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redmond12 · Jun 1, 2007, 11:18 AM

We are planning on replacing our 3 ft high deck with a concrete patio about 12" thick and 30 ft wide. If we had to do it we will have to pour concrete over the hardi plank siding. Talked to a couple of concrete contractors they said they will apply metal flashing and pour concrete over the siding and that it should not be a problem. Is it safe to do that? I am concerned, will it cause moisture problems in the inside of the house in the long run? Thanks for any reg. this.

ballengerb1 · Jun 1, 2007, 01:20 PM

First off you are using way more concrete than needed for a patio. 4' is good enough for a patio. 6" for a driveway. This would lower your patio 8" but if you need it higher use gravel. You need a better concrete guy. If he told you 12" he was taking your money and building a bomb shelter. Not a patio. Also, you don't pour up againist siding. The sliding should be removed, flashing installed and a spacer (celotex) installed.

redmond12 · Jun 1, 2007, 01:37 PM

Originally Posted by redmond12

We are planning on replacing our 3 ft high deck with a concrete patio about 12" thick and 30 ft wide. If we had to do it we will have to pour concrete over the hardi plank siding. Talked to a couple of concrete contractors they said they will apply metal flashing and pour concrete over the siding and that it should not be a problem. Is it safe to do that? I am concerned, will it cause moisture problems in the inside of the house in the long run? Thanks for any reg. this.

Thanks a lot for your reply. I had forgot to mention, it is 4" concrete and the rest will be crushed concrete. I was skeptical about removing the siding, flashing installed and a spacer (celotex) installed. Is it perfectly safe to pour concrete and gravel against this? Will it cause moisture problems inside the house after a few years? Also can you explain the purpose of celotex?

ballengerb1 · Jun 1, 2007, 01:45 PM

"Is it perfectly safe to pour concrete and gravel against this?" Which this, the siding or the celotex? Siding bad, celotex good. It will provide a slip joint between you home structure and the concrete pad. That pad will more ever so slightly as the seasons change but the house will not move.

redmond12 · Jun 1, 2007, 02:11 PM

Originally Posted by redmond12

We are planning on replacing our 3 ft high deck with a concrete patio about 12" thick and 30 ft wide. If we had to do it we will have to pour concrete over the hardi plank siding. Talked to a couple of concrete contractors they said they will apply metal flashing and pour concrete over the siding and that it should not be a problem. Is it safe to do that? I am concerned, will it cause moisture problems in the inside of the house in the long run? Thanks for any reg. this.

Thanks for the clarification. I meant over celotex. Does the same process of removing, flashing and spacing apply to lapbands as well? Also we will be closing up about 6 crawlspace vents from the back of our house, if we build the high patio, is it fine to do that? Do we have to install more vents else where?

ballengerb1 · Jun 2, 2007, 10:14 AM

You probably need more vents or add a power vent. You need air to flow and circulate to remove moisture coming up through the soil.

glavine · Jun 2, 2007, 06:00 PM

I Don't See A Problem With Pouring Up To The Hardi Siding, This Is The Concrete Siding Correct? As Far As Flashing, If You Had A Deck To Begin With There Should Be Flashing Already Installed Behind The Hardi Board,
And Ballengerb1 Is Right 12" Is Way Over Kill, And I Question How Youd Support That,
4" In Standard, If Your Worried About Crack You Can Have Some Fiberglass Added To It, And Yes To Vents