Hi there we are wanting to lay a new sod lawn and was wondering if it is ok to till old lawn in.
If the reason that you are replacing the lawn is because it has become overgrown with perennial weeds such as dandelions and creeping Charlie than it would be best to remove the weeds first. If necessary use a sod cutter to remove what is left of the old lawn rather than tilling. Next consider amending the soil with organic matter such as compost before you put down new sod so that you will get the new sod off to a good start.
You may also find the following links helpful:
Good luck with your new lawn.