Before starting work on any historic roof it is important to carry out an appraisal of its construction and detailing.  This will guide the detailed survey which should be done before or during stripping. 

The appraisal of Penmaen cottage took about 30 minutes

Penmaen appraisal.pdf


The survey will cover all the aspects of the roof identified in the appraisal but will examine the slating or tiling in more detail.  It should also describe the condition of each part of the roof - eaves, ridge, valleys, hips, abutments etc, and explain the cause of any deterioration - whether the roof has performed satisfactorily or if it has deteriorated prematurely because of some inherent defect (see technical investigation below).  For non-expert readers it can include explanations of special slating or tiling methods or detailing and roofing terminology.

The Cwmydwrgi survey took one day.


Technical Investigation

Any roof survey will include some technical assessment but when there is any doubt about the durability of the slates or the suitability of its construction a detailed investigation should be done covering

  1. -its present condition;

  2. -its constructional details or, if it is deteriorated

  3. -at least an estimate of its original constructional details; and

  4. -an explanation of why it has deteriorated or failed.

It can also comment on whether the details were inherently unsuitable and recommend changes for repair or renewal.

Pitchford Church survey >

Recording a roof >


The final step is to assess the roof’s conservation value or importance in a local, regional or national context and to provide an opinion on the effectiveness of the construction - whether it was satisfactory when first constructed or was inherently defective.  If it was defective recommendations on improvements can be made.

The investigation and re-slating of Penmaen Cottage is available in three videos -

Penmaen Cottage videos >

Technical Investigation