Keystone
SAWHORSE
Thoughts on attachment
-
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2012 IRC Deck Attachment
- Thread starter Keystone
- Start date
dhengr
Bronze Member
Keystone:
It gets crazier with each edition of the codes. Within the next edition or so, it will take a week or ten days to just figure out if and where you can fit any bolts in a ledger. Alternatively, Simpson and others will come out with a $7000 piece of hardware which supports the house off the deck and causes the 10x12' deck to cost a cool $196,000, including steel piling foundation to bedrock. And, we’ll still have many deck builders just throwing any size screw, lag screw or through bolt into a ledger beam pressed against vinyl siding with foam back-up and finally into an unknown rim joist. Some of this sh.. takes a little knowledge and thought and is very difficult to codify in a way that covers every condition.
Most of what the guy talks about; spacing, stagger, end distance and edge distance; and how the deck loads the ledger, which loads the bolt, which loads the rim jst., or how the bolts load/split/crush the wooden members, are all uncommon, common sense, and used to be encompassed in engineering judgement, experience and std. knowledge of designing in wood. In an effort to democratize the codes and design and building in general, it has been ordained that we come up with these complexified codes, tabulations, flow charts, etc., for the simplest things, so that anyone can do this designing and building. If only, they can follow the complex formulas, recipes and flow charts to the perfect design, they don’t really have to know anything about building.
We should rightly be concerned about safe and secure decks. We can not provide a code provision for every or any deck design, under all conditions, in any location, with multi-directional gravitational forces, plus dynamic forces. Some things just can’t or shouldn’t be done. To me, the sign of a good code would be to cover the important bases, but not any and all possible variations, so that a reasonable intelligent and experienced practitioner can implement it. And, a reasonable bldg. inspector can interpret it too, but he might have to make a decision or two also, not just parse verbiage. Why wouldn’t you expect the builder to open up the bldg. enough so he knows what the detail is at the rim jst.? Including bldg. jst. orientation, stud locations, wall top pl. condition, interior fl. diaphragm and its nailing. Then design a deck and deck ledger which works with that. And, every possible deck might not work with that, without some very special detailing. To try to codify this process and all the possible variations is just crazy. But, that seems to be where we are going.
It gets crazier with each edition of the codes. Within the next edition or so, it will take a week or ten days to just figure out if and where you can fit any bolts in a ledger. Alternatively, Simpson and others will come out with a $7000 piece of hardware which supports the house off the deck and causes the 10x12' deck to cost a cool $196,000, including steel piling foundation to bedrock. And, we’ll still have many deck builders just throwing any size screw, lag screw or through bolt into a ledger beam pressed against vinyl siding with foam back-up and finally into an unknown rim joist. Some of this sh.. takes a little knowledge and thought and is very difficult to codify in a way that covers every condition.
Most of what the guy talks about; spacing, stagger, end distance and edge distance; and how the deck loads the ledger, which loads the bolt, which loads the rim jst., or how the bolts load/split/crush the wooden members, are all uncommon, common sense, and used to be encompassed in engineering judgement, experience and std. knowledge of designing in wood. In an effort to democratize the codes and design and building in general, it has been ordained that we come up with these complexified codes, tabulations, flow charts, etc., for the simplest things, so that anyone can do this designing and building. If only, they can follow the complex formulas, recipes and flow charts to the perfect design, they don’t really have to know anything about building.
We should rightly be concerned about safe and secure decks. We can not provide a code provision for every or any deck design, under all conditions, in any location, with multi-directional gravitational forces, plus dynamic forces. Some things just can’t or shouldn’t be done. To me, the sign of a good code would be to cover the important bases, but not any and all possible variations, so that a reasonable intelligent and experienced practitioner can implement it. And, a reasonable bldg. inspector can interpret it too, but he might have to make a decision or two also, not just parse verbiage. Why wouldn’t you expect the builder to open up the bldg. enough so he knows what the detail is at the rim jst.? Including bldg. jst. orientation, stud locations, wall top pl. condition, interior fl. diaphragm and its nailing. Then design a deck and deck ledger which works with that. And, every possible deck might not work with that, without some very special detailing. To try to codify this process and all the possible variations is just crazy. But, that seems to be where we are going.
GBrackins
Registered User
with a free standing deck you don't have to worry about it
Daddy-0-
Moderator
We require decks to be freestanding OR attached to a treated band board by local amendment. We check the band at the footing inspection. If it cannot be verified or if deck will attach to brick veneer then automatic freestanding.
MikeC
Silver Member
Up until now I had been complaining about PA being stuck in 2009 and earlier. Crazy stuff like that makes me want to start looking for a new line of work. If I can't figure it out, how can I ask a builder to do it?
dhengr
Bronze Member
Daddy-O:
Do you really mean a treated band board or rim jst.? You won’t find that on many houses, will you? Or do you mean a treaded ledger board affixed directly the house rim jst., and properly flashed? Certainly, the free standing deck structure requires more attention to design and details as relates to lateral loading.
Do you really mean a treated band board or rim jst.? You won’t find that on many houses, will you? Or do you mean a treaded ledger board affixed directly the house rim jst., and properly flashed? Certainly, the free standing deck structure requires more attention to design and details as relates to lateral loading.
Sifu
SAWHORSE
- Joined
- Sep 3, 2011
- Messages
- 2,813
dhengr and Daddy-o,
When I was building I supplied and had the framers install a treated rim joist to be installed in the floor system. That sounds like what Daddy-O is refering to. This resulted in treated wood running far beyond the area of just the deck so that if any water got behind the flashing it still had some defense. Then I flashed over it, then I bolted on the treated deck ledger. I tried to do all this at the floor stage which made it a lot easier. I did a lot of side jobs tearing out old, rotted rim boards at decks and didn't want to go back on my own work. And yes, if we had a free-standing deck the prescriptive lateral bracing applied to all sides, not just the front.
When I was building I supplied and had the framers install a treated rim joist to be installed in the floor system. That sounds like what Daddy-O is refering to. This resulted in treated wood running far beyond the area of just the deck so that if any water got behind the flashing it still had some defense. Then I flashed over it, then I bolted on the treated deck ledger. I tried to do all this at the floor stage which made it a lot easier. I did a lot of side jobs tearing out old, rotted rim boards at decks and didn't want to go back on my own work. And yes, if we had a free-standing deck the prescriptive lateral bracing applied to all sides, not just the front.
Keystone
SAWHORSE
MikeC Its to easy to give up, no matter what path you take there will always be something that makes you scratch your head.
Daddy-O Like the idea of PT rimboard, can certainly suggest when new home with deck is built.
IMO, it appears all attached decks will require engineering in the very near future unless the fastener companies save the day. I personally will have my own deck become free standing when it reaches the point of replacement.
Daddy-O Like the idea of PT rimboard, can certainly suggest when new home with deck is built.
IMO, it appears all attached decks will require engineering in the very near future unless the fastener companies save the day. I personally will have my own deck become free standing when it reaches the point of replacement.
Daddy-0-
Moderator
I do mean a treated band board in the floor system. If the existing house band is not PT we require that it be replaced with PT or the deck must be freestanding.
With new houses we check for treated band at the back door during the veneer inspection and make notes on the permit. I.E. " 10' treated band installed at rear door" when they add the deck or stoop in five years we have a record as to what was there.
Like I said this is local amendment not IRC.
With new houses we check for treated band at the back door during the veneer inspection and make notes on the permit. I.E. " 10' treated band installed at rear door" when they add the deck or stoop in five years we have a record as to what was there.
Like I said this is local amendment not IRC.
We use treated rims in deck/porch areas whether freestanding or attached, have been on a second floor deck when the rims, joist ends,etc departed. My post supported decks are still bolted to the house for alignment but not for vertical load. Treated and metal flashings are a problem, this doubles the problem. The galvy at Lowes in the deck parts aisle is not for contact with ACQ, so we've switched to vinyl with an unknown lifespan. Copper is fine but I haven't had anyone willing to go that route.
further aside, we wrapped an open web floor with treated ply. I had to open up one section later and the gang nail plates were rusting where in contact with the ply. It may have been the ACQ but the homeowner had also been very liberal with TSP above. Not sure which it was but started wondering what pressure washers and deck cleaners do.
I've also wondered about corbels for support.
further aside, we wrapped an open web floor with treated ply. I had to open up one section later and the gang nail plates were rusting where in contact with the ply. It may have been the ACQ but the homeowner had also been very liberal with TSP above. Not sure which it was but started wondering what pressure washers and deck cleaners do.
I've also wondered about corbels for support.
dhengr
Bronze Member
Daddy-O:
I did understand that this was a local addendum to the IRC, but now others have expressed like mind. It seems to me that the real intent of this must be to force free standing decks, which can be every bit as problematic, from the stability standpoint, as a deck connected to the bldg. through a ledger, when not done by a competent designer and builder, and to accepted engineering standards. Although, by forcing the free standing deck you do eliminate the potential water intrusion problem at the ledger. We should have insisted on proper ledger attachment and flashing, and proper deck bracing years ago, and we would not have the rash of failures we are seeing now. And, it seems to me that a PT rim board does not solve this problem.
The PT rim board would not be difficult to accomplish on a new bldg., at locations which might receive a deck. But, how can you stop there? If the rim board can get wet because of inferior flashing, that moisture can wick up to the fl. diaphragm material and nailing, and will certainly drain down to the top wall plates and the studs, which should most certainly be treated too.
Suggesting that people replace a good rim board with a new PT rim board will likely cause many more problems than it is intended to address. The strength of the bldg., fl. diaphragm and the rim board are dependant upon their proper interconnection, and the rim board connection to the sill pl. or wall pls. below. And, you are telling people to rip that out, whatever it is as it exists, and then replacing it with a new PT rim board which is very difficult to reattach properly. Now, the integrity of the ledger connected to the rim board is dependant upon this likely inferior reconnection.
I would sooner see them cut a pocket to fit the ledger fairly snugly, all the way back to the outer face of the rim board. I would flash this entire pocket to the outside of the wall, before installing the ledger; at the top, up behind the sheathing and down the face of the rim board; at the ends full height end dams to the outside and finally to be caulked with the ledger ends, to the siding; at the bottom this flashing should slope to the outside like a Zee flashing should, thus the ledger does not sit down tight on this flashing. This flashing can be a sticky-back flashing or ice and water guard or some such. A second Zee flashing at the top goes behind the sheathing or Tyvek and over the top of the ledger to be placed. This flashing should preferably extend out far enough to offer some protection to the ends of the deck joists at the ledger. Then, if the decking runs parallel to the ledger, I glue 5" long PT wedges to the top of the deck joists so the last deck board, which fits up under the top flashing, slopes away from the ledger/deck jst. connection area. That deck board drips 3-4" away from the ledger/deck jst. connection area.
I would bet in this latter scheme before I’d have some carpenter ripping out a good existing rim board, and doing a poor job of reattaching a new PT rim board. And, I’ll bet that when you start mixing in some PT lumber, half the time they’ll be using the wrong nails and hardware. Then I would pay particular attention to their ledger attachment and flashing details.
I did understand that this was a local addendum to the IRC, but now others have expressed like mind. It seems to me that the real intent of this must be to force free standing decks, which can be every bit as problematic, from the stability standpoint, as a deck connected to the bldg. through a ledger, when not done by a competent designer and builder, and to accepted engineering standards. Although, by forcing the free standing deck you do eliminate the potential water intrusion problem at the ledger. We should have insisted on proper ledger attachment and flashing, and proper deck bracing years ago, and we would not have the rash of failures we are seeing now. And, it seems to me that a PT rim board does not solve this problem.
The PT rim board would not be difficult to accomplish on a new bldg., at locations which might receive a deck. But, how can you stop there? If the rim board can get wet because of inferior flashing, that moisture can wick up to the fl. diaphragm material and nailing, and will certainly drain down to the top wall plates and the studs, which should most certainly be treated too.
Suggesting that people replace a good rim board with a new PT rim board will likely cause many more problems than it is intended to address. The strength of the bldg., fl. diaphragm and the rim board are dependant upon their proper interconnection, and the rim board connection to the sill pl. or wall pls. below. And, you are telling people to rip that out, whatever it is as it exists, and then replacing it with a new PT rim board which is very difficult to reattach properly. Now, the integrity of the ledger connected to the rim board is dependant upon this likely inferior reconnection.
I would sooner see them cut a pocket to fit the ledger fairly snugly, all the way back to the outer face of the rim board. I would flash this entire pocket to the outside of the wall, before installing the ledger; at the top, up behind the sheathing and down the face of the rim board; at the ends full height end dams to the outside and finally to be caulked with the ledger ends, to the siding; at the bottom this flashing should slope to the outside like a Zee flashing should, thus the ledger does not sit down tight on this flashing. This flashing can be a sticky-back flashing or ice and water guard or some such. A second Zee flashing at the top goes behind the sheathing or Tyvek and over the top of the ledger to be placed. This flashing should preferably extend out far enough to offer some protection to the ends of the deck joists at the ledger. Then, if the decking runs parallel to the ledger, I glue 5" long PT wedges to the top of the deck joists so the last deck board, which fits up under the top flashing, slopes away from the ledger/deck jst. connection area. That deck board drips 3-4" away from the ledger/deck jst. connection area.
I would bet in this latter scheme before I’d have some carpenter ripping out a good existing rim board, and doing a poor job of reattaching a new PT rim board. And, I’ll bet that when you start mixing in some PT lumber, half the time they’ll be using the wrong nails and hardware. Then I would pay particular attention to their ledger attachment and flashing details.
Daddy-0-
Moderator
We have had multiple deck failures because the deck attachment pulled off the house. What we have found is that the lag bolts were wicking water into the house band even with proper flashing. This would cause the band to rot around the lag bolt allowing the lag to pull out when the deck was loaded. The PT band is required here to resist this type of structural failure. If the deck is attached to the house it must be flashed against the house and counterflashed and cannot attach through siding.
If the band is replaced it must be properly attached to the existing joists or TJI's. Sometimes this requires additional blocking etc. Sometimes strapping is appropriate. Lots of ways to skin that cat. I can say that I have never seen the PT band pull off the deck when installed this way but I have seen many decks separate from the house because they were only lagged to syp band or rimboard. I have also seen decks that were 30 years old that were only nailed to the house. Go figure!
Of course...freestanding decks need lateral bracing as do all decks when they reach 6' tall or so.
Somewhere on this forum I posted a link to our county prescriptive deck building guide. It even includes pre made plans. I will try to find the link.
If the band is replaced it must be properly attached to the existing joists or TJI's. Sometimes this requires additional blocking etc. Sometimes strapping is appropriate. Lots of ways to skin that cat. I can say that I have never seen the PT band pull off the deck when installed this way but I have seen many decks separate from the house because they were only lagged to syp band or rimboard. I have also seen decks that were 30 years old that were only nailed to the house. Go figure!
Of course...freestanding decks need lateral bracing as do all decks when they reach 6' tall or so.
Somewhere on this forum I posted a link to our county prescriptive deck building guide. It even includes pre made plans. I will try to find the link.
Daddy-0-
Moderator
Try this link.
http://www.chesterfield.gov/WorkArea/DownloadAsset.aspx?id=4142
That is our deck guide. It lists all of the methods approved in our county and includes fill in the blank plans.
Sorry the scratch and sniff version sold out the first year.
http://www.chesterfield.gov/WorkArea/DownloadAsset.aspx?id=4142
That is our deck guide. It lists all of the methods approved in our county and includes fill in the blank plans.
Sorry the scratch and sniff version sold out the first year.
Francis Vineyard
Registered User
Unless Simpson Stong Tie or another complany comes up with a better idea in the near future an alternative may be prefabricated modular decks that could be popular at the local big box hardware stores and online. At first I would have laughed at the prices but what people will pay for the no hassle convenience of prefab tool sheds, gazebos, pools, carports, plus stuff like bottled water, etc.
Francis
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Francis
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Keystone
SAWHORSE
Maybe SEARS can regain its prior footholh within the industry...