ChatterBank1 min ago
Wood Framed House
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Why can`t this type of house have interior wall insulation pumped through the outer brick walls? TIA.
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Yes, as Albags, I believe this to be associated with breathability.
A modern timberframe house is built of a cavity construction and the 'timberframe' element replaces the inner masonry structure. Over the last 40 years as insulating the building shell has become more of a priority, traditional dual-leaf masonry shells have done this by first changing the brick inner leaf to block, then progressively more insulative block structures (Durox or equivalent) have been developed. As a retrofit to these properties, the 'foam-fill' industry sprung up as a quick win to provide additional insulation to older properties. I first had cavity insulation put into one of these properties in about 1981.
The problem (now) with early timberframe structures is that they were designed around the building standards pertinent at the time. This meant producing a building fabric of a u-value (the measure of heat transmission through the building fabric and lost to the outside) that was at least equivalent to that of a brick or early type of block wall. The timberframe industry could easily do this by putting rockwool batts (fibreglass equivalent) between the timber studwork. As building standards' requirements for thermal performance have enhanced, the industry has adapted the designs by increasing the width of the studwork and/or using better quality insulation between the studs (Celotex rigid foam type).
However the reason why you can't fit the retrofit solution of cavity foam to your house is tied to the design of a timberframe; timber has to breathe or it rots. Those old enough may remember the World in Action? programme in the early 80s that exposed the way that Barrett Homes were misinstalling timberframe structures through the use of polythene sheet on both sides of the studwork. This virtually killed of the development of the industry in the UK for 20 years. A modern timberframe has a polythene sheet attached to the inside, under the plasterboard top surface. So this side is sealed and it prevents warm moisture from the house going through the walls - it rises and goes out through the roofspace. On the outside of the studwork, facing the cavity, is a breathable lining that assures some airflow. This is essential; block it by cavity foam and you run the risk of timber decay.
There may now be solutions being experimented with to ocercome this, to allow retrospective injection of foam to older timberframed structures, but I'm not aware of them.
A modern timberframe house is built of a cavity construction and the 'timberframe' element replaces the inner masonry structure. Over the last 40 years as insulating the building shell has become more of a priority, traditional dual-leaf masonry shells have done this by first changing the brick inner leaf to block, then progressively more insulative block structures (Durox or equivalent) have been developed. As a retrofit to these properties, the 'foam-fill' industry sprung up as a quick win to provide additional insulation to older properties. I first had cavity insulation put into one of these properties in about 1981.
The problem (now) with early timberframe structures is that they were designed around the building standards pertinent at the time. This meant producing a building fabric of a u-value (the measure of heat transmission through the building fabric and lost to the outside) that was at least equivalent to that of a brick or early type of block wall. The timberframe industry could easily do this by putting rockwool batts (fibreglass equivalent) between the timber studwork. As building standards' requirements for thermal performance have enhanced, the industry has adapted the designs by increasing the width of the studwork and/or using better quality insulation between the studs (Celotex rigid foam type).
However the reason why you can't fit the retrofit solution of cavity foam to your house is tied to the design of a timberframe; timber has to breathe or it rots. Those old enough may remember the World in Action? programme in the early 80s that exposed the way that Barrett Homes were misinstalling timberframe structures through the use of polythene sheet on both sides of the studwork. This virtually killed of the development of the industry in the UK for 20 years. A modern timberframe has a polythene sheet attached to the inside, under the plasterboard top surface. So this side is sealed and it prevents warm moisture from the house going through the walls - it rises and goes out through the roofspace. On the outside of the studwork, facing the cavity, is a breathable lining that assures some airflow. This is essential; block it by cavity foam and you run the risk of timber decay.
There may now be solutions being experimented with to ocercome this, to allow retrospective injection of foam to older timberframed structures, but I'm not aware of them.
Yes, B, modern timberframes (not just Barrett's) became unsaleable for a year or two whilst the Agrement Board / Building Research Establishment sought to reassure the industry and customers that, when done properly, timberframe was absolutely fine. Meanwhile all major builders switched back to dual masonry leaves for a decade.
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