Start the project with a roof area calculator.
Roof surface temperature calculation.
Calculating the surface area of a sloped roof can be time consuming without the right tools.
Your job is to calculate and illustrate the temperature gradient through a roof assembly composed of a gravel surfaced built up roof 3 4 inch thick perlite insulation 2 inch thick polyisocyanurate insulation two ply felt and asphalt membrane vapor retarder 1 2 inch thick gypsum board and metal deck.
An approximate equation for the sol air temperature ts of the outside surface of a given wall or roof is.
1 roof square 100 square feet.
The base width is the distance from one corner of your roof to the other at its base on the short side of your house.
Click on the red button to compute sri and roof surface temperature.
The length l times the height h of a triangle is twice its area a2.
Ambient conditions and reference surface properties specified in next worksheet.
For the calculation of surface temperature and heat flux the roof figure 1 was approximated by three homogeneous layers figure 2.
Once you work through the basic triangle we will review a typical roof and how to apply some simple math to calculate how much material you will need for a roof used in our hypothetical example.
Our roof calculator uses base length and base width to find the estimated area.
7 5 cm of cellular concrete representing the top slab and the topping 2.
7 cm dead air space ventilation and spacer blocks ignored 3.
To compute solar reflectance index sri and roof surface temperature based on solar reflectance r and thermal emittance e using astm standard e 1980.
The rooftop temperature results from two different properties.
Input r and e in blue and green cells.
The following tools estimate the area of a roof as well as the amount of materials necessary to construct a roof of a given area.
The house base area is the area of land that the house covers and for more complex shapes can be estimated using the area calculator.
20 cm of cellular concrete.
Ts to a id is hso a absorption coefficient of outside surface id direct solar radiation on surface.
The ability of the material to reflect the sun s energy back into the atmosphere called solar reflectance and the amount of heat the material rejects instead of absorbs called thermal emittance both are measured on a scale from 0 to 1 with higher scores translating into cooler roofs.
