Repair Replace Rotted Cantilevered Balcony Deck

by Adam
(Port Washington, WI)

I have a cantilevered balcony deck that is in need of repair and replacing decking from rot.

The deck is approximately 4' x 14' on a house that I recently purchased in Wisconsin. The house was a foreclosure and wasn't maintained properly.

The decking (2 x 10 pt) was beginning to rot as well as the wood balusters. I started to tear off the fascia and deck boards and found some pretty good rot. The joists look pretty good for the most part with minimal rot, I think.

Couple of questions: is there any way to test the wood using a foolproof method to detect rot?

Also, I have been in talks with a sheet metal bender who suggested making "U" shaped caps to place over the top of the joists to ensure any moisture in the future won't penetrate the top of the joists. Is that a good idea?

Lastly, if the joists can be saved, I would like to find a good lightweight composite to replace the decking, any suggestions?

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Jul 14, 2013
Here are some suggestions
by: Editor - Rich Bergman

You are doing a good job of inspecting this deck.

Pay special attention to the ledger board because if it is showing signs of rot you have to replace it. And you also need to make sure it was connected properly to the band board of the floor deck of the house.

When you are reviewing the ledger board also take a good look at the flashing detail from the house to the ledger. Flashing should go well up under the siding and overlap the ledger board and and second piece ideally between the back of the ledger and the band board.

You really want a waterproof connection.

There is no foolproof way to detect rot in wood other than a good visual and physical inspection. Press any suspect areas with a screwdriver to see if the wood is soft and flaky or if there is mold. All of these indicate rot is in process.

Now once your review is complete you have to start thinking about replacing all the bad decking and joists and ensuring that they will remain dry and healthy for a long long time.

Thankfully there are several solutions for protecting the joists from rotting. Certainly having a custom sheet metal cap made is a great idea but you may be able to use something already made. I think the Rot Not product is a good idea. It no longer exists. Consider using joist tapes instead. One of the best is G-Tape.

Check it out here.

There are other solutions like just using 30# roofing felt in thin strips which is quite helpful. Find the strips is a bit challenging though and you would likely have to go to a roofing supply store.

Also you can use an adhesive ice and water-shield like the Grace or Blue Skin products. This are very good but probably on the more expensive side.

And then there are locking spacers that grip the joist and lock under each deck board so they never fall off and have a sloped top so all the water and debris drip away from the joist and do not accumulate in the space between the deck boards. This is a very affordable preventative option also.

Check out the Lock in Deck Spacers here and see a video on that page also.

So there are some very good choice available. The capping systems are excellent and a bit more money but great solutions. The adhesive wraps are very good. And then you have the lower cost spacer joist protection spacers.

Composite decking is inherently heavy and dense. The only exception I have seen to this are the hollow extruded types of synthetic deck boards. But they seem to be less common on the market.

Regardless, you are heading in the right direction with your repair and replacement strategy to give this old deck some needed tender love and care.

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