacing deck...questions...


Am I seeing a seam in the middle of that beam with cross braces holding it together? Ouch.

You know, you might thing about a piece of steel or an exterior rated glue lam beam for that major length. You have enough support for either with the posts, this time anchored to sonitubed concrete and not a retaining wall as I see it? Either would give you a nice, trustworthy front edge. Set it and forget it. You will need someone to measure carefully and draw some plans. People amaze me with their fear of architects and structural engineers. Most I use charge less than I used to for painting houses. And they sail you through permit and even inspection issues every single time.

I cannot tell how long the spans are on the sides. Probably overkill but steel or glue lam is not that expensive. Why not use it for the front edges too if they are long.

You can solid color stain exterior glue lams to fit in. You can paint steel or veneer it with would to match the decking.

Jeeze Louise, that deck must be rated for a maximum occupancy of 1.5 people, a cat and a dog.

Last edited by user1007; 05-26-2011 at 11:59 AM.
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Old 05-26-2011, 01:10 PM   #4
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Replacing deck...questions...


Quote:
Originally Posted by sdsester View Post
Am I seeing a seam in the middle of that beam with cross braces holding it together? Ouch.

You know, you might thing about a piece of steel or an exterior rated glue lam beam for that major length. You have enough support for either with the posts, this time anchored to sonitubed concrete and not a retaining wall as I see it? Either would give you a nice, trustworthy front edge. Set it and forget it. You will need someone to measure carefully and draw some plans. People amaze me with their fear of architects and structural engineers. Most I use charge less than I used to for painting houses. And they sail you through permit and even inspection issues every single time.

I cannot tell how long the spans are on the sides. Probably overkill but steel or glue lam is not that expensive. Why not use it for the front edges too if they are long.

You can solid color stain exterior glue lams to fit in. You can paint steel or veneer it with would to match the decking.

Jeeze Louise, that deck must be rated for a maximum occupancy of 1.5 people, a cat and a dog.
No, those 4x6 cross braces at between two 2x12s that are lagged to the opposite 4x6s. Nothing is attached to the retaining wall as we built that ourselves after we purchased the home.

The spans on the sides vary (get this) from 7' 8" to 8' 7"...not sure where he was going with this.

Anyways, if I run the beams parallel to the house, I could get by with an engineered beam to cover that 14' span over the patio? The only problem is I would then have a beam spacing of 12' assuming distance between ledger and outer beam. If I'm planning to use 2x8 joists 16' OC, is that an acceptable spacing?
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Old 05-26-2011, 02:26 PM   #5
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Replacing deck...questions...


I was not thinking of a beam to just span the patio. I would bit the bullet and go the full length with steel or whatever. I don't think it would cost you that much more by the time you factor in fasteners and so forth. With a solid beam structure, I don't see why you couldn't frame whatever you wanted so long as the ledger on the house was strong enough?
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Old 05-26-2011, 08:58 PM   #6
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Replacing deck...questions...


Quote:
Originally Posted by sdsester View Post
I was not thinking of a beam to just span the patio. I would bit the bullet and go the full length with steel or whatever. I don't think it would cost you that much more by the time you factor in fasteners and so forth. With a solid beam structure, I don't see why you couldn't frame whatever you wanted so long as the ledger on the house was strong enough?

So you're talking about having one beam span the entire 32'? What would a steel I-Beam require to sit on? I'm assuming a 6x6 post would not be sufficient? What effect would cross bracing have on adding to the support (sort of what is done now, but correctly)?
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Old 05-27-2011, 09:21 AM   #7
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Replacing deck...questions...


Quote:
Originally Posted by Daniel Holzman View Post
When I built my deck, my building inspector supplied me with a copy of "Prescriptive Residential Wood Deck Construction Guide", based on the 2006 IRC. This guide supplies definitive instructions on how to size beams, joists, posts and decking, how much bracing is required, how to install stairs, rails and landings, and details for a wide range of connections. I don't know what code you operate under in PA, but I would go to the building inspector and discuss code issues with them. If they have this guide, it is excellent, lots of diagrams, and pretty thorough. If you have no building inspector, or you don't need a permit, I would order a copy of this guide anyway, if you follow the rules in the booklet you will be OK.
Thanks for that (I actually found an updated version online).

On a side note, I would also like to build a gable extension over the deck inline with what you see already out front. Everything I've read about these roofs is that they also need to have the posts run straight through the deck into footings just like deck supports, correct? I've heard SOME people say the roof beams can be placed right on top of the girder below if it's off sufficient size, but I'm not sure. Comments?
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Old 05-27-2011, 06:43 PM   #8
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Replacing deck...questions...


Here's something I sketched up showing possible beam location/placement. The area in question is where the outside corners are. How do I attach another beam running down the length of the house to that shared 6x6 that's already notched for the beam going the other direction?


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Old 05-27-2011, 07:11 PM   #9
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Replacing deck...questions...


I hate to say it on a DIY site but some times?

You need an architect or structural engineer in on this. Or at least a local contractor with experience in this.

Structural steel is different from wood, obviously. Of course you have to support it as a beam somewhere but not so often as wood. It, unless you plan on raising elephants, will not flex at all across a long span. I love glue lam engineered beams almost as much for appearance I guess. Steel can be smaller and cheaper than glue lams though.

Right now, from the pictures you showed, you are in trouble. And bless you from wanting to repair the situation.

Your deck is cantilevered off whatever anchors along the top end of it are anchored into the framing of your house. Those posts and braces to them over the large span are angel wings.

They are not just holding the deck up? They are keeping the ledger anchored to your house from possibly yanking at that bearing wall as the weight of all the deck fails.

You are approaching this perfectly with drawing and thought. I really admire you.

This wrap around deck redesign of yours is not a DIY project. You cannot replicate what is there, and I know you know that.

Private email me if you would like me to find an architect in your area. I promise he/she will save you money lad and I promise you will love the experience. He/she will cost you no more than you GP, dentist or even maid or lawn care pros.

- Steven

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