Help- Varied Flagstone patio foundation


  #1  
Old 10-31-05, 07:20 AM
Krusty
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Help- Varied Flagstone patio foundation

I have an existing porch with a concrete slab foundation and want to have a flagstone porch/patio that extends beyond the concete foundation under the covered porch. The uncovered portion of the new flagstone patio will be on concrete (from an old sidewalk) and dirt.

I want to elevate the flagstone patio/porch approximately 10 inches above the exisiting concrete slab.


Since I have a varied foundation to start from, I need help deciding on what material to use to raise the entire space.

Can I use crushed rock to elevate the entire footprint approximately 6 inches. Then 2 inches or so of masonry sand and then mortar the flagstone on top of that?

Some of the crushed rock will be on concrete and some of it will be on dirt. I Will there be any issues with this approach? Suggestions?

Thanks!
 
  #2  
Old 10-31-05, 09:09 AM
Join Date: Mar 2005
Location: USA
Posts: 5,650
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Help- Varied Flagstone patio foundation

You will probably have differential settlement between the area on concrete nad the area on dirt. No matter how much you compact the base you put on top of the dirt there will likely be cracks in the mortar between the flagstones.

Have you considered not laying the flagstones with no mortar between them?

Dick
 
  #3  
Old 10-31-05, 10:34 AM
Krusty
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810 crushed sand

Someone suggested I use 810 crushed sand to build up the patio. Is that ok?
 
  #4  
Old 10-31-05, 11:13 AM
Join Date: Mar 2005
Location: USA
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I do not know what a 810 sand is. That must be a local/state specification.

Any base material must be compacted well. The sand for a setting bed should be 1" to 1 1/2" thick.

If you use mortar, you expect a crack when you go from the base on concrete to the base on dirt.

Dick
 
 

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