Why are insulation upstands used when insulating a concrete floor?
Insulation upstands are a key part of correctly insulating concrete floors. This post looks at what they are, as well as why and how they should be used with concrete floor insulation.
What are upstands?
When you are insulating a concrete floor a strip of insulation should be laid vertically around the edge of the room. This vertical strip of insulation is called an upstand. The top of this should be level with the top of the floor screed / concrete that will cover the insulation, and the bottom of it should be level with the bottom of the floor insulation and closely butted up to it, so that it forms a right angle with it.
Why are upstands needed?
Upstands are used to prevent cold bridging at the edge of the floor where it meets the wall. A cold bridge or a thermal bridge is a weak spot in the insulation where heat can be lost. By using upstands this cold bridge can be much reduced or even eliminated, increasing the thermal performance of the floor insulation. Basically, they stop the heat from seeping out of the edges of the floor where the screed / concrete meets the wall. The wall insulation should also overlap the upstand to help prevent this. Upstands are required on floors where a concrete screed will be laid above the insulation. They are not required on floating timber floors as the timber does not offer the same path for heat loss.
To ensure that the upstand prevents the cold bridging from occurring at least 20mm thickness of insulation should be used to form the upstand. The upstand should also overlap the wall insulation, with a minimum of 150mm from the bottom of the wall insulation to top of insulation upstand. The upstand should be tightly fitted to the floor insulation and the wall.
Further details about this can be found in the Structural Quick Guide and for more information on insulating concrete floors, take a look at our blog post on this subject: How to insulate a concrete floor.
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