We have T1-11 siding that is looking the worse for wear: some rotted
patches, some delamination. I don't know what is underneath it -- just
What would be involved in replacing it by Hardie-Plank? *Not* installing
the H-P over the T1-11. Insulation between the joists, plywood over the
joists, then Tyvek housewrap, then the Hardie-Plank?
Would it be possible to replace one panel at a time, or would I (or a
contractor) have to do a whole wall in one go?
Am I missing anything?
Seems reasonable to do what you are proposing, The big question is what do you find when you remove the T1-11???? One problem doing it panel by panel is the Tyvek wrap will be in a lot of smaller pieces, not one continuous piece.
T1-11 is typically nailed directly to the studs. In addition to it's
function as siding, it also serves a structural function as sheathing.
Basically, it provides diagonal reinforcement to prevent the wall from
racking, and it ties the wall together (top plates, studs, bottom plates)
to hold the building together in earthquakes or strong winds.
Hardi-plank (or any horizonital lap siding) by itself will not provide any
kind of structural strength.
The best solution would be to repair the areas that are rotted or
delaminated with new sheathing the same thickness as your T1-11. Then you
can install your housewrap and siding of your choice on top of that. It
will be less work and your building will be stronger.
On Mon, 22 Jun 2015 04:50:28 +0000 (UTC), HerHusband
Good to know.
If you don't put another layer over the T1-11, you should know that
there are 2, maybe 3, maybe more patterns to T1. The grooves vary in
width, and maybe some other dimension is different. Home Depot had
the one that didn't match but Lowes matched perfectly. There are other
suppliers too. I'd certainly want it to match, even if I were covering
I got the roofer to replace one piece of T1 which had been damaged by
the sun and too little restaining. I had painted it the previous day.
I know that in the attic there is nothing underneath, but somehow I
don't remember seeing that.
I see that I did write "Hardie-Plank," but I meant "Hardie-*Panel*" --
4x8 or 4x9 sheets. (It was getting late, and I was suffering from an
excess of hemoglobin in my caffeine stream.)
That would be quicker and cheaper, but there wouldn't be the
additional(?)* insulation. And maybe there are sections of the T1-11
that have not yet revealed their crappiness.
*Is there any insulation at all there now? I have no idea. And there may
be some kind of subsidy or tax credit for beefing up the insulation.
I believe Hardi-panel is rated for structural sheathing if you follow the
manufacturers specific nailing instructions. That said, I've read several
reviews questioning it's strength (it's just a compressed cement fiber
board after all). I wouldn't want to risk it myself.
You could drill holes top and bottom of each stud bay and blow in
insulation. That's fairly standard practice for retrofitting insulation in
older homes. Then install your new hardi-panel over the T1-11 when you're
It shouldn't take too much time to walk around the building and evaluate
the siding. Certainly less effort than removing and replacing it all.
On Sunday, June 21, 2015 at 10:00:49 PM UTC-4, Percival P. Cassidy wrote:
If there is no sheathing beneath the T1-11 and you add it and
then siding, I'd consider what that does in relation to windows,
doors, etc. Assuming the siding is the same thickness, then you'll
be built out an additional 5/8". IDK if they typically put up
T1-11 with sheathing underneath or not. You'd certainly have
better protection against water getting in with it.
Hmm... Good point, I forgot to consider that.
On the other hand, the windows and doors probably have flanges that are
nailed to the existing T1-11. Replacing the siding would require the
removal of those windows and doors, with the associated caulking, flashing,
interior finishes. etc.
It would be easier to leave the existing siding in place and flash/trim the
windows as needed to accomodate the extra thickness. I would probably build
wood frames around each window then butt the new siding up to the frame. If
the window ever needed to come out you could simply remove the frame
without damaging the new siding.
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