How Flat Is Enough? - Windows, Siding and Doors - Contractor Talk

How Flat Is Enough?

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Old 05-12-2015, 11:02 AM   #1
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How Flat Is Enough?

I have a house with 2" Roxul IS installed on the exterior, continuous. 1x3 furring screwed thru insulation into studs, and then Hardie (most likely).

The roxul is cool stuff, first time I've used their rigid product. Quite strong under compression, but the furring can be adjusted inwards a bit. So I do have the opportunity to flatten the walls, just by adjusting the tension on the screws thru the furring.

I'm not normally a sider, so the question is, how flat is flat enough to make a good substrate for the siding? +- 1/8"? 1/16"?

It's for my own place.
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Old 05-12-2015, 11:41 AM   #2
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Re: How Flat Is Enough?

We recently did a project like this using roxul called Maison Reciprocity look it up. But I was def difficult getting that pretty even for siding out a string on it and get it into planar relation.


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Old 05-12-2015, 01:53 PM   #3
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Re: How Flat Is Enough?

Not sure what depth is acceptable and even if you get it perfect there is the chance that the studs will dry out and bow anyway. I would spend most of your time on the walls with large areas of siding that have few or no fenestrations. Short walls (less than 12') and walls with windows and doors are harder for someone to eyeball and notice deficiencies in the flatness of the wall.
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