QGD with Bf4

Hi, I am actually studying the variation of QGD with white playing 5.Bf4 after the theorical moves goes ... O-O 6.e3 My question is: is there any drawback to delay the e3 moves and play 6.h3!? the idea is to avoid the Nh5 attack on the bishop and go back to d2 as the move h3 gives the h2 square to hide the bishop.

What line r u talking about ? d4 d5 c4 e6 nc3 nf6 cxd5 exd5 Bf4 c6 and now instead of e3 h3?

I would assume that is the line he is talking about.

d4 d5 c4 e6 Nc3 Nf6 cxd5 exd5 Bf4 c6

h3 is going to be too slow. Also after Nh5?? there is Qxh5. So e3 stops Nh5.

The lines with Bf4 also don't give a lot to white black can play 6. Bf5 with fairly easy play. Once the light bishops get traded white cant really hope for much.

I suppose you could make a case for 7 Nge2 for white where there is some hope I guess for an advantage but nothing serious. And tbh there I might even prefer black though white should objectively be ever so slightly better. The knight will go to g3

So Nge2 Nbd7 Ng3 Bg6 and its about equal white can I guess also try h4 h5 ideas but it shouldn't amount to anything. The knight on g3 if anything is misplaced.

Ah i think he means different line . Becouse he said theory after is 0-0... So this line : 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 Be7
5. Bf4 O-O and now instead of 6. e3 he wants to play 6. h3 . I checked the database and went over some lines with engine and 6. h3 just gives all opening edge away. So just go 6. e3 and it looks like 6. nh5 isnt that good of a move actually so u dont have to worry about it . If they go 6. Nh5 just go 7. Be5 and if they play f6 just go to g3 and if nxg3 hxg3 u have open file for the rook and black has horrible king- side structure. And if they wanna attack ur bishop again with the knight with 7. Nc6 just 8. cxd5 if 8. Nxe5 u play 9. dxe5 and u r winning a pawn in this line . And if 8. exd5 now 9. h3 if 9. Nxe5 u take 10. dxe5 and make a threath of g4 traping a knight so only move is 10 . g6 and now u take on d5 . And if 9. h3 Be6 for example now u play 10. Bh2 and all of his pieces r missplaced.

There is only one line in which 5...0-0 can follow 5.Bf4 :
1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 Be7 5.Bf4 0-0
(or other move orders like 1.d4 Nf6 2.c4 e6 3.Nf3 d5, 1.Nf3 d5 2.d4 Nf6 3.c4 e6 or 1.c4 e6 2.Nf3 d5 3.d4 etc.)

6.h3 is a move that doesn't achieve much by itself. It doesn't prepare a g4 push or doesn't restrict Black's queen bishop (already restricted by its own pawn on e6). It cannot be used to prepare 7.cxd5 (and keep Black's queen bishop restricted in the event of 7...exd5) because Black will play 7...Nxd5 instead and attack the exposed bishop on f4. As a useful waiting move, 6.h3 is superseded by 6.a3 (much more useful ; a Petrosian Queen's Indian could also reach the same position).

This leaves one possible reason to play 6.h3, namely to safeguard the bishop against Nh5 as is said in the original post. However, this argument is refuted. Indeed, White welcomes 6.e3 Nh5 7.Bg3 Nxg3 8.hxg3 (or 7.Be5 f6 8.Bg3 Nxg3 9.hxg3) because it opens the h-file for an attack against Black's castled king. White will play Qd2 and a timely 0-0-0.

That's why 6.h3 would be a weak move, prophylactic against something that is actually in White's favour. If your opponent wants to go wrong, let him.

6 h3 has been played, but 6 e3 is stronger as it helps to develop Bf1. Example:

Thanks guys, I found it very useful.
The line was of course 1.d4 d5 2. c4 e6 3. Nc3 Nf6 4.Nf3 Be7 5.Bf4