questions about composite decking

[Duffield, SASS #23454]

While the lockdown is in place, we have decided to replace our wood deck with composite decking.  

Mamma wants me to put the new decking on top of the existing deck, rather than remove the old boards and put the new ones on the old supports.

Can any of you who have experience building decks with composite  advise me on this?  It just doesn't feel right to not remove the old boards. 

They are not rotten, the paint/stain wears off in about six months.

Are there any brands of decking that I should avoid?

 

Thanks,

Duffield

[Tom Bullweed]

I would think that moisture trapped between the existing wood and composite overlay would expedite rot and mold.

[Badlands Bob #61228]

The stuff the sell around here is called Trex.  There are several brands.  It's about 4 times the cost of pressure treated 5/4" decking boards.  I recently priced them to replace the decking on a 16'x16' deck and it was close to $2,000 just for the composite decking.  If you want your new deck boards to lay flat, you must remove the old ones.  It's a good time to inspect your framing at the same time.  

[Doc Shapiro]

Remove the old ones.  Otherwise you're gonna get a host of problems and end up doing it anyway, with 3x the labor.

 

[Tennessee williams]

Plus one to the the pards above... Yes, remove the old boards no matter which new ones you choose. Overlay will greatly increase the speed at which the old boards will rot. 

[Michigan Slim]

The truth has been told above. One thing that hasn't been mentioned is to use quality fasteners. Putting in a nice, expensive deck and having your fasteners rust would suck.

[sassnetguy50]

It is a personal choice:

How set is Mamma on this idea and how will that affect your life?

How will your body handle the extra labor?  Doc Shapiro has the labor correct but didn’t mention the added material cost and potential injury.

[Badlands Bob #61228]

And don't use the standard phillips head screws to put the new decking down with.  The phillips heads will strip out driving them into the dry/hard framing underneath.  Use the star drive screws.  Home Depot has them and they usually come with a star drive bit.  They are also much easier to remove in 10 years when you have a deck board go bad or split.  

[Trigger Mike]

I once looked at a dock with composite and it was scalding hit in the summer verses wood but last much longer

[Major General Shagnasty]

Keep the wood deck and get a better quality oil stain. If you try to put paint over an existing oil stain you will be sanding the whole deck to get the peeling paint off the boards. I found out the hard way, I was off with some guys on a week end Harley camp out/ride and when I got back home the wife painted the deck for a church women's up coming tea party. Three years later it's all peeling.   

[Charlie Harley, #14153]

I’ve built three composite decks and wouldn’t use any other material.  Pay the material cost up front and enjoy much less maintenance and no splinters on your feet.

 

Remove the old boards first for reasons discussed above.

 

They make a screw specific for composite decks.  No need for pilot holes.

 

Trex has a system where you don’t need screws through the boards. The boards’ sides have a slot and a special inter-board fitting is used. It works very well, easy to install, and looks great.

[Pat Riot]

Tennessee = Humidity and Rain

 

Definitely remove the old wood. 

[Duffield, SASS #23454]

12 hours ago, Doc Shapiro said:

Remove the old ones.  Otherwise you're gonna get a host of problems and end up doing it anyway, with 3x the labor.

 

That is about what I thought, but the boss needed convincing.  All of the replies have helped.

8 hours ago, Badlands Bob #61228 said:

And don't use the standard phillips head screws to put the new decking down with.  The phillips heads will strip out driving them into the dry/hard framing underneath.  Use the star drive screws.  Home Depot has them and they usually come with a star drive bit.  They are also much easier to remove in 10 years when you have a deck board go bad or split.  

That has been my experience.  I no longer use phillips  screws when star drives are available.

7 hours ago, Major General Shagnasty said:

Keep the wood deck and get a better quality oil stain. If you try to put paint over an existing oil stain you will be sanding the whole deck to get the peeling paint off the boards. I found out the hard way, I was off with some guys on a week end Harley camp out/ride and when I got back home the wife painted the deck for a church women's up coming tea party. Three years later it's all peeling.   

Repainting is definitely a consideration.  The boards are in good shape, and will probably outlive me, if we can find a paint that will hold up to foot traffic.  We have been using Sherwin-Williams deck stain, and it wears off in about six or seven months.  I am considering Seal-Krete Epoxy-Seal garage floor  paint.  

 

Thanks for all the replies,

Duffield

[Charlie Harley, #14153]

1 hour ago, Duffield, SASS #23454 said:

.  I am considering Seal-Krete Epoxy-Seal garage floor  paint

The epoxy won’t flex with the wood and will crack the first autumn. Concrete is much more stable than wood. 

[bgavin]

All the TREX installations I've seen have a tendency to sag between joists.
This tells me a closer joist spacing is required to avoid sagging.

[Eyesa Horg]

9 minutes ago, bgavin said:

All the TREX installations I've seen have a tendency to sag between joists.
This tells me a closer joist spacing is required to avoid sagging.

My deck joists are 16" OC and there indeed is a slight sag between them. I've been told 12" OC is a better bet. In this case though I'd just remove the old wood deck and replace with the composite. The sag is noticeable, but not absurd.

[Happy Jack, SASS #20451]

Sag with composite decking is a significant concern. You need 12" OC to prevent it. I was going to replace my decks with composite but I have over 900sqft and 24" OC support. Would cost a lot and adding in 12" OC supports will be a big issue. I am just going to replace the boards as necessary.

[Big Sage, SASS #49891 Life]

I have had a Trex deck for 15 years and love it. The only thing I do is wash it down.

 

It does have their fastening system that was mentioned. The only problem that I have had is several of the boards have pulled up during the winter when the moistures turns to ice, The expansion of the ice broke the composite material and the board was loose. I cut a 2x4 block and screwed it to the side of the joist underneath and added some waterproof glue to the top for the deck board to stick to, and it has been fine since.

[Eyesa Horg]

I just measured the sag in mine. It's about 40 degrees out and the sag is about 1/16th in the center between joists. Come summer it does get just a little more noticeable. For a 1/16th or so I wouldn't worry too much about sag on a 16" center system. My deck is just over 13 years old now. FWIW

[Red Wolf]

You definitely want to remove the old decking first.  As said before, you are looking at a host of problems if you don't.

 

I would recommend Azek brand decking.  It is a little more expensive compared to Trex, Fiberon and Wolf, but it is much lighter, easier and faster to install.  There are a few different ways to install the decking.  I've used the cortex plugs the most, but that can get old pretty quickly.  I would suggest the Camo fastening tool which self spaces the deck boards.  I would also use a self adhering membrane ie; ice and water before you put the new decking down.  16" spacing is acceptable for Azek, but for stairs you want 12" spacing.

 

Are there any railings that you have to work around or replace too?

 

Feel free to pm me if you have any questions.

 

Red Wolf

[Sarge]

Went through this two years ago.  Bought a tool called a Demo Deck removal tool.  Cost about $70 from the company I bought the new decking from.  Worth every penny.  Remove the old deck.  You'll alleviate a lot of problems later on.