replying to geraldthehamster, Peter G wrote:
You need to have tapered board to do a proper join. Any doubts just go to
www.british-gypsum.com and look at their instructions. fill the tapered valley
with jointing paper and compound. Let dry. Sand smooth if not skimming and
seal and undercoat. Skim if desired; but even they say skimming is an option
these days, not a necessity.

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