Deck Sagging and Rotting

Just a sliver of wood stuck in the hole will help, the very old trick was a wooden match stick. Or a screw a little longer than was there.

If you have a few extra minutes go to Fine Home buildings website and watch the Ultimate Deck Build 2015. It's several videos that goes over all the steps they took and why building a deck. I know it doesn't solve your problem, but I know some of the steps they took actually explains why your deck failed. Granted their solutions are probably the most expensive way to fix it, but you might get some ideas to help.
I hope it does help. I hate redoing other peoples work but it happens all the time, and to be honest with you I don't really blame the original carpenters anymore. Sometimes their ideas just don't work out or they don't educate themselves as best they can, and 99% of people don't want to pay for educated long lasting work. I even catch myself sometimes trying to justify paying somebody less qualified to do the work because it's considerably cheaper.

I would have liked to have seen the ground dug out and sloped away at least 6 inches deep. Then filled with local cheapest rock to provide airflow and drainage. Then I would have minimum covered the tops of the joists with tar paper. If the money allowed it something with a sticky back, but that stuff is costly. So that is what I would have done to start. Now with the damage done the cheapest thing to do would be to do just that but only where the damage is ... shovel out the dirt where you can, dump in the rock, and replace the rot then cover the tops. This might get you by for another 10 to 15 years maybe. That is what I think would be the absolute cheapest. If it was mine however I agree with the others I would probably start over. It really sucks but I think a correctly built deck should last you at least 25 to 35 years depending on you climate and since I didn't see a lot of mold I don't think your climate is overly moldy.

My 2 cents.

Thanks for your response, you've laid out much to consider. I will mark down another vote for tar paper. Here is a product named Quick-Fix Protecto Wrap which I purchased at HD. I was about to put it down on the 25' of original beam which I did not replace, but I second guessed myself. I became concerned that it might make the rot accelerate instead of slow. The Protecto Wrap came in a 30' roll and cost around $25.00 if I remember. I also decided not to use it because I became concerned that it might harm the lizards. The warnings about the chemicals that the materials contain were very strongly worded.

Here is how the deck looks today.



I had to rip off 3/4" from the sisters to clear the cement pad. It would have almost been very nearly the same thing to just sister 2X6's onto the original 2X8's, but that's all good.





I have screwed in 2X4s onto the sister joists so that the screws holding down the planks will have something to bite into. I used two 3/8" bolts and PL400 glue to secure the joists & sisters together. I will be using 10 D nails in addition to that.

I've unfortunately noticed that the deck is coming apart in other areas. Here is a picture of the original 4-joist beam, 25' of which I'm not replacing since it looks OK for the moment. You can see that the 2X8 and the 2X6 which are toe nailed together at the top of the picture are separated from the two 2X6's at the bottom of the picture which are secured to the post.

Should I use a big bolt to pull this mess back together? Hammer in new nails maybe? Or just ignore this?

Here is another area where I can look down between the boards and see the the 10 Nails are not holding. Should I jam a brace of some sort under it? Bolt? Leave it alone and hope for the best?




The air circulation must be improved to reduce the rate of failure. I want to rip a tiny bit off of the planks that I have up. I am considering renting a table saw with a good vacuum system. I tried ripping them while they were screwed down, as Trex recommended, butthe results were a bit inconsistent, and it was very messy.

And I will be sure to check out the Ultimate Deck Build video you recommended. Thanks

I would put one or 2 bolts in just don't go over board, and don't OVER tighten. Your not trying to take the warp out your just trying to prevent future warping. If you attempt to take the warp out you just might end up putting more pressure in places you can't see. just enough where you feel like it will keep it from completely separating. I would still consider putting the tar/protecto wrap on. If it's going to be under the deck boards your lizards should be safe.... but you know them better than I do. It's probably only toxic if the eat/bath in it.

Other than that it looks good. Again focus on the fact that you adding life to the deck. Your not making it last forever just giving it another 10 to 15 years hopefully.

I would bolt the beam but don't close the gap, then you have the shear strength and left the gap open just put a wedge beside the bolt.

I would also add nails or screws to the sisters. You are trying to make them one so they bend and warp or whatever together.
If you think about just bending the joint at some point one piece will split at the line of the bolts. 3 nails 6 to 8" OC.
With the bolts you have shortened the joint to the distance between the bolts

I think I follow you but want to check. Below are 4 "lines" of 3 10D nails. The sister joist is yellow, the bolts are red. The original joist which was cut back is brown. Each line of 3 nails is 6 to 8 inches from the others. Correct?



Also, again I want to be sure, you are talking about the nail pattern in each of the 14 sister joists, correct? You are not saying I should put nails in the places that are coming apart. For that I need a minimal amount of large bolts, and don't over tighten.

SFLman said:

I think I follow you but want to check. Below are 4 "lines" of 3 10D nails. The sister joist is yellow, the bolts are red. The original joist which was cut back is brown. Each line of 3 nails is 6 to 8 inches from the others. Correct?

Also, again I want to be sure, you are talking about the nail pattern in each of the 14 sister joists, correct? You are not saying I should put nails in the places that are coming apart. For that I need a minimal amount of large bolts, and don't over tighten.

Click to expand...

Yes and yes:

Well, that's some pretty good exercise! 12 more to go.

SFLman said:

Well, that's some pretty good exercise! 12 more to go.

Click to expand...

I would just space the top boards and cut the last one to fit.

That's a good idea and I would prefer to do that. I've noticed that some of the planks are bowed, and I don't know how they are going to get along with the table saw I'm going to rent.

If you look at the plank labeled AON you can see a pretty dramatic curve to the left at the far end of the plank. That's not a trick of the camera, that dude is considerably bowed!



But there are some irregularities which pose problems when considering the idea of ripping one down and shifting the other planks over. The whole deck, it seems to me, could not be done that way, or it would be really difficult.

There are three big lamps bolted into the deck, here is one of them. I would probably have to call in an electrician before moving it.



A few feet away from the lamp, there is also an irregular notch cut out of the bottom of this plank. So this plank looks to me like it's not movable.



The planks which go around the posts which hold up the hot tub cover have holes cut in them. Not impossible to fix, but difficult.

But I could, by taking out just 6 more boards create a clean rectangle in which to do your plan. It would be 13 planks across and stretch the entire length of the deck. The rectangle is outlined in yellow:



Questions: How odd is this rectangle going to look in relationship to the rest of the decK?

And, these joists are not in the greatest shape. Is putting a bunch of new screw holes in these joists going to be a problem?

To start, I do not understand the notch in pictures 2 and 3.

Just a few thought on cutting the boards.
1. what is it you are trying to do by cutting them, could just put them back and drill some holes between to allow water to run thru.
2. table saws are great for cutting sheet stock not so much for what you are doing, not impossible but needs some experience.
3. not that hard to jig up a skill saw, type of jig would depend on how comfortable you are with the saw.

SFLman said:

But I could, by taking out just 6 more boards create a clean rectangle in which to do your plan. It would be 13 planks across and stretch the entire length of the deck. The rectangle is outlined in yellow:

Questions: How odd is this rectangle going to look in relationship to the rest of the decK?

And, these joists are not in the greatest shape. Is putting a bunch of new screw holes in these joists going to be a problem?

Click to expand...

You will want to brag to all your friends about the work you did, this would just give them a chance for them to ask.:

1) The planks have almost no space between them in the area where the rotting occurred. But, it is not necessarily why the rotting happened. Even so, the reason for slicing down the planks a little is to promote evaporation.

2) It's just $50 to rent a table saw. I think I'm going to end up trying it.

3) I have looked up ways to make a circular saw into a table saw, where you screw the saw to a big board and turn it upside down and use a zip tie on the trigger and the on/off button of a power strip to turn the saw on and off. I think renting is the better way to go.

If slicing a little off of each plank doesn't work, I may use your idea of ripping one down and just scooting them over. However, since they aren't going to be wedged together, and since some of them are bent, it may end up being difficult to get the planks to lay nicely.

SFLman said:

1) The planks have almost no space between them in the area where the rotting occurred. But, it is not necessarily why the rotting happened. Even so, the reason for slicing down the planks a little is to promote evaporation.

2) It's just $50 to rent a table saw. I think I'm going to end up trying it.

3) I have looked up ways to make a circular saw into a table saw, where you screw the saw to a big board and turn it upside down and use a zip tie on the trigger and the on/off button of a power strip to turn the saw on and off. I think renting is the better way to go.

If slicing a little off of each plank doesn't work, I may use your idea of ripping one down and just scooting them over. However, since they aren't going to be wedged together, and since some of them are bent, it may end up being difficult to get the planks to lay nicely.

Click to expand...

I said build a jig not a table saw.
Your choice.
cutting a warped piece on the table saw
Stand 8 ft away to try to support a 14 ft board, attempt to hold it tight to the fence as you cut it, the other end flops down causing a big curve over the table.
So now you need a table of sorts to catch the other end, a second fence of sorts to hold it tight to the first fence.
Or you build a jig out of a 2x10 and a couple chunks of 2x4.

As your boards were tight the space will have to be exactly what you cut off.
Put a spacer between the fixed piece and the loose piece
Where the curve is to hard to straighten by hand a 2x4 screwed to the side of the joist can be used as a lever to push it in tight to the spacer.

Constant measuring open space that is left to make sure everything is straight and will finish as required, some adjustment of the space may be needed.

The jig.
drill a hole in about the center in the front and back of the table on the skill saw.
Lay a 2x8 or 2x10 on the side of the deck, just about where your table is sitting in that last photo
Lay a deck board on top of the 2x10 and line that up with the out side edge
Lay a 2x4 beside that and screw it down to the 2x10
These pieces only needs to be about 3 ft long but longer is fine too.
Wire or zip tie the blade guard up out of the way.
Remove the deck board.
Set the saw on the 2x4 so the the larger part of the table is over the 2x4 and the blade is over the 2x10, set the blade depth so it doesn't quit touch the wood below.
If you are going to use 3" nail for a spacer, place one in front of the saw and one behind the saw tight to the 2x4.
Place a level or something straight against both nails.
Adjust the saw so the teeth of the blade are just touching that straight edge check both front and back of the blade and screw the saw down, double check the teeth are right.
Remove level and the 2 spacer nails.
Lift and lock the blade out of the way and replace the deck board along side the 2x4.
You have that little fence that attaches to the saw that you tried to use before
Set the in so it captures the other side of the deck board, not to tight.
Now you can slide the board thru and get a feel for how it will work adjust as required
Zip tie the trigger on the saw and lower the blade so it is cutting into the 2x10 about 1/8".
If you have a serge protector with a switch on it, that would be good to plug the saw in to.

You will have to come up with a plan too hold this in place as it will want to slide.
Remember, you will be looking at the wrong end of the saw when you are feeding the board in

I've pretty much convinced myself not to cut down the planks.

The joists are in fairly good condition, and the rotting was caused by bad structure design, not by the planks being too close together.

In however many years, whenever it's necessary, the part over the lawn can be cut away, and the part over the cement could be left for a little longer.

I'll think it over for a day or two and then maybe I'll close this project out.

That was my first thought, if you do that and end up with a joint over the beam, maybe caulking the crack for that one may save a problem