Re: Re: Extensions and existsing septic Tank/Percolation Home › Forums › Ireland › Extensions and existsing septic Tank/Percolation › Re: Re: Extensions and existsing septic Tank/Percolation August 12, 2006 at 12:26 am #782876 AnonymousInactive @Fairfield wrote: Exempt extensions can only be 40 sq m in total so you can only build an additional 22 sq m. Engineer is mixing up enforcement issues with exempted development and is thus incorrect. Agree Latest News