U-value

It is a measure of a heat loss. Units W/m2K which shows how many watts are lost per square meter of material when the temperature between inside and outside are different even 1K.

To find the U-value, you need to know thickness (m) of the materials and thermal conductivity (lambda).

Firstly, calculate the R-value, thermal resistance, (m2K/W)  by thickness/thermal conductivity:

R = l/lambda

Secondly, you need to add all R-values together, for example, if you are calculating wall U-value, find a sum of brick, cavity, insulation, block R-values.

Rtotal = R1 + R2 +...

Finally, to find U-value, thermal transmittance, (W/m2K), you have to divide 1 from the total R-value.

U = 1/Rtotal


Below is an example of U-value calculation according to my sketch of cavity wall section.

Specification

Every drawing requires annotations and specifications. This is needed to explain drawing's details to someone who will read the drawings. Also, specifications is an important when describing fabrics and its' performance. 

That is some examples of my sketches with annotations and some parts of specification sheet. 

Full fill cavity wall lintel detail

Eaves detail

Partial fill cavity wall sill detail