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Kildonan, South Uist

Kildonan, South Uist

Insulation to walls, roof, windows and doors

Overview

The aim of this project was to demonstrate methods and materials that could be used to upgrade the thermal performance of a building type commonly perceived as being difficult to treat, which were sympathetic to the aesthetic and fabric requirements of the building.

Approach

Existing Fabric

The property examined in this case study is a mass masonry building constructed around 1935, of cement mortared whinstone rubble. It has a pitched slate roof with two dormer windows. The roof space is floored and a coom ceiling has been utilised to allow this space to function as two bedrooms.

Internally the walls are lined with v-groove timber lining which had decayed significantly in some rooms. One gable wall was plastered ‘on the hard’.

The property lies in an exposed rural location where wind and driving rain are a significant factor. The hard impervious stone, combined with the use of cement mortar, means that the walls would likely become damp at various times of the year, and thus the vapour permeability of the upgrade measures and their ability to disperse water vapour would be able to be properly tested in relatively extreme conditions.

Kildonan pre int attic SEC_300X185

Image: Attic space of Kildonan property before retrofit interventions

Improvement measures

Insulation improvements were made to the walls, coom ceiling, windows, floors and the external door. Two insulation products were used on the walls - a wood fibreboard and a calcium silicate board. Wood fibreboard was also used on the ceiling.

A trial double glazed sash and case window was produced locally on the Island, using designs drawn from similar styled and aged properties. Polycarbonate secondary glazing was also used, as in the Wells O' Wearie case study.

Aerogel insulation boards were used in the dormers, the floor and the external door.

Further details of the products used and the installation techniques adopted can be seen in the full case study, which can be downloaded from the top right of this page.

Kildonan post int roof insul SEC_300X185

Image: Plasterboard lining removed to show roof insulation

Kildonan post int attic logger SEC_300X185

Image: Heat flux sensors and data logger installed after retrofit measures had been completed

Performance

The thermal performance of the external walls in both the ground and upper floor rooms was measured, as was the performance of the upper floor ceiling, prior to commencing the work. These measurements were undertaken by Edinburgh Napier University with the results being broadly in line with other testing work carried out for Historic Scotland.

 

The pre- and post- insulation U-values

Building element

Pre-intervention U-value (W/m2K)

Post- intervention U-value (W/m2K)

Measures undertaken

Ground floor, floor

3.9

0.8

Aerogel board

Ground floor, south wall

2.1

1.0

Wood fibreboard

First floor, north wall

2.1

0.4

Calcium silicate board

First floor, coom ceiling

1.6

0.8

100mm wood fibreboard

First floor, dormer cheek

1.7

1.2

Aerogel board

First floor, ceiling

1.9

0.4

    Wood fibreboard

 

 

Lessons

The insulation measures installed in the cottage at Kildonan, South Uist have demonstrated a variety of ways in which the thermal performance of a building of this type can be improved. 

Glasgow Caledonian University conducted a co-heating test to identify the benefits of the retrofit work. The test report can be downloaded on the right.

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