Hardie Plank Over Old Ceder. Allowed?

woodworkbykirk

im getting ready to start a siding job on a house which currently has cedar shingles on it, were replacing the windows and doors,also doing blown in insulation into the wall cavitys. to me it makes sense to strip it all off and then tyvek, vertically strap then side. but the homeowner and general are considering skipping stripping off the old and strapping over the cedar in order to save time and money

i sent an email to james hardies customer service address asking the question if their would be any issues with going over the old and havent gotten a response ( 6 weeks ago).

any verdicts?

Teetorbilt

This would go to local codes and only someone from your jurisdiction would be qualified to reply.

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SLSTech

As Teetorbilt states - it is up to your building department

Assuming it is - The real question after that is it a good idea? What is the condition of the shingles, any rot, water intrusion, bows in the wall, etc... Those items might push towards removal.

There is nothing wrong with the strapping method but you have to be careful (like always) with the flashing & drainage details. I will generally always push hard for stripping it down to the sheathing & going from there just like roof shingles.

In your case - if you can't sell the GC on it & there is no code saying you can't do it, just get it done properly

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Markon

I always tell customers I do things the way I would do to my own house. Without a thought, I would strip it all off. Is this 4x8 or lap. If it's lap, no matter how much time you spend doing it correctly, it will end up looking like the ocean, full of waves. They want to go over it, they should vinyl it. Saving money has cost people a fortune.

neolitic

See, here's where I don't need a code book.
There is no way anything good can come
from making a rotten wood sandwich.
All other things aside, unless you are sure
that the moisture content of the old stuff
is near zero, there is no where for it to go
that isn't a potential problem.
Do it right, do it once.

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Jason Whipple

If I were asked to do this for a customer, I wouldn't.

Being that you're working for a GC that is calling the shots should take some liability of you if things go wrong. Make sure you get that in writing if you do it!

Assuming their is house wrap or tar paper under the cedar, a second layer over the cedar would be a bad idea. This would just trap the moister in the old siding and it will increase the rate that it will take to eventually rot, bringing along mold and insect problems with it.

If you don't put it on, Hardie will not warranty it. Read "best practices" on their site. It must be installed over some form of building paper so it has a drainage plain. The strapping is a good idea for all applications.

Even if you don't strip the siding, you'll still need to pull the trim (corners, rakes, and freeze) and fir those areas out as their own "special" condition so you can get everything on the same plain again. Thats gonna take some time to do and do it nicely.

The most they might save the customer is the cost of a dumpster or two. This installation sounds problematic to me.

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Historic House Restoration, Cincinnati, Ohio
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woodworkbykirk

i wanted strip it, my other guy wanted to strip it. we did blown in insulation in the walls last week in prep for it, tuck taped over the holes.

the gc said stripping the shingles would mean losing some r-value in the walls. as for another layer of building paper, were not doing that, just strapping straight to the shingles and pine clapboard on the rear addition, most of its good the only bad spots are over the porch roof where the cedar shingles were installed tight to the roof as opposed to 1 1/2' gap required by code.

im especially worried about things going bad because this is a regular customer with the general, i believe its the 5th or 6th job for the ho

neolitic

That is B/S, he's worried about
losing $ values in his wallet.

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genecarp

STRIP IT, stupid idea to go over, they will regret it

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Jason Whipple

Kirk,

Has anyone tested the moisture level of the existing siding? That would be a good place to start.

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Jason E Whipple, General Manager
Historic House Restoration, Cincinnati, Ohio
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Houston's

Down here Louisiana, i saw some hardi over vinyl siding.. very smart..

Driftwood

No, but i shake over hardy every day! Not in My world

WNYcarpenter

Find another employer! you're going to learn bad habbits. Good contractors do work the right way.

needthingsdone?

That's easy advice to throw out there...but unless things in WNY are better than most everywhere else... most of us can't just find a new employer at will.
How about adding something constructive to the conversation and help this guy make his case to the GC that he's working for now.
Just my .02

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woodworkbykirk

[quote=WNYcarpenter;509933]Find another employer! you're going to learn bad habbits. Good contractors do work the right way.[/quote



trust me its something that has crossed my mind, somedays the first thing i say to myself is "why the does he want me to do this, that way. its not gonna work its gonna be a callback", when i do things my way we have happy customers and only get called back for additional work. and the worse part is, he says he doesnt understand why he can only get jobs in the high end homes once and a while as opposed to all the time like he says he used to. is he full of bs or

hes getting ready to retire and just doesnt care anymore. as for me i think he's hoping ill take over when he does but i also have a few high end contractors who want me on site yesterday theyve seen my work on high profile jobs so....