PARTY WALL etc. ACT 1996
12. Security for expenses
(1) An adjoining owner may serve a notice requiring the building owner before he begins any work in the exercise of the rights conferred by this Act to give such security as may be agreed between the owners or in the event of dispute determined in accordance with section 10.
(2) Where —
(a) in the exercise of the rights conferred by this Act an adjoining owner requires the building owner to carry out any work the expenses of which are to be defrayed in whole or in part by the adjoining owner; or
(b) an adjoining owner serves a notice on the building owner under subsection (1),
the building owner may before beginning the work to which the requirement or notice relates serve a notice on the adjoining owner requiring him to give such security as may be agreed between the owners or in the event of dispute determined in accordance with section 10.
(3) If within the period of one month beginning with —
(a) the day on which a notice is served under subsection (2); or
(b) in the event of dispute, the date of the determination by the surveyor or surveyors, the adjoining owner does not comply with the notice or the determination, the requirement or notice by him to which the building owner’s notice under that subsection relates shall cease to have effect.
13. Account for work carried out
(1) Within the period of two months beginning with the day of the completion of any work executed by a building owner of which the expenses are to be wholly or partially defrayed by an adjoining owner in accordance with section 11 the building owner shall serve on the adjoining owner an account in writing showing —
(a) particulars and expenses of the work; and
(b) any deductions to which the adjoining owner or any other person is entitled in respect of old materials or otherwise;
and in preparing the account the work shall be estimated and valued at fair average rates and prices according to the nature of the work, the locality and the cost of labour and materials prevailing at the time when the work is executed.
(2) Within the period of one month beginning with the day of service of the said account the adjoining owner may serve on the building owner a notice stating any objection he may have thereto and thereupon a dispute shall be deemed to have arisen between the parties.
(3) If within that period of one month the adjoining owner does not serve notice under subsection (2) he shall be deemed to have no objection to the account.
14. Settlement of account
(1) All expenses to be defrayed by an adjoining owner in accordance with an account served under section 13 shall be paid by the adjoining owner.
(2) Until an adjoining owner pays to the building owner such expenses as aforesaid the property in any works executed under this Act to which the expenses relate shall be vested solely in the building owner.