Author Topic: Deck repair question  (Read 9184 times)

0 Members and 1 Guest are viewing this topic.

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Deck repair question
« on: March 29, 2017, 12:59 AM »
Hi guys,

I have a deck that extends out 8' and only attaches to the house, in other words there are not any posts holding up the deck.  The deck boards that are not protected by the eves of the house have started to rot.  I plan to rebuild the deck at some point, but for now I would like to repair it. 

How do I go about repairing the 2x8 supports without replacing them?  I was thinking of bolting another 2x8 up to them, but since the deck is only supported at the house I'm not sure about adding the extra weight.  I also though about just replacing the deck boards and using longer screws to get down to solid wood, but I'm not sure how far down that is.

Another thing a little unusual is the deck floor boards are 2x4 cedar.  The house was built in the 60's and the deck was part of the design.

Any repair ideas?

Thanks for the help,
Tom

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


Offline Bob D.

  • Posts: 631
Re: Deck repair question
« Reply #1 on: March 29, 2017, 05:03 AM »
If I am understanding what you are describing you have a deck which extends out form the house 8 feet and is supported only by 2x8 joists cantilevered out from the house with no additional support in the form of posts or braces.

And, that this deck is in need of replacement or repair, and you believe you may need to use longer screws to reach solid wood as you describe it in these 2x8s.

Is that correct?

Can you provide a photo which will help us all visualize your situation better.
-----
It's a table saw, do you know where your fingers are?

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #2 on: March 30, 2017, 12:17 AM »
Yes, that is correct.  The outer 4 feet of the deck that is exposed to rain and sun is what needs repaired.  I was going to sister some 2x8x8's to the existing joists to have solid wood to attach the deck boards, but I'm concerned about adding the extra weight to the deck. 

I'm still thinking of using long screws to attach the deck boards to the existing joists or possibly just attaching 2x8x4's to the existing joists to save weight.  They are 16" apart, so I might be able to get by without having to sister each one.

As far as photos, I've been a member of this forum for years and haven't had any luck getting pictures to post, but I can take a few and try.

Tom

Offline rizzoa13

  • Posts: 545
Re: Deck repair question
« Reply #3 on: March 30, 2017, 05:17 AM »
I'd probably sister new 2x8 cedar boards. If you used pressure treated to sister you'd be adding significant weight. Can your deck handle that weight? Don't know, but I'd try to keep the additional weight down if possible.

Are the cantilevered framing members also the floor joists for the interior of the house? Is the ceiling finished underneath that floor? I'm actually curious because to really rebuild it correctly you'd need to slide in as long of a board as possible and bolt it to the existing ones. Either that or support the outer edge of the deck back and down to the house on an angle.

Offline JBag09

  • Posts: 160
Re: Deck repair question
« Reply #4 on: March 30, 2017, 06:42 AM »
If it is cantilevered, for every foot it extends beyond you need two feet inside was the rule of thumb a boss taught me a long time ago, but to go back 16ft is almost as strange as them going 8ft out with no supports.
Personally, I'd put some support underneath, maybe a foot or two back from the front and then sister your joists. But I tend to overdue stuff.


Sent from my iPhone using Tapatalk

Offline kevinculle

  • Posts: 140
Re: Deck repair question
« Reply #5 on: March 30, 2017, 07:09 AM »
The 2:1 cantilever rule for joists is correct and that makes this deck quite unusual; an 8' cantilevered deck using 2x8 joists (equivalent to a 16' span between supports) seems to be well beyond published joist span tables and possibly the structure was not properly engineered in the 1st place.  An easy fix would be to add outer supports, address rotting joists and end up with a more conventional structure.  If you want to keep the cantilevered structure I would strongly recommend consulting a structural engineer as there are real risks to you and your guests if this is not properly resolved.

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #6 on: March 31, 2017, 12:28 AM »
Thanks for the advice and comments, but my way of thinking is that this thing has been on the house for 50+ years so I would say it was designed and built right.

The deck joists do run the same direction as the floor joists in the house which run the width of the house - 40'.  I've looked inside and outside and can't see how it is attached.  I will find out when I rebuild the deck sometime in the future.

I do like the idea of sistering a cedar board to save weight, but an internet search came up with only sistering to the section of the joist that was showing some rot.  If that is safe, I could just attach a 3-4 foot section of 2x8 which would give a solid board to attach the deck boards and not add as much weight.

Thanks,
Tom

Offline rizzoa13

  • Posts: 545
Re: Deck repair question
« Reply #7 on: March 31, 2017, 06:51 AM »
Not having seen the extent of the rot or having felt the structure from above We can't really tell you how much to sister.

If it's structurally sound and you just need something to screw your deck boards to then by all means sister small blocks to it for nailers. Personally I'd go back at least a few feet to good sound material and lag bolt your blocks back there also.

I'd just rebuild the entire thing though because I hate bandaids especially st my own house.

Offline kevinculle

  • Posts: 140
Re: Deck repair question
« Reply #8 on: March 31, 2017, 08:42 AM »
Thanks for the advice and comments, but my way of thinking is that this thing has been on the house for 50+ years so I would say it was designed and built right.

The deck joists do run the same direction as the floor joists in the house which run the width of the house - 40'.  I've looked inside and outside and can't see how it is attached.

Thanks,
Tom

Tom,

Based on your description the only explanation that makes sense is that the joists in your deck are the floor joists in the house extended out through the wall, otherwise you would necessarily be seeing a long run (16' if properly constructed) inside the house where the deck joists were joined to the floor joists.  One aspect of proper engineering is to provide a means of future maintenance and repair...if my suspicion is correct that seems to be missing here.  A lot has changed in 50 years including building codes.  Do as you see fit but an elevated deck is not a wise place to take structural shortcuts.

Offline Bob D.

  • Posts: 631
Re: Deck repair question
« Reply #9 on: March 31, 2017, 02:15 PM »
The 2:1 cantilever rule for joists is correct and that makes this deck quite unusual; an 8' cantilevered deck using 2x8 joists (equivalent to a 16' span between supports) seems to be well beyond published joist span tables and possibly the structure was not properly engineered in the 1st place.  An easy fix would be to add outer supports, address rotting joists and end up with a more conventional structure.  If you want to keep the cantilevered structure I would strongly recommend consulting a structural engineer as there are real risks to you and your guests if this is not properly resolved.

I agree, and it's why I asked for the clarification earlier. Eight feet seems excessive (and unsafe) with no support.
-----
It's a table saw, do you know where your fingers are?

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #10 on: April 01, 2017, 10:57 AM »
I didn't include this in the original post as it was a repair question and not a deck design question, but the rim joist sets on two horizontal steel I-beams that travel the width of the house.  So the deck is attached to the house and rests on nearly 50' long steel beams.  The rim joist and where the joists attach to it seem sound.  The top of the joists that are exposed to sun and snow and ice and rain have some rot on the surface, but I haven't taken up the deck board to see how deep it goes.

And yes Rizzola, if I had the money now I would just rebuild it, but when I bought the house a few years ago I updated a lot of things so I waiting for the money to build back up before I do a major rebuild.

Tom

Offline rizzoa13

  • Posts: 545
Re: Deck repair question
« Reply #11 on: April 01, 2017, 02:06 PM »
I'm a little confused. If it's a cantilever deck then there isn't really a rim joist on the house side, the deck joists go back on through the house.

Is there blocking in between the joists at the house side or is there a one piece rim joist?

Offline Cheese

  • Posts: 3460
Re: Deck repair question
« Reply #12 on: April 01, 2017, 02:34 PM »
I guess I'm curious how high this deck is above the ground. If it's only 4' or less above the ground, then why not just install some additional vertical supports at the 5'-6' mark. This means that the sistering joists can be shorter, which means lighter and there will be an additional bearing for them. Any visual issues with the additional vertical supports can be hidden with landscaping and plants, especially the climbing variety.

I guess I assumed that the deck joists actually were connected into the structure inside the building envelope. If they're just connected to a rim joist then that's a lot more scary issue...especially if they project out 8'.

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #13 on: April 04, 2017, 10:42 AM »
Maybe I'm using the wrong term.  I was thinking the rim joist runs perpendicular to the joists.  This board, whatever it's called, is at the outer edge of the deck.

The deck is 7-8' off the ground.

Tom


Offline SRSemenza

  • Global Moderator
  • *
  • Posts: 7924
  • Finger Lakes Region, NY State , USA
Re: Deck repair question
« Reply #14 on: April 04, 2017, 10:52 AM »
I am just trying to visualize how the deck is actually attached to the house and stays up? It seriously can't just be bolted to the house with eight feet sticking out unsupported?  Is it actually cantilevered or something else?

Seth

Offline leakyroof

  • Posts: 1958
Re: Deck repair question
« Reply #15 on: April 04, 2017, 10:54 AM »
I am just trying to visualize how the deck is actually attached to the house and stays up? It seriously can't just be bolted to the house with eight feet sticking out unsupported?  Is it actually cantilevered or something else?

Seth
  Can we NOT get any pictures of this deck?.  It's got all of us curious... [popcorn]
Not as many Sanders as PA Floor guy.....

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #16 on: April 05, 2017, 01:06 AM »
It really is cantilevered, but like I said earlier, there are two horizontal steel i-beams that run along the basement ceiling and extend out that support the board that the joists attach to.  The deck is around both sides and the back of the house and there are not any vertical posts supporting it.  It only extends out 8' along an 18' section behind the house, the rest of it is about 4' wide.  The deck is sturdy, I was just asking about a good way to repair some rot before I get around to rebuilding the whole thing.

Well I just spent over a half hour trying to upload a few photos and no luck.  I don't know if it's because I'm using a Mac or what, but I've never had any luck getting photos to post.

Tom

Offline Bob D.

  • Posts: 631
Re: Deck repair question
« Reply #17 on: April 05, 2017, 04:55 AM »
So you're saying that these two I-beams are cantilevered out under the 8 foot wide section of deck and the deck joists are supported by the beams?
-----
It's a table saw, do you know where your fingers are?

Offline Cheese

  • Posts: 3460
Re: Deck repair question
« Reply #18 on: April 05, 2017, 09:25 AM »
It really is cantilevered, but like I said earlier, there are two horizontal steel i-beams that run along the basement ceiling and extend out that support the board that the joists attach to.  The deck is around both sides and the back of the house and there are not any vertical posts supporting it.  It only extends out 8' along an 18' section behind the house, the rest of it is about 4' wide.  The deck is sturdy, I was just asking about a good way to repair some rot before I get around to rebuilding the whole thing.

Well I just spent over a half hour trying to upload a few photos and no luck.  I don't know if it's because I'm using a Mac or what, but I've never had any luck getting photos to post.


Ok, I missed the 2 horizontal I-beams part... [doh]...now this thing starts to make sense, unfortunately, now we really need to see some photos because this isn't the typical deck that the average Joe would be familiar with. Certainly I've never dinged around with one like this and I'm known for incorporating "hybrid building techniques".  [eek]  Important information would include the the width and thickness of top & bottom flanges and the height and thickness of the web.

Everything I post here is from a MAC or iPhone, so that's not the issue. Maybe you could e-mail the photos to @SRSemenza and Seth could then post them?

Offline SRSemenza

  • Global Moderator
  • *
  • Posts: 7924
  • Finger Lakes Region, NY State , USA
Re: Deck repair question
« Reply #19 on: April 05, 2017, 10:13 AM »
It really is cantilevered, but like I said earlier, there are two horizontal steel i-beams that run along the basement ceiling and extend out that support the board that the joists attach to.  The deck is around both sides and the back of the house and there are not any vertical posts supporting it.  It only extends out 8' along an 18' section behind the house, the rest of it is about 4' wide.  The deck is sturdy, I was just asking about a good way to repair some rot before I get around to rebuilding the whole thing.

Well I just spent over a half hour trying to upload a few photos and no luck.  I don't know if it's because I'm using a Mac or what, but I've never had any luck getting photos to post.

Tom


I think the word horizontal was confusing me. I read about the beams but didn't get the direction they were running. Beams are perpendicular to the house wall  that the deck is built against?

Did you try the picture posting info I sent your way last week?  Sending you a message now.

Seth

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #20 on: April 06, 2017, 12:10 AM »
Bob,  The I-beams stick out from the house and support the board that the joists attach to.  I called it a rim joist but that must not be right because it seemed to confuse folks.   So the joists and the beams run in the same direction.

Cheese,  How do you get the photos on here from your iphone? I took the photos off my iphone and put them in iphoto, but cannot seem to attach them here.  I tried drag and drop and searched for the img number to attach here with no luck. 

Seth,  Thanks for the info on getting photos uploaded but I'm still not having any luck.  If cheese doesn't have any tips for me I might just email them to you.  Or just show you at the next Festool Connect [laughing].  And yes, the beams are perpendicular to the house wall (which are vertical!)

Tom

Offline SRSemenza

  • Global Moderator
  • *
  • Posts: 7924
  • Finger Lakes Region, NY State , USA
Re: Deck repair question
« Reply #21 on: April 26, 2017, 03:13 PM »
Here are Tom's pictures. Sorry for the delay.


       


       


       


       


Seth

Offline Peter Halle

  • Global Moderator
  • *
  • Posts: 10775
  • Let's Redux / Revive / Rewind / Rollback the FOG!
Re: Deck repair question
« Reply #22 on: April 26, 2017, 06:29 PM »
Are there 4 steel ibeams under your deck - 2 straight - parallel to the joists and then 2 diagonals out to the outside corners of the deck that extends further out?

It would be fun to see what the framing looks like above the basement ceiling.

I am asking because I want to send images to my architect brother who usually does all his own engineering before having it reviewed and stamped by others (35 years experience).

Peter
Disclaimer:  I have been involved with the development of some TSO Products.  I have offered thoughts and ideas freely.  I am not paid but I may receive products during the development process or afterwards.

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #23 on: April 27, 2017, 12:18 AM »
Peter,

The beams that run parallel to the joists extent all the way under the house, but the two smaller diagonal beams only extend a few feet into the basement. 

The previous owner gave the the architectural drawing for the house but I haven't unrolled them yet to look at them.

Thanks Seth for posting the pictures for me,  I hope it clears up what I've been talking about.

Tom

Offline SRSemenza

  • Global Moderator
  • *
  • Posts: 7924
  • Finger Lakes Region, NY State , USA
Re: Deck repair question
« Reply #24 on: April 27, 2017, 12:25 AM »
Maybe do a little more investigating of the rot.


   I think I would try removing a couple of the deck boards so that you can get to the 2 x 8 joists in a couple spots and see how far the rot goes. If it's not too bad then maybe just do the deck boards for now. Try to pick the worst looking spots to check. No loss since the deck boards need replacing anyway. Also you might want to replace them with wider than a 2 x 4. That way if you come across a bad spot in a joist you will be more likely to be able to span the bad spot and not have the whole width of the  2 x 4 in the rotted place. If the joists are too far gone you can re-figure at that point.

Seth

Offline kevinculle

  • Posts: 140
Re: Deck repair question
« Reply #25 on: April 27, 2017, 09:10 AM »
OK now this starts to make sense, the deck is indeed cantilevered but the structural members that carry the cantilever are steel I-beams...the pictures are a bit unclear but apparently the I-beams are 8" deep set on diagonals with the 2x8 joists of the deck let into the web of the I-beams.  I can't imagine that this construction would have been permitted without signoff by a structural engineer, but who knows depending on the jurisdiction.  Your objective should be to replace any unsound joists with attachment details replicating the original construction.  You would also be well advised to refresh the I-beams with a coat of high quality finish for corrosion protection.

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #26 on: April 29, 2017, 10:53 PM »
Thanks,

Kevin the 2x8's actually set on top of the steel beams. I also plan on painting the steel beams because they do have some surface rust.


Offline Holmz

  • Posts: 3875
Re: Deck repair question
« Reply #27 on: April 29, 2017, 11:15 PM »
Thanks,

Kevin the 2x8's actually set on top of the steel beams. I also plan on painting the steel beams because they do have some surface rust.

Like with POR15?

Offline rizzoa13

  • Posts: 545
Re: Deck repair question
« Reply #28 on: April 30, 2017, 07:56 AM »
Ok so now thst you've posted pictures it's pretty easy to give repair advice.

A: you plan to remove and replace all of the deck boards.
         Remove all the decking and sister 2x8s to the rotten joists spanning the rotted areas. You can decide how long the 2x8s need to be based on how deep the rot goes from the topside of the joists down. If a 2x8 is completely rotted through the lay up a full length 2x8 spanning from the steel I-beam tk steel I-beam.

B: you plan to replace only the rotted decking board.
         From the open underside push a 2x8 into the stud cavity next to where you want to sister it that runs the entire length of the span between the two I-beams. You have a few options on how to get it to fit. You could bevel one top side of the board to allow it to turn more easily. You'll still need to beat the crap out of it to get it to turn over as you flip it up. You can rip the 2x8 down say a half inch, flip it in place and shim underneath at the I-beams with something suitably strong. Maybe a piece of 1/2" steel stock.

No matter how you get the boards in there, lag bolt it all together and make sure the top of your sisters boards are flush with the existing framing. Relay your new decking and attach it to any good wood you can.

Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: Deck repair question
« Reply #29 on: May 04, 2017, 12:30 AM »
I hadn't heard of POR15.  I was going to look for something at one of the home centers or Sherwin Williams.  Is the POR15 system a better than average product?

Rizzoa,

After I started removing the deck boards, and after I had sistered 5' boards to the joists, I found the joists that sit on the steel beams and support the other joists were badly rotted.  So now that I have to replace those boards I might as well replace the joists too.  The span is 22' and the company that gave me an estimate said they would use shorter board rather than a single 22' board.  Would you have an idea where to put the joint where the boards butt up to each other?  I was thinking between the steel beams.  There are a couple places that sell 22' boards but I haven't checked into delivery fees yet.  I would think that, as long as the boards were straight, that it might be best to use a single board.

Tom