Question about Siding and Sheathing in a house

I will be having my house re-sided with either cedar lap siding or cedar shingles (currently it has cedar shakes that are poorly installed (not sufficient overlap.) I have several questions.
#1--the sheathing underneath is shiplap (looks like 1x8 boards). Is this significantly less strong than plywood sheathing? Would it be worth my effort to have a layer of plywood installed over the top of this shiplap sheathing? Also, this shiplap sheathing is installed horizontally...I've heard its supposed to be diagonal...is this a bad thing?
#2 When the siding people are installing the siding (and possibly plywood), how on earth can they avoid the posibility of piercing a wire or plumbing fixture?
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joe said: the sheathing underneath is shiplap (looks like 1x8 boards). Is this significantly less strong than plywood sheathing? Would it be worth my effort to have a layer of plywood installed over the top of this shiplap sheathing?

Also, this shiplap sheathing is installed horizontally...I've heard its supposed to be diagonal...is this a bad thing?

When the siding people are installing the siding (and possibly plywood), how on earth can they avoid the posibility of piercing a wire
or plumbing fixture?

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If the old shiplap is in half decent shape I would not rip it out and replace it. It is almost twice the thickness of 1/2" plywood and is a far stronger material. A vapor barrier might or might not be called for based on what is under the shiplap.
If your plumbing and wiring are installed as they should be no nail can reach them. I doubt that a nail longer than 1.5" will be used for the siding so even if wiring and plumbing are not 100% right the chance of hitting something are very small.
Colbyt
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How old is the house? Is it plumb and level? If it has lasted a few years without significant problems, it's clearly o.k. for local conditions.
I leave the answer to someone with more experience, but I understand that cedar needs special treatment: compatible flashing material and installation to let it dry from behind.
I think you are concerned about nails going into the wall cavity and doing damage... Choose nails carefully and that will help. There are no guarantees.
TB
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First off, cedar siding comes in various thicknesses. Don't get the thin stuff like on my previous house. It cracks all over. In fact I don't know why anyone would get cedar at all. Too much maintenence. Go with cement board.

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I wouldn't replace the sheathing unless it is damaged or rotted, and then I would only replace the bad bits. You might want to consider some sort of vapor barrier if there isn't already one there (tyvek is good) between the sheathing and siding.
the nails shouldn't be a problem because they should not penetrate beyond the sheathing....
--JD

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... what the others have said so far: ditto.
Definitely think of a vapor barrier (Tyvek or equivalent) while you have the siding off. Also, if you live in a climate where it gets cold for any part of the year, consider adding some polyisocyanurate insulating foam board before you put up the new siding.
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Check out http://www.cedarbureau.org /
great information there.
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joe wrote:

budget wouldn't break the bank...Tyvek is decent, but for the same price I recommend a product called typar. It's a lot more tear resistant during the installation process, but more importantly the tannins in wood siding or wood shingles drastically reduce the surface tension of water that might get through the siding (even with proper installation) with wind driven rain or through capillary action, rendering tyvek nearly useless. Typar is the only one of the largest 5 housewrap competitors to pass in independent testing (ASTM D-799) when used with alternate home cladding (stucco, wood shingling). also gives a decent amount of energy conservation the the house (35% or so for heating, 15 or so for cooling)...if you want some info feel free to get in contact...
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joe wrote:

budget wouldn't break the bank...Tyvek is decent, but for the same price I recommend a product called typar. It's a lot more tear resistant during the installation process, but more importantly the tannins in wood siding or wood shingles drastically reduce the surface tension of water that might get through the siding (even with proper installation) with wind driven rain or through capillary action, rendering tyvek nearly useless. Typar is the only one of the largest 5 housewrap competitors to pass in independent testing (ASTM D-799) when used with alternate home cladding (stucco, wood shingling). also gives a decent amount of energy conservation the the house (35% or so for heating, 15 or so for cooling)...if you want some info feel free to get in contact...
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