Joining 4x2 and 100mm joists

[vice]

Hi. Hope a few of you might be able to help me. I've had to remove three quarters of a floor built with 4x2 joists, including the joists. There are several dwarf wall across the span and I've removed the floor and joists up to one wall. I intend to joist up some 4x2 joists to match but joists are now 47x100 (95-97mm really).

So..since my new joists aren't as high as the old ones. Is it better to sit the new ones on the dwarf wall and pad up on the top with some very thin wood? or raise the new joists up so that the tops line up with the old ones using wood/cement? I'm bolting together with 3 M10 coach screws anyway.

One - on the top of the drawf wall the joists sit on wooden caps. I've set these in cement but they aren't stuck and can in fact move a bit. I'm presuming that doesn't matter since gravity tends to stay in the same direction. Correct? Or should I try and stick the joist on better? bitumen? PVA?

Thanks in advance for any help

 

[gregers]

if cost is not a problem,then remove all the floor and rebed new wall plates down to the correct height that you require,or leave whats left and pack under new joists with dpc/slate/packers etc to original height

 

[vice]

thanks gregers. I've actually just finished rebuilding it all with a few new walls and wooden caps/(plates?) on them. the DPC is a good idea. I only need a couple of mm max.
What do you think would be the best way to attach dpc? staple gun? or is there a special adhesive.
Cheers

 

[r896neo]

just set it under them, its not going to go anywhere?