上（に）on top of that
You make one point and stack a second on top that pushes the same way: good with good, or bad with bad. It is その上 or それに done inside one sentence.
good on good
This hotel is close to the station, and on top of that, the rooms are spacious.
bad on bad
On top of getting lost, I even lost my wallet.
How to form it
Plain form + 上（に）
近い上に, 迷った上に, 取れない上に. A な-adjective takes な and a noun の, or either takes である: 複雑な上に, 休日の上に, 医師である上に. The に can drop, mostly in writing.
Which 上?
The word before 上 and the kana after it tell you which one you have, and how to read it.
"After doing, and on that basis".
Please check the contents, and then sign.
Dictionary form or noun + の + 上でN2
"In doing, for the purposes of".
the things you need for daily life
Plain form + 上（に）N2This page
"On top of that": a second point of the same kind.
This place is cheap, and on top of that, the food is good.
"Now that", then what you are bound to do. Stiff.
Now that I have taken it on, I will see it through.
Noun + 上N2
Straight after the noun, read じょう: "in terms of".
legally; health reasons; given your position
In use
Both points are about the same person, place or situation. The second usually has も, or まで for the last straw. You hear it in conversation and read it in reviews and the news.
He has a lot of experience, and on top of that, he explains things clearly.
It is raining today, and the wind is strong as well, so the match has been postponed.
You can't get a reservation, and they don't sell tickets on the day either.
Two things to know
Both points push the same way
A good point and a bad one don't add up.
Sounds odd: この
This apartment is big, and on top of that, it's far from the station.
広いが、駅から遠い.
It adds a fact, not a next step
After a た-form it still means "and on top of that". A step you take first, with a request or a decision after it, is 上で.
Not said: 資料を
(Please read the handout and then ask your questions.)
読んだ上で.
Close neighbours
しN4
Piles up reasons inside one sentence. Lighter, for conversation.
It's raining, and it's windy too, so I'm not going out today.
に加えてN2
"In addition to", after a noun. It simply adds one thing to another. For writing and careful speech.
In addition to rising labor costs, shortages of raw materials have also become a problem.
Check yourself
1Which one fits?
この
Choose an answer to see why.
2Which one fits?
先生と
Choose an answer to see why.
More sentences
The new system is complicated to operate, and on top of that, it runs slowly.
This area has good transport links, and the rent is fairly low as well.
She is a doctor, and she also knows a lot about local public health work.
The food at this restaurant is delicious, and the staff are attentive as well.
These shoes are light and, on top of that, stand up to rain.