A question came up on a recent party wall job which led to an interesting debate on what the section 11(11) expenses should cover when one owner re-builds a party fence wall as a party wall and the other owner later makes use of it.

Section 11(11) of the Act states that:

Where use is subsequently made by the adjoining owner of work carried out solely at the expense of the building owner the adjoining owner shall pay a due proportion of the expenses incurred by the building owner in carrying out that work; and for this purpose he shall be taken to have incurred expenses calculated by reference to what the cost of the work would be if it were carried out at the time when that subsequent use is made.

It normally falls to the appointed surveyors to agree what is covered before going on to calculate the cost of the works at current rates.

The award that we were agreeing related to a single storey rear extension to a terraced house in Fulham. Approximately 5 years previously the adjoining owner had built a similar extension and as part of that work had demolished a 1500mm high brick shared boundary wall and re-built it as a Building Regulation compliant cavity wall also astride the boundary i.e. a party wall.

Being a party wall it was available for the current building owner to use as party of their proposed extension. As adjoining owner’s surveyor I discussed 3 possible options with the building owner’s surveyor.

That the section 11(11) costs be based upon the cost of constructing:

• The whole wall that is being enclosed upon including the foundation.
• The whole wall but not the foundations.
• The whole wall minus the area of the original party fence wall.

I argued the case for Option 1 but the building owner’s surveyor maintained that he’d agreed many similar awards on the basis of Option 3 over the years.

After an extended phone call (all good natured I should add!) we agreed to put the question to the selected Third Surveyor for an informal opinion.

His opinion was ‘I would tend to go with 3. It could include allowance for the better foundations if appropriate’.

As it was an informal opinion we didn’t get any further explanation but I took ‘better foundations’ to mean new foundations (as that’s what were constructed) whereas the building owner’s surveyor took it to mean a 60% contribution (as the original foundations, which were grubbed out, were 400mm deep and the new foundations were 1000mm deep).

In the end we agreed that the section 11(11) expenses should cover the new wall minus the area of the original party fence wall but including the whole of the new foundation. It still didn’t seem logical to me but having had an informal opinion from the Third Surveyor there was little point in risking a formal referral on the same point.

I later put the question to an expert legal panel made up of 2 specialist property barristers and 1 specialist property solicitor at one of our local party wall forum meetings and they were unanimous that option 1 should have been adopted. Which just goes to show that even when you’re sure you’re right you have to compromise when you’re outnumbered.

Should you require advice on a party wall matter you are welcome to contact us via email or on 020 7183 2578.