Jump to content


Filling cracks on an exterior patio deck

  • Please log in to reply
9 replies to this topic

#1 ehunter

  • Senior Member

  • PipPipPip
  • 348 posts
  • Joined: Mar-29 2008

Posted June 08 2010 - 9:22 PM

I had one guy tell me to use caulk... but I thought caulk was for joints only.
This surface gets a lot of California sun to expand and contract the wood.
My original thought was to just jamb up the cracks with the paint I will use
to finish the job. If the paint is too thick though it wont run into and fill
up the cracks. I don't want to thin up the paint, not much at least.
What kind of filler would you use... or how would you handle this?

#2 DerrickT

  • Way too many!

  • 51,489 posts
  • Joined: Mar-29 2007
  • LocationEphrata, Pa

Posted June 08 2010 - 9:34 PM

There are a couple of different routes you can go. Mohawk makes super glue, 3 different thickness that you could inject into the cracks to help prevent them from cracking further, then you could fill with wood putty which will eventually crack again or you could rub some wood glue in the cracks and sand the gule while its wet and dust will mix with the glue and create a putty filling in the cracks. Caulking it will fix it for a short time but I think thats eventually gonna crack again.

My nieghbor has wood post on his porch that cracked and he used bondo. That was 3 years ago and I think its still holding.

DMS# 2573

#3 CaptRandy

  • Senior Member

  • PipPipPip
  • 350 posts
  • Joined: Oct-20 2009

Posted June 08 2010 - 9:51 PM

Boards are screwed in, flip them to see how other side is.

#4 ehunter

  • Senior Member

  • PipPipPip
  • 348 posts
  • Joined: Mar-29 2008

Posted June 08 2010 - 10:56 PM

Bottom sides seem ok to me. There are some hairline cracks except I dont think they go all the way through the 1" plank as the grain of the wood is not tight there.
If the grain was tight, I could see maybe a crack following all the way through the plank. These cracks may be to due to pealing stemming from a lack of grain. (my non-expert opinion of course)

#5 mybeach

  • 5,000 Post Club!

  • PipPipPipPipPipPip
  • 7,775 posts
  • Joined: Dec-11 2006

Posted June 09 2010 - 12:14 AM

I've just done this to my deck, and removed all of the rotten wood around some of the screws, which of course left big holes.
I tried several different two-part putties, but BONDO was the easiest, strongest and cheapest. That stuff will outlast the deck.
If you are staining, then all bets are off. If you are painting, BONDO is the way to go. See my thread about mixing bondo for longer working time.

#6 speedracer

  • Way too many!

  • PipPipPipPipPipPipPip
  • 19,604 posts
  • Joined: Sep-12 2005

Posted June 09 2010 - 10:08 PM

The wood is in tension. When you fill a crack with putty or epoxy etc. you simply move the tension to another area, hence another crack. Using flexible Polyurethane caulk will allow the wood to expand and contract without doing any harm to the wood.

You're getting sleepy. ....very sleepy.....

#7 ehunter

  • Senior Member

  • PipPipPip
  • 348 posts
  • Joined: Mar-29 2008

Posted June 10 2010 - 2:30 PM

Well, my plan was to try the bondo on some boards and some polyurethane on others.

After trying the bondo, this process is just going to take too long. To do an 8ft board took 25min + mixing. I figure this would take me 2 days just to apply bondo.

After the bondo dried, it took 25 minutes to sand off so that the plank would not look worked on. So this sanding would take another 2 days to do a good job. I am not willing to put that kind of time in it.

I think things will go slightly faster with the polyurethane but not enough for me to make it worth it.

So what I am going to do is thin out some of the paint to the point it runs into the cracks and fills them. Then apply a much thicker cap on top. Then I will have 5 years more to think about how I want to do it the next time.

#8 gadwall8

  • Way too many!

  • 18,876 posts
  • Joined: Jun-14 2001
  • LocationUneverheardofitstan

Posted June 11 2010 - 7:07 PM

As was mentioned, filling the "cracks" only introduces a new fulcrum for the wood to check further.

Seal the ends (wood is like a straw) and let it be.

What you are proposing is shoveling merde against the proverbial tide- pardon my french

"I came into this world naked, screaming at the top of my lungs, and covered in someone else's blood. I got no problem leaving it that way."

#9 mybeach

  • 5,000 Post Club!

  • PipPipPipPipPipPip
  • 7,775 posts
  • Joined: Dec-11 2006

Posted June 11 2010 - 8:24 PM

I used it to fill holes where water had seeped into the screw holes and rotted the wood over time. I didn't fill cracks, per se, but I can see what you mean by the tension in the wood. Bondo works great as a hole filler, mix up small batches and apply with a plastic trowel. It hardly needs any sanding if you work it properly.
If you have rotted wood, you can blast it out with a pressure washer, or you can dig it out with a chisel and use the bondo to fill the hole. It's a very cost effective solution to patching rotted wood, and it will hang on to vertical surfaces without sagging when applied properly. It has been used for years as a wood repair product. I give it a thumbs up.

#10 Homer1

  • 1,000 Post Club!

  • PipPipPipPipPip
  • 1,035 posts
  • Joined: Jan-16 2010

Posted June 14 2010 - 6:38 PM

the cracks look totally normal to me; it's wood and it's outside- that is to be expected, and i wouldn't worry about it.