This calculator was invaluable to me when I came to construct the walls as it very quickly shows where to fix your wall studs to the base and top plates, avoiding having to do almost any calculation yourself, and showing you graphically how things will look and where your OSB panels will be.
Wall framing calculator at Blocklayer.com
It's fairly straightforward to use but will probably need some tinkering from the default settings. These are the typical adjustments I made with a couple of screenshots of my calculations for a straight wall and rake wall further below.
Wall framing calculator menu options
Wall length
Will obviously depend on your build but make sure you enter the correct length, remembering that this is the length of the frame you are constructing and may not be your overall (outside) wall length if it is going to be fitted between the two side walls for example.
Sheet width
Set to 1200. While the thickness of timber sheeting in the UK is measured metrically, in mm, the length and width are still imperial 8'x4'. Therefore the only OSB I could get hold of was 4 feet wide (so 1220mm) so I had to trim it all down by 20mm. It's worth the hassle if you want a 400mm stud spacing, which will also help you out later when you come to fit the plasterboard on the inside, as plasterboard sheets will be 1200mm wide rather than 1220mm...
Studs/sheet
Set to 4 if you want a 400mm spacing.
Stud thickness and Stud Width
I changed these to 46 and 96 respectively, as that's what my 2x4s came in as.
Stud height
If you're constructing a level wall (with the base and top plates parallel to eachother) then this setting doesn't matter. If you're building a rake wall, though, where the top plate will be at an angle and all the studs at different heights, then definitely populate this field, as it then calculates the heights of all the studs for you too. The height you need to input is the lower end of your wall. It might need a bit of playing around with, and do remember that your actual floor to ceiling height isn't just the length of the studs, but also the base plate and top plate, so make sure you've accounted for that before you start cutting your rake wall lengths. You'll see in the example image below, that my rake wall (lowest) height is 2162mm. This is because in my build the low wall height was 2300mm which, when you take off the 46mm base plate and the 46mm x2 double top plate gives you the length of the stud.
Rake angle
My roof and side walls fell at a 1:40 ratio meaning that the roof of about 4m was 10cm higher at the front than the back. This equates to an angle of about 1.43ยบ (just ask google if you have a different ratio) so that's what I input here. Leave this field blank if you're building a straight wall.
Scale
Not really needed but shows you a more representative image if you tick this.
End options
Play around with these if you'd like a visual of what they are. I used the 'Double + Gap' option for my front and back walls, with the 'Single Ends' option for the side rake walls, as you don't want adjoining walls both having double studded ends.
Sheet options
Choose external sheet and it draws a line to show you where your 1200mm sheets will be.
Marking points
Underneath the image generated it shows clearly the measurements you need to mark out for the fixing of your studs to the base plate (and top plate if the wall is straight). I prefer to change these measurements to show 'To Near Side' rather than 'to Centres' as I find it a bit more accurate but this is a personal preference.
Example 1 - my rear wall with double ends
Example 2 - my side rake walls
What about doors and windows?
If you're wondering about windows and doors, I calculated the walls above first of all, and then used these plans to work out where I would put the doors and windows and how big they would be, to minimise on as much additional stud work as possible. Because I was ordering custom sized doors and windows this was fine, but if you are using second hand or fixed size options then you will have to factor that in. Also it's important to stress that windows and doors require many more elements in the wall to support them as well as the broader building (e.g. king studs, jack studs, cripple studs, lintels) so look into that too.
Wall framing calculator at Blocklayer.com
It's fairly straightforward to use but will probably need some tinkering from the default settings. These are the typical adjustments I made with a couple of screenshots of my calculations for a straight wall and rake wall further below.
Wall framing calculator menu options
Wall length
Will obviously depend on your build but make sure you enter the correct length, remembering that this is the length of the frame you are constructing and may not be your overall (outside) wall length if it is going to be fitted between the two side walls for example.
Sheet width
Set to 1200. While the thickness of timber sheeting in the UK is measured metrically, in mm, the length and width are still imperial 8'x4'. Therefore the only OSB I could get hold of was 4 feet wide (so 1220mm) so I had to trim it all down by 20mm. It's worth the hassle if you want a 400mm stud spacing, which will also help you out later when you come to fit the plasterboard on the inside, as plasterboard sheets will be 1200mm wide rather than 1220mm...
Studs/sheet
Set to 4 if you want a 400mm spacing.
Stud thickness and Stud Width
I changed these to 46 and 96 respectively, as that's what my 2x4s came in as.
Stud height
If you're constructing a level wall (with the base and top plates parallel to eachother) then this setting doesn't matter. If you're building a rake wall, though, where the top plate will be at an angle and all the studs at different heights, then definitely populate this field, as it then calculates the heights of all the studs for you too. The height you need to input is the lower end of your wall. It might need a bit of playing around with, and do remember that your actual floor to ceiling height isn't just the length of the studs, but also the base plate and top plate, so make sure you've accounted for that before you start cutting your rake wall lengths. You'll see in the example image below, that my rake wall (lowest) height is 2162mm. This is because in my build the low wall height was 2300mm which, when you take off the 46mm base plate and the 46mm x2 double top plate gives you the length of the stud.
Rake angle
My roof and side walls fell at a 1:40 ratio meaning that the roof of about 4m was 10cm higher at the front than the back. This equates to an angle of about 1.43ยบ (just ask google if you have a different ratio) so that's what I input here. Leave this field blank if you're building a straight wall.
Scale
Not really needed but shows you a more representative image if you tick this.
End options
Play around with these if you'd like a visual of what they are. I used the 'Double + Gap' option for my front and back walls, with the 'Single Ends' option for the side rake walls, as you don't want adjoining walls both having double studded ends.
Sheet options
Choose external sheet and it draws a line to show you where your 1200mm sheets will be.
Marking points
Underneath the image generated it shows clearly the measurements you need to mark out for the fixing of your studs to the base plate (and top plate if the wall is straight). I prefer to change these measurements to show 'To Near Side' rather than 'to Centres' as I find it a bit more accurate but this is a personal preference.
Example 1 - my rear wall with double ends
Example 2 - my side rake walls
What about doors and windows?
If you're wondering about windows and doors, I calculated the walls above first of all, and then used these plans to work out where I would put the doors and windows and how big they would be, to minimise on as much additional stud work as possible. Because I was ordering custom sized doors and windows this was fine, but if you are using second hand or fixed size options then you will have to factor that in. Also it's important to stress that windows and doors require many more elements in the wall to support them as well as the broader building (e.g. king studs, jack studs, cripple studs, lintels) so look into that too.