Houlston Manor is an unlisted box-framed farmhouse, which has been substantially altered and updated over the centuries. Originally a single storey building, subsequent owners added a second storey and a new chimney stack and the original timber-framed front wall was replaced with brick. In more recent years the roof has been replaced, the attic insulated and central heating added.
However, despite these modifications, the house was always chilly, the windows rotten and draughty and the southern gable end was letting in wind driven rain through failed pointing.
The owners wanted to replace the windows, insulate the walls and improve the overall appearance of the house.
After deciding on timber casement windows to replace the rotten sashes, the owners opted for a system which combines external wood fibre board as insulation with a lime render as a weather-proofer. This provided a sustainable insulation solution, addressed the problem of deteriorating pointing and helped to improve the aesthetic of the property.
In addition, as Houlston Manor is a solid-walled construction with no damp-proof course, breathable insulation materials were chosen to allow vapour to transfer through the walls to help reduce the risk of condensation.
Wood fibre insulation is available in various thicknesses, and the thicker the insulating layer, the warmer the house will be. At Houlston Manor, the owners opted for 160mm wood fibre insulation boards which were fixed directly onto the brickwork of the property, before being covered with two coats of lime render consisting of a basecoat (with reinforcing fibreglass mesh) and a decorative finishing coat. The house eaves were extended to ensure that the roof had enough overhang once the external insulation board and lime render were added.
As a result of the retrofit, Houlston Manor is now warm, cosy and weather-proof. The owners immediately enjoyed a 59% reduction in energy costs and expected that to improve further as the original brick walls dried out. In addition, with the choice of a classic white render, the house now has a cohesive and streamlined appearance.
Photography: Lime Green Products