What do they mean when they say “Not rated for structural use” ?
I am building a 3500 sq ft workshop with 16 ft walls.
I had planned to “cheat” a bit … no OSB … just put T1-11 right onto the 2 x 6 studs (Z trim between the two sheets).
Lowes offers two “LP SmartSide 76 Engineered Panel Siding” chooses.
One is $41 and says not rated for structural use.
The other has exactly the same specifications (thickness .. warranty … ) but is $59 and says “rated for structural use”.
What is the difference?
Does this matter in my application?
Home Depot offers a “DuraTemp” version but it is “real” plywood and gets bad ratings as far as warp … but it is only $33 a sheet.
Any suggestions ?????
Mike
Replies
It means that it has not been tested and approved for use in structural applications. Check with your local code authority before you do it. Depending upon what your region approves you may possibly be able to get away w/out plywood by using let-in wood or steel for wind bracing. Back in the 90’s it was quite popular to use rigid foam for sheathing, so let-in was used a lot. While it would probably take a lot of force to bring a wall down with your siding, it really isn’t that hard and very cheap to let-in a diagonal brace.
Awesome!
I remember working on a house that I saw this done ... wondered why since I had never seen it before.
SInce they offer the siding in both rated and non rated, I guess I could also use the rated just on the corners (I remember using plywood rather than osb o the corners of the last house we built.
Thanks !!!!!!!!
Mike
I do think the structural siding might be thicker than the non-rated, but I haven’t installed the stuff in awhile so might be wrong.
Hello, I have a bit of recent experience with this, so here are some thoughts:
I just replaced an addition on my house. The previous one was built in (i think) the 80s? It was done this way, 2x4 framing, T1-11 sheeting only, z flashing between sheets.
Why did we replace? Long story short, it was in terrible shape, lots of rot, termite damage, etc, and wanted to move windows/doors around a bit. It was far cheaper to replace than fix.
When rebuilding local code wouldn't allow it to be done the same way (because of window sizing we actually had to add steel), but that's OK. They also wouldn't allow it for insulation code (air infiltration), or structural reasons (but they might have allowed it with a different design, don't know for sure). It's a living space, so we are happy with what we ended up with.
Back to the T1-11. It's not just on our house, but the detached garage. It's been problematic. In what ways?
1. Even with the Z flashing it always swells and rots at the bottom (and top) couple of inches. This is because it was installed first, and finished second (I think I have seen articles on FHB about this)
2. For fixing, instead of replacing whole panels, I would just cut off 18" or so, and add Z-flashing. This often meant taking of trim (which was also rotted in the same area). Unfortunately this sometimes damaged the underlying house wrap, so more labor.
3. Anything that I replaced I carefully primed and painted all sides/ends before installation. I'm not paid by the hour so this was easy. If you are doing a fresh install definitely prime the ends and at least a few inches up the back side. My preference is to do the first color coat before installation for visual appeal. YMMV.
4. Perhaps not a big problem for a shop, but a big problem for a house: Every time the wind blew outside, it blew inside as well. Air leaks bigly around the ship lap joints.
5. Weather tight details around windows and door is more difficult because of the grooves in the T1-11. There are ways to deal with that at installation time, but it adds effort and cost. Shortcuts cause problems in a surprisingly short time.
When I built a large shed (nothing compared to what you are doing, only around 200 ft), I did it all traditionally, and then put up Hardiplank T1-11 equivalent 4x8 sheets. It was quick (although it is brittle, so be careful when nailing and handling), and it took paint so well! It matches the house and garage nicely, and was far less effort to finish then traditional T1-11 was. If paying someone to paint it would have reduced the cost of Hardiplank sheets substantially.
Thanks so very much for all the info!!!!!!!!!!
I looked at a lot of "rotten" T1-11 houses.
As you said, all seem to loose the bottom 12"
I am looking at using something similar to what you used ... LP SmartSide. It has a 50 year (well pro rated) warranty. It is pre primed.
I am letting the sheets overhang the block on the bottom by 1" ... and there is about a 1/2" gap behind this before it touches the block.
I am hoping this lets it dry so there should be less rot.
I don't know if I will have time but my plan is to paint the bottom edge (front and back) before they stand up the walls.
I am also thinking about caulking between the sheets while they go up.
I know it is not the "right" way to build a shell .... but as per usual, limited by my pocket book and my imagination.
I am 57 ... so lets say I have a good 30 year left (87). I usually try building things so they stay up forever .... maybe for ever will only be 30 years?
Thanks so much again !!!!!!!!!!!!!!
Mike
Don't you guys use sheathing paper under siding. Tyvek works well too.
Having installed pine T1-11 on dozens of homes I have to say I wouldn't use it on my own home if it were free. As others have mentioned it's a maintenance nightmare, it rots, always. I've painted both sides and bottom edges, caulked joints, sealed around Z flashings and it still rots. Possibly if you primed and painted all surfaces of every sheet, did a careful installation and made sure you caulked well it might last, however, I wouldn't bet on it.
What I have done, including on our own home and for many customers is to cut the bottom edge up anywhere from 3 1/2 to 11 inches up from the ground, install aluminum or SS Z flashing and fill the gap with 1 X Pvc trim. I think it looks good and if you paint the bottom edge of the T1-11 and gap it off the Z flashing it doesn't rot. Also, don't seal the gap with caulk, the whole idea is to leave an air gap so the bottom edge doesn't sit in water.
Just a couple of comments, mostly concerning getting the shear value out of the T1-11:
You said 16' high walls. You didn't say (or I missed) what local wind and earthquake concerns are. Here in the Puget Sound region of the Northwest, we are very concerned about earthquakes and depending on the location, also concerned about wind loads. The engineers that I have worked with over the years would be concerned about the nailing of the T1-11 to the bottom plate and most likely require horizontal blocking or more between the lower 8' sheets and upper 8' sheets of sheathing/siding (T1-11). Also, they would likely be very concerned about putting just z flashing between a narrow band of siding and whatever is above it. And 16' tall walls would almost for sure require more and wider studs than 2x4 at 16" o.c.
But I'm not that structural engineer - I have just been corrected by them often over the last 40 years, as an architect..
Here in Vermont ... very little worry of earthquake.
Wind is another question. I am at the base of a ski mountain. I watched an outhouse be blown over twice while building the house ... I think the person on the next road said they recorded a gust of 73 mph a few years back.
I am planning to put up blocking between the tow sheets.
From what I can tell ... and I have "bounced" the design off an engineer ... 2 x 6 at 16" centers with center blocking should be fine.
***** and after all this, a new problem ......
So, I called LP today .. they are discontinuing the non structural product.
So, if I am going to pay $60 a sheet for structural T1-11 then maybe other items will be in the same price range.
Price is even more a problem it the siding material has now gone up by %50 .
I see LP (and Hardie) both offer lap siding that can be put directly onto studs according to their product catalog.
LP suggests I can use a 16" x 16 ft piece of their siding vertically installed to make board and batten.
Nice thing about this ... no z trim in the middle ... one long piece.
I like that ... I can nail the heck out of it since they will all be covered.
No sure what I would use for the battens ???????
OK ... I am open to any and all suggestions again. If T1-11 has a lot of issues, any other product in the same price range I should look at?
Mike
Vinyl siding will probably be your cheapest option. Will have to install sheathing beforehand though. You will be sheathing the walls, but will save time and $ by not needing to caulk and paint.
You can do structural corrugated steel as well, but that is a lot different look.
I am a rural area ... no building inspection (only septic) but they do frown on building that don't "fit it".
I did the house exactly that way .... sheeting and vinyl siding.
I am wondering now it I go with the LP SmartSide as a board and batten look.
They offer a 16" x 16' ... this would be easy to put up ... then just put a ??? batten over each joint.
I do know there would be more maintenance in the long run ... but I think the end product will look better and be a lot more durable than vinyl.
Hmmmmmm ..... ideas ... ideas ... ideas ...
You have to be careful using the composite siding in high moisture areas. It can swell up and fail it it is not carefully painted and caulked
t1-11 or apa 303 sheathing can be used for structural sheathing. but there are restrictions. The minimum thickness must be the same as the specified rated sheathing. 2. Since it has a ship lap vertical joint the nailing must go into the full thickness. This means that you will need a 3x stud at every joint so that you can maintain the 3/8" edge distance for nails. alternatively, you can use a doubled 2x nailed every 16" vertically w 16 common nails. Of course I am referring to apa rated plywood sheathing. The composite sheathing does not have any structural rating. Many times plywood stamped not for structural use are actually panels that have been rejected for one reason or another. One last thing Is this a permitted structure? if so what is the requirement for lateral bracing on the approved plans. 16' hi walls are quite a wind load. Anyway, it is legal to use per Uniform Building Code. Look in the sheathing and nailing tables in chapter 5. For a simple box A rated t 1-11 sheathing blocked at horizontal joint sand as I specified should be sufficient except for seismic zone 4.