FORMULA SHELF
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The arithmetic behind the work: what to measure, what to type in, and what the answer comes out as. Every formula says what the symbols mean and gives a worked example, so you can check it against a job you have already done.
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clean equation with clear symbols. It is a convenience, not an authority:
double-check every result yourself, especially doses, loads, torque and
safety-critical settings.
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Construction
1 formulas
Insulation thickness for a roof or wall
R-value = thickness (mm) / thermal conductivity (W/mK)
SYMBOLS · conductivity: mineral wool 0.04, expanded polystyrene 0.038, PIR board 0.023, cellulose 0.04, and air is 0.025
UNITS · m2K/W
HOW TO USE
For working out how much insulation to buy. Rule of thumb: 100 mm of mineral wool is about R2.5, and a well insulated roof wants R4 or better.
EXAMPLE
150 mm of PIR: 0.150 / 0.023 = 6.5, so R6.5.
insulation
thickness
r value
mineral wool
pir
SOURCES & PROVENANCE
1 listed
This page is an AI-organised index. The label means the grouping and cross-links were compiled with AI; the information itself comes from the public-domain books, reports and manuals listed below. Open any source to read the local copy or follow the link to the original publication.
AI-ORGANISED INDEX
Runchero formula index
index
AI-organised depot index
The index is AI-organised; the linked sources are not.
Formulas collected and indexed with AI. The calculators are convenience tools; double-check every result before using it.