Cantilever Deck Problems - Rotten Wood

[Mark W Pugh]

So, I have this cantilever deck that was built in 1979. The deck floor joists extend from the interior, which also holds up the floor in two rooms and the gable end structure walls off the foundation/block. I have numerous exterior floor joist portions that have rotted and need replaced. It appears these joists/boards are NOT treated lumber, and were sealed and painted with something. I think I have a good plan to replace, but I don't know what kinds of boards to use. I have access to the full length of all boards, drive in garage ceiling is not finished.

Now, wondering how to attack this.

1. If I use treated lumber, it will shrink as it dries. Since the floor joists actually holds up interior gable end walls, and interior walls, do I need to worry about using pressure treated wood and it shrinking and causing problems?

2 - If I were to use interior wood, how would one treat the interior wood to prevent rotting on the exterior?

3. KDAT lumber - should this be a consideration? Expensive, but......?

4. How would you attack this?

5. I was thinking about sistering the floor joists. Coming in with the exterior joist by 6', then using 3' on either side of the the joist's butted ends. I would add a board on both sides of the joist's mating ends, and bolt together with the use of construction adhesive. Obviously, securing back to floor, bottom plates, etc.

What say you?

[Lee Schierer]

Your first step should probably check building codes to see if your cantilever deck is permitted. Then consult a good structural engineer for proper support sizing and materials.

[Mark W Pugh]

Your first step should probably check building codes to see if your cantilever deck is permitted. Then consult a good structural engineer for proper support sizing and materials.

First, the house was built in 1979 in an area that had no inspections. Today, the only inspection that are required, for a total house build, is for the septic system. The cantilever deck is already there.

So, I have a problem I must fix. I hold no one responsible/liable for the work I do. I'm not a contractor, but I can find my way around a shop and home construction.

So, I need advice on how others have done, or would do this. You can message me vs putting here on-line.

Thanks for any inputs

[Wayne Lomman]

Do you have time to buy your treated timber and let it dry? Otherwise, buy a dry durable species. It's generally a bad idea to try to protect a low grade timber. Cheers

[Tom M King]

The only cantilevered deck I ever built had steel that went from being bolted to interior floor joists, and had treated wood bolted to it on the outside. The exterior wood can be replaced without bothering any other part of the structure. I think it was 1979 when I built that house too.

[Dave Zellers]

Cantilevered decks are a bad idea. I was involved with a couple 30 years ago and both developed serious problems. They leak and invite bugs into the house.

My advice is to cut off the cantilever, seal the house, and if you want a deck there, build it independently from the house, supported on both ends.

[Mark W Pugh]

Cantilevered decks are a bad idea. I was involved with a couple 30 years ago and both developed serious problems. They leak and invite bugs into the house.

My advice is to cut off the cantilever, seal the house, and if you want a deck there, build it independently from the house, supported on both ends.

Can't do this. This is a huge access out of the house. The house is brick, so independent support from the brick is not an option.

[Mark W Pugh]

Do you have time to buy your treated timber and let it dry? Otherwise, buy a dry durable species. It's generally a bad idea to try to protect a low grade timber. Cheers

I agree with this. KDAT lumber is expensive, but may be my only option.

[Aaron Rosenthal]

I was a contractor for over 20 years, and built many a deck.
Is it possible for you to PM me a few pictures and I'll do what I can to help.

[Chuck Wintle]

Your first step should probably check building codes to see if your cantilever deck is permitted. Then consult a good structural engineer for proper support sizing and materials.
I would absolutely have an engineer provide input for this deck.

[Stephen Tashiro]

The deck floor joists extend from the interior, which also holds up the floor in two rooms and the gable end structure walls off the foundation/block.






My advice is to cut off the cantilever, seal the house, and if you want a deck there, build it independently from the house, supported on both ends.

Can't do this. This is a huge access out of the house. The house is brick, so independent support from the brick is not an option.


I suggest you post some pictures. From the verbal descriptions, it isn't clear why you can't independently support a deck with posts.

[Eric Keller]

I was thinking the deck was too far off the ground for posts, but if it provides access that doesn't sound quite right. AFAIK, most decks are built with a ledger board, and aren't completely independent. Flashing the ledger is well understood, but still a common site for water intrusion and house failure. Still have to fix the penetrations though.

[Scott Brader]

First, the house was built in 1979 in an area that had no inspections. Today, the only inspection that are required, for a total house build, is for the septic system. The cantilever deck is already there.

So, I have a problem I must fix. I hold no one responsible/liable for the work I do. I'm not a contractor, but I can find my way around a shop and home construction.

So, I need advice on how others have done, or would do this. You can message me vs putting here on-line.

Thanks for any inputs

My concern would be that whoever buys your house someday may hold you responsible for the work you do. That's why I would definitely get an engineer or at least a licensed contractor involved. You want to make sure whatever fix you do will not only support the deck without damaging the integrity of the house, but will also pass muster with a home inspector who may look at the house as part of a future sale.

Scott

[Al Launier]

LVL engineered lumber is very strong, yet unsuitable for typical pressure treatment due to the glue lines & materials. So, you might want to consider the use of Paralam Plus PSL. Reference https://www.weyerhaeuser.com/woodproducts/engineered-lumber/parallam-psl/parallam-plus-psl/. Having that exterior preservation treatment would be very beneficial over the long term.

Sistering the internal joists, then bolting (lag bolts or through body bound bolts/washers/nuts, carriage bolts/washers/nuts) & using construction adhesive would certainly provide for a secure means of attaching the cantilevered joists. However, in our neck of the woods when cantilevering, the structural framing members typically has the internal length of the framing member twice the length of the exterior cantilevered portion. Example: For 4' exterior cantilever the interior length should be 8'. Depending on the size of the deck, these joists could be quite long to maintain the 2/1 ratio. Your proposed method, although strong, would result in only 1 1/2' on either side of the butt joint. I would suggest longer splice places, but confirm with the local building inspector.

Assuming the internal joists are still in good condition, and resting on a pressure treated sill plate on top of a sill seal, and are still in good condition, then sistering the joists, i.e. typically alongside of each other rather than butting together with splice plates, is typically the method used around here nailing them together.

You have a serious construction project on your hands, so check with the local building inspectors to conform to building codes.

[Robert Engel]

How wide are the joists?

I probably wouldn't worry too much about PT wood shrinking.

2x lam beams will work, too.

Sister on to existing joists using lag bolts w/glue even better.

[Bill Dufour]

FYI: six died in this balcony collapse caused by dry rot. Within a month or so the city closed the fishing pier as being unsafe.
Bil lD.

https://www.mercurynews.com/2017/06/01/berkeley-state-releases-documents-on-cause-of-deadly-balcony-collapse/

[Lee Schierer]

A couple more thoughts:
1. Regular laminated beams are not rated for exterior use.
2. Lag bolts are no longer acceptable for structural loads.
3. Though you may not be worried about the structure, if someone gets hurt because it collapses, guess who pays the freight.
4. Just because the house was built in 1979 does not mean the deck was properly built to start with.
5. Ohio has adopted the IBC and the IRC (https://www.iccsafe.org/wp-content/uploads/Code_Adoption_Maps.pdf) for the entire state.

[John K Jordan]

I agree with this. KDAT lumber is expensive, but may be my only option.

I prefer KDAT, we are usng it in certain places on a new deck now.

For a cantilever, I would look into using steel. Either way, it needs to be professionally engineered. IMO

JKJ

[Mark W Pugh]

I'll try to get some pix when I get home. The deck sticks out 5.5' from the exterior wall. The joists extend in the house about 10'. Again, all are accessible.

Thanks for the replies.

[David Helm]

You said the house is brick. Is it brick veneer (regular wood framing and sheathing with the brick on the outside) or solid, multi-course brick? If veneer (likely given when the house was built) you would be better off cutting off the joists, install a ledger and build the deck independent of the cantilever.

[Mark W Pugh]

You said the house is brick. Is it brick veneer (regular wood framing and sheathing with the brick on the outside) or solid, multi-course brick? If veneer (likely given when the house was built) you would be better off cutting off the joists, install a ledger and build the deck independent of the cantilever.

It's veneer. How would I install a ledger on the veneer? I thought that was not to code.

Pictures to follow.

[Ole Anderson]

My last trip to Menard's included some PT 2x10's 12 and 16 feet. Surprised they were kiln dried without asking for KDAT. They were $22.47 and $16.98 each respectively. As long as you replace in kind, and you haven't noticed any bounce problems, you should be good to replace. I wouldn't sister to already rotting external joists either. Lag screws, not bolts, are your friend. Run them in with an impact driver, no pre-drilling like with lag bolts. Or bolt through as you stated.

[David Helm]

It's veneer. How would I install a ledger on the veneer? I thought that was not to code.

Pictures to follow.

ou drill through the veneer, or mortar, and attach the ledger to the rim joist using appropriate fasteners (ledger lock is a good one).
Y

[Mark W Pugh]

388362

Deck in need of repair.

388363

Inside photos

388364

388365

So, I have access to the joists, both below and above the floor they support.

[Stephen Tashiro]

I was thinking about sistering the floor joists. Coming in with the exterior joist by 6'

That would be a typical repair technique.



then using 3' on either side of the the joist's butted ends.


I don't understand what you mean by that.
.

Looking at the photos, I hope you have a brick saw.

Edit: I see what you mean. You will cut off the end of each joist somewhere inside the house and removed the end of the joist. You will replace the end with a new board and splice the new board to the rest of the existing joist using a third board.

[phil harold]

Okay
Follow the old rule of thumb
if the cantilever is 5' you need at least 10' inside
treated wood should work by sistering existing floor joists
I wood also install crush blocks to support the the upper wall

when you start removing brick you could be opening a can of worms
if the joists are rotting, the wall system could also be compromised

good luck

[roger wiegand]

Having dealt with this problem before I'd ditch the cantilever, which will be an unending source of problems, and put in posts both at the house and the edge of the deck to support it without relying on the house structure. You can tie it to the house, but do it in such a way that you can flash the connection properly. Let the new post and beam system actually hold the deck up. Your current system is a recipe for allowing water, rot, and termites into the structure of your house; a classically bad idea.

[phil harold]

Roger You want him to put posts and beams in his driveway?
I sure hope no one hits them!

388362

Having dealt with this problem before I'd ditch the cantilever, which will be an unending source of problems, and put in posts both at the house and the edge of the deck to support it without relying on the house structure. You can tie it to the house, but do it in such a way that you can flash the connection properly. Let the new post and beam system actually hold the deck up. Your current system is a recipe for allowing water, rot, and termites into the structure of your house; a classically bad idea.

[Chuck Wintle]

Your first step should probably check building codes to see if your cantilever deck is permitted. Then consult a good structural engineer for proper support sizing and materials.
This is what you need to do because of the liability it places on you. has your insurance company weighed in on the subject?

[Al Launier]

Roger You want him to put posts and beams in his driveway?
I sure hope no one hits them!

I suspect Roger was thinking that the apron was wide enough for a vehicle to swing around to enter the garage. That holding true, there could be a post at each corner of the deck and at the center, for a total of (6) posts. Again, given an adequate driveway apron, that would work & be structurally sound and a least expensive alternative. It would allow for joists to be installed (sistered) to the existing joists & supported by a ledger boards on top of,or attached, to the posts without affecting the brick wall, all this providing there is no joist rot inside the house. As for the post on the entry side of the apron he could add some type of framework to increase the visibility of the post to prevent driving into it.

I think Roger has presented a very viable and cost effective way to remedy this problem. Also, if there is enough land with adequate setback the driveway apron could be expanded if needed. This would basically leave the house alone.

[David Helm]

If you go the "sister" route bear in mind that the sisters have to go from bearing point to bearing point. Otherwise the only support for the sister will be the nails to the other joist. Not adequate support and does not meet code if not bearing point to bearing point.

[Charlie Velasquez]

If you go the "sister" route bear in mind that the sisters have to go from bearing point to bearing point. Otherwise the only support for the sister will be the nails to the other joist. Not adequate support and does not meet code if not bearing point to bearing point.

Wouldn't all the force on the interior part of the sisters be going upwards?
I don't know the condition of the interior part of the current joists wrt supporting the actual house structure. If they are affected it may entail temporary support and replacing the entire joists system. As mentioned, a structural engineer should be consulted. It looks to present enough problems that safety should not be compromised to save money. It may cost a lot more in the end.

[Al Launier]

Wouldn't all the force on the interior part of the sisters be going upwards?
I don't know the condition of the interior part of the current joists wrt supporting the actual house structure. If they are affected it may entail temporary support and replacing the entire joists system. As mentioned, a structural engineer should be consulted. It looks to present enough problems that safety should not be compromised to save money. It may cost a lot more in the end.

Typically the "moment" forces from weight on the cantilevered portion would want to raise the joists inside the house, but the more significant weight of the floor above this counteracts.
If the joists within the house are rotted, or headed that way, then you are correct in that the entire system needs to be addressed by a professional qualified in home construction, typically an engineer.

However, the pictures don't really show the condition of the interior joists. They have to be "probed" to determine this in addition to visual appearance.

[Stephen Tashiro]

To me, the terminology 'sistering" would apply if the original joists were left in place and other boards were attached to their sides. What Mark describes in his original post apparently involves removing the ends of the joists and "splicing" new ends onto the joists by attaching the new ends to the old joist and a third board..

Can somene comment on how hard it is to remove the end of a floor joist from under an existing floor? When the new joist is put in place, how is the subfloor attached to the new joist - by brackets?

[Lee Schierer]

After looking at your photos;

1. You can't attach a ledger board because you don't have a rim joist inside the building in that area.
2. Free standing decks that high off the ground are generally not allowed by code.
3. Your existing joists have water damage that comes inside the house based on the water stains in your photos on the wood and the insulation. Your floor and outside stud wall may not be properly supported depending on the extent of the rot to the joists and the sill.
4. Sistering will require more than 6 feet inside the building to support a cantilevered deck.
5. Removing one floor joist at a time is going to be a ton of work, and your sill could also be rotted. Your entire floor will become free floating unless you put in screws from above.

It would appear that your only recourse is to remove the deck and install new joists that run to the main beam inside the house. This will buy you maybe 15years, possibly more before you have the same problem again, because even with treated lumber, you will not be able to permanently seal the wood penetration through the outside wall of the house.

[roger wiegand]

If you don't like posts out in the drive (perhaps not my greatest idea, but I'd do it before the cantilever option), you could fabricate a steel support -- sink a vertical beam into a hefty foundation at the ends and middle close to the house with a braced horizontal member to hold up the deck. You'd need an engineer to spec it out. I've had two houses where I needed to deal with rot reaching well back into the house as a result of the cantilever design and lousy flashing; repair was a major PITA. Hence my aversion to that method.

[Mark W Pugh]

After looking at your photos;

1. You can't attach a ledger board because you don't have a rim joist inside the building in that area.
2. Free standing decks that high off the ground are generally not allowed by code.
3. Your existing joists have water damage that comes inside the house based on the water stains in your photos on the wood and the insulation. Your floor and outside stud wall may not be properly supported depending on the extent of the rot to the joists and the sill.
4. Sistering will require more than 6 feet inside the building to support a cantilevered deck.
5. Removing one floor joist at a time is going to be a ton of work, and your sill could also be rotted. Your entire floor will become free floating unless you put in screws from above.

It would appear that your only recourse is to remove the deck and install new joists that run to the main beam inside the house. This will buy you maybe 15years, possibly more before you have the same problem again, because even with treated lumber, you will not be able to permanently seal the wood penetration through the outside wall of the house.


The photo that shows water damage is the only joist that has that kind of rot. All other joists just have rot on the exterior portion. I would screw the floor down to the new joists from the rooms above.

I will add, the water damage was due to leakage around the door, and not coming in from the joist. This all happened before I moved in, 2000. There is separation between the brick veneer and the block foundation.

A lot to think about here.

[matteo furbacchione]

What you have there can be redone exactly as it is now, no question. It would be technically easy but be very time consuming and a hell of a wrestling match... And I'm sure you are aware you'll probably have to do it yourself as no licensed carpenters would want to take on the risk and liability...

The way I see it is you'll have to rip off the rim/header/trimmer joist and railings. Rip all the insulation and what not down from inside to expose all of the joists all the way back to the beam or bearing wall. Rip up the carpet upstairs to expose the floor back to the beam or bearing wall. Don't forget you'll probably have wiring and plumbing to contend with. Which means you'll have to get them rerouted as this is a project that will take some time... Then start cutting each affected joist out individually and sliding in a new one before moving to the next. That would entail running a sawzall between the joist and the flooring to cut the nails/screws with a metal blade. Doing them one at a time should eliminate possible sagging issues. Then you'll need some sort of frame set up to hold up the new joist while you slide it in, then nail/screw the floor down to it. Don't forget a vapour barrier between the new wood and brick.

To compensate for shrinkage in new wood you'll need to factor in shimming the new material up as it shrinks. Not difficult, just have to be diligent in watching it and acting on it. You won't be able to seal up the building to any degree (which will never be 100%) until the the movement has stopped.

Don't cheap out and use non-treated wood, not unless you want to do it all over again sooner rather than later.

Easy Peasy!

Is it the right way to do it - absolutely not. But I'm not the one footing the bill so you have to determine what you can afford and sleep with.

And as is the case your mileage may vary.

[Mark W Pugh]

What you have there can be redone exactly as it is now, no question. It would be technically easy but be very time consuming and a hell of a wrestling match... And I'm sure you are aware you'll probably have to do it yourself as no licensed carpenters would want to take on the risk and liability...

The way I see it is you'll have to rip off the rim/header/trimmer joist and railings. Rip all the insulation and what not down from inside to expose all of the joists all the way back to the beam or bearing wall. Rip up the carpet upstairs to expose the floor back to the beam or bearing wall. Don't forget you'll probably have wiring and plumbing to contend with. Which means you'll have to get them rerouted as this is a project that will take some time... Then start cutting each affected joist out individually and sliding in a new one before moving to the next. That would entail running a sawzall between the joist and the flooring to cut the nails/screws with a metal blade. Doing them one at a time should eliminate possible sagging issues. Then you'll need some sort of frame set up to hold up the new joist while you slide it in, then nail/screw the floor down to it. Don't forget a vapour barrier between the new wood and brick.

To compensate for shrinkage in new wood you'll need to factor in shimming the new material up as it shrinks. Not difficult, just have to be diligent in watching it and acting on it. You won't be able to seal up the building to any degree (which will never be 100%) until the the movement has stopped.

Don't cheap out and use non-treated wood, not unless you want to do it all over again sooner rather than later.

Easy Peasy!

Is it the right way to do it - absolutely not. But I'm not the one footing the bill so you have to determine what you can afford and sleep with.

And as is the case your mileage may vary.

So, there is not that much to move, electrical/water/other. And access from the floor above is not a problem. The carpet has to come up anyway.

The real question, do I need to replace the joist all the way back to to perpendicular joist? I would like to cut off the joist about 6' foot inside. Bring the new joist in, butt the two together, and sister together with a 6' board on each side of the butt joint. I would use adhesive and bolts. Then screw to flooring above. Where the new joist exits the house, attach new joist to wall base plate, and the plate on supporting block.

I guess I need a structural engineer/architect see if this is code/afe.

[matteo furbacchione]

Unless I was going to redo the whole deck and floor right I wouldn't do any "slight" changes to how it was built. Just incase there were liabilities incurred down the road. An engineer is an option but I would be surprised if they would sign off on such modifications. YMMV

[Jerome Sidley]

Cantilevered decks are a bad idea. I was involved with a couple 30 years ago and both developed serious problems. They leak and invite bugs into the house.

My advice is to cut off the cantilever, seal the house, and if you want a deck there, build it independently from the house, supported on both ends.

This is good advice!

[Osvaldo Cristo]

No personal experience but I reminded casually I had read about that recently: http://www.deckmagazine.com/design-construction/framing/cantilevers-in-the-2015-code_o

I hope that can help you.

All the best.