Submitted by SloightlyOnTheHuh t3_zwegbg in DIY

I'm fitting bifold doors between the living room and hall. The current aperture is 1730mm and the required aperture is 1683mm. I've worked out a plan to frame the aperture to about that size BUT the door frame has a width of 1673 mm. Can anyone explain why I need to plan for a 5 mm gap each side. Would it be better to make the aperture nearer the size of the frame to minimise shimming?

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oOorolo t1_j1u5r0u wrote

It's so shims can be inserted to make sure the door frame is vertical and plumb. Rough openings are exactly that, rough openings, and are rarely perfectly square and plumb. The gap and shims give you room to adjust it so your doorway is square

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SloightlyOnTheHuh OP t1_j1u62cv wrote

Cool, so if I frame the rough aperture fairly square can I slim down that 5 mm each side because I know I'll have removed most of the error in the outer framing? I'll only have minimal tweaking to do I hope.

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oOorolo t1_j1u6vz9 wrote

You can, but the idea of having a minimum 1/4 inch or 5mm is pretty standard practice, so you can insert 2 wedge shims, one per side to square your frame. Leaving a smaller gap leaves less room for shims and my result in a twisted frame if only 1 shim can be inserted.

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muckpucker t1_j1ukac1 wrote

If you are concerned about the visual gaps on either side, you can add trim pieces that extend past the gap, similar to door casing, except it fits to the inside of the jamb, not the outside.

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SloightlyOnTheHuh OP t1_j1w528w wrote

Thanks, I'll go look at door a lot to see how they are trimmed. I can always learn by inspecting other peoples work

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skydiver1958 t1_j1x4ydh wrote

One rule off rough framing. Bigger is better. It's easier to add then subtract.

Eg: When I frame a door opening for say a 30 inch x 80 inch door the RSO (rough stud opening) is 2 1/2 wider and 2 1/2 inches higher. This gives you room to shim your door jambs perfect.

The number one fails I see of DIY is trying to frame RSO tight. Not how it's done.

Now bi folds can be a little tricky. Follow the instructions for your finished opening but the concept is the same

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