Uninsulated Flat Roof

If you don t want to put vinyl backed insulation in your roof what other options are there.

Uninsulated flat roof.

The typical u value of an existing uninsulated flat roof is 1 5w m2k. U value has an inverse relationship to r value. The target should be to achieve a u value of 0 25w m2k or better. The slate is new and the flat roof is good for another 5 7 years.

It should be of the maximum available thickness. Reference table for u values u value is the coefficient of transmission i e the transmission of heat through the materials which compose the building s envelope or outer shell. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. But a preinstalled membrane may be even more effective at removing condensation.

An uninsulated roof has a u value of approximately 2 5 w m2k however adding insulation can achieve a value of 0 18 w m2k. If moisture has nowhere to go it will gather around joists and eventually undermine the insulation. While insulation for a flat roof is expensive and can account for as much as 25 of the total installation cost there are a number of important benefits to having it in place. The higher the r value the greater the insulation performance.

Flat roofs do not have eaves so there are no soffits holes on the underside to allow air flow. Reduce extreme temperature fluctuations inside your home. Proper ventilation in flat roofs. However in many situations the insulation may need to be primarily or entirely below the flat roof membrane and between the roof joists if so what are the best options.

R value measures how well certain building insulation materials can resist heat. How dr pstop can help the answer is a product called dr pstop which is a felt like material with a rubber backer that can be applied to the back side of metal panels that will trap the moisture as the condensation forms. When you have an un insulated roof you have to live with rather uncomfortable room temperatures inside the home. When determining how much insulation you need don t guesstimate calculate.

It also lets hot air escape in the summer. As a rule any roof with a pitch below 10 is classified as a flat roof. Unvented flat roofs a technical discussion flat roofs have often been built with the insulation all on top of the vapor closed drainage plane as this avoids dew point condensation issues inboard of the roofing. This means that your approach to insulation will differ from a standard pitched roof.

Ventilation is necessary to allow moisture accumulated inside to escape. The type that is right for your flat roof insulation job depends upon the state of the roof expert opinion on the best type and your budget. To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity.