Roof Over A Roof How To Insulate

Currently the built up asphalt roof is installed over homasote or something similar and a roof deck made of wood planks.

Roof over a roof how to insulate.

He plans on replacing the low slope built up roof with an epdm membrane and the question is how to insulate it correctly. When building a roof there is obviously a requirement to meet the building regulations or standards which dictate what the minimum u value is that your roof should meet. There is a requirement when refurbishing a roof to have a minimum u value of 0 18 w m k in england and wales but for a complete re roof in wales the minimum u value required is 0 15 w m k. There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing.

Apply continuous air control membrane to existing roof sheathing or implement continuous air control at roof sheathing. Use 1 5 or 1 75 inch roofing nails. The materials used to insulate under the roof include batts of mineral or glass wool insulation held in place by battens of wood attached to and across the rafters. Also note that a new fully adhered membrane is installed on the original roof deck replacing the one installed 17 years ago is folded down to catch the top edge of the wall water control layer.

Install rigid insulation board in multiple layers with joints offset vertically and horizontally between adjacent layers. Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam. Place the top of each starter shingle firmly against the bottom of the shingle immediately above it and even with the eaves then nail it into place. An advantage of spray foam is it s quick whereas foam board needs to be cut and measured which can be a chore.

In this post we take a look at one method of insulating a curved roof. Eric dymond lives in a 1920s baltimore row house that needs a new roof. There are lots of different ways to insulate this type of roof but one of the best methods calls for the installation of rigid foam insulation above the roof sheathing. Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation.

To insulate the roof itself you either use spray foam or retrofit with it with rigid foam board. Remove existing roofing and non adhered underlayment to expose roof sheathing. It is possible to insulate a curved roof and still provide a high level of thermal performance.