Plan the trim for metal siding

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Forum topic by curliejones posted 06-30-2014 10:50 AM 1247 views 0 times favorited 3 replies Add to Favorites Watch
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145 posts in 1684 days

06-30-2014 10:50 AM

Topic tags/keywords: workshop build metal siding trim work j-channel

From hot and humid SE Louisiana. I’m planning to use sheet metal for siding two adjoining sides of a 4-sided building (OK – Thinking inside the box – a rectangular-shaped shop, I’m a dull boy!). I have used PBR panel in roofing applications but not for siding. I have a stick-built shop with 2×6 studs 16” oc, 7/16 osb sheathing, and horizontal stripping to provide an air space over the radiant barrier foil I applied to the outside of the structure. I now need to plan for a finished look with metal siding and want to safeguard against water intrusion during a storm. On these 2 walls that are to receive sheet metal I have a couple of windows and a ventilating fan, a passenger door (3’0” x 6’8”), and a roll up door that measures 6’wide and 7’ tall. – How do I trim and fit these into an overall neat appearance that keeps water out? Is J-channel the answer here? It does not seem that substantial. I plan to use roll flashing to protect the window sills, but I’d like to trim with hopes of never getting water behind the siding to begin with. – The other two faces of the building, other than sheet metal, will be vertically-nailed 12” wide cement board. I plan to use J-channel at the corners to start the sheet metal where it meets the cement board and caulk the joint. Since the two sheet metal-sided faces adjoin, I thought I’d use an outside corner trim (think metal building) there.
Along the rake wall (rear of the building) I need something to hide the cut edge at the top of the wall where it meets the soffit. Would this be J-trim again? The tall wall faces an even taller carport to be built later, but a top trim would be in order there also to minimize the openings at the top of the panel.
I’ll attach a picture (before horizontal stripping) showing the front of the shop. The left side (tall wall) and the rear rake wall are the two that will receive sheet metal. – Any advice or resources for learning that you may send me to are greatly appreciated.

-- Like Guy Clark sez - "Sometimes I use my head, Sometimes I get a bigger hammer"

3 replies so far

View Grandpa's profile


3256 posts in 2094 days

#1 posted 06-30-2014 02:33 PM

I have a metal shop and it has “J” channel around the doors. The man door leaked forever until I built a roof over it. The overhead doors never leaked. Did you make a pocket in the floor for the door to rest in. If not it will have water coming in under the door. My first thought was maybe he should change the overhead door. I bought a couple of overhead doors years ago. They were narrow like yours and they cost about $800 each. I could have bought a 8 wide by 7 tall door for about $250 in those days but we were locked in on that size. back to your original question. Properly installed “J” channel should work fine. Don’t make any extra holes in it and don’t rely on caulk at this point. Caulk is a last resort method.

Thanks for allowing me to be the first to comment…......

View DiggerJ's profile


69 posts in 954 days

#2 posted 06-30-2014 03:14 PM

Think of it like another roof, only in a different orientation. You would take precautions to keep water from creeping in around edges, pipes, valleys, etc. You CAN use the same logic around areas on a vertical face.

Some might talk of overkill or whatever, but if this is your shop…why not treat yourself to some longer term protection. You didn’t say what you are using for trim around openings, so I will speak generically. Areas that have potential for rain/storm exposure and only have trim layed in beside components (think J channel or F channel) can sometimes benefit from a flat or bent piece or coil or flashing behind them. Some people caulk between siding Channels and the door frames, but it is better to give the water a place to go. Water that is forced or runs down the groove between the channel and the opening frames will run down the aluminum and run our the bottom. Same can be done around the windows. It is cheap protection.

I had an old-time builder show me a trick for deck building that works with this principle. When building a deck, before you place your deck boards, roll a piece of 6” flashing down the joists and slightly bend the sides down a bit on each side of the joist. water that runs down between the decking boards will run off of the boards and off of the flashing and protect the wood under structure. Cheap, and works great. Since water loves to soak into the board edges, the coil wil protect it. Think of haw many decks have the supports rot from moisture continually soaking in. People will put sealer on the top of the decking, but the rest is still soaking up moisture.

It is really nice to hear the inspector say you have built the best deck they have inspected (I am not in the business), but even nicer to drive by it 25+ years later and still see it is looking great!


-- Digger -- If you work long enough and hard enough to make it idiot-proof...the world will build a better idiot!

View carlpayne's profile


1 post in 742 days

#3 posted 10-11-2014 11:19 AM

I have a 40’x60’ steel buildings colorado built 5 years back. It need regular inspection. Metal roof, metal sidings are not too tough but for proper foundation and insulation you will need a professional.

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