# Bubbling MDO panel.



## Teoli (Feb 27, 2010)

Guys I need a little assist on a paint job I did three years ago.

You can see from the pics where it's starting to bubble. The horizontal pieecs are Azek but the larger panels are MDO. A resin impregnated paper over ext. grade plywood. 

I primed everything with a BM oil primer over all surfaces, back, sides, front. Everything was then painted with a regular ext. grade laytex BM paint. Then caulked with Solar Seal. 

Now I'm having this issue. 
How do I approach this? Peal off bad section/ sand / reprime / paint?

Can I cover with a wood filler? a patch of 4" by 6". Will it last?

How did I screw this up?

Thanks.


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## Pete'sfeets (Mar 20, 2011)

Groovy an opportunity to gripe at the carpenter, the reason it peeled , let's do that first, where is the drip edge, it particularily bothers me to see the weakness in todays wood workers, you can use a metal one or you can cut one with a router, it directs the water to drip instead of rolling down the surface, beveling the top edge of an otherwise square edge also helps to cut down on dry rot in the corners on the bottom, that's next years fix. Backpriming trim that might get exposed to elements if the caulk fails or the trim warps because there are no grooves in the backside of the trim , you know that old time workmanship no one would seem to cost out. As for fixing, I'd try razoring out the loose till there is fixed material, apply automotive bodyfiller the non strand kind, plain stuff and when it stiffens up say five minutes use a scraper to shave it smooth, two coat it so there's no roughage, then I like the MH or dyna patch, it is like a super fine plaster but for exterior, then prime and paint, after five hours, caulk it with exterior type caulk.


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## Pete'sfeets (Mar 20, 2011)

sorry I see there is a rounded edge on the bottom , my bad.... guess I got excited Crap backprimed too! I really don't read much anyhow the drip edge is missing , hope the close to the ground part was considered


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## Teoli (Feb 27, 2010)

Good start. I'll look into a small router profile that I can run under the trim where the drip edge should be. I did give it a slight incline when I put it in. Obviously not enough.

Everything was backprimed....thoroughly. I'm not a painter, but that much I do know. 

The "bondo" idea I'm hesitant about. Theres two sides to that fence. Some say it will pop out because it doesn't expand/contract at the same rate as the surface it's on. But thats why I'm asking.

Not familiar with MH or Dyna Patch. I'll have to google that.

Then....Clean, Recaulk, make it pretty.

Thanks.

As far as the weak woodworkers. Well, thats why I used Azek for the trim. I've never had issues with MDO before. Next time if they can afford it, I'll make it all Azek.


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## Pete'sfeets (Mar 20, 2011)

I use the bondo all the time for the rotting wood, they sell architectural stuff at about fifty bucks a quart but the 14 buck bondo works too, unless you have a historical building I say nuts to that. Sometimes the paint primer does have a hard time sticking to the bondo, it's so hard and oozes a residue but the fine exterior plaster kinda takes care of that. Don't beat yourself up over the drip edge , just a wild guess, and the pine these days, being from new growth trees instead of the old type they used to have , I don't know that wood type, sorta red pine/fir but much harder to cut. It could even be that water have leached in from above the drip edge spot like sill and window corner, it happens. Yer a good sport , I love to rant!


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## jsheridan (Mar 12, 2011)

I think if there was something you did wrong generally, you'd have more than just that area. That's moisture. The sill and underside seem tight, but then again it only takes a pinhole over two to three years. Could some moisture be getting in at the top of the bay, running down the face board and getting caught on the top of the MDO. I think I see a little blister just above the Azek just to the right of the window. Moisture can travel a good distance internally sometimes before it makes an appearance. Or, could it be moisture transfer from inside? What's on the other side of that wall, a bath? You say primed all six sides of MDO, could it have been wet before priming? As to fixing, follow Pete's advice, however, I'm no fan of MH or any exterior patching compound (though I haven't tried them all). Everyone I've tried has failed. Bondo has about the best chance, I've found. I would also take a palm sander and feather out the edges after you cut to knock the profile down a bit, it'll help the patching effort. One thing I've done in the past on flat surface patching is to sink some holes on the perimeter of the patch (inside the cut area) which puts some patch footings down into the MDO, rather than just being superificial patch. Find the source of the failure and allow couple of weeks after to dry out. Good Luck.

PS I do rant on carpenters, but I cut you a break lol.


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## Leo G (May 12, 2005)

It is water. It got in there somehow. That is what you need to correct before you even decide to do the repair.


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## WarriorWithWood (Jun 30, 2007)

Find a moisture meter and check the level in the wood, I've seen that happen with a bad piece of MDO before (not saying thats the cause here). Honestly it looks like the piece wasn't edge primed so it sucked in the water. Whatever you do don't use car bondo on it, that will pop out within a couple freeze thaw cycles (it's formulated to expand with metal not wood). I would either use Abatron, Minwax (looks the same as bondo but formulated for wood) after cutting it back until you get to a stable coating.


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## MAULEMALL (May 16, 2010)

WarriorWithWood said:


> Find a moisture meter and check the level in the wood, I've seen that happen with a bad piece of MDO before (not saying thats the cause here). Honestly it looks like the piece wasn't edge primed so it sucked in the water. *Whatever you do don't use car bondo on it, that will pop out within a couple freeze thaw cycles (it's formulated to expand with metal not wood).* I would either use Abatron, Minwax (looks the same as bondo but formulated for wood) after cutting it back until you get to a stable coating.


 I have repairs that are 13 years old that look exactly as they did the day I did them..

If you aren't comfortable doing the repair get a big can and practice..

Make sure you mix correctly with the correct ratios ..


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## WarriorWithWood (Jun 30, 2007)

good for you, you were lucky.


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## jsheridan (Mar 12, 2011)

WarriorWithWood said:


> Find a moisture meter and check the level in the wood, I've seen that happen with a bad piece of MDO before (not saying thats the cause here). Honestly it looks like the piece wasn't edge primed so it sucked in the water. Whatever you do don't use car bondo on it, that will pop out within a couple freeze thaw cycles (it's formulated to expand with metal not wood). I would either use Abatron, Minwax (looks the same as bondo but formulated for wood) after cutting it back until you get to a stable coating.


Bondo was selling so much compound to the trades that they made a special blend for us. You should be able to get it at the store that sells Behr paint, or they may carry it lumber yards or hardwares.


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## Teoli (Feb 27, 2010)

After reading the following posts and doing some critical thinking I think I'm narrowing it down.

I know I primed every side. Not an issue so much.

I think this particular side of the panel gets soaked more than average. This may be due to the lawn sprinkler. Almost horizontal rain in effect. So I'm going to wait a few weeks until it warms up and I can really dry it out. 

Then I'm going to hit it with some heavy duty epoxy product. Drilling or carving out the edges a little deeper sounds like a good plan. It's expensive stuff but sounds like the best option.

The critical issue may be finding where the water is really penetrating. The sprinkler is probably killing me. Solar Seal is my favorite bombproof caulk. I'll have to really seal up the edges everywhere.

Then a fresh coat of paint and wait.


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## jsheridan (Mar 12, 2011)

I thought of another possible source of water infiltration, after you mentioned the sprinkler. Regardless of the source of the h2O, it's entering the structure somehow. I had an issue on a job where the water was rotting out the sills with no apparent means of entry. It was coming in through the window track where it sits on the sill, and it was occuring on the side that takes the windblown rain. The sprinkler may be throwing the water right on the sill and it's entering through there. To solve moisuture issues, you sometimes have to think outside the box. Just another possibility, you can see the pix here.


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## Teoli (Feb 27, 2010)

Well, I'm glad it doesn't look as bad as that photo on your site. 

The homeowner hasn't mentioned it to me yet. I"m doing some interior crown for him this week and just happened to notice the bubble as I checked on my old work.

This kind of stuff just eats me up. I never worry about my interior work. Exterior work is so unforgiving. I rack my brain thinking I should have replaced the existing tyvek when I had the old rotten plywood removed, or I should have put firring strips underneath to help it breath or any number of other fixes. AArrggg. 

Thanks for the help everyone. 

Now I need to look in the archives to see if I can find a good moisture meter.


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## JHC (Jun 4, 2010)

Leo G said:


> It is water. It got in there somehow. That is what you need to correct before you even decide to do the repair.


 I am betting on this one too. It looks like it got wet to me.


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## GPI (Jan 13, 2005)

Looks as if the water is coming from a little higher up, there is bubbleing above the trim just to the lower right of the center window.Recheck seal around window, maybe some wind driven rain getting in.


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## Leo G (May 12, 2005)

Come to think of it, this is really not your issue. This is a builder issue. If water is getting in there it is somehow built wrong. Caulk is not suppose to act as flashing and proper building technique. Unless this is on your own home then have the person who put it together fix it and then come out with your brush and paint it. Then hand them the invoice.


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## boman47k (Oct 13, 2006)

Last picture toward the wall with the vent in it, is that partial runs of caulk? 

A few places look like they have partial runs of new caulk. Maybe it is just the shadows.


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## Teoli (Feb 27, 2010)

boman47k said:


> Last picture toward the wall with the vent in it, is that partial runs of caulk?
> 
> A few places look like they have partial runs of new caulk. Maybe it is just the shadows.


Yeah, thats just shadows.

Tomorrow, I'll put up the "before" pics. They're on a different hard drive. They'll show what I had to deal with. It was really ugly. 

When I went back today. I felt the bubble. The plywood feels good. It's not mushy or soft. The paint has just separated. When it's warmer out I'll tackle this repair job.

Leo....The original builder did this addition about 8 years. He's long gone. When I put up the "before" pics tomorrow you'll see what I had to deal with. I vastly improved the look and build quality. But the unknown water penetration issue is what I'm dealing with. After the repair I'll repaint and recaulk thoroughly and discreetly. 

I'm thinking of maybe adding a small 1" circular vent in the repaired location to let it breathe. Any thoughts on that? At this point I'm not willing to take this all apart.


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## Teoli (Feb 27, 2010)

This is a pic of the bay window after I started to take it apart to see what was going on. 2+ years ago. As you can see he didn't prime anything. It all rotted out. Took a little less than 5 years.
There is tyvek underneath.

I cut out all of the bad sections from under the window sill and replaced with new that was primed all 6 six sides. I also replaced the trim with Azek and added little trim details I cut from 5/4x4 Azek to cover the corners vertically. I knew they would eventually open and the cancer could start. The Azek is great and will always look good.

Everything was thoroughly caulked and put together. Coated screws and galvanized nails.

The problem is my bubble. 

So...does the little vent sound stupid to manage airflow. After I cut out the bubble and fix with wood epoxy. The inside of the hole of course would be caulked.
I'll also caulk around the perimeter of the window. I honestly don't see much where water could get in. The other side of the wall is their dining room.


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## Warren (Feb 19, 2005)

What was the original cause of the damage? Bay windows are notorious for this kind of trickle damage. Most Tues the cause is higher up. It sucks, but I would net the water is sell getting in. Do a thorough investigation of the areas above before you redo that.


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## Teoli (Feb 27, 2010)

I thought it was just a crappy prep and paint job. Now I know otherwise. If it doesn't get a chance to dry out then you get what's in the pic. 
It's a cancer.


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## Pete'sfeets (Mar 20, 2011)

Wow look at all the moldy wood I thought you said YOU primed it. Someone else perhaps. Oh well I really liked the vent part. As for that little bubble ya we all live in one. Go ahead spend fifty bucks on a slow drying bondo , or by new plywood. A hardener could be used to stiffen up the dry rot wood, it isn't rediculously expensive it is sort of like a cement conditioner. I wonder if glue isn't such a bad thing. If you leave it to the average painter , he's going to use the same sort of caulk he has for interior jobs instead of caulk specifically meant for exterior and waiting four hours for it to dry is of course out the question since we are here to paint. I have hobbies but no time to do them.


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## jsheridan (Mar 12, 2011)

Check the window tracks.


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## Teoli (Feb 27, 2010)

Pete'sfeets said:


> Wow look at all the moldy wood I thought you said YOU primed it. Someone else perhaps. Oh well I really liked the vent part. As for that little bubble ya we all live in one. Go ahead spend fifty bucks on a slow drying bondo , or by new plywood. A hardener could be used to stiffen up the dry rot wood, it isn't rediculously expensive it is sort of like a cement conditioner. I wonder if glue isn't such a bad thing. If you leave it to the average painter , he's going to use the same sort of caulk he has for interior jobs instead of caulk specifically meant for exterior and waiting four hours for it to dry is of course out the question since we are here to paint. I have hobbies but no time to do them.


Just in case anyone is wondering the same thing..... The second picture I posted was a BEFORE work began picture. I removed all of the old rotten wood and REPLACED with new fresh properly primed / painted and caulked wood.

I would never put my name on a repair job using the old rotten crap.

Thanks for the help everyone. I'll post a pic of the repair in a few weeks when it's warmer and I can dry it out.


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## boman47k (Oct 13, 2006)

Is that tyvek showing from *behind* the wood at the bottom in the last picture?


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## Teoli (Feb 27, 2010)

Yeah, either that or typar. I can't remember which.


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