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condoowner 06-15-2013 07:29 PM

Small hairline cracks in fiberglass balcony
Hi, I cant believe that searching the web I could find nothing but forums discussing about boats and kayak stuff, but I have other problems with fiberglass.

I recently cleaned up my fiberglass balcony using only a brush and a garden hose, and I uncovered about 6 or 7 small hairline cracks. Obviously, I am worried about water going inside the balcony and rotting the plywood core which will require replacement of the entire 12x12 balcony ($$$).

Are there any techniques, products or methods to fix these cracks for good?

The structural integrity of the balcony seems intact so I sure hope its only cosmetic for now but I dont want the issue to evolve into something I cant manage.


WindowsonWashington 06-16-2013 06:56 AM

Can you post up a picture?

Is the surface available for a re-coating process with either something like a gel filler or something that we use to re-coat flat roof applications.

If it is not coated with some sort of UV stabilization agent (either integral to the material or a top dress coating), you are bound to get some UV degradation over time.

condoowner 06-16-2013 07:27 AM

1 Attachment(s)
The surface is flat and accessible as it is located near the end of the balcony but not too close to the railing, so I believe it could be easily repaired or patch.

I really dont know if the fiberglass has integral UV protection agent since the balconies are 8 years old and nothing has been mentioned to the first buyers. I asked the other owners, nobody knows. Lets assume not since I am in Quebec and here, sorry to say, everything is crap.

I can assure you that nothing has been done on the balcony. The previous owner didn't care much and didn't do any maintenance whatsoever.

Important to mention, the cracks are located in a low spot area where water usually ponds after rain and such. These cracks were unveiled after I brushed the dark deposits left by years of ponding and no cleaning..

Attached is a picture of the crack.

I wonder if its still under warranty? Would fiberglass deckings have a 10 year warranty? Ill check my documents in the meantime.


condoowner 06-16-2013 12:30 PM

I went to a local home improvement store and they only had 2 products capable (according to the teenager working there...) of fixing the FG balcony.

One of them was a 2 part liquid. Cant tell exactly what it is but I believe it is some kind of resin that once mixed will cure and harden. The instructions recommended to sand the are to repair with a 80 grit sandpaper.

The FG cloth was sold separately.

The other product was more or less a all-in-one kit with the 2 parts liquids, the FG mesh, a spatula, etc..

Whatever I end up using, it needs to be very close to the original deck color (light clay/grey color) and shouldnt show up as a thick layer which will be apparent...

Ideally, since the deck is neither perforated or broken thru, I think only a resistant resin to fill the hairline crack in the gel coat would do.


nealtw 06-16-2013 09:49 PM

Fibreglass is just a glass mat and a resin that is two parts, once mixed you have a limited amount of working time.
Find a store that sells this stuff. They will give you instuction and match the colour for you. Get the instruction and do perp work before you buy the material. Usually you want to grind it down to the wood to make sure it is stuck to wood, if there are voids, grind some more, the patch may be bigger than it looks, and everthing has to be really dry when you put the new stuff down.

condoowner 06-18-2013 03:45 PM

So I went ahead and did pretty much what you guys suggested. The cracks (most of them) were not all the way down to the plywood. The largest as shown on the picture above, had propagated all the way to the plywood but was pretty much the only one.

I used a dremel tool and gouged the cracks to remove them. Then I used a 2 part FG resin and gently coated the cracks going about 1/2" outside of the crack. I think this may work.

Now my problem (and I suspected it would happen) is that the resin being fairly transparent (kinda maple syrup colored), now you can clearly see the gouges and the resin being darker than the balcony creates a nice dark spot.

Whats my best way to hide the repairs permanently (kinda)? Paint??

nealtw 06-18-2013 04:37 PM

That's why you find a supplier that can match the colour for you, and if you didn't lay some new glass over your patch it won't last. This wants to be scived back about 6" on each side of the crack in a taper to the depth of the crack. When you find a supplier he will have samples to show what you need to do. When I said grin it out I was thinking a belt sander or an angle grinder with 36 grit sandpaper.

nealtw 06-18-2013 05:28 PM

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