AskCodeMan

recently the home was stripped of old lp siding and replaced with Nichiha lap siding. It was extremely wavy and contractor tried to correct by face nailing with finish nails. Did not correct problem. The siding was going over rigid foam that was 18 years old. He also was ladder jumping causing foam to have holes and was not using guides on nail gun. Some nails were to close to top and others just missed. Stated he installed correctly according to manufacturer- he was told not to come back. Hired another contractor who removed siding and put up osb then wrap and siding went on straight with very little wave. Should the first contractor have known that the finished product would be wavy and that it would be unsatifactory due the ugly waving? How important was it to nail properly and use ladder jacks.? What other issues would have caused such a poor job from the first contractor? we realize some of the studs may have been a little out of plum (not many) but there were huge gaps under the siding and most were waving.thanks

From the Nichiha installation instructions: (place cursor over link, right click, select 'Open in New Window') http://www.nichiha.com/pdf/Installation ... R05.13.pdf

On the first page below Fig. 1: (underlining and bold are mine)
- When installing Sierra Premium Shake and Smooth boards, it is recommended that an APA rated 7/16” OSB or plywood sheathing be used. Boards may be installed over non-structural sheathing such as foam, fiber builder board, and gypsum type panels. Non-structural sheathing thickness should not exceed 1”. Due to the compressive nature of some non-structural sheathings, care must be taken not to overdrive the fastener and compress the sheathing. The fastener length must be increased by the thickness of the non structural sheathing.

The above installation guide also refers to the general installation guide: http://www.nichiha.com/pdf/Installation ... 007.08.pdf

This again refers to the use of "Ensure that an APA rated 7/16" OSB (oriented strand board) or 1/2" plywood is used."

Thus, while foam "may be" used, they highly recommend the use of a structural sheathing.

The first contractor "should have" - for good workmanship - shimmed the studs which were not in-plane with each other to make a straight in-plane wall to install the siding on. Most installation instructions state that the installing contractor is responsible for accepting the surface on which their installation goes or bringing it to the attention of responsible parties to address before installing their product, not afterward.

Thanks for the quick response
How important is the nail gun- pressure- etc in relationship to the wavy problem- would most contractors stop upon realizing that the finished product would be unacceptable due to being wavy and having gaps everywhere- what would most repitable contractors have done to resolve issue

Most reputable contractors would have found the cause and brought it to your attention, offering you several options to solve the problem, all at your expense, which would have been less expensive than doing it all over like you did.