But it kept Everton firmly in fourth spot in the Barclays Premier League and sent Reading into the bottom three after a desperate run of seven successive defeats.
Moyes' side head off for their UEFA Cup tie in Norway on Wednesday against Brann Bergen in high spirits.
He said: "It was a plain ugly win, but there were times that we played well. I told the lads they had to do better, but on a very difficult pitch we got the result we needed.
"But give credit to Reading, they did well and could have got something.
"But I think we deserved the result even if we did not play as well as we could have done.
"I don't think we can catch Chelsea, they are too strong, but we will keep going and we are looking upwards rather than down at teams below us."
Reading boss Steve Coppell accepted that Jagielka's goal was legitimate despite claims for offside.
He said: "The goal was our fault because when we cleared the corner we did not close up properly or get the ball away far enough.
"We did not come out of defence in unison, that was pretty obvious, and it cost us.
"I've seen it now again and it was not offside, but we had plenty of chances ourselves to get something from the game.
"We were not living off scraps, there was plenty of good play and at times we had them on the ropes.
"We were the better side at half-time and we made some really good opportunities. We hit the woodwork and then had a decent shout for a penalty towards the end for handball."