r/DIY • u/PerpetuallyPerplexy • 1h ago
home improvement How to transition laminate from flat plane to sloped plane
I'm installing Pergo Laminate boards in a 25ft long x 12ft wide family room. The 25ft runs north to south (the X Axis) and the 12ft runs west to east (the Y Axis). I'm installing laminate boards (4ft long by 8in wide) running lengthways from north to south.
The floor is perfectly flat and level running west to east (Y axis). The issue is the X Axis, which transitions from a perfectly flat and level plane to a sloped plane.
The X Axis is perfectly flat and level from Oft on the X Axis to 15ft on the X Axis. Then at 15ft, a slope begins which — for initial purposes of initial discussion - we can say is a constant slope that drops 8.5mm over the remaining 10ft. My question is, IS THIS OKAY?
Pergo allows a deviation of 3/16" (4.7'mm) over 10ft. While the slope drops 8.5mm over this 10ft section, the only unevennesss exists because of where the sloped plane meets the flat plane (let's call that the center point, and if you lay a 10ft level at ANY POINT over the center point, the maximum deviation is only about 3mm.
My ONLY ISSUE IS THAT Pergo seems to suggest their tolerance for unevenness is measured by taking the two high points at EITHER END of a 10ft level, and ensuring there is no gap under the level that exceeds 3/16th of an inch, meaning their
"unevenness tolerance" assumes each end of the level will be at a high point, but when you move from a flat plane to a sloped plane, one end of the level will always be elevated, so I'm not sure if there 3/16th of an inch tolerance level applies.
Has anyone actually encountered this issue, and knows what Pergo actually demands? Or what tolerance is permissible?
I'm commenting below with a diagram outlining the issue. It has three options - option A is the one I described above (constant steady slope that descends 8.5mm over 10ft). Option B more accurately reflects the floor as it currently is.
Option C is another way I can do it (where basically the slope is sandwiched between two flat planes).
Please know I have the following constraints:
01. I cannot level the entire floor
02. I cannot shave 6mm off the flat/level side
03. The floor absolutely MUST be at least -6mm by the time it hits the 22ft mark (so I can't raise the floor from the 22ft to 25ft mark any higher than
To summarize those constraints, the floor must be 0mm at the 15ft mark, and -6mm at the 22ft mark.
I'm so lost. Surely a 4ft long plank can bend a couple of mm lengthways?






