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LP Smartside panel over t1-11


Slalom's Avatar
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12-04-17, 10:36 AM   #1 (permalink)  
LP Smartside panel over t1-11

Hello,

I have a 1979 home in Minnesota with t1-11 siding over 1" rigid foam panels and 2x4 studs. I would like to apply matching LP smartside panels over the top.

1. Do I need to apply additional WRB between old and new siding?

2. How would I handle window and door trim and flashing to maintain water integrity.

thanks!

 
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12-04-17, 11:14 AM   #2 (permalink)  
Hard to say without seeing the house, trim, windows, etc. If the new siding thickness will not be built past the trim you will have to scribe everything to fit and caulk all the edges. Technically you do not need another layer of wrb if you already have one. But if any water gets behind your l.p. it might rot the t1-11 if there is no new web on top of the old.

Additionally you will run into trouble if you have an electrical meter mounted to the outside of the house since it can't usually be pulled away. Same for hose bibs and other fixed items. Going around A.C. lines is tricky. A lot of times it's best to block those areas off with a separate 2 piece mounting block (made from a non rotting material like Azek pvc) then just install the siding around the mounting block.

Best scenario would be to remove the t1-11 where possible... And if it goes behind something permanent (like an exterior mounted electrical service panel) cut the siding around the perimeter... trim the edges... Then side around it.

Depending on how your windows are trimmed, or you might need to retrim them.

What's the motive for leaving the t1-11? Is it one of those houses where there is no plywood sheathing behind the siding... only the foam?

 
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12-04-17, 11:23 AM   #3 (permalink)  
Yes it is only t1-11 over the foam. I will try to attach a photo. The current siding is original and cracking peeling on the south side.


 
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12-04-17, 11:26 AM   #4 (permalink)  
limited Photo of south side of home depicting window trim, deck etc.

https://photos.app.goo.gl/rMbEGWUbEWwl03233

 
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12-04-17, 11:48 AM   #5 (permalink)  
Yeah, that's about what I was picturing. If you have to leave the siding on (I would really recommend removing it) you will probably want to put on a new wrb, remove ALL the door and window trim, and extend those door and window jambs out another 1". Put new 5/4" window and door trim on... Put new z-flashing behind the wrb and over the top trim. Scribe all the siding to fit around your trim. Remove all corner and soffit trim, and if you are using lp panels, apply new 3/4" corner trim on top of the siding.

If you ever got new windows or doors in the future, the surface of the t1-11 (and wrb) would be the surface that your nailing flanges would be mounted to... it would be your new wall thickness. It's another reason you would add a new wrb over the existing siding. So that future windows could be correctly flashed to that wrb.

You would want to make sure your deck is flashed correctly and not fastened right over the top of the t1-11. If it is, you will want to remove some perimeter decking... and add new ledger flashing behind the wrb before you side. In some cases it's best to just use a skilsaw and cut 5 5/8" off... then add your flashing, blocking (add framing as needed) then put down a new 5 1/2" perimeter board.

 
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