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Please help with my board on board external wall design

I'm in middle Georgia - zone 3 mixed humid climate with 2565 heating degree days, 1948 cooling degree days. I'm building a 1600 sf house on a slab on the last lot of an old community of board on board cedar patio homes. The inner boards were 1x8" and the outers 1x6" overlapped 1" so the widths all looked the same.

They were nailed directly over let in blocking with no sheathing.
They suffer from air infiltration and require repainting every 4 to 5 years.

My builder and I want to reproduce the look using fiber cement siding. There's a HOA so I have to match pretty closely. I've read everything I could find online and am grateful for what I've learned here, in spite of my head swimming.

We came down to deciding between 4x8' hardi-panel with faux 1x6 Miratec battens, or 8 1/4" Hardie-plank lap siding installed vertically with the same 1x6" Miratec battens . Each of these to be installed over 2x4 studs and 7/16" OSB then housewrapor felt..

The builder's sub wanted to nail the 4x8' Hardie-panels directly to the OSB while I felt we needed an airsapace. Framers here aren't used to installing cladding over furring and I have to weigh the cost of financing their learning curve against the benefit I would get.

We're leaning toward 8 1/4" hardi-plank installed vertically covered by 1x6" Miratec battens overlapping the Hardie-plank by 1 1/4"' which will match the neighborhood after painting. That would leave 3 1/4" channels behind the battens which I'm hoping would be adequate to vent the wall.

This is a long way from the vision of a 2x6" stud wall with advanced framing, exterior foam, and furring master metal furring I began with, and not as energy efficient as I had hoped. But I've pulled my hair out given this constraint of matching the board on board look, complying with Hardie's attachment recommendations, staying in the neighborhood price range, and my own limited budget.

I could use some expert advice. Given the constraints, will what we've proposed work? Is 15 lb felt preferred over Tyvek? Leave the back of the Hardi-plank unprimed or not? Is incurring the cost of outsulation worth it in my zone? Better ideas welcomed!

Thanks in advance,


Asked by Jay Apalachi
Posted Aug 13, 2011 9:03 PM ET
Edited Aug 13, 2011 10:28 PM ET


2 Answers

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With vertical siding you are going to want horizontal nailing, and what could be more perfect than battens nailed across the framing? It would be quite easy to install foam outsulation, install felt over that, then nail 1x3 across, hitting each stud. That will make the siding install a piece of cake.

I don't see the benefit of installing 4x8 sheets of Hardie, and would use the 8" planks.

Answered by David Meiland
Posted Aug 13, 2011 10:43 PM ET


I live just north of you, Jay. We're in a little drought now, I know, but I wouldn't feel good about building without the rainscreen, especially if you're going to seal the house as much as you can. You know that drought is going to end! Good luck with the project.

Answered by 5C8rvfuWev
Posted Aug 14, 2011 10:54 AM ET

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