Siding question

[Oljarhead]

I apologize of this has been asked too many times already but I'm a little perplexed by something:

I've always seen siding applied directly over the tyvex on top of the OSB sheeting or just T1-11 nailed to the studs without sheeting.  But I've noticed here that a lot of folks are installing OSB sheeting, Tyvex, then putting in 1x2's and then the siding on top of those.  This would leave a 3/4" gap between the Tyvex and the siding.

Can you tell me why?  I'm curious and am wondering if this is anew technique and/or is used for insulation purposes.

Thanks!
Erik

[MountainDon]

It's called a rainscreen wall. The space is to allow the free drainage of water that may get behind the siding material. In some cases like ScottA's exterior it may make a lot of sense. However, or regular siding (wood, vinyl, Hardie plank), my opinion for what it's worth, is that it is a wate of time and makes window and door flashing and trimming a more difficult task.

Water will not bridge a space larger than 3/8", hence spacing must be 3/8 or greater. It's usually done larger because of the types of available materials.

[MountainDon]

Rain screen walls are actually commonplace in commercial buildings. The fancy looking glass , stone, metal and so on facades on many buildings are cosmetic only. The waterproofing is behind it.

On a cabin or house there is no reason that house wrap or the old standby, tar paper or building felt, along with seal adhesive flashing products like Vycor can not make as weather tight seal. The siding material is then just cosmetic. Properly installed siding like Hardie planl or real wood siding will keep virtually all the water where it belongs, on the outside. Properly installed flashing and building paper leads the water towards the outside.

[Oljarhead]

Thanks Don!

I have to admit I really appreciate your efforts to answer my questions!  Specially becuase of my Libertarian rants! *snicker* -- Thank You.

So, if I wrap the cabin correctly is there any reason to use OSB and then T1-11 other then the added R1 or so?

[MountainDon]

So, if I wrap the cabin correctly is there any reason to use OSB and then T1-11 other then the added R1 or so?

Not sure if we're on the same path here. There are cabins built just using the T1-11 as the one and only sheathing. I actually built my shed using 4x8 Hardie panel cement board as the one and only exterior wall sheathing.

For a cabin you should use OSB or plywood sheathing as the structural layer, then use wrap or good old 'tar paper' to keep the weather out. Flash the windows and doors. Then use a cosmetic siding to make it look better.

You could go ahead and use some kind of panel like T1-11 4x8 sheets over the studs and be done with it. Well, caulk the panel joints and maybe use batter boards over the joints. That would work for a part time cabin MTL, there are houses in my neighborhood that are built like that. I wouldn't want it for my house or even my cabin that I hope to be using or decades to come. We use it full time May through August. It's not the extra small R-value that I'm after. I see the OSB or plywood that's under the wrap as the layer that's giving me rigidity. The finish coat is the eye candy. To my eyes, if a single layer is used there is more chance of structural degradation as it weathers.


How tall are your walls going to be? One advantage to the typical OSB, then wrap and then the cosmetic layer is that you can buy OSB in 9 and 10 oot sheets. On a wall taller that 8 ft you can use the longer sheets to enable the sheathing to drop down over the rim joist and up the wall to perhaps cover the full height. EG: we have a regular 8 foot wall and ceiling height. I bought 4x9 sheets to sheath the exterior. The wall is very strong with the 4x9 sheets nailed to the rim joists and seamless all the way to the top or cap plate.

[Oljarhead]

Good to know!  I plan on 10' walls to give an extra 2' in the loft for the kids sleeping area (we've got 5 of them ranging from 15-21).

So 10' OSB would make sense.

I was planning a simple T1-11 siding with batter boards over the joints.  But this sounds like a good way to go -- would you use 3/8th OSB then the Tyvex and T1-11 or do you think 1/2" is better under this ap?

[MountainDon]

7/16" OSB.  3/8 is fine for making curved surfaces and then it's used in a double layer with the joints between panels offset.

I have a personal preference for #15 building paper/felt or walls over the synthetic products. #30 for the roof. There are pro and con discussions around here but in short under certain conditions the synthetics can trap liquid water behind them. Tar paper will wick it out and get it dry. The synthetics are made to allow water vapor a path through, but not liquid water. Tyvek, Typar, etc are great for a commercial builder... they save time.

T1-11 is an acceptable cosmetic layer. It does tend to soak up the paint or stain a lot more than other products.

[Oljarhead]

Hmmm...T1-11 is cheap and I'm trying to keep my costs down.  What other options are available that aren't too spendy?  I like the old style look you get with T1-11 and batting.

[sharbin]

The use of furring strips will depend on the siding. If you will be installing wood siding (cedar or pine) the supplier would indicate that there has to be furring strips. The reason for that is, in addition to the drainage of water, is to help aerate the back of the wood to keep it from rotting/wrapping. If you are installing vinil siding then there is no need for it if you flash the sides right.

Sharbin

[MushCreek]

I'm planning to put 1" foam outside of my sheathing, then furring, then Hardi plank. The foam is for a thermal break, plus a little more R, and the furring is to fasten the Hardi to without having to go all the way through the foam (and find the studs). Can't think of the name, but there's a company that makes a special vent to put at the bottom of your siding to keep critters out of the drainage plane, while still allowing air flow.

[MountainDon]

Cora-vent or something like like

[sharbin]

The simplest (and cheapest) way is to put an insect screen that you can buy at a local hardware store and just staple it at the bottom of the furring strip (bring it behind and then over). Aluminum would be the best choice as it will resist more critters nibling on it than glass fibre.

[Woodswalker]

Erik,

I used just a layer of T1-11 on my cabin, directly fastened to the studs with lots of deck screws that match in color.  Plan to eventually install 1 x 3 cedar batten boards to cover the joints between sheets.  Extra roof overhang keeps virtually all rain from even hitting the siding.  The exterior veneer of mine is rough-sawn fir.  Stained it with cedar-color penetrating oil stain.  Don is correct about it sucking up lots of stain.  Think mine took about 5 gallons.  Located a lumber yard (in Rochester) that had "shop-grade" T1-11 for about $20/sheet, rather than the $32+ the box stores charge.  Quality is plenty-good for a cabin.  There are a few plugs glued into the surface veneer to replace knot-holes. After staining, these are not really noticeable from more than 10' or so.

My place is 10 miles E of Republic, on a hill overlooking Lake Curlew - not very far from you.  Look forward to watching your progress here.

Steve

[Oljarhead]

Erik,

I used just a layer of T1-11 on my cabin, directly fastened to the studs with lots of deck screws that match in color.  Plan to eventually install 1 x 3 cedar batten boards to cover the joints between sheets.  Extra roof overhang keeps virtually all rain from even hitting the siding.  The exterior veneer of mine is rough-sawn fir.  Stained it with cedar-color penetrating oil stain.  Don is correct about it sucking up lots of stain.  Think mine took about 5 gallons.  Located a lumber yard (in Rochester) that had "shop-grade" T1-11 for about $20/sheet, rather than the $32+ the box stores charge.  Quality is plenty-good for a cabin.  There are a few plugs glued into the surface veneer to replace knot-holes. After staining, these are not really noticeable from more than 10' or so.

My place is 10 miles E of Republic, on a hill overlooking Lake Curlew - not very far from you.  Look forward to watching your progress here.

Steve

Rochester NY?

I've found OSB T1-11 at Home Depot for around $19.87 a sheet and thought of using that with house wrap and good insulation.  Of course, I understand the structural strength additive that sheeting provides but I've also heard it isn't really needed.

So I guess it's a matter of preference.

My question is this:  Did you go with 4" walls or 6" walls?  House wrap or felt?  

Sounds like you are in Ferry county but we're definitely neighbors!

[Woodswalker]

Rochester, WA - about 25 miles S of Olympia.  I was referring to 5/8" T1-11, with rough-sawn fir exterior, and grooves every 4" parallel to the long (8') sides.  I suspect the HD price you mention is for thinner stuff.  Or, perhaps the price has dropped that much due to the economy and housing bust.  I just went with 4" walls, none of which are load-bearing, due to the plans I used.  The 4 x 4 PT foundation posts run up the full height of the wall, and with double 2 x 10 headers between them, carry all of the roof load.  Did not use any house-wrap or tar paper.  The T1-11 sheets are screwed directly to the studs and posts.  The rough framing was done 3 summers ago, and have had no problems.  Insulated walls with 4" fiberglass batts, with kraft paper to the interior.  Haven't tallied up the total costs yet, because I am still working on the interior, but expect it to be under $10K.  Check out my thread on this site for pics and lots of descriptions.

Steve

[Oljarhead]

Rochester, WA - about 25 miles S of Olympia.  I was referring to 5/8" T1-11, with rough-sawn fir exterior, and grooves every 4" parallel to the long (8') sides.  I suspect the HD price you mention is for thinner stuff.  Or, perhaps the price has dropped that much due to the economy and housing bust.  I just went with 4" walls, none of which are load-bearing, due to the plans I used.  The 4 x 4 PT foundation posts run up the full height of the wall, and with double 2 x 10 headers between them, carry all of the roof load.  Did not use any house-wrap or tar paper.  The T1-11 sheets are screwed directly to the studs and posts.  The rough framing was done 3 summers ago, and have had no problems.  Insulated walls with 4" fiberglass batts, with kraft paper to the interior.  Haven't tallied up the total costs yet, because I am still working on the interior, but expect it to be under $10K.  Check out my thread on this site for pics and lots of descriptions.

Steve

Sure thing!  Which thread?

[MountainDon]

Regarding the use of screws for scuring sheathing/T1-11 or whatever to studs...

Screws used like this could have a potential problem. The problem being that most screws have poorer performance than nails in shear strength. Screws have great ull out resistance, but they will break long beore nails will when subjected to a sideways force. This is the reason that screws are not approved for this use by any building codes. Even if one is building without the constaraints of codes it might be advisable to think the shething/siding attachment method through.

Screws cost more than nails. or those who believe in conspiracies about big business imposing building code changes on us for their own benefit this deserves some thought. The screw people simply can not provide a product that meets the shear strengths required, otherwise I'm sure the screw people might be doing that to us.

[Oljarhead]

Regarding the use of screws for scuring sheathing/T1-11 or whatever to studs...

Screws used like this could have a potential problem. The problem being that most screws have poorer performance than nails in shear strength. Screws have great ull out resistance, but they will break long beore nails will when subjected to a sideways force. This is the reason that screws are not approved for this use by any building codes. Even if one is building without the constaraints of codes it might be advisable to think the shething/siding attachment method through.

Screws cost more than nails. or those who believe in conspiracies about big business imposing building code changes on us for their own benefit this deserves some thought. The screw people simply can not provide a product that meets the shear strengths required, otherwise I'm sure the screw people might be doing that to us.

I only use screws for flooring and actually, this time I nailed instead.  Easier then trying to run my drill on the generator and quieter!

But I've not yet thrown out the idea of using T1-11 as siding though I think I'd install it over felt or wrap rather then straight to the studs.

one thing I will say though, is that long before there was wrap/felt houses were built and lasted well  So I'm saying it can't be done, just that I think it's a good idea -- though I'm uncertain when dealing with one sheeting layer rather then two.

Thanks for the reference on the T1-11 by the way.  Though for me it would cost more due to shipping.  I'm out East -- 4 hours or so -- from you.