Hardie board install question

[daddo]

My BIL has an old portable building (16 x 12) that needs new siding. It has the old panel T11 fiber type that is warped and rotted some. He doesn't want to remove the old siding, but just vertical strip 1 x 4"s on the 24" centers and nail up the 8.25" Hardie board. 

Is 5/16" Hardie going to be ok with this or does it need full backing?

[crokett™]

I don't know. I think it needs full backing. Why doesn't he want to install it straight over the existing T11?

[Stwood_]

Hardie normally stays straight and true. But I've never seen it spanned.

[K. L. McReynolds]

When I last worked with Hardie products(lap siding), we installed it directly on 1" thick hard foamboard, which was screwed to OSB sheathing, with screws. This was in 2005 or 2006. Back then, if the material was soaked by water on the ends, the material absorbed the moisture and swelled a little.

If I were doing what he is considering, I'd pull the old siding----adding over it just encapsulates the problem areas---and they keep rotting. Kinda one of those do it right, or do it over things.

[Mr_Mike]

I would pull the existing T-111 and replace with Hardipanel. Looks just like T-111. Takes paint well.

I did that on my pool house since its next to water. 12 years and the paneling looks brand new. Hardi also makes 1x4 cement trim. Makes the building look water proof. Of course, studs and sill plates are still whatever they were and as rotted as they were.

[EricU]

I think it would be worthwhile to read the application guidelines.  I wish I had on my shed, had to go back and put more studs in.

[tomsteve]

from the installation instructions:
HardiePlank® lap siding can be installed over braced wood or steel studs spaced a maximum of 24 in. o.c. or directly to minimum 7/16 in. thick OSB sheathing. See General Fastening Requirements. Irregularities in framing and sheathing can mirror through the finished application.

http://www.jameshardie.com/d2w/installat...-us-en.pdf

[daddo]

Thanks.
I got with him and talked him into pulling the siding, adding studs to 16" centers and using Hardie 4 x 8 panels. Insulation is cheap- re-insulate.

[rwe2156]

I have a fair bit of experience with Hardie planking.

What you're doing is fine, but I would put house wrap under the siding. You can use thermoply sheets in lieu of battens

I prefer to screw the sheets, but if you nail, but sure to use spiral or ring shank screws.

I don't think you necessarily need to remove all the ply, just the rotted part. Then wrap if there is none underneath, and use 2 1/2" screws or nails directly into studs.

[daddo]

I have a fair bit of experience with Hardie planking.

What you're doing is fine, but I would put house wrap under the siding.  You can use thermoply sheets in lieu of battens

I prefer to screw the sheets, but if you nail, but sure to use spiral or ring shank screws.

I don't think you necessarily need to remove all the ply, just the rotted part.  Then wrap if there is none underneath,  and use 2 1/2" screws or nails directly into studs.

 He has a lot of 30# felt stored away.