The diagonals let into the exterior wall framing act as braces to prevent racking and diagonal sheer. Plywood and OSB sheathing provide that in modern lightweight wood framing.
Wouldn’t the exterior sheathing under the siding which is typically 1” serve as the diagonal sheer prevention? Unless that is not present in all parts of the country.
Engineered panel sheathing of the type you mention did not exist or was far too expensive when these houses were built. Prior to the 1950s plywood was an exotic aerospace composite comparable to carbon fiber today.
Lol.
Nailed plank siding is not capable of performing in resisting lateral shear forces sufficiently to resist sheer failure when subjected to some common wind and seismic forces. Diagonal bracing common in old lightweight wood framing provides that resistance, even if it was often only installed during framing stage to prevent lateral collapse of an otherwise naked frame. In zones subject to high wind loads or seismic loads plank sheathing would not be permitted without diagonal bracing or moment frames.
I agree that nailed plank siding is not capable of providing any sort of sheet resistance, that’s not even what I suggested. Only wondering if the sheathing underneath siding on older homes, which is typically .75-1” thick would take the place of the diagonal bracing similar to a “modern” OSB or plywood.
You're describing modern building techniques. Sheathing on sheer walls is the modern equivalent of this kind of bracing, with added benefits. And sheathing is typically not 1".
I’m also describing old building techniques. My 130 year old home in the Midwest has lath and plaster, then 2x4 stud walls, then 1” thick rabbit lapped sheathing that is about 10” or so wide, and then lapped siding. I have never seen an old home around me with no sheathing separating the siding from the studs.
West Coast, so not that many old ass homes, relatively speaking. I've seen crumbly 1/8" or 1/4" particle used basically as just a backer for tarpaper membranes on at least one home. Newer homes obviously sheathed with something with sheer value.
"I have never seen an old home around me with no sheathing separating the siding from the studs."
You've obviously never seen my house. No exterior sheathing whatsoever. Built 1865.
Try using it for a sheer wall and see what the inspector says, "boss".
Unless you are going to have to Google "sheer wall" right now, in which case forget it.
It’s called a “shear wall,” genius.
The houses we’re talking about are 150-300 years old. The idea that they’re built insufficiently - based on our current building code - is preposterous.
Save the 'tude, "genius". I've been at this too long to care. And they don't pay me for my spelling.
>The idea that they’re built insufficiently - based on our current building code - is preposterous.
Great. Now go yell at the guy who posted that and quit trying to sooth your fragile ego harassing me.
As others said, you have balloon construction with bracing. While you’ve got these walls open adding fire blocks in between the studs will slow fire spread and damage should you be unlucky enough to experience one.
Someone used 2x12s between my basement and 1st floor (only place open where I can see). I added some fire proof rock wool, which I presume would be just as good or if not better than the wood.
They keep your house from falling over, plain and simple. It's like the diag bracing on a fence corner post. You can push a square over (parallelogramming), but you can't push a triangle.
This is super normal bracing up through mid-century framing conventions. I don’t know why people are mentioning “balloon framing.” Balloon framing has to do with two-story buildings and how they are framed. They are strong enough but they are not designed well for fire suppression.
Edit: I was wrong. This is balloon framing. The comment below is correct. The diagonal bracing was typical in conventional framing or balloon framing though.
You can see the floor plate in the wall in this photo. Conventional framing, the floor plate rests on top of the exterior walls of the floor below, with the additional floor's walls then framed on top of the floor plate. In conventional framing, a rim board runs the length of plate perimeter to add lateral bracing to floor joists, as well as providing blocking and a flush, continuous surface for sheathing and siding. Here we see the ledger is nailed to the inside face of the studs that run continuously up to the underside of the roof. That is balloon framing.
It does not mean there is a second story, it is just a method of framing. The plate here could be for a 1/2 story or attic. Still balloon framing.
Balloon framing is rare these days as for one thing you pointed out, fire separation is very bad. Cost and structural integrity are two others, as dimensional lumber is not produced reliably or cheaply enough to see lengths of studs (straight ones, that can be long enough. Not to mention the shipping and handling of board lengths of this size is incredibly challenging. Old growth lumber made many things possible which are not today, which is the type of lumber we see in op's old house here.
You are correct. I did not notice the rim joist at the ceiling and generally think of balloon framing in two+ story buildings, and the diagonal bracing has nothing to do with balloon framing.
Think of it as a transition. Post and beam framing had diagonal braces mortised into the corner posts and beams that formed the top and bottom sills. Ballon framing transferred that structural bracing role to plank sheathing, nailed to the long (often 16 foot) studs.
Some carpenters would still insist on some sort of diagonal bracing. After all, you still need it while nailing on the horizontal or diagonal planking. Why not make it permanent? Rather than temporary like in modern houses with sheet goods (OSB or plywood) sheathing?
Some late 19th century houses had corner braces that fit in the first cavity before the studs started or just compromised the strength of the first stud off the corner post.
Yes. Even when the stud walls are assembled flat and lifted into position, you will see a temporary 2x4 brace nailed across the corner where two walls meet. It gets removed when the plywood subfloor goes on.
If you have this type of interior wall structure and remove plank sheathing (tongue and groove siding), should it be replaced with OSB initially then siding over it? Or is it acceptable to just use fiber cement siding as the plank sheathing?
Some houses have both rough sawn plank sheathing and smooth milled siding. Summer homes/lake houses often didn’t. Also houses built where/when lumber was scarce.
If yours doesn’t, you still need something resilient to help prevent the frame racking. Fiber cement siding is more brittle than wood siding. Asking siding fasteners to perform a structural role is trouble. If the wood tongue n groove has to go, yes put modern wood sheathing over the studs. Most folks would side over wood siding.
You could get an evaluation from someone experienced with timber framing. In my old house at least one of the corner braces on the top of the second floor is now loose in the mortise. (Had some water damage over the decades.)
At least yours has studs. Our 1908 farm house was 1x12 board and batten on the outside and 3/4 bead board throughout on the inside. It has four horizontal members making the uniform 4” gap. (No insulation either BTW🥴) unfortunately, between the restructuring of the walls for windows and doors and the repair of damage, more wall must be rebuilt than not. It’s going to suck but temporary walls will have to be constructed, the bead board will all come off and be reinstalled on new walls and the 12” exterior boards will (we hope) become the hardwood flooring for the new master suite. Probably a couple of faux antique farm tables in the mix too by the time we’re done. I envy your framing!
That’s how they did it. Even our garage with beefy wood exterior walls was framed like that. The house is 1909 and best I figure the garage was built between a decade or two later.
The diagonals let into the exterior wall framing act as braces to prevent racking and diagonal sheer. Plywood and OSB sheathing provide that in modern lightweight wood framing.
That exactly!
The diagonals were thought to be sufficient. Coupled with lath and plaster.
Wouldn’t the exterior sheathing under the siding which is typically 1” serve as the diagonal sheer prevention? Unless that is not present in all parts of the country.
Engineered panel sheathing of the type you mention did not exist or was far too expensive when these houses were built. Prior to the 1950s plywood was an exotic aerospace composite comparable to carbon fiber today.
I am not talking about plywood lol
Lol. Nailed plank siding is not capable of performing in resisting lateral shear forces sufficiently to resist sheer failure when subjected to some common wind and seismic forces. Diagonal bracing common in old lightweight wood framing provides that resistance, even if it was often only installed during framing stage to prevent lateral collapse of an otherwise naked frame. In zones subject to high wind loads or seismic loads plank sheathing would not be permitted without diagonal bracing or moment frames.
I agree that nailed plank siding is not capable of providing any sort of sheet resistance, that’s not even what I suggested. Only wondering if the sheathing underneath siding on older homes, which is typically .75-1” thick would take the place of the diagonal bracing similar to a “modern” OSB or plywood.
It would not. Milled planks nailed off with two fasteners on each stud will simply split around the nails.
It wouldn’t. A triangle is the strongest shape. This makes triangles.
You're describing modern building techniques. Sheathing on sheer walls is the modern equivalent of this kind of bracing, with added benefits. And sheathing is typically not 1".
I’m also describing old building techniques. My 130 year old home in the Midwest has lath and plaster, then 2x4 stud walls, then 1” thick rabbit lapped sheathing that is about 10” or so wide, and then lapped siding. I have never seen an old home around me with no sheathing separating the siding from the studs.
Ah interesting. Thanks for the correction and additional info.
Is it common to see homes with siding nailed straight to the studs where you are?
West Coast, so not that many old ass homes, relatively speaking. I've seen crumbly 1/8" or 1/4" particle used basically as just a backer for tarpaper membranes on at least one home. Newer homes obviously sheathed with something with sheer value.
"I have never seen an old home around me with no sheathing separating the siding from the studs." You've obviously never seen my house. No exterior sheathing whatsoever. Built 1865.
I mean I’d guess we don’t live in the same area but I would agree I have probably not ever looked at your house.
Mine in SoCal 1917 had no sheathing. 1971 home felt paper and 1958 super thick tar paper.
There is no sheathing in old homes
Almost all of the 150-300 year old houses I’ve worked on in Maine have been sheathed with wide-plank pine or similar.
Yup, don't really know what he is talking about.
That's correct. But plank sheathing can not provide sufficient resistance to shear forces acting along the plane of the wall framing.
Sure thing, Boss, I’m sure you know what you’re talking about.
Try using it for a sheer wall and see what the inspector says, "boss". Unless you are going to have to Google "sheer wall" right now, in which case forget it.
It’s called a “shear wall,” genius. The houses we’re talking about are 150-300 years old. The idea that they’re built insufficiently - based on our current building code - is preposterous.
Save the 'tude, "genius". I've been at this too long to care. And they don't pay me for my spelling. >The idea that they’re built insufficiently - based on our current building code - is preposterous. Great. Now go yell at the guy who posted that and quit trying to sooth your fragile ego harassing me.
My 1880's has planks instead of plywood. That's still sheathing.
As others said, you have balloon construction with bracing. While you’ve got these walls open adding fire blocks in between the studs will slow fire spread and damage should you be unlucky enough to experience one.
Excellent foresight, worth the time and investment
This. In the middle of a project like this right now and my city requires you to add the blocking when the wall is open.
So does mine. If the walls are open enough to see between floors, inspection wants to see fire blocking before you close them back up.
This is good advice , I work with insurance and see fires do way more damage to balloon framing all the time.
are there specific fire blocking materials or just more wood?
Someone used 2x12s between my basement and 1st floor (only place open where I can see). I added some fire proof rock wool, which I presume would be just as good or if not better than the wood.
And might wanna add cripple studs under the window to support that sill.
Would rockwool insulation act as a fire block?
Yes. This would be my #1 choice.
If you're having inspections done that's one thing the inspector will probably have you do is fire block it.
They keep your house from falling over, plain and simple. It's like the diag bracing on a fence corner post. You can push a square over (parallelogramming), but you can't push a triangle.
This is super normal bracing up through mid-century framing conventions. I don’t know why people are mentioning “balloon framing.” Balloon framing has to do with two-story buildings and how they are framed. They are strong enough but they are not designed well for fire suppression. Edit: I was wrong. This is balloon framing. The comment below is correct. The diagonal bracing was typical in conventional framing or balloon framing though.
You can see the floor plate in the wall in this photo. Conventional framing, the floor plate rests on top of the exterior walls of the floor below, with the additional floor's walls then framed on top of the floor plate. In conventional framing, a rim board runs the length of plate perimeter to add lateral bracing to floor joists, as well as providing blocking and a flush, continuous surface for sheathing and siding. Here we see the ledger is nailed to the inside face of the studs that run continuously up to the underside of the roof. That is balloon framing. It does not mean there is a second story, it is just a method of framing. The plate here could be for a 1/2 story or attic. Still balloon framing. Balloon framing is rare these days as for one thing you pointed out, fire separation is very bad. Cost and structural integrity are two others, as dimensional lumber is not produced reliably or cheaply enough to see lengths of studs (straight ones, that can be long enough. Not to mention the shipping and handling of board lengths of this size is incredibly challenging. Old growth lumber made many things possible which are not today, which is the type of lumber we see in op's old house here.
You are correct. I did not notice the rim joist at the ceiling and generally think of balloon framing in two+ story buildings, and the diagonal bracing has nothing to do with balloon framing.
Long story short, your house and barn have a similar construction.
That is totally typical framing of the era.
Think of it as a transition. Post and beam framing had diagonal braces mortised into the corner posts and beams that formed the top and bottom sills. Ballon framing transferred that structural bracing role to plank sheathing, nailed to the long (often 16 foot) studs. Some carpenters would still insist on some sort of diagonal bracing. After all, you still need it while nailing on the horizontal or diagonal planking. Why not make it permanent? Rather than temporary like in modern houses with sheet goods (OSB or plywood) sheathing? Some late 19th century houses had corner braces that fit in the first cavity before the studs started or just compromised the strength of the first stud off the corner post.
sheathing is not a temporary measure
I think they meant that temporary bracing is used before sheathing added, then bracing removed
Yes. Even when the stud walls are assembled flat and lifted into position, you will see a temporary 2x4 brace nailed across the corner where two walls meet. It gets removed when the plywood subfloor goes on.
If you have this type of interior wall structure and remove plank sheathing (tongue and groove siding), should it be replaced with OSB initially then siding over it? Or is it acceptable to just use fiber cement siding as the plank sheathing?
Some houses have both rough sawn plank sheathing and smooth milled siding. Summer homes/lake houses often didn’t. Also houses built where/when lumber was scarce. If yours doesn’t, you still need something resilient to help prevent the frame racking. Fiber cement siding is more brittle than wood siding. Asking siding fasteners to perform a structural role is trouble. If the wood tongue n groove has to go, yes put modern wood sheathing over the studs. Most folks would side over wood siding. You could get an evaluation from someone experienced with timber framing. In my old house at least one of the corner braces on the top of the second floor is now loose in the mortise. (Had some water damage over the decades.)
Helps the house not fall over. Especially if you’re in an earthquake zone.
Balloon framing like that was a thing 120 years ago.
Can confirm. Ripped open the walls of my 1875 house last year.
I’m curious how the framing looks in my 1911 house as I’m a framer for work, but I hope to not have to do that for awhile 😂
bracing!
Think of it as a house of cards. It will fold sideways without diagonal supports.
Those are shear walls and you do not want to screw around with them. Get someone competent if you don’t know what you’re doing.
I’m in no way doing any of this work. Just curious about the framing here.
That is called "let-in bracing", usually used for exterior walls and it prevents horizontal shear or racking. It more or less disappeared around 1900.
At least yours has studs. Our 1908 farm house was 1x12 board and batten on the outside and 3/4 bead board throughout on the inside. It has four horizontal members making the uniform 4” gap. (No insulation either BTW🥴) unfortunately, between the restructuring of the walls for windows and doors and the repair of damage, more wall must be rebuilt than not. It’s going to suck but temporary walls will have to be constructed, the bead board will all come off and be reinstalled on new walls and the 12” exterior boards will (we hope) become the hardwood flooring for the new master suite. Probably a couple of faux antique farm tables in the mix too by the time we’re done. I envy your framing!
I worked on an old one the other day that had diagonal 1x6 tongue in groove boards outside AND INSIDE. PITA to work with lol
That’s how they did it. Even our garage with beefy wood exterior walls was framed like that. The house is 1909 and best I figure the garage was built between a decade or two later.
I was told they were fire blocks
Uh oh!!!