Wednesday, 21 March 2012

Week 3 - Gutter design & damaged chimney stack

This is the third week on site already and every week brings along with it new challenges. Water, proved again to be the main culprit and also the chimney stack needed some attention. In addition to this we have expanded our research on the origins of the water furrow and its relevance at the time Oom Paul lived in Pretoria.

This week we came closer to understanding the extent of the water damage and how to remedy it. Close inspection revealed the failure of the ‘modern’ gutter fittings. The 'modern' fittings referred to were presumably fitted in the last renovation of the museum (1950’s). These didn’t have any historic reference to the authentic gutters fitted to the house.

The gutters have pulled away from the timber bargeboard, allowing rainwater to flow between the gutter and the wall. This resulted in decay of the timber and the exposed porous plaster absorbed unnecessary water. A second problem became obvious: the gutters didn’t have adequate fall, allowing water to dam in the gutters. These tiny dams became fertile ground for weeds to grow in, further preventing the free runoff of rain water.

Damming of water in ‘modern’ gutter. Visible damage to timber.

Accumulation of water turns gutters into weed gardens and occasional bird baths.

It was thus decided to remove the ‘modern’ gutters. They will be replaced by new gutters that closely resemble the original gutter design. Reference to the original gutter profiles and fixtures, were derived from selected photographs from the Ditsong archive.

Photo of Kruger House in 1953 

  Photo of Kruger House 1894 depicting 3 ZARP guards and horse.

We incorporated an extra feature to prevent the damaging of rain water: a 50├śmm galvanised steel pipe, fixed at regular intervals with an opening to the bottom of the gutter. This allows excess water to escape should a blockage occur. The gutters will be of 0.8mm sheet metal and produced in lengths of 1.8m (6ft). These specifications closely resemble those of the original gutter. A purpose made gutter bracket, or holder bat, will be manufactured to secure the gutters to the structure.

Drawings of new gutters. – Aphane WIEW Architects + Urban Designers

I will keep everyone up-to-date as the gutters get fitted by the main contractor GDK Construction.

The second item/issue this week is the damaged chimney stack.

The museum has four open hearth fire places which served to keep the house warm during the cold Highveld winters. The flues of the fire places join together in two separate chimney stacks in the roof space. We noticed that one of the stacks is severely damaged. It is unclear what has caused the damage. It could have been anything from weathering through time or being hit by lighting in a storm.

Damaged chimney stack, northern face.

The stack will be demolished down to the roof finish. It will then be rebuilt and the new plaster finish will replicate the original decorative plaster finish.

Interestingly, we discovered a steel ring bolt or bracket on the northern face of the damaged stack. The exact use of the bolt is not clear. We presume it was there to fix a pendant from. Once the stack has been taken down, we hope to get a better idea as to the function of the ring.

Our intention is to place the ring back in its original place on the reconstructed chimney.

Steel ring found on chimney stack.

The story of the water furrow continues from our blog entry on week 2.

A colleague of mine, Ahmed Alkayyali, did research of his own on the origins of Pretoria’s water furrows. He came across some interesting artifacts, more specifically, drawings in the national archive.

The drawings date from 1889 and depict the water system of Pretoria at that time.

Drawing dating from 1889 indicating the water system at the time. – National Archive.

Ahmed’s research led to a graphical representation of a time line connected to the evolution of Pretoria’s water supply. From the drawing one notices the water being channelled from the south at the Fountains Valley,bottom of the drawing, to Church Square depicted by the plus sign in the middle of the drawing. From Church Square the water was channelled through town by connecting furrows. On the right of the drawing the Apies River forms the eastern edge of the central business district (CBD).

Graphical time line of water supply in Pretoria. – Ahmed Alkayyali

To  see more of Ahmed work just follow the link.

Be sure to visit the blog next week to find out what has been happening on site.

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