Header Plate or Door Frame

[Skavenger]

Hi;

I am building a workshop in my garden which needs to look sh** hot. I have an Irish Oak UPVC window already fitted and the wife wants me to fit a solid oak door (From Wickes) rather than a second hand one or DIY.

My external opening is 910 x 2130mm on top is a wall plate (on top of which are the roof joists) and either side at the base is a 3 course single skin block wall on top of which is a 3 x 2 timber frame. So no trimmers or header.
Here is the pic of the inside:

The door we have found is a Wickes London External Oak Veneer Door 4 Panel (2032mm x 813mm) and the frame is a Wickes Premium Hardwood Door Frame with external dimensions of 2118 x 901mm. Whilst the frame will fit the opening it will not provide enough space for a header plate or trimmers.
Can I fit this door frame without a header under the wall plate or trimmer studs either side?

It states that there are 3 sizes of this door (1981mm x 838mm & 1981mm x 768mm) but I cannot find the 768mm version on their site and the frame for the 1981mm x 838mm is 2067mm x 926mm which is too wide for my opening.

Do I need to fit trimmers either side of the opening and a header and then also fit a door frame? If so I will need to make a custom door. I could re-do the timber frame either side of the door opening and double up the vertical studs and reduce the area that you can see with insulation in it but I will only be able to fit the 768mm door due to the lower half being blocks?

 

[Jadele]

I would just double the thickness of the existing sides by removing some insulation and screwing in some extra support. The header is there to pass the overhead loads to the trimmers to the floor and seeing as it looks like there won't be much weight above I can't see you will have an issue just screwing the frame straight in. You could screw some flat bar on the inside across the opening to give it extra strength and try to prevent any bending over time which may cause binding on the top edge of the door and frame but I doubt that will happen unless a lot of weight will be over the opening.

 

[Doggit]

So what is the size of the opening; that will give us a better idea. As well as getting a smaller door, you can also cut the height down, and then cut the size of the frame to match. Rememebr that you want to fit the frame from behind so that you don't have any screws in the frame itself.

 

[Skavenger]

I bought a Framed Ledge and Brace door and a Pre Built frame from Jewsons. The door opening is 213 x 91 as stated in the first post.

To get the frame to fit I have cut some 35 x 220 timber in half down the centre and have been planing it to fit snug either side so the door frame is now lined along its entire length and the header will sit on this so I don't think I will need to add any additional trimmer timbers on the inside but once its in I'll take some photos and check back.

 

[Jadele]

I think it will be fine, its only a shed doesn't have to be perfect