Garage Siding Repair

[cls89]

Plan on making some repairs to the fiber cement siding on my detached garage.

Problem
1. Not enough ground clearance between the bottom edge of the siding and ground. About 2-4” of ground clearance depending on where you measure. See attached photo.

2. No Z flashing to help keep moisture out

Solutions
1. To address the ground clearance problem, saw a horizontal line to cut away the bottom 6-8”,

2 Slide painted aluminum Z flashing up behind the siding and put a PVC skirt board on. See attached diagram for visual.

Questions
1. When I install the Z flashing, do I need to shim out the siding to help with drainage?

2. Are there any flaws with my approach?

3. Any other actions i could or should take?

4. Should I put crushed stone / river rock around the perimeter of the garage to help with drainage?

 

[jack stand]

I believe that you'll need 2" of clearance (might be 3") between the Z and the bottom edge of the hardie to be in installation compliance.
I don't know how they've managed to talk people into this as an exterior siding product that's basically only water resistant (for a short time) at best and there's a installation or handling excuse for their warranty claims.

 

[cls89]

I believe that you'll need 2" of clearance (might be 3") between the Z and the bottom edge of the hardie to be in installation compliance.
I don't know how they've managed to talk people into this as an exterior siding product that's basically only water resistant (for a short time) at best and there's a installation or handling excuse for their warranty claims.

Fiber cement installation instructions show a 1/4" gap between the flashing and bottom and edge. See diagram below.

 

[jack stand]

That's a lot better than I remember they wanted. Is that hardie's drawing? I quit using or selling it because the customers didn't like the excessive gaps that was called for above any "splashing" situation especially with a wall above a step flashed roof.

 

[cls89]

That's a lot better than I remember they wanted. Is that hardie's drawing? I quit using or selling it because the customers didn't like the excessive gaps that was called for above any "splashing" situation especially with a wall above a step flashed roof.

Company is called Allura. Below is their installation guide.

https://sp.menardc.com/main/items/media/PLYCE001/Install_Instruct/A1503-Basic-Install-Panel-fnl.pdf

 

[Kpaige]

Your plan is very solid and with your style siding you don’t have to shim. Try to get the z flashing behind your house wrap if possible.
Very solid plan same thing we have done hundreds of times, we do that same thing on wall runs where shingles meet siding.

 

[cls89]

Your plan is very solid and with your style siding you don’t have to shim. Try to get the z flashing behind your house wrap if possible.
Very solid plan same thing we have done hundreds of times, we do that same thing on wall runs where shingles meet siding.

Thank you. The only other question I have has to do with the thickness of the PVC skirt board. I can purchase 5/16” thick PVC which would match the thickness of the siding, or I can do 3/4” thick PVC. The only concern I have with the thicker stuff is that it will stick out a little bit and still create a water shelf, but that’s what the z flashing is for so I don’t think it would matter.

 

[larry4406]

PVC really expands when heated by the sun and darker colors make it worse. Because of this, we use a product called Boral at the day job and rarely use pvc anymore.

 

[Kpaige]

And me personally would use 3/4” the z flashing takes care of the water and it’s going to be noticed so why not make it noticeable like trim.

 

[CraigStu]

Can you remove the siding below your cut? That will help some w/ offset at the surface. Yes, I'd do some stone. On our last house I found that just pouring the stone so I had about a 6in border I could then run the mower w/ the deck overhanging the stone a little. That was a lot easier than parts of the house where the previous owner had used landscape boards to contain the stone that were tall enough the mower deck butted against them. Of course that required a weed wacker to clean the grass edge. Which removed the stain he had applied.

 

[larry4406]

This is Hardy lap siding, Z-flash over white painted 5/4 pvc.

OP - ignore the flashing over the stone. You would have vertical flashing there against your slab edge.

 

[cls89]

This is Hardy lap siding, Z-flash over white painted 5/4 pvc.

OP - ignore the flashing over the stone. You would have vertical flashing there against your slab edge.

Thank you for sharing this. For the bottom edge of the PVC trim that interfaces the concrete, what do you mean by having vertical flashing against the slab edge?

 

[larry4406]

Thank you for sharing this. For the bottom edge of the PVC trim that interfaces the concrete, what do you mean by having vertical flashing against the slab edge?

 

[Kpaige]

This highly depends on how the building is built.
In Mn you would never extend flashing out like that as the slab fluctuates and moves.

 

[larry4406]

This highly depends on how the building is built.
In Mn you would never extend flashing out like that as the slab fluctuates and moves.

OP is asking how to edge band his slab with PVC or similar and how to install z-flash above so as to fix bottom rot. That was the purpose of me posting a similar picture and saying ignore the horizontal flashing.

In my case, I have the angled flashing below the PVC to kick out water on top of a sloped stone capped patio wall. What I have is very typical of how siding would transition to rowlock brick or stone. The OP would not have this.