So you want to make a door opening into a room. But how do you go about it.
Simple.
A standard door opening in the UK is 916mm clear opening. This allows for a wheel chair to access the property and is a compulsory requirement.
First things first, mark out an opening 916 wide on your sole and head plate ensuring that you keep everything plumb and level. Next mark out the position of your cripple studs, (two number to either side of the opening) and your king stud, (to either side of the cripple studs).
Make a beam 1068 long. Cut two king studs at 2301 long. Cut 4 cripple studs at 2076 long. Now we have the materials to make the door opening.
But first rewind, I can hear you asking. Where did all those figures come from? OK let me explain.
The beam length came from the width of the door opening 916 + the number of cripples 4 x 38 (width of cripple) = 152. So 916 +152 = 1068.
The wall is load bearing and needs to be full height. So we take the full height of the wall 2.453 less the top and bottom plates 152mm to get the height of the stud, which is 2301mm.
Are you with me so far? OK then.
The cripple studs are set to carry the beam, which will be placed into the wall at the top directly under the top plate. The beam depth is 38+ 225 + 38 = 301 mm deep. So to find the length of the cripple we take the height of the wall 2.453 – 76 (depth of the bottom plate) = 2.377 less the depth of the beam 301 = 2076mm for the cripple stud.
Now we can start to put it all together. First nail two cripples together making sure that all edges are flush together. It is best to use a side stitching technique to prevent the nails from penetrating through to the other side. Once you have this done for both sets of cripples nail them to the king stud keep the bottom of the stud and cripples flush and plumb.
Now take your stud and cripple pack and fix it into the wall, once again taking care to keep everything plumb and level. Repeat for the second pack. Once you have these fixed into place and are satisfied they are secure take your beam and fit it into place over the cripples, nailing with a side stitch pattern and face nailing through the king stud to secure the beam in place.
Finally place a cross rail at 2050mm from the finished floor across the door opening to finish the door opening. And that is how to frame a door opening.